Prepaid expenses and other assets

129.8

78.1

31.8

36.9

Assets, Current, Total

824.0

718.9

Utility Plant, at Original Cost

Electric

13,094.6

12,128.7

Less-accumulated depreciation

4,880.7

4,828.3

Net utility plant in service

8,213.9

7,300.4

Construction work in progress

307.1

900.0

Nuclear Fuel, Net of Amortization

69.1

79.2

Public Utilities, Property, Plant and Equipment, Net

8,590.1

8,279.6

Investments and Other Assets

Nuclear decommissioning trust fund

193.1

199.0

Regulatory Assets

986.4

1,034.6

Goodwill

169.0

Other Assets, Noncurrent

81.5

74.6

Investments and Other Assets, Total

1,430.0

1,477.2

Collateralized note payable

10,844.1

10,475.7

Current Liabilities

Notes payable

12.0

4.0

190.0

171.0

Commercial paper

139.1

358.3

Current maturities of long-term debt

1.1

15.1

Accounts payable

230.1

388.0

Accrued taxes

118.7

30.4

Accrued interest

58.2

41.3

Accrued compensation and benefits

40.6

35.2

Other Liabilities, Current

2.8

30.7

24.7

Liabilities, Current, Total

823.3

1,070.8

Deferred Credits and Other Liabilities

Asset retirement obligations

1,269.1

1,089.7

Deferred tax credits

125.4

126.0

274.8

195.9

Other Liabilities, Noncurrent

515.1

508.6

Regulatory liabilities

280.1

282.7

82.9

88.9

Liabilities, Noncurrent, Total

2,547.4

2,291.8

Common shareholders' equity

Common Stock, Value, Issued

2,645.0

2,639.3

Retained earnings

1,042.7

967.8

Treasury Stock, Value

(2.6)

(2.3)

Accumulated other comprehensive loss

(14.2)

^[1]

(18.7)

^[1]

Common Shareholders' Equity, Total

3,670.9

3,586.1

Commitments and Contingencies

39.0

Long-term debt

3,763.5

^[2]

3,488.0

^[2]

Total Capitalization

7,473.4

7,113.1

Liabilities and Equity, Total

10,844.1

10,475.7

Preferred Stock 3 Point 80 [Member]

10.0

Preferred Stock 4 Point 50 [Member]

10.0

Preferred Stock 4 Point 20 [Member]

7.0

Preferred Stock 4 Point 35 [Member]

Cash and cash equivalents

12.0

Kansas City Power and Light Company [Member]

Current Assets

2.6

2.7

Funds on deposit

2.2

0.6

Receivables, net

146.8

128.9

Related party receivables

57.0

68.8

Accounts receivable pledged as collateral

110.0

Fuel inventories, at average cost

70.4

58.8

Materials and supplies, at average cost

114.1

110.1

Deferred refueling outage costs

25.3

12.5

Refundable income taxes

57.5

Prepaid expenses and other assets

3.8

5.0

28.5

32.7

Assets, Current, Total

560.7

587.6

Utility Plant, at Original Cost

Electric

9,577.5

8,737.3

Less-accumulated depreciation

3,665.9

3,658.7

Net utility plant in service

5,911.6

5,078.6

Construction work in progress

211.0

791.2

Nuclear Fuel, Net of Amortization

69.1

79.2

Public Utilities, Property, Plant and Equipment, Net

6,191.7

5,949.0

Investments and Other Assets

Nuclear decommissioning trust fund

193.1

199.0

Regulatory Assets

734.9

745.7

Other Assets, Noncurrent

32.0

29.5

Investments and Other Assets, Total

960.0

974.2

Collateralized note payable

7,712.4

7,510.8

Current Liabilities

110.0

Commercial paper

82.1

358.3

Current maturities of long-term debt

14.0

Accounts payable

185.5

305.2

Related party payables

12.6

Accrued taxes

127.8

23.6

Accrued interest

41.3

29.0

Accrued compensation and benefits

40.6

35.2

Other Liabilities, Current

1.5

12.5

12.4

Liabilities, Current, Total

601.3

901.8

Deferred Credits and Other Liabilities

Asset retirement obligations

1,052.5

1,016.9

Deferred tax credits

124.1

124.3

237.5

177.7

Other Liabilities, Noncurrent

492.2

485.4

Regulatory liabilities

161.9

172.0

61.5

59.2

Liabilities, Noncurrent, Total

2,129.7

2,035.5

Common shareholders' equity

Common Stock, Value, Issued

1,563.1

Retained earnings

853.7

726.8

Accumulated other comprehensive loss

(10.9)

(14.9)

Common Shareholders' Equity, Total

2,405.9

2,275.0

Commitments and Contingencies

Long-term debt

2,575.5

^[2]

2,298.5

^[2]

Total Capitalization

4,981.4

4,573.5

Liabilities and Equity, Total

$ 7,712.4

$ 7,510.8

[1]	Net of tax
[2]	Does not include $50.0 million and $21.9 million EIRR Series 2005 bonds because the bonds were repurchased in September 2015 and are held by KCP&L.

Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Utility Plant, at Original Cost
Nuclear fuel, amortization	$ 184.1	$ 187.5
Common shareholder's equity
Common stock - shares authorized (in shares)	250,000,000.0	250,000,000.0
Common stock-shares issued (in shares)	154,464,616.0	154,254,037.0
Treasury stock- shares (in shares)	100,427	91,281
Preferred Stock 3 Point 80 [Member]
Cumulative preferred stock
Cumulative preferred stock par value (in dollars per share)	$ 100.00	$ 100.00
Cumulative preferred stock, Shares issued (in share)	100,000	100,000
Preferred Stock, Dividend Rate, Percentage	3.80%	3.80%
Preferred Stock 4 Point 50 [Member]
Cumulative preferred stock
Cumulative preferred stock par value (in dollars per share)	$ 100.00	$ 100.00
Cumulative preferred stock, Shares issued (in share)	100,000	100,000
Preferred Stock, Dividend Rate, Percentage	4.50%	4.50%
Preferred Stock 4 Point 20 [Member]
Cumulative preferred stock
Cumulative preferred stock par value (in dollars per share)	$ 100.00	$ 100.00
Cumulative preferred stock, Shares issued (in share)	70,000	70,000
Preferred Stock, Dividend Rate, Percentage	4.20%	4.20%
Preferred Stock 4 Point 35 [Member]
Cumulative preferred stock
Cumulative preferred stock par value (in dollars per share)	$ 100.00	$ 100.00
Cumulative preferred stock, Shares issued (in share)	120,000	120,000
Preferred Stock, Dividend Rate, Percentage	4.35%	4.35%
Kansas City Power and Light Company [Member]
Utility Plant, at Original Cost
Nuclear fuel, amortization	$ 184.1	$ 187.5
Common shareholder's equity
Common stock - shares authorized (in shares)	1,000.0	1,000.0
Common stock-shares issued (in shares)	1.0	1.0

Consolidated Statements of Income and Comprehensive Income (USD $)
In Millions, except Per Share data, unless otherwise specified

3 Months Ended

9 Months Ended

Sep. 30, 2015

Sep. 30, 2014

Sep. 30, 2015

Sep. 30, 2014

Operating Revenues

Electric revenues

$ 781.4

$ 782.5

$ 1,939.5

$ 2,016.0

Operating Expenses

Fuel

124.5

142.3

332.0

392.9

Purchased power

52.1

61.2

146.3

185.7

Transmission

23.9

19.3

65.1

55.6

Utility operating and maintenance expenses

182.5

164.1

537.4

528.2

Other Cost and Expense, Operating

82.4

76.6

245.7

226.7

General taxes

58.0

55.8

162.8

159.2

1.3

3.5

2.4

Costs and Expenses, Total

524.7

519.3

1,492.8

1,550.7

Operating Income (Loss)

256.7

263.2

446.7

465.3

Non-operating income

0.9

5.4

9.1

18.8

Non-operating expenses

(1.4)

(2.8)

(8.7)

(9.8)

Interest charges

(51.0)

(43.6)

(148.3)

(141.3)

Income before income tax (expense) benefit and income (loss) from equity investments

205.2

222.2

298.8

333.0

(Income) loss from equity investments, net of income taxes

(78.6)

(74.7)

(109.6)

(109.8)

0.2

(0.1)

0.9

0.1

Preferred stock dividend requirements

126.8

147.4

190.1

223.3

0.4

1.2

Earnings (loss) available for common shareholders

126.4

147.0

188.9

222.1

Average number of basic common shares outstanding (in shares)

154.2

153.9

154.1

153.8

Average number of diluted common shares outstanding (in shares)

154.8

154.3

154.8

154.2

Basic Earnings Per Share

$ 0.82

$ 0.96

$ 1.23

$ 1.44

Diluted earnings per share

$ 0.82

$ 0.95

$ 1.22

$ 1.44

Comprehensive Income

Reclassification to expenses, net of tax

126.8

147.4

190.1

223.3

Other comprehensive income

1.4

1.3

4.2

6.6

Derivative hedging activity, net of tax

1.4

1.3

4.2

6.6

Amortization of net losses included in net periodic benefit costs, net of tax

0.1

0.3

Change in unrecognized pension expense, net of tax

0.1

0.3

Total other comprehensive income (loss)

1.4

4.5

^[1]

6.9

^[1]

Comprehensive income (loss)

128.2

148.8

194.6

230.2

Common Stock, Dividends, Per Share, Declared

$ 0.245

$ 0.23

$ 0.735

$ 0.69

Kansas City Power and Light Company [Member]

Operating Revenues

Electric revenues

526.3

533.4

1,314.1

1,363.9

Operating Expenses

Fuel

89.4

107.2

237.3

289.0

Purchased power

22.9

27.4

73.4

86.8

Transmission

16.2

12.5

42.3

35.1

Utility operating and maintenance expenses

122.9

112.8

365.8

369.1

Other Cost and Expense, Operating

58.7

53.4

175.0

157.7

General taxes

45.4

44.2

125.1

124.6

(1.3)

(0.2)

(1.3)

Costs and Expenses, Total

355.5

356.2

1,018.7

1,061.0

Operating Income (Loss)

170.8

177.2

295.4

302.9

Non-operating income

0.6

4.5

6.3

15.7

Non-operating expenses

(1.8)

(2.8)

(5.7)

(6.4)

Interest charges

(34.8)

(31.1)

(100.4)

(92.8)

Income before income tax (expense) benefit and income (loss) from equity investments

134.8

147.8

195.6

219.4

(50.5)

(53.3)

(68.7)

(72.9)

84.3

94.5

126.9

146.5

Comprehensive Income

Reclassification to expenses, net of tax

84.3

94.5

126.9

146.5

Other comprehensive income

1.3

1.2

4.0

3.9

Derivative hedging activity, net of tax

1.3

1.2

4.0

3.9

Total other comprehensive income (loss)

1.3

1.2

4.0

3.9

Comprehensive income (loss)

$ 85.6

$ 95.7

$ 130.9

$ 150.4

[1]	Net of tax

Consolidated Statements of Cash Flows (USD $)
In Millions, unless otherwise specified

9 Months Ended

Sep. 30, 2015

Sep. 30, 2014

Cash Flows from Operating Activities

Adjustments to reconcile income to net cash from operating activities:

$ 190.1

$ 223.3

Deferred income taxes, net

245.7

226.7

Amortization of:

Nuclear fuel

18.4

18.2

Other

35.3

36.4

110.1

120.3

Investment tax credit amortization

(1.1)

(1.0)

(Income) loss from equity investments, net of income taxes

(0.9)

(0.1)

Other operating activities

9.7

(61.8)

Net cash from operating activities

607.3

562.0

Cash Flows from Investing Activities

Utility capital expenditures

(520.9)

^[1]

(553.3)

Allowance for borrowed funds used during construction

(4.3)

(10.0)

Purchases of nuclear decommissioning trust investments

(35.3)

(21.9)

Proceeds from nuclear decommissioning trust investments

32.8

19.4

Proceeds from sale of transmission assets

37.7

Other investing activities

(34.5)

(16.3)

Net cash from investing activities

(562.2)

(544.4)

Cash Flows from Financing Activities

Issuance of long-term debt

348.8

Issuance fees

(2.6)

Issuance of common stock

2.3

3.7

Repayment of long-term debt

(87.0)

(13.4)

Net change in short-term borrowings

(211.2)

107.8

Net change in collateralized short-term borrowings

19.0

(4.0)

Dividends paid

(114.6)

(107.5)

Other financing activities

(1.8)

(2.0)

Net cash from financing activities

(47.1)

(15.4)

Net Change in Cash and Cash Equivalents

(2.0)

2.2

Cash and Cash Equivalents at Beginning of Year

13.0

10.6

Cash and Cash Equivalents at End of Period

11.0

12.8

Kansas City Power and Light Company [Member]

Cash Flows from Operating Activities

Adjustments to reconcile income to net cash from operating activities:

126.9

146.5

Deferred income taxes, net

175.0

157.7

Amortization of:

Nuclear fuel

18.4

18.2

Other

20.8

22.6

19.8

33.0

Investment tax credit amortization

(0.7)

Other operating activities

103.6

32.4

Net cash from operating activities

463.8

409.7

Cash Flows from Investing Activities

Utility capital expenditures

(410.2)

(455.9)

Allowance for borrowed funds used during construction

(3.0)

(8.6)

Purchases of nuclear decommissioning trust investments

(35.3)

(21.9)

Proceeds from nuclear decommissioning trust investments

32.8

19.4

Proceeds from sale of transmission assets

4.7

Other investing activities

(19.7)

(7.2)

Net cash from investing activities

(435.4)

(469.5)

Cash Flows from Financing Activities

Issuance of long-term debt

348.8

Issuance fees

(2.6)

Repayment of long-term debt

(85.9)

Net change in short-term borrowings

(276.2)

112.4

Net money pool borrowings

(12.6)

(0.2)

Dividends paid

(54.0)

Net cash from financing activities

(28.5)

58.2

Net Change in Cash and Cash Equivalents

(0.1)

(1.6)

Cash and Cash Equivalents at Beginning of Year

2.7

4.0

Cash and Cash Equivalents at End of Period

$ 2.6

$ 2.4

[1]	Capital expenditures reflect year to date amounts for the periods presented.

Consolidated Statements of Common Shareholders' Equity (USD $) In Millions, except Share data, unless otherwise specified	Total	Kansas City Power and Light Company [Member]	Common Stock [Member]	Common Stock [Member] Kansas City Power and Light Company [Member]	Retained Earnings [Member]	Retained Earnings [Member] Kansas City Power and Light Company [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Other Comprehensive Income (Loss) [Member] Kansas City Power and Light Company [Member]
Beginning balance at Dec. 31, 2013			$ 2,631.1	$ 1,563.1	$ 871.4	$ 636.4	$ (2.8)	$ (25.3)	$ (20.2)
Beginning balance, treasury stock (in shares) at Dec. 31, 2013							(129,290)
Beginning balance (in shares) at Dec. 31, 2013			153,995,621	1
Issuance of common stock			5.5
Issuance of common stock (in shares)			214,241
Equity compensation expense, net of forfeitures			0.4
Unearned Compensation [Abstract]
Issuance of restricted common stock			(2.0)
Forfeiture of restricted common stock			0
Compensation expense recognized			1.5
Stockholders' Equity, Other			1.1
Net income (loss)	223.3	146.5			223.3	146.5
Dividends:
Common stock					(106.3)	(54.0)
Preferred stock - at required rates					(1.2)
Performance shares					(0.6)
Treasury shares acquired							(2.2)
Treasury shares acquired (in shares)							(85,062)
Treasury shares reissued							2.6
Treasury shares reissued (in shares)							118,965
Derivative hedging activity, net of tax	6.6	3.9						6.6	3.9
Change in unrecognized pension expense, net of tax	0.3							0.3
Ending balance at Sep. 30, 2014	3,603.4	2,275.7	2,637.6	1,563.1	986.6	728.9	(2.4)	(18.4)	(16.3)
Ending balance (in shares) at Sep. 30, 2014			154,209,862	1
Ending balance, treasury stock (in shares) at Sep. 30, 2014							(95,387)
Beginning balance at Jun. 30, 2014
Unearned Compensation [Abstract]
Net income (loss)	147.4	94.5
Dividends:
Derivative hedging activity, net of tax	1.3	1.2
Change in unrecognized pension expense, net of tax	0.1
Ending balance at Sep. 30, 2014	3,603.4	2,275.7		1,563.1
Ending balance (in shares) at Sep. 30, 2014				1
Beginning balance at Dec. 31, 2014	3,586.1	2,275.0	2,639.3	1,563.1	967.8	726.8	(2.3)	(18.7)	(14.9)
Beginning balance, treasury stock (in shares) at Dec. 31, 2014	(91,281)						(91,281)
Beginning balance (in shares) at Dec. 31, 2014			154,254,037	1
Issuance of common stock			5.5
Issuance of common stock (in shares)			210,579
Equity compensation expense, net of forfeitures			1.4
Unearned Compensation [Abstract]
Issuance of restricted common stock			(2.4)
Forfeiture of restricted common stock			0.4
Compensation expense recognized			1.3
Stockholders' Equity, Other			(0.5)
Net income (loss)	190.1	126.9			190.1	126.9
Dividends:
Common stock					(113.4)	0
Preferred stock - at required rates					(1.2)
Performance shares					(0.6)
Treasury shares acquired							(1.9)
Treasury shares acquired (in shares)							(73,326)
Treasury shares reissued							1.6
Treasury shares reissued (in shares)							64,180
Derivative hedging activity, net of tax	4.2	4.0						4.2	4.0
Change in unrecognized pension expense, net of tax	0.3							0.3
Ending balance at Sep. 30, 2015	3,670.9	2,405.9	2,645.0	1,563.1	1,042.7	853.7	(2.6)	(14.2)	(10.9)
Ending balance (in shares) at Sep. 30, 2015			154,464,616	1
Ending balance, treasury stock (in shares) at Sep. 30, 2015	(100,427)						(100,427)
Beginning balance at Jun. 30, 2015
Unearned Compensation [Abstract]
Net income (loss)	126.8	84.3
Dividends:
Derivative hedging activity, net of tax	1.4	1.3
Change in unrecognized pension expense, net of tax	0
Ending balance at Sep. 30, 2015	$ 3,670.9	$ 2,405.9		$ 1,563.1
Ending balance (in shares) at Sep. 30, 2015				1
Ending balance, treasury stock (in shares) at Sep. 30, 2015	(100,427)

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2015

Accounting Policies [Abstract]

Summary of Significant Accounting Policies [Text Block]

1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Organization

Great Plains Energy, a Missouri corporation incorporated in 2001, is a public utility holding company and does not own or operate any significant assets other than the stock of its subsidiaries. Great Plains Energy's wholly owned direct subsidiaries with significant operations are as follows:


•	KCP&L is an integrated, regulated electric utility that provides electricity to customers primarily in the states of Missouri and Kansas. KCP&L has one active wholly owned subsidiary, Kansas City Power & Light Receivables Company (KCP&L Receivables Company).

•

KCP&L Greater Missouri Operations Company (GMO) is an integrated, regulated electric utility that provides electricity to customers in the state of Missouri. GMO also provides regulated steam service to certain customers in the St. Joseph, Missouri area. GMO has two active wholly owned subsidiaries, GMO Receivables Company and MPS Merchant Services, Inc. (MPS Merchant). MPS Merchant has certain long-term natural gas contracts remaining from its former non-regulated trading operations.

Great Plains Energy also wholly owns GPE Transmission Holding Company, LLC (GPETHC). GPETHC owns 13.5% of Transource Energy, LLC (Transource) with the remaining 86.5% owned by AEP Transmission Holding Company, LLC (AEPTHC), a subsidiary of American Electric Power Company, Inc. GPETHC accounts for its investment in Transource under the equity method. Transource is focused on the development of competitive electric transmission projects.

Each of Great Plains Energy's and KCP&L's consolidated financial statements includes the accounts of their subsidiaries. Intercompany transactions have been eliminated.

Great Plains Energy's sole reportable business segment is electric utility. See Note 19 for additional information.

Basic and Diluted Earnings per Common Share Calculation

To determine basic earnings per common share (EPS), preferred stock dividend requirements are deducted from net income before dividing by the average number of common shares outstanding. The effect of dilutive securities, calculated using the treasury stock method, assumes the issuance of common shares applicable to performance shares and restricted stock.

The following table reconciles Great Plains Energy's basic and diluted EPS.



	Three Months Ended September 30				Year to Date September 30
	2015		2014		2015		2014
Income	(millions, except per share amounts)
Net income	$	126.8	$	147.4	$	190.1	$	223.3
Less: preferred stock dividend requirements	0.4		0.4		1.2		1.2
Earnings available for common shareholders	$	126.4	$	147.0	$	188.9	$	222.1
Common Shares Outstanding
Average number of common shares outstanding	154.2		153.9		154.1		153.8
Add: effect of dilutive securities	0.6		0.4		0.7		0.4
Diluted average number of common shares outstanding	154.8		154.3		154.8		154.2
Basic EPS	$	0.82	$	0.96	$	1.23	$	1.44
Diluted EPS	$	0.82	$	0.95	$	1.22	$	1.44

Anti-dilutive shares excluded from the computation of diluted EPS are detailed in the following table.



	Three Months Ended September 30		Year to Date September 30
	2015	2014	2015	2014
Performance shares	—	108,832	—	108,832
Restricted stock shares	—	73,671	—	71,860

Dividends Declared

In November 2015, Great Plains Energy's Board of Directors (Board) declared a quarterly dividend of $0.2625 per share on Great Plains Energy's common stock. The common dividend is payable December 21, 2015, to shareholders of record as of November 30, 2015. The Board also declared regular dividends on Great Plains Energy's preferred stock, payable March 1, 2016, to shareholders of record as of February 8, 2016.

New Accounting Standards

In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) No. 2014-09, Revenue from Contracts with Customers, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The ASU will replace most existing revenue recognition guidance in Generally Accepted Accounting Principles (GAAP) when it becomes effective. In August 2015, the FASB issued ASU No. 2015-14, deferring the effective date of ASU No. 2014-09 one year, from January 1, 2017, to January 1, 2018. The Companies plan to adopt ASU No. 2014-09 on January 1, 2018. The standard permits the use of either the retrospective or cumulative effect transition method. The Companies are evaluating the effect that ASU No. 2014-09 will have on their consolidated financial statements and related disclosures and have not yet selected a transition method nor have they determined the effect of the standard on their ongoing financial reporting.

In April 2015, the FASB issued ASU No. 2015-03, Simplifying the Presentation of Debt Issuance Costs, which requires that debt issuance costs related to a recognized debt liability be presented on the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. Great Plains Energy and KCP&L currently include debt issuance costs in Other - Investments and Other Assets on their consolidated balance sheets. The new guidance is to be applied retrospectively and is effective for interim and annual periods beginning after December 15, 2015, with early adoption permitted. The Companies intend to early adopt ASU No. 2015-03 for the 2015 Form 10-K.

Supplemental Cash Flow Elements [Abstract]

The entire disclosure for the organization, consolidation and basis of presentation of financial statements disclosure, and significant accounting policies of the reporting entity. May be provided in more than one note to the financial statements, as long as users are provided with an understanding of (1) the significant judgments and assumptions made by an enterprise in determining whether it must consolidate a VIE and/or disclose information about its involvement with a VIE, (2) the nature of restrictions on a consolidated VIE's assets reported by an enterprise in its statement of financial position, including the carrying amounts of such assets, (3) the nature of, and changes in, the risks associated with an enterprise's involvement with the VIE, and (4) how an enterprise's involvement with the VIE affects the enterprise's financial position, financial performance, and cash flows. Describes procedure if disclosures are provided in more than one note to the financial statements.

+ References+ Details

Supplemental Cash Flow Information

9 Months Ended

Sep. 30, 2015

Cash Flow, Supplemental Disclosures [Text Block]

2. SUPPLEMENTAL CASH FLOW INFORMATION



Great Plains Energy Other Operating Activities
Year to Date September 30	2015			2014
Cash flows affected by changes in:	(millions)
Receivables	$	(13.2	)	$	(70.4	)
Accounts receivable pledged as collateral	(19.0		)	4.0
Fuel inventories	(10.8		)	23.3
Materials and supplies	(2.9		)	1.7
Accounts payable	(121.9		)	(75.2		)
Accrued taxes	89.2			91.2
Accrued interest	16.9			11.4
Deferred refueling outage costs	(12.8		)	15.8
Pension and post-retirement benefit obligations	48.8			24.8
Allowance for equity funds used during construction	(3.8		)	(13.2		)
Fuel recovery mechanism	36.6			(21.3		)
Solar rebates paid	(7.3		)	(43.9		)
Other	9.9			(10.0		)
Total other operating activities	$	9.7		$	(61.8	)
Cash paid during the period:
Interest	$	121.2		$	115.6
Income taxes	$	0.2		$	0.1
Non-cash investing activities:
Liabilities accrued for capital expenditures	$	23.4		$	50.5



KCP&L Other Operating Activities
Year to Date September 30	2015			2014
Cash flows affected by changes in:	(millions)
Receivables	$	(6.2	)	$	(70.5	)
Fuel inventories	(11.6		)	18.3
Materials and supplies	(4.0		)	0.5
Accounts payable	(83.1		)	(34.7		)
Accrued taxes	162.3			118.2
Accrued interest	12.3			10.8
Deferred refueling outage costs	(12.8		)	15.8
Pension and post-retirement benefit obligations	48.8			23.6
Allowance for equity funds used during construction	(2.9		)	(12.3		)
Fuel recovery mechanism	1.8			1.4
Solar rebates paid	(6.0		)	(14.8		)
Other	5.0			(23.9		)
Total other operating activities	$	103.6		$	32.4
Cash paid during the period:
Interest	$	79.1		$	72.9
Non-cash investing activities:
Liabilities accrued for capital expenditures	$	15.7		$	44.4

Receivables

9 Months Ended

Sep. 30, 2015

Receivables [Abstract]

Loans Notes Trade And Other Receivables Disclosure And Transfers And Servicing Of Financial Asset [Text Block]

3. RECEIVABLES

Great Plains Energy's and KCP&L's receivables are detailed in the following table.



	September 30				December 31
		2015				2014
Great Plains Energy		(millions)
Customer accounts receivable - billed		$	28.1			$	1.1
Customer accounts receivable - unbilled		81.4				75.3
Allowance for doubtful accounts - customer accounts receivable		(4.1		)		(2.8		)
Other receivables		68.0				86.7
Total		$	173.4			$	160.3
KCP&L
Customer accounts receivable - billed		$	27.6			$	0.6
Customer accounts receivable - unbilled		59.3				49.7
Allowance for doubtful accounts - customer accounts receivable		(1.9		)		(1.2		)
Other receivables		61.8				79.8
Total		$	146.8			$	128.9

Great Plains Energy's and KCP&L's other receivables at September 30, 2015, and December 31, 2014, consisted primarily of receivables from partners in jointly owned electric utility plants and wholesale sales receivables.

Sale of Accounts Receivable – KCP&L and GMO

KCP&L and GMO sell all of their retail electric accounts receivable to their wholly owned subsidiaries, KCP&L Receivables Company and GMO Receivables Company, respectively, which in turn sell an undivided percentage ownership interest in the accounts receivable to Victory Receivables Corporation, an independent outside investor. Each of KCP&L Receivables Company's and GMO Receivables Company's sale of the undivided percentage ownership interest in accounts receivable to Victory Receivables Corporation is accounted for as a secured borrowing with accounts receivable pledged as collateral and a corresponding short-term collateralized note payable recognized on the balance sheets. At September 30, 2015, and December 31, 2014, Great Plains Energy's accounts receivable pledged as collateral and the corresponding short-term collateralized note payable were $190.0 million and $171.0 million, respectively. At September 30, 2015, and December 31, 2014, KCP&L's accounts receivable pledged as collateral and the corresponding short-term collateralized note payable were $110.0 million.

KCP&L and GMO each sell their receivables at a fixed price based upon the expected cost of funds and charge-offs. These costs comprise KCP&L's and GMO's loss on the sale of accounts receivable. KCP&L and GMO service the receivables and each receive an annual servicing fee of 1.5% of the outstanding principal amount of the receivables sold to KCP&L Receivables Company and GMO Receivables Company. KCP&L and GMO do not recognize a servicing asset or liability because management determined the collection agent fees earned by KCP&L and GMO approximate market value. KCP&L's agreement expires in September 2016 and allows for $110 million in aggregate outstanding principal amount at any time. GMO's agreement expires in September 2016 and allows for $65 million in aggregate outstanding principal from mid-November through mid-June and then increases to $80 million from mid-June through mid-November.

Information regarding KCP&L's sale of accounts receivable to KCP&L Receivables Company and GMO's sale of accounts receivable to GMO Receivables Company is reflected in the following tables.



Three Months Ended September 30, 2015	KCP&L				KCP&L Receivables Company				Consolidated KCP&L				GMO				GMO Receivables Company				Consolidated Great Plains Energy
	(millions)
Receivables (sold) purchased		$	(495.5	)		$	495.5			$	—			$	(267.4	)		$	267.4			$	—
Gain (loss) on sale of accounts receivable ^(a)		(6.3		)		6.1				(0.2		)		(3.4		)		3.4				(0.2		)
Servicing fees received (paid)		0.8				(0.8		)		—				0.4				(0.4		)		—
Fees paid to outside investor		—				(0.3		)		(0.3		)		—				(0.2		)		(0.5		)
Cash from customers (transferred) received		(489.5		)		489.5				—				(267.7		)		267.7				—
Cash received from (paid for) receivables purchased		483.4				(483.4		)		—				264.4				(264.4		)		—
Interest on intercompany note received (paid)		0.1				(0.1		)		—				—				—				—



Year to Date September 30, 2015	KCP&L				KCP&L Receivables Company				Consolidated KCP&L				GMO				GMO Receivables Company				Consolidated Great Plains Energy
	(millions)
Receivables (sold) purchased		$	(1,234.0	)		$	1,234.0			$	—			$	(656.7	)		$	656.7			$	—
Gain (loss) on sale of accounts receivable ^(a)		(15.6		)		15.1				(0.5		)		(8.3		)		8.1				(0.7		)
Servicing fees received (paid)		2.0				(2.0		)		—				1.0				(1.0		)		—
Fees paid to outside investor		—				(0.7		)		(0.7		)		—				(0.4		)		(1.1		)
Cash from customers (transferred) received		(1,205.6		)		1,205.6				—				(646.0		)		646.0				—
Cash received from (paid for) receivables purchased		1,190.5				(1,190.5		)		—				638.0				(638.0		)		—
Interest on intercompany note received (paid)		0.2				(0.2		)		—				0.1				(0.1		)		—



Three Months Ended September 30, 2014	KCP&L				KCP&L Receivables Company				Consolidated KCP&L				GMO				GMO Receivables Company				Consolidated Great Plains Energy
	(millions)
Receivables (sold) purchased		$	(472.9	)		$	472.9			$	—			$	(251.3	)		$	251.3			$	—
Gain (loss) on sale of accounts receivable ^(a)		(6.0		)		5.9				(0.1		)		(3.1		)		3.2				—
Servicing fees received (paid)		0.8				(0.8		)		—				0.4				(0.4		)		—
Fees paid to outside investor		—				(0.3		)		(0.3		)		—				(0.2		)		(0.5		)
Cash from customers (transferred) received		(471.5		)		471.5				—				(253.2		)		253.2				—
Cash received from (paid for) receivables purchased		465.6				(465.6		)		—				250.0				(250.0		)		—
Interest on intercompany note received (paid)		0.1				(0.1		)		—				—				—				—



Year to Date September 30, 2014	KCP&L				KCP&L Receivables Company				Consolidated KCP&L				GMO				GMO Receivables Company				Consolidated Great Plains Energy
	(millions)
Receivables (sold) purchased		$	(1,206.9	)		$	1,206.9			$	—			$	(643.0	)		$	643.0			$	—
Gain (loss) on sale of accounts receivable ^(a)		(15.3		)		14.9				(0.4		)		(8.1		)		7.9				(0.6		)
Servicing fees received (paid)		2.0				(2.0		)		—				1.0				(1.0		)		—
Fees paid to outside investor		—				(0.9		)		(0.9		)		—				(0.5		)		(1.4		)
Cash from customers (transferred) received		(1,187.3		)		1,187.3				—				(630.5		)		630.5				—
Cash received from (paid for) receivables purchased		1,172.4				(1,172.4		)		—				622.6				(622.6		)		—
Interest on intercompany note received (paid)		0.2				(0.2		)		—				—				—				—

Nuclear Plant

9 Months Ended

Sep. 30, 2015

Nuclear Plant [Abstract]

Nuclear Plant

4. NUCLEAR PLANT

KCP&L owns 47% of Wolf Creek Generating Station (Wolf Creek), its only nuclear generating unit. Wolf Creek is located in Coffey County, Kansas, just northeast of Burlington, Kansas. Wolf Creek's operating license expires in 2045. Wolf Creek is regulated by the Nuclear Regulatory Commission (NRC), with respect to licensing, operations and safety-related requirements.

Spent Nuclear Fuel and High-Level Radioactive Waste

Under the Nuclear Waste Policy Act of 1982, the Department of Energy (DOE) is responsible for the permanent disposal of spent nuclear fuel. Wolf Creek paid the DOE a quarterly fee of one-tenth of a cent for each kilowatt hour (kWh) of net nuclear generation delivered and sold for the future disposal of spent nuclear fuel. KCP&L's 47% share of these costs were charged to fuel expense. The Nuclear Energy Institute, a number of individual utilities, and the National Association of Regulatory Utility Commissioners sued the DOE seeking the suspension of this fee. In January 2014, the DOE submitted a proposal to Congress to set the fee at zero, which became effective on May 16, 2014.

In 2010, the DOE filed a motion with the NRC to withdraw its then pending application to the NRC to construct a national repository for the disposal of spent nuclear fuel and high-level radioactive waste at Yucca Mountain, Nevada. An NRC board denied the DOE's motion to withdraw its application. In 2011, the NRC reexamined its decision and ordered the licensing board, consistent with budgetary limitations, to close out its work on the DOE's application. In August 2013, a federal court of appeals ruled that the NRC must resume its review of the DOE's application.

Wolf Creek is currently evaluating alternatives for expanding its existing on-site spent nuclear fuel storage to provide additional capacity prior to 2025. Management cannot predict when, or if, an off-site storage site or alternative disposal site will be available to receive Wolf Creek's spent nuclear fuel and will continue to monitor this activity.

Low-Level Radioactive Waste

Wolf Creek disposes of most of its low-level radioactive waste (Class A waste) at an existing third-party repository in Utah. Management expects that the site located in Utah will remain available to Wolf Creek for disposal of its Class A waste. Wolf Creek has contracted with a waste processor that will process, take title and dispose in another state most of the remainder of Wolf Creek's low-level radioactive waste (Classes B and C waste, which is higher in radioactivity but much lower in volume). Should on-site waste storage be needed in the future, Wolf Creek has current storage capacity on site for about four years' generation of Classes B and C waste and believes it will be able to expand that storage capacity as needed if it becomes necessary to do so.

Nuclear Decommissioning Trust Fund

The following table summarizes the change in Great Plains Energy's and KCP&L's nuclear decommissioning trust fund.



	September 30 2015				December 31 2014
Decommissioning Trust		(millions)
Beginning balance January 1		$	199.0			$	183.9
Contributions		2.5				3.3
Earned income, net of fees		2.4				3.6
Net realized gains		0.9				0.4
Net unrealized gains (losses)		(11.7		)		7.8
Ending balance		$	193.1			$	199.0

The nuclear decommissioning trust is reported at fair value on the balance sheets and is invested in assets as detailed in the following table.



	September 30, 2015													December 31, 2014
	Cost Basis		Unrealized Gains			Unrealized Losses				Fair Value			Cost Basis			Unrealized Gains			Unrealized Losses				Fair Value
	(millions)
Equity securities	$	89.4		$	42.2		$	(3.2	)		$	128.4		$	87.2		$	50.6		$	(0.7	)		$	137.1
Debt securities	59.0			3.2			(0.3		)		61.9			55.4			3.8			(0.1		)		59.1
Other	2.8			—			—				2.8			2.8			—			—				2.8
Total	$	151.2		$	45.4		$	(3.5	)		$	193.1		$	145.4		$	54.4		$	(0.8	)		$	199.0

The weighted average maturity of debt securities held by the trust at September 30, 2015, was approximately 7 years. The costs of securities sold are determined on the basis of specific identification. The following table summarizes the realized gains and losses from the sale of securities in the nuclear decommissioning trust fund.



	Three Months Ended September 30						Year to Date September 30
	2015			2014			2015			2014
	(millions)
Realized gains	$	0.6		$	0.3		$	3.2		$	1.0
Realized losses	(0.5		)	(0.1		)	(2.3		)	(0.7		)

Regulatory Matters	9 Months Ended
Regulatory Matters	Sep. 30, 2015
Regulated Operations [Abstract]
Regulatory Matters	5. REGULATORY MATTERS KCP&L Kansas Rate Case Proceedings In January 2015, KCP&L filed an application with The State Corporation Commission of the State of Kansas (KCC) to request an increase to its retail revenues of $67.3 million, with a return on equity of 10.3% and a rate-making equity ratio of 50.48%. The request included costs to install environmental upgrades at the La Cygne Station, upgrades at Wolf Creek and other infrastructure and system improvements made to be able to provide reliable electric service. In September 2015, KCC issued an order for KCP&L authorizing an increase in annual revenues of $48.7 million, a return on equity of 9.3% and a rate-making equity ratio of 50.48%. The rates established by the order took effect on October 1, 2015, and are effective unless and until modified by KCC or stayed by a court. KCP&L Missouri Rate Case Proceedings In October 2014, KCP&L filed an application with the Public Service Commission of the State of Missouri (MPSC) to request an increase to its retail revenues of $120.9 million (subsequently adjusted to $112.7 million), with a return on equity of 10.3% and a rate-making equity ratio of 50.36%. The request included recovery of increased transmission and property tax expenses, costs to install environmental upgrades at the La Cygne Station, upgrades at Wolf Creek and other infrastructure and system improvements made to be able to provide reliable electric service. KCP&L also requested authorization to implement a Fuel Adjustment Clause (FAC). In September 2015, the MPSC issued an order for KCP&L authorizing an increase in annual revenues of $89.7 million, a return on equity of 9.5% and a rate-making equity ratio of approximately 50.09%. The MPSC also approved KCP&L’s request to implement a FAC. The rates established by the order took effect on September 29, 2015, and are effective unless and until modified by the MPSC or stayed by a court. Notices of Appeal of the September 2015 MPSC order were filed with the Missouri Court of Appeals, Western District, by KCP&L in October 2015 and by The Office of the Public Counsel in November 2015 regarding various issues.

Goodwill and Intangible Assets	9 Months Ended
Goodwill and Intangible Assets	Sep. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets [Text Block]	6. GOODWILL Accounting rules require goodwill to be tested for impairment annually and when an event occurs indicating the possibility that an impairment exists. The annual impairment test for the $169.0 million of GMO acquisition goodwill was conducted on September 1, 2015. The goodwill impairment test is a two step process. The first step compares the fair value of a reporting unit to its carrying amount, including goodwill, to identify potential impairment. If the carrying amount exceeds the fair value of the reporting unit, the second step of the test is performed, consisting of assignment of the reporting unit's fair value to its assets and liabilities to determine an implied fair value of goodwill, which is compared to the carrying amount of goodwill to determine the impairment loss, if any, to be recognized in the financial statements. Great Plains Energy's regulated electric utility operations are considered one reporting unit for assessment of impairment, as they are included within the same operating segment and have similar economic characteristics. The determination of fair value of the reporting unit consisted of two valuation techniques: an income approach consisting of a discounted cash flow analysis and a market approach consisting of a determination of reporting unit invested capital using market multiples derived from the historical revenue, EBITDA, net utility asset values and market prices of stock of peer companies. The results of the two techniques were evaluated and weighted to determine a point within the range that management considered representative of fair value for the reporting unit. Fair value of the reporting unit exceeded the carrying amount, including goodwill; therefore, there was no impairment of goodwill.

Asset Retirement Obligation Disclosure [Abstract]

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References+ Details

Asset Retirement Obligations

9 Months Ended

Sep. 30, 2015

Asset Retirement Obligations [Text Block]

7. ASSET RETIREMENT OBLIGATIONS

Asset retirement obligations (AROs) associated with tangible long-lived assets are legal obligations that exist under enacted laws, statutes and written or oral contracts, including obligations arising under the doctrine of promissory estoppel. These liabilities are recognized at estimated fair value as incurred with a corresponding amount capitalized as part of the cost of the related long-lived assets and depreciated over their useful lives. Accretion of the liabilities due to the passage of time is recorded to a regulatory asset and/or liability. Changes in the estimated fair values of the liabilities are recognized when known.

KCP&L has AROs related to decommissioning Wolf Creek, site remediation of its Spearville Wind Energy Facilities, asbestos abatement, removal of storage tanks and closure and post-closure of ponds and landfills containing coal combustion residuals (CCRs). GMO has AROs related to asbestos abatement, removal of storage tanks and closure and post-closure of ponds and landfills containing CCRs.

Additionally, certain wiring used in Great Plains Energy's and KCP&L's generating stations include asbestos insulation, which would require special handling if disturbed. Due to the inability to reasonably estimate the quantities or the amount of disturbance that will be necessary during dismantlement at the end of the life of a plant, the fair value of this ARO cannot be reasonably estimated at this time. Management will continue to monitor the obligation and will recognize a liability in the period in which sufficient information becomes available to reasonably estimate its fair value.

On April 17, 2015, the Environmental Protection Agency (EPA) published new regulations to regulate the disposal of CCRs at electric generating facilities. See Note 12 under the heading Solid Waste for additional information regarding the CCR rule. The CCR rule represents legal obligations of Great Plains Energy and KCP&L as to the closure and post-closure of its ponds and landfills containing CCRs. As a result of the CCR rule, Great Plains Energy and KCP&L increased their AROs $69.5 million and $51.3 million, respectively, in the second quarter of 2015.

The following table summarizes the change in Great Plains Energy's and KCP&L's AROs.



		Great Plains Energy						KCP&L
	September 30			December 31			September 30			December 31
		2015			2014			2015			2014
		(millions)
Beginning balance		$	195.9		$	158.8		$	177.7		$	141.7
Additions		54.5			—			34.6			—
Revision in timing and/or estimates		15.0			26.8			16.7			26.8
Accretion		9.4			10.3			8.5			9.2
Ending balance		$	274.8		$	195.9		$	237.5		$	177.7

Pension Plans and Other Employee Benefits

9 Months Ended

Sep. 30, 2015

Compensation and Retirement Disclosure [Abstract]

Pension Plans and Other Employee Benefits

8. PENSION PLANS AND OTHER EMPLOYEE BENEFITS

Great Plains Energy maintains defined benefit pension plans for substantially all active and inactive employees, including officers, of KCP&L and GMO, and its 47% ownership share of Wolf Creek Nuclear Operating Corporation (WCNOC) defined benefit plans. For the majority of employees, pension benefits under these plans reflect the employees' compensation, years of service and age at retirement; however, for union employees hired after October 1, 2013, the benefits are derived from a cash balance account formula. Effective in 2014, the KCP&L non-union plan was closed to future employees. Great Plains Energy also provides certain post-retirement health care and life insurance benefits for substantially all retired employees of KCP&L, GMO and its 47% ownership share of WCNOC.

KCP&L and GMO record pension and post-retirement expense in accordance with rate orders from the MPSC and KCC that allow the difference between pension and post-retirement costs under GAAP and costs for ratemaking to be recognized as a regulatory asset or liability. This difference between financial and regulatory accounting methods is due to timing and will be eliminated over the life of the plans.

The following tables provide Great Plains Energy's components of net periodic benefit costs prior to the effects of capitalization and sharing with joint owners of power plants.



	Pension Benefits						Other Benefits
Three Months Ended September 30	2015			2014			2015			2014
Components of net periodic benefit costs	(millions)
Service cost	$	11.4		$	9.1		$	0.8		$	0.9
Interest cost	12.5			12.7			1.7			2.0
Expected return on plan assets	(13.0		)	(12.7		)	(0.7		)	(0.7		)
Prior service cost	0.2			0.2			0.7			0.8
Recognized net actuarial loss	12.9			12.4			0.1			—
Transition obligation	—			—			0.1			—
Net periodic benefit costs before regulatory adjustment	24.0			21.7			2.7			3.0
Regulatory adjustment	(3.5		)	(0.6		)	1.4			1.1
Net periodic benefit costs	$	20.5		$	21.1		$	4.1		$	4.1

	Pension Benefits						Other Benefits
Year to Date September 30	2015			2014			2015			2014
Components of net periodic benefit costs	(millions)
Service cost	$	34.0		$	27.2		$	2.5		$	2.7
Interest cost	37.7			38.1			5.1			6.0
Expected return on plan assets	(38.8		)	(38.1		)	(2.2		)	(2.1		)
Prior service cost	0.6			0.6			2.3			2.4
Recognized net actuarial loss	38.5			37.2			0.2			—
Transition obligation	—			—			0.1			0.1
Net periodic benefit costs before regulatory adjustment	72.0			65.0			8.0			9.1
Regulatory adjustment	(9.3		)	(1.4		)	4.2			3.3
Net periodic benefit costs	$	62.7		$	63.6		$	12.2		$	12.4

Year to date September 30, 2015, Great Plains Energy contributed $29.5 million to the pension plans and expects to contribute an additional $49.4 million in 2015 to satisfy the minimum Employee Retirement Income Security Act of 1974, as amended (ERISA) funding requirements and the MPSC and KCC rate orders, the majority of which is expected to be paid by KCP&L. Also in 2015, Great Plains Energy expects to make contributions of $10.2 million to the post-retirement benefit plans, the majority of which is expected to be paid by KCP&L.

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

The entire disclosure for pension and other postretirement benefits.

+ References+ Details

Equity Compensation

9 Months Ended

Sep. 30, 2015

Equity Compensation

9. EQUITY COMPENSATION

Great Plains Energy's Long-Term Incentive Plan is an equity compensation plan approved by Great Plains Energy's shareholders. The Long-Term Incentive Plan permits the grant of restricted stock, restricted stock units, bonus shares, stock options, stock appreciation rights, limited stock appreciation rights, director shares, director deferred share units and performance shares to directors, officers and other employees of Great Plains Energy and KCP&L. Forfeiture rates are based on historical forfeitures and future expectations and are reevaluated annually.

The following table summarizes Great Plains Energy's and KCP&L's equity compensation expense and the associated income tax benefit.



	Three Months Ended September 30				Year to Date September 30
	2015		2014		2015		2014
Great Plains Energy	(millions)
Equity compensation expense	$	3.7	$	1.0	$	4.6	$	6.4
Income tax benefit	1.4		0.3		1.7		2.3
KCP&L
Equity compensation expense	$	2.5	$	0.6	$	3.1	$	4.4
Income tax benefit	0.9		0.1		1.1		1.5

Performance Shares

Performance share activity year to date September 30, 2015, is summarized in the following table. Performance adjustment represents the number of shares of common stock issued related to performance shares and can vary from the number of performance shares initially granted depending on Great Plains Energy's performance over a stated period of time.



	Performance Shares			Grant Date Fair Value*
Beginning balance January 1, 2015		534,016			$	25.11
Granted		232,838			24.03
Earned		(25,844	)		19.48
Forfeited		(46,927	)		25.68
Performance adjustment		(77,515	)		19.48
Ending balance September 30, 2015		616,568			25.60

* weighted-average

At September 30, 2015, the remaining weighted-average contractual term was 1.3 years. The weighted-average grant-date fair value of shares granted was $22.46 and $24.03 for the three months ended and year to date September 30, 2015, respectively. The weighted-average grant-date fair value of shares granted was $28.78 for the three months ended and year to date September 30, 2014. At September 30, 2015, there was $7.8 million of total unrecognized compensation expense, net of forfeiture rates, related to performance shares granted under the Long-Term Incentive Plan, which will be recognized over the remaining weighted-average contractual term. The total fair value of performance shares earned and paid was $0.5 million and $2.8 million year to date September 30, 2015, and 2014, respectively.

The fair value of performance share awards is estimated using the market value of the Company's stock at the valuation date and a Monte Carlo simulation technique that incorporates assumptions for inputs of expected volatilities, dividend yield and risk-free rates. Expected volatility is based on daily stock price change during a historical period commensurate with the remaining term of the performance period of the grant. The risk-free rate is based upon the rate at the time of the evaluation for zero-coupon government bonds with a maturity consistent with the remaining performance period of the grant. The dividend yield is based on the most recent dividends paid and the actual closing stock price on the valuation date. For shares granted in 2015, inputs for expected volatility, dividend yield and risk-free rates ranged from 16%-17%, 3.72%-4.03% and 0.86%-1.02%, respectively.

Restricted Stock

Restricted stock activity year to date September 30, 2015, is summarized in the following table.



	Nonvested Restricted Stock			Grant Date Fair Value*
Beginning balance January 1, 2015		267,390			$	22.31
Granted and issued		91,880			25.88
Vested		(109,246	)		19.68
Forfeited		(15,644	)		24.81
Ending balance September 30, 2015		234,380			24.76

* weighted-average

At September 30, 2015, the remaining weighted-average contractual term was 1.5 years. The weighted-average grant-date fair value of shares granted was $24.20 and $25.88 for the three months ended and year to date September 30, 2015, respectively. The weighted-average grant-date fair value of shares granted was $25.10 and $25.69 for the three months ended and year to date September 30, 2014, respectively. At September 30, 2015, there was $2.9 million of total unrecognized compensation expense, net of forfeiture rates, related to nonvested restricted stock granted under the Long-Term Incentive Plan, which will be recognized over the remaining weighted-average contractual term. The total fair value of shares vested was $0.1 million and $2.1 million for the three months ended and year to date September 30, 2015, respectively. The total fair value of shares vested was $0.5 million and $1.9 million for the three months ended and year to date September 30, 2014, respectively.

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

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Short-term Borrowings and Short-term Bank Lines of Credit	9 Months Ended
	Sep. 30, 2015
Short-term Borrowings and Short-term Bank Lines of Credit [Abstract]
Short-term Borrowings and Short-term Bank Lines of Credit [Text Block]	10. SHORT-TERM BORROWINGS AND SHORT-TERM BANK LINES OF CREDIT Great Plains Energy's $200 Million Revolving Credit Facility Great Plains Energy's $200 million revolving credit facility with a group of banks expires in October 2019. The facility's terms permit transfers of unused commitments between this facility and the KCP&L and GMO facilities discussed below, with the total amount of the facility not exceeding $400 million at any one time. A default by Great Plains Energy or any of its significant subsidiaries on other indebtedness totaling more than $50.0 million is a default under the facility. Under the terms of this facility, Great Plains Energy is required to maintain a consolidated indebtedness to consolidated capitalization ratio, as defined in the facility, not greater than 0.65 to 1.00 at all times. At September 30, 2015, Great Plains Energy was in compliance with this covenant. At September 30, 2015, Great Plains Energy had $12.0 million of outstanding cash borrowings at a weighted-average interest rate of 1.75% and had issued $0.2 million in letters of credit under the credit facility. At December 31, 2014, Great Plains Energy had $4.0 million of outstanding cash borrowings at a weighted-average interest rate of 1.69% and had issued no letters of credit under the credit facility. KCP&L's $600 Million Revolving Credit Facility and Commercial Paper KCP&L's $600 million revolving credit facility with a group of banks provides support for its issuance of commercial paper and other general corporate purposes and expires in October 2019. Great Plains Energy and KCP&L may transfer up to $200 million of unused commitments between Great Plains Energy's and KCP&L's facilities. A default by KCP&L on other indebtedness totaling more than $50.0 million is a default under the facility. Under the terms of this facility, KCP&L is required to maintain a consolidated indebtedness to consolidated capitalization ratio, as defined in the facility, not greater than 0.65 to 1.00 at all times. At September 30, 2015, KCP&L was in compliance with this covenant. At September 30, 2015, KCP&L had $82.1 million of commercial paper outstanding at a weighted-average interest rate of 0.43%, had issued letters of credit totaling $2.7 million and had no outstanding cash borrowings under the credit facility. At December 31, 2014, KCP&L had $358.3 million of commercial paper outstanding at a weighted-average interest rate of 0.48%, had issued letters of credit totaling $2.7 million and had no outstanding cash borrowings under the credit facility. GMO's $450 Million Revolving Credit Facility and Commercial Paper GMO's $450 million revolving credit facility with a group of banks provides support for its issuance of commercial paper and other general corporate purposes and expires in October 2019. Great Plains Energy and GMO may transfer up to $200 million of unused commitments between Great Plains Energy's and GMO's facilities. A default by GMO or any of its significant subsidiaries on other indebtedness totaling more than $50.0 million is a default under the facility. Under the terms of this facility, GMO is required to maintain a consolidated indebtedness to consolidated capitalization ratio, as defined in the facility, not greater than 0.65 to 1.00 at all times. At September 30, 2015, GMO was in compliance with this covenant. At September 30, 2015, GMO had $57.0 million of commercial paper outstanding at a weighted-average interest rate of 0.43%, had issued letters of credit totaling $2.5 million and had no outstanding cash borrowings under the credit facility. At December 31, 2014, GMO had no commercial paper outstanding, had issued letters of credit totaling $3.2 million and had no outstanding cash borrowings under the credit facility.

Commitments and Contingencies Disclosure [Abstract]

The entire disclosure for short-term debt.

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Long-Term Debt

9 Months Ended

Sep. 30, 2015

Debt Disclosure [Abstract]

Long-Term Debt

11. LONG-TERM DEBT

Great Plains Energy's and KCP&L's long-term debt is detailed in the following table.



		September 30				December 31
	Year Due	2015				2014
KCP&L			(millions)
General Mortgage Bonds
2.47% EIRR bonds^(a)	2017-2035		$	110.5			$	146.4
7.15% Series 2009A (8.59% rate)^(b)	2019		400.0				400.0
4.65% EIRR Series 2005	2035		—				50.0
Senior Notes
5.85% Series (5.72% rate)^(b)	2017		250.0				250.0
6.375% Series (7.49% rate)^(b)	2018		350.0				350.0
3.15% Series	2023		300.0				300.0
3.65% Series	2025		350.0				—
6.05% Series (5.78% rate)^(b)	2035		250.0				250.0
5.30% Series	2041		400.0				400.0
EIRR Bonds
0.02% Series 2007A and 2007B^(c)	2035		146.5				146.5
2.875% Series 2008	2038		23.4				23.4
Current maturities			—				(14.0		)
Unamortized discount			(4.9		)		(3.8		)
Total KCP&L excluding current maturities^(d)			2,575.5				2,298.5
Other Great Plains Energy
GMO First Mortgage Bonds 9.44% Series	2016-2021		6.8				7.9
GMO Senior Notes
8.27% Series	2021		80.9				80.9
3.49% Series A	2025		125.0				125.0
4.06% Series B	2033		75.0				75.0
4.74% Series C	2043		150.0				150.0
GMO Medium Term Notes
7.33% Series	2023		3.0				3.0
7.17% Series	2023		7.0				7.0
Great Plains Energy Senior Notes
6.875% Series (7.33% rate)^(b)	2017		100.0				100.0
4.85% Series	2021		350.0				350.0
5.292% Series	2022		287.5				287.5
Current maturities			(1.1		)		(1.1		)
Unamortized discount and premium, net			3.9				4.3
Total Great Plains Energy excluding current maturities^(d)			$	3,763.5			$	3,488.0


^(a)	Weighted-average interest rates at September 30, 2015


^(b)	Rate after amortizing gains/losses recognized in OCI on settlements of interest rate hedging instruments


^(c)	Variable rate


^(d)	Does not include $50.0 million and $21.9 million EIRR Series 2005 bonds because the bonds were repurchased in September 2015 and are held by KCP&L.

KCP&L General Mortgage Bonds

In March 2015, KCP&L repaid its $14.0 million secured Series 2005 Environmental Improvement Revenue Refunding (EIRR) bonds at maturity.

In September 2015, KCP&L purchased in lieu of redemption its $50.0 million and $21.9 million secured EIRR Series 2005 bonds. As of September 30, 2015, the bonds were still outstanding, but were not reported as a liability on the balance sheet since they are being held by KCP&L. KCP&L has the ability to remarket these bonds to third parties whenever it determines market conditions are sufficiently attractive to do so.

KCP&L Senior Notes

In August 2015, KCP&L issued, at a discount, $350.0 million of 3.65% unsecured Senior Notes, maturing in 2025.

Commitments and Contingencies

9 Months Ended

Sep. 30, 2015

Commitments and Contingencies

12. COMMITMENTS AND CONTINGENCIES

Environmental Matters

Great Plains Energy and KCP&L are subject to extensive federal, state and local environmental laws, regulations and permit requirements relating to air and water quality, waste management and disposal, natural resources and health and safety. In addition to imposing continuing compliance obligations and remediation costs, these laws, regulations and permits authorize the imposition of substantial penalties for noncompliance, including fines, injunctive relief and other sanctions. The cost of complying with current and future environmental requirements is expected to be material to Great Plains Energy and KCP&L. Failure to comply with environmental requirements or to timely recover environmental costs through rates could have a material effect on Great Plains Energy's and KCP&L's results of operations, financial position and cash flows.

Great Plains Energy's and KCP&L's current estimates of capital expenditures (exclusive of Allowance for Funds Used During Construction (AFUDC) and property taxes) over the next five years to comply with environmental regulations are in the following table. The total cost of compliance with any existing, proposed or future laws and regulations may be significantly different from these cost estimates provided.



	2015		2016		2017		2018		2019
	(millions)
Great Plains Energy	$	119.1	$	62.2	$	158.4	$	103.4	$	99.9
KCP&L	104.5		51.5		132.9		86.9		84.3

The Companies expect to seek recovery of the costs associated with environmental requirements through rate increases; however, there can be no assurance that such rate increases would be granted. The Companies may be subject to materially adverse rate treatment in response to competitive, economic, political, legislative or regulatory factors and/or public perception of the Companies' environmental reputation.

The following discussion groups environmental and certain associated matters into the broad categories of air and climate change, water, solid waste and remediation.

Clean Air Act and Climate Change Overview

The Clean Air Act and associated regulations enacted by the EPA form a comprehensive program to preserve and enhance air quality. States are required to establish regulations and programs to address all requirements of the Clean Air Act and have the flexibility to enact more stringent requirements. All of Great Plains Energy's and KCP&L's generating facilities, and certain of their other facilities, are subject to the Clean Air Act.

Best Available Retrofit Technology (BART) Rule

The EPA BART rule directs state air quality agencies to identify whether visibility-reducing emissions from sources subject to BART are below limits set by the state or whether retrofit measures are needed to reduce emissions. BART applies to specific eligible facilities including KCP&L's La Cygne Nos. 1 and 2 in Kansas; KCP&L's Iatan No. 1, in which GMO has an 18% interest, and KCP&L's Montrose No. 3 in Missouri; GMO's Sibley Unit No. 3 and Lake Road Unit No. 6 in Missouri; and Westar Energy, Inc.'s (Westar) Jeffrey Unit Nos. 1 and 2 in Kansas, in which GMO has an 8% interest. Both Missouri and Kansas have approved BART plans.

KCP&L has a consent agreement with the Kansas Department of Health and Environment (KDHE) incorporating limits for stack particulate matter emissions, as well as limits for NO_x and SO₂ emissions, at its La Cygne Station that will be below the presumptive limits under BART. KCP&L further agreed to use its best efforts to install emission control technologies to reduce those emissions from the La Cygne Station prior to the required compliance date under BART, but in no event later than June 1, 2015. In August 2011, KCC issued its order on KCP&L's predetermination request that would apply to the recovery of costs for its 50% share of the environmental equipment required to comply with BART at the La Cygne Station. In the order, KCC stated that KCP&L's decision to retrofit La Cygne was reasonable, reliable, efficient and prudent and the $1.23 billion cost estimate is reasonable. KCP&L expects the final cost of the project to be approximately $75 million below the $1.23 billion cost estimate. KCP&L's 50% share of the estimated cost is $615 million. In September 2011, KCP&L commenced construction of the La Cygne Station project and at September 30, 2015, had incurred approximately $531 million of cash capital expenditures. The remaining cash capital expenditures are included in the estimated capital expenditures table above. The environmental equipment was placed in-service at La Cygne No. 2 in March 2015 and at La Cygne No. 1 in April 2015.

Mercury and Air Toxics Standards (MATS) Rule

In December 2011, the EPA finalized the MATS Rule that will reduce emissions of toxic air pollutants, also known as hazardous air pollutants, from new and existing coal- and oil-fired electric utility generating units with a capacity of greater than 25 MWs. The rule establishes numerical emission limits for mercury, particulate matter (a surrogate for non-mercury metals) and hydrochloric acid (a surrogate for acid gases). The rule establishes work practices, instead of numerical emission limits, for organic air toxics, including dioxin/furan. MATS Rule compliance commenced at KCP&L’s Iatan Station in April 2015 and will commence at KCP&L's La Cygne Station in December 2015. In June 2015, the U.S. Supreme Court reversed the judgment of the Court of Appeals for the D.C. Circuit, which had upheld the MATS Rule, and remanded the MATS Rule for further proceedings consistent with its opinion. The Supreme Court held that the EPA was required by the Clean Air Act, but had failed, to consider costs when the EPA made the initial decision that regulating air toxics was appropriate and necessary. KCP&L’s and GMO’s other affected coal-fired units will take actions to be compliant in April 2016, unless the D.C. Circuit Court issues an order which results in alternate compliance actions. Estimated capital costs to comply with the MATS Rule are included in the estimated capital expenditures table above.

Industrial Boiler Rule

In December 2012, the EPA issued a final rule that would reduce emissions of hazardous air pollutants from new and existing industrial boilers. The final rule establishes numeric emission limits for mercury, particulate matter (as a surrogate for non-mercury metals), hydrogen chloride (as a surrogate for acid gases) and carbon monoxide (as a surrogate for non-dioxin organic hazardous air pollutants). The final rule establishes emission limits for KCP&L's and GMO's existing units that produce steam other than for the generation of electricity. The final rule does not apply to KCP&L's and GMO's electricity generating boilers, but would apply to most of GMO's Lake Road boilers, which also serve steam customers, and to auxiliary boilers at other generating facilities. The rule became effective in January 2013 and allows three to four years for compliance. Estimated capital costs to comply with the Industrial Boiler Rule are included in the estimated capital expenditures table above.

SO₂ NAAQS

In June 2010, the EPA adopted a more stringent primary National Ambient Air Quality Standard (NAAQS) for SO₂ by establishing a new 1-hour standard at a level of 0.075 ppm and revoking the two existing primary standards of 0.140 ppm evaluated over 24 hours and 0.030 ppm evaluated over an entire year. In July 2013, the EPA designated a part of Jackson County, Missouri, which is in the Companies' service territory, as a nonattainment area for the new 1-hour SO₂ standard. The Missouri Department of Natural Resources (MDNR) will now develop and submit their state implementation plan to the EPA to return the area to attainment of the standard, which may include stricter controls on certain industrial facilities. The Companies are unable to determine if there will be any financial and/or operational impacts until the state implementation plan is complete.

Climate Change

The Companies' current generation capacity is primarily coal-fired and is estimated to produce about one ton of CO₂ per MWh, or approximately 22 million tons and 17 million tons per year for Great Plains Energy and KCP&L, respectively. The Companies are subject to existing greenhouse gas reporting regulations and certain greenhouse gas permitting requirements. Federal or state legislation concerning the reduction of emissions of greenhouse gases, including CO₂, could be enacted in the future. At the international level, while the United States is not a current party to the international Kyoto Protocol, it has agreed to undertake certain voluntary actions under the non-binding Copenhagen Accord and pursuant to subsequent international discussions relating to climate change, including the establishment of a goal to reduce greenhouse gas emissions. International agreements legally binding on the United States may be reached in the future. Greenhouse gas legislation has the potential of having significant financial and operational impacts on Great Plains Energy and KCP&L; however, the ultimate financial and operational consequences to Great Plains Energy and KCP&L cannot be determined until such legislation is passed. In the absence of new Congressional mandates, the EPA is proceeding with the regulation of greenhouse gases under the existing Clean Air Act.

In August 2015, the EPA finalized CO₂ emission standards for new, modified and reconstructed affected fossil-fuel-fired electric utility generating units. The standards would not apply to Great Plains Energy's and KCP&L's existing units unless the units were modified or reconstructed in the future.

In August 2015, the EPA finalized its Clean Power Plan which sets CO₂ emission performance rates for existing affected fossil fuel-fired electric generating units. Specifically, the EPA translated those performance rates into a state goal measured in mass and rate based on each state’s generation mix. The states have the ability to develop their own plans for affected units to achieve either the performance rates directly or the state goals, with guidelines for the development, submittal and implementation of those plans. Nationwide, by 2030, the EPA projects the Clean Power Plan would achieve CO₂ emission reductions from the power sector of approximately 32% from CO₂ emission levels in 2005.

The EPA has finalized an interim CO₂ goal rate reduction in Kansas and Missouri (average of 2022-2029) of 34% and 26%, respectively, and 2030 targets in Kansas and Missouri of 44% and 37%, respectively. The baseline for these reductions is 2012 CO₂ emissions adjusted by the EPA. The EPA has also finalized mass based CO₂reduction goals.

States are required to submit final plans to implement the Clean Power Plan or an extension request to the EPA by September 2016. States receiving an extension request must submit final plans by September 2018. An EPA plan with either a rate-based or mass-based trading program has yet to be finalized and can be enforced in states that fail to submit approved plans by the deadlines established in the final guidelines.

Compliance with the Clean Power Plan has the potential of having significant financial and operational impacts on Great Plains Energy and KCP&L; however, the ultimate financial and operational consequences to Great Plains Energy and KCP&L cannot be determined until the state plans to implement the Clean Power Plan are known. Several lawsuits have been filed challenging the Clean Power Plan.

The Companies are subject to existing renewable energy standards in Missouri. Management believes that national renewable energy standards are also possible. The timing, provisions and impact of such possible future requirements, including the cost to obtain and install new equipment to achieve compliance, cannot be reasonably estimated at this time.

Clean Water Act

The Clean Water Act and associated regulations enacted by the EPA form a comprehensive program to restore and preserve water quality. Like the Clean Air Act, states are required to establish regulations and programs to address all requirements of the Clean Water Act, and have the flexibility to enact more stringent requirements. All of Great Plains Energy's and KCP&L's generating facilities, and certain of their other facilities, are subject to the Clean Water Act.

In May 2014, the EPA finalized regulations pursuant to Section 316(b) of the Clean Water Act regarding cooling water intake structures pursuant to a court approved settlement. KCP&L generation facilities with cooling water intake structures are subject to the best technology available standards based on studies completed to comply with such standards. The rule provides flexibility to work with the states to develop the best technology available to minimize aquatic species impacted by being pinned against intake screens (impingement) or drawn into cooling water systems (entrainment). Estimated costs to comply with Section 316(b) of the Clean Water Act are included in the estimated capital expenditures table above.

KCP&L holds a permit from the MDNR covering water discharge from its Hawthorn Station. The permit authorizes KCP&L to, among other things, withdraw water from the Missouri River for cooling purposes and return the heated water to the Missouri River. KCP&L has applied for a renewal of this permit and the EPA has submitted an interim objection letter regarding the allowable amount of heat that can be contained in the returned water. Until this matter is resolved, KCP&L continues to operate under its current permit. Future water permit renewals at KCP&L's Iatan Station and at GMO's Sibley and Lake Road Stations could also be impacted by the allowable amount of heat that can be contained in the returned water. Great Plains Energy and KCP&L cannot predict the outcome of these matters; however, while less significant outcomes are possible, these matters may require a reduction in generation, installation of cooling towers or other technology to cool the water, or both, any of which could have a significant impact on Great Plains Energy's and KCP&L's results of operations, financial position and cash flows.

In September 2015, the EPA finalized a revision of the technology-based effluent limitations guidelines and standards regulation to make the existing controls on discharges from steam electric power plants more stringent. The final rule sets the first federal limits on the levels of toxic metals in wastewater that can be discharged from power plants. The new requirements for existing power plants would be phased in between 2018 and 2023.

The final rule establishes new or additional requirements for wastewaters associated with the following processes and byproducts at certain KCP&L and GMO stations: flue gas desulfurization, fly ash, bottom ash, flue gas mercury control, and combustion residual leachate from landfills and surface impoundments. Estimated capital costs to comply with the final rule are included in the estimated capital expenditures table above.

Solid Waste

Solid and hazardous waste generation, storage, transportation, treatment and disposal are regulated at the federal and state levels under various laws and regulations. In December 2014, the EPA finalized regulations to regulate CCRs under the Resource Conservation and Recovery Act (RCRA) subtitle D to address the risks from the disposal of CCRs generated from the combustion of coal at electric generating facilities. The Companies use coal in generating electricity and dispose of the CCRs in both on-site facilities and facilities owned by third parties. The rule requires periodic assessments; groundwater monitoring; location restrictions; design and operating requirements; recordkeeping and notifications; and closure, among other requirements, for CCR units. The rule was promulgated in the Federal Register on April 17, 2015, and is effective six months after promulgation with various obligations effective at specified times within the rule. Estimated capital costs to comply with the CCR rule are included in the estimated capital expenditures table above. See Note 7 for information regarding an increase in Great Plains Energy's and KCP&L's AROs as a result of the CCR rule.

Remediation

Certain federal and state laws, including the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), hold current and previous owners or operators of contaminated facilities and persons who arranged for the disposal or treatment of hazardous substances liable for the cost of investigation and cleanup. CERCLA and other laws also authorize the EPA and other agencies to issue orders compelling potentially responsible parties to clean up sites that are determined to present an actual or potential threat to human health or the environment. GMO is named as a potentially responsible party at a disposal site for polychlorinated biphenyl (PCB) contamination, and retains some environmental liability for several operations and investments it no longer owns. In addition, GMO also owns, or has acquired liabilities from companies that once owned or operated, former manufactured gas plant (MGP) sites, which are subject to the supervision of the EPA and various state environmental agencies.

At September 30, 2015, and December 31, 2014, KCP&L had $0.3 million accrued for environmental remediation expenses, which covers ground water monitoring at a former MGP site. The amount accrued was established on an undiscounted basis and KCP&L does not currently have an estimated time frame over which the accrued amount may be paid.

In addition to the $0.3 million accrual above, at September 30, 2015, and December 31, 2014, Great Plains Energy had $1.4 million accrued for the future investigation and remediation of certain additional GMO identified MGP sites and retained liabilities. This estimate was based upon review of the potential costs associated with conducting investigative and remedial actions at identified sites, as well as the likelihood of whether such actions will be necessary. This estimate could change materially after further investigation, and could also be affected by the actions of environmental agencies and the financial viability of other potentially responsible parties; however, given the uncertainty of these items the possible loss or range of loss in excess of the amount accrued is not estimable.

GMO has pursued recovery of remediation costs from insurance carriers and other potentially responsible parties. As a result of a settlement with an insurance carrier, approximately $1.4 million in insurance proceeds less an annual deductible is available to GMO to recover qualified MGP remediation expenses. GMO would seek recovery of additional remediation costs and expenses through rate increases; however, there can be no assurance that such rate increases would be granted.

The entire disclosure for commitments and contingencies.

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Legal Proceedings	9 Months Ended
Legal Proceedings	Sep. 30, 2015
Legal Proceedings [Abstract]
Contingencies Disclosure [Text Block]	13. LEGAL PROCEEDINGS GMO Western Energy Crisis In response to complaints of manipulation of the California energy market, The Federal Energy Regulatory Commission (FERC) issued an order in July 2001 requiring net sellers of power in the California markets from October 2, 2000, through June 20, 2001, at prices above a FERC-determined competitive market clearing price, to make refunds to net purchasers of power in the California market during that time period. Because MPS Merchant was a net purchaser of power during the refund period, it has received approximately $8 million in refunds through settlements with certain sellers of power. MPS Merchant estimates that it is entitled to approximately $12 million in additional refunds under the standards FERC has used in this case. FERC has stated that interest will be applied to the refunds but the amount of interest has not yet been determined. In December 2001, various parties appealed the July 2001 FERC order to the United States Court of Appeals for the Ninth Circuit (Ninth Circuit) seeking review of a number of issues, including expansion of the refund period to include periods prior to October 2, 2000 (the Summer Period). MPS Merchant was a net seller of power during the Summer Period. On August 2, 2006, the Ninth Circuit issued an order finding, among other things, that FERC did not provide a sufficient justification for refusing to exercise its remedial authority under the Federal Power Act to determine whether market participants violated FERC-approved tariffs during the Summer Period. The court remanded the matter to FERC for further consideration. If FERC determines that MPS Merchant violated then-existing tariffs or laws during the Summer Period and that such violations affected market clearing prices in California, MPS Merchant could be found to owe refunds. Due to the uncertainties remaining in the case, the potential refund or range of potential refunds owed by MPS Merchant are not reasonably estimable.

The entire disclosure for loss and gain contingencies. Describes any existing condition, situation, or set of circumstances involving uncertainty as of the balance sheet date (or prior to issuance of the financial statements) as to a probable or reasonably possible loss incurred by an entity that will ultimately be resolved when one or more future events occur or fail to occur, and typically discloses the amount of loss recorded or a range of possible loss, or an assertion that no reasonable estimate can be made.

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+ Details

Related Party Transactions and Relationships

9 Months Ended

Sep. 30, 2015

14. RELATED PARTY TRANSACTIONS AND RELATIONSHIPS

KCP&L employees manage GMO's business and operate its facilities at cost, including GMO's 18% ownership interest in KCP&L's Iatan Nos. 1 and 2. The operating expenses and capital costs billed from KCP&L to GMO were $45.5 million and $137.7 million, respectively, for the three months ended and year to date September 30, 2015. These costs totaled $41.4 million and $128.6 million, respectively, for the three months ended and year to date September 30, 2014. Additionally, KCP&L and GMO engage in wholesale electricity transactions with each other. KCP&L's net wholesale sales to GMO were $0.1 million and $0.2 million for the three months ended and year to date September 30, 2015, respectively. KCP&L's net wholesale sales to GMO were $1.6 million and $12.6 million for the three months ended and year to date September 30, 2014, respectively.

KCP&L and GMO are also authorized to participate in the Great Plains Energy money pool, an internal financing arrangement in which funds may be lent on a short-term basis to KCP&L and GMO from Great Plains Energy and between KCP&L and GMO. At December 31, 2014, KCP&L had a money pool payable to GMO of $12.6 million. The following table summarizes KCP&L's related party net receivables.



	September 30			December 31
		2015			2014
		(millions)
Net receivable from GMO		$	43.6		$	38.2
Net receivable from Great Plains Energy		13.4			18.0

Derivative Instruments and Hedging Activities Disclosure [Abstract]

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References+ Details

Derivative Instruments

9 Months Ended

Sep. 30, 2015

Derivative Instruments and Hedging Activities Disclosure [Text Block]

15. DERIVATIVE INSTRUMENTS

Great Plains Energy and KCP&L are exposed to a variety of market risks including interest rates and commodity prices. Management has established risk management policies and strategies to reduce the potentially adverse effects that the volatility of the markets may have on Great Plains Energy's and KCP&L's operating results. Great Plains Energy's and KCP&L's interest rate risk management activities have included using derivative instruments to hedge against future interest rate fluctuations on anticipated debt issuances. Commodity risk management activities, including the use of certain derivative instruments, are subject to the management, direction and control of an internal commodity risk committee. Management maintains commodity price risk management strategies that use derivative instruments to reduce the effects of fluctuations in wholesale sales, fuel and purchased power expense caused by commodity price volatility.

Counterparties to commodity derivatives expose Great Plains Energy and KCP&L to credit loss in the event of nonperformance. This credit loss is limited to the cost of replacing these contracts at current market rates. Derivative instruments, excluding those instruments that qualify for the normal purchases and normal sales (NPNS) election, which are accounted for by accrual accounting, are recorded on the balance sheet at fair value as an asset or liability. Changes in the fair value of derivative instruments are recognized currently in net income unless specific hedge accounting criteria are met, except hedges that are recorded to a regulatory asset or liability consistent with KCC and MPSC regulatory orders.

Great Plains Energy and KCP&L have posted collateral, in the ordinary course of business, for the aggregate fair value of all derivative instruments with credit risk-related contingent features that are in a liability position. At September 30, 2015, Great Plains Energy and KCP&L have posted collateral in excess of the aggregate fair value of their derivative instruments; therefore, if the credit risk-related contingent features underlying these agreements were triggered, Great Plains Energy and KCP&L would not be required to post additional collateral to their counterparties. For derivative contracts with counterparties under master netting arrangements, Great Plains Energy and KCP&L can net all receivables and payables with each respective counterparty.

Commodity Risk Management

KCP&L's risk management policy uses derivative instruments to mitigate exposure to market price fluctuations for wholesale power. KCP&L has designated these financial contracts as economic hedges (non-hedging derivatives). Currently, the fair values of these instruments are recorded as derivative assets or liabilities with an offsetting entry to the consolidated statements of income. In connection with KCP&L's September 2015 MPSC rate order, future contracts will be included in a fuel recovery mechanism which allows the change in the timing of recognition to be recorded on the balance sheet in either a regulatory asset or regulatory liability. Recovery of actual costs will not impact earnings, but will impact cash flows due to the timing of the recovery mechanism.

KCP&L and GMO have Transmission Congestion Rights (TCRs) that they utilize to hedge against congestion costs and protect load prices in the Southwest Power Pool, Inc. (SPP) Integrated Marketplace, which began operations in March 2014. These financial contracts have been designated as economic hedges (non-hedging derivatives). Currently, the fair values of these instruments assigned to KCP&L's Missouri jurisdiction are recorded as derivative assets or liabilities with an offsetting entry recorded to electric revenue. In connection with KCP&L's September 2015 MPSC rate order, future TCR's will be included in a fuel recovery mechanism which allows the change in the timing of recognition to be recorded on the balance sheet in either a regulatory asset or regulatory liability.

The fair values of these instruments assigned to KCP&L's Kansas jurisdiction and GMO are recorded as derivative assets or liabilities with an offsetting entry recorded to a regulatory asset or liability. For KCP&L's Kansas jurisdiction and GMO, the settlement costs are included in their fuel recovery mechanisms. A regulatory asset or liability is recorded to reflect the change in the timing of recognition authorized by KCC and MPSC. Recovery of actual costs will not impact earnings, but will impact cash flows due to the timing of the recovery mechanism.

GMO's risk management policy uses derivative instruments to mitigate price exposure to natural gas price volatility in the market. At September 30, 2015, GMO had financial contracts in place to hedge approximately 49%, 30%, 14% and 7% of the expected on-peak natural gas generation and natural gas equivalent purchased power price exposure for the remainder of 2015, 2016, 2017 and 2018, respectively. The fair value of the portfolio will settle against actual purchases of natural gas and purchased power. GMO has designated its natural gas hedges as economic hedges (non-hedging derivatives). In connection with GMO's 2005 Missouri electric rate case, it was agreed that the settlement costs of these contracts would be recognized in fuel expense. The settlement cost is included in GMO's fuel recovery mechanism. A regulatory asset or liability is recorded to reflect the change in the timing of recognition authorized by the MPSC. Recovery of actual costs will not impact earnings, but will impact cash flows due to the timing of the recovery mechanism.

MPS Merchant, which has certain long-term natural gas contracts remaining from its former non-regulated trading operations, manages the daily delivery of its remaining contractual commitments with economic hedges (non-hedging derivatives) to reduce its exposure to changes in market prices. Within the trading portfolio, MPS Merchant takes certain positions to hedge physical sale or purchase contracts. MPS Merchant records the fair value of physical trading energy contracts as derivative assets or liabilities with an offsetting entry to the consolidated statements of income.

The gross notional contract amount and recorded fair values of open positions for derivative instruments are summarized in the following table. The fair values of these derivatives are recorded on the consolidated balance sheets. The fair values below are gross values before netting agreements and netting of cash collateral.



	September 30					December 31
	2015					2014
	Notional Contract Amount		Fair Value			Notional Contract Amount		Fair Value
Great Plains Energy	(millions)
Futures contracts
Non-hedging derivatives	$	26.7	$	(4.5	)	$	14.9	$	(2.4	)
Forward contracts
Non-hedging derivatives	19.3		3.5			29.7		4.1
Transmission congestion rights
Non-hedging derivatives	9.2		(0.2		)	28.3		2.6
Option contracts
Non-hedging derivatives	—		—			1.7		0.1
KCP&L
Futures contracts
Non-hedging derivatives	$	1.5	$	0.1		$	—	$	—
Transmission congestion rights
Non-hedging derivatives	6.8		(0.2		)	23.6		3.1

The fair values of Great Plains Energy's and KCP&L's open derivative positions and balance sheet classification are summarized in the following tables. The fair values below are gross values before netting agreements and netting of cash collateral.

Great Plains Energy

Balance Sheet

Asset Derivatives

Liability Derivatives

September 30, 2015

Classification

Fair Value

Derivatives Not Designated as Hedging Instruments

(millions)

Commodity contracts

Other

4.0

5.2

December 31, 2014

Derivatives Not Designated as Hedging Instruments

Commodity contracts

Other

8.6

4.2

KCP&L

Balance Sheet

Asset Derivatives

Liability Derivatives

September 30, 2015

Classification

Fair Value

Derivatives Not Designated as Hedging Instruments

(millions)

Commodity contracts

Other

0.4

0.5

December 31, 2014

Derivatives Not Designated as Hedging Instruments

Commodity contracts

Other

4.0

0.9

The following tables provide information regarding Great Plains Energy's and KCP&L's offsetting of derivative assets and liabilities.



Great Plains Energy
											Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts Recognized			Gross Amounts Offset in the Statement of Financial Position				Net Amounts Presented in the Statement of Financial Position			Financial Instruments			Cash Collateral			Net Amount
September 30, 2015	(millions)
Derivative assets		$	4.0		$	(0.4	)		$	3.6		$	—		$	—		$	3.6
Derivative liabilities		5.2			(5.0		)		0.2			—			—			0.2
December 31, 2014
Derivative assets		$	8.6		$	(1.2	)		$	7.4		$	—		$	—		$	7.4
Derivative liabilities		4.2			(3.5		)		0.7			—			—			0.7



KCP&L
											Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts Recognized			Gross Amounts Offset in the Statement of Financial Position				Net Amounts Presented in the Statement of Financial Position			Financial Instruments			Cash Collateral			Net Amount
September 30, 2015	(millions)
Derivative assets		$	0.4		$	(0.3	)		$	0.1		$	—		$	—		$	0.1
Derivative liabilities		0.5			(0.4		)		0.1			—			—			0.1
December 31, 2014
Derivative assets		$	4.0		$	(0.9	)		$	3.1		$	—		$	—		$	3.1
Derivative liabilities		0.9			(0.9		)		—			—			—			—

At September 30, 2015, and December 31, 2014, Great Plains Energy offset $4.6 million and $2.3 million, respectively, of cash collateral posted with counterparties against net derivative positions.

See Note 17 for information regarding amounts reclassified out of accumulated other comprehensive loss for Great Plains Energy and KCP&L.

Great Plains Energy's accumulated OCI at September 30, 2015, includes $9.3 million that is expected to be reclassified to expenses over the next twelve months. KCP&L's accumulated OCI at September 30, 2015, includes $8.8 million that is expected to be reclassified to expenses over the next twelve months.

The following tables summarize the amounts of gain (loss) recognized for the change in fair value of commodity contract derivatives not designated as hedging instruments for Great Plains Energy and KCP&L.



Great Plains Energy
	Three Months Ended September 30						Year to Date September 30
Derivatives Not Designated as Hedging Instruments	2015			2014			2015			2014
Location of Gain (Loss)	(millions)
Electric revenues	$	(0.2	)	$	(10.0	)	$	(7.9	)	$	(12.3	)
Fuel	(0.1		)	0.8			(1.2		)	1.8
Purchased power	(0.2		)	(4.8		)	(1.4		)	(4.4		)
Regulatory asset	(1.9		)	3.2			(5.1		)	(0.9		)
Regulatory liability	—			(0.2		)	—			—
Total	$	(2.4	)	$	(11.0	)	$	(15.6	)	$	(15.8	)



KCP&L
	Three Months Ended September 30						Year to Date September 30
Derivatives Not Designated as Hedging Instruments	2015			2014			2015			2014
Location of Gain (Loss)	(millions)
Electric revenues	$	(0.2	)	$	(10.0	)	$	(7.9	)	$	(12.3	)
Fuel	1.1			1.0			1.3			1.1
Regulatory asset	(0.1		)	1.7			(0.1		)	(0.5		)
Total	$	0.8		$	(7.3	)	$	(6.7	)	$	(11.7	)

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

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+ Details

Fair Value Measurements

9 Months Ended

Sep. 30, 2015

Fair Value Disclosures [Abstract]

Fair Value Measurements

16. FAIR VALUE MEASUREMENTS

GAAP defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. GAAP establishes a fair value hierarchy, which prioritizes the inputs to valuation techniques used to measure fair value into three broad categories, giving the highest priority to quoted prices in active markets for identical assets or liabilities and lowest priority to unobservable inputs. A definition of the various levels, as well as discussion of the various measurements within the levels, is as follows:

Level 1 – Unadjusted quoted prices for identical assets or liabilities in active markets that Great Plains Energy and KCP&L have access to at the measurement date.

Level 2 – Market-based inputs for assets or liabilities that are observable (either directly or indirectly) or inputs that are not observable but are corroborated by market data.

Level 3 – Unobservable inputs, reflecting Great Plains Energy's and KCP&L's own assumptions about the assumptions market participants would use in pricing the asset or liability.

Great Plains Energy and KCP&L record cash and cash equivalents and short-term borrowings on the balance sheet at cost, which approximates fair value due to the short-term nature of these instruments.

Great Plains Energy and KCP&L record long-term debt on the balance sheet at amortized cost. The fair value of long-term debt is measured as a Level 2 liability and is based on quoted market prices, with the incremental borrowing rate for similar debt used to determine fair value if quoted market prices are not available. At September 30, 2015, the book value and fair value of Great Plains Energy's long-term debt, including current maturities, were $3.8 billion and $4.1 billion, respectively. At December 31, 2014, the book value and fair value of Great Plains Energy's long-term debt, including current maturities, were $3.5 billion and $3.8 billion, respectively. At September 30, 2015, the book value and fair value of KCP&L's long-term debt, including current maturities, were $2.6 billion and $2.8 billion, respectively. At December 31, 2014, the book value and fair value of KCP&L's long-term debt, including current maturities, were $2.3 billion and $2.6 billion, respectively.

The following tables include Great Plains Energy's and KCP&L's balances of financial assets and liabilities measured at fair value on a recurring basis. The fair values below are gross values before netting arrangements and netting of cash collateral.



Description	September 30 2015			Level 1		Level 2			Level 3
KCP&L		(millions)
Assets
Nuclear decommissioning trust ^(a)
Equity securities		$	128.4	$	128.4		$	—		$	—
Debt securities
U.S. Treasury		27.4		27.4			—			—
U.S. Agency		1.8		—			1.8			—
State and local obligations		4.0		—			4.0			—
Corporate bonds		28.4		—			28.4			—
Foreign governments		0.3		—			0.3			—
Cash equivalents		2.8		2.8			—			—
Total nuclear decommissioning trust		193.1		158.6			34.5			—
Self-insured health plan trust ^(b)
Equity securities		1.1		1.1			—			—
Debt securities		7.2		—			7.2			—
Cash and cash equivalents		6.4		6.4			—			—
Total self-insured health plan trust		14.7		7.5			7.2			—
Derivative instruments ^(c)		0.4		0.1			—			0.3
Total		$	208.2	$	166.2		$	41.7		$	0.3
Liabilities
Derivative instruments ^(c)		0.5		—			—			0.5
Total		$	0.5	$	—		$	—		$	0.5
Other Great Plains Energy
Assets
Derivative instruments ^(c)		$	3.6	$	—		$	2.9		$	0.7
SERP rabbi trusts ^(d)
Equity securities		0.1		0.1			—			—
Fixed income funds		16.9		—			16.9			—
Total SERP rabbi trusts		17.0		0.1			16.9			—
Total		20.6		0.1			19.8			0.7
Liabilities
Derivative instruments ^(c)		4.7		4.6			—			0.1
Total		$	4.7	$	4.6		$	—		$	0.1
Great Plains Energy
Assets
Nuclear decommissioning trust ^(a)		$	193.1	$	158.6		$	34.5		$	—
Self-insured health plan trust ^(b)		14.7		7.5			7.2			—
Derivative instruments ^(c)		4.0		0.1			2.9			1.0
SERP rabbi trusts ^(d)		17.0		0.1			16.9			—
Total		228.8		166.3			61.5			1.0
Liabilities
Derivative instruments ^(c)		5.2		4.6			—			0.6
Total		$	5.2	$	4.6		$	—		$	0.6



Description	December 31 2014			Level 1			Level 2			Level 3
KCP&L		(millions)
Assets
Nuclear decommissioning trust ^(a)
Equity securities		$	137.1		$	137.1		$	—		$	—
Debt securities
U.S. Treasury		22.9			22.9			—			—
U.S. Agency		3.5			—			3.5			—
State and local obligations		4.1			—			4.1			—
Corporate bonds		28.1			—			28.1			—
Foreign governments		0.5			—			0.5			—
Cash equivalents		2.3			2.3			—			—
Other		0.5			—			0.5			—
Total nuclear decommissioning trust		199.0			162.3			36.7			—
Self-insured health plan trust ^(b)
Equity securities		1.3			1.3			—			—
Debt securities		7.6			—			7.6			—
Cash and cash equivalents		6.2			6.2			—			—
Total self-insured health plan trust		15.1			7.5			7.6			—
Derivative instruments ^(c)		4.0			—			—			4.0
Total		$	218.1		$	169.8		$	44.3		$	4.0
Liabilities
Derivative instruments ^(c)		0.9			—			—			0.9
Total		$	0.9		$	—		$	—		$	0.9
Other Great Plains Energy
Assets
Derivative instruments ^(c)		$	4.6		$	—		$	3.4		$	1.2
SERP rabbi trusts ^(d)
Equity securities		0.1			0.1			—			—
Fixed income funds		17.8			—			17.8			—
Total SERP rabbi trusts		17.9			0.1			17.8			—
Total		22.5			0.1			21.2			1.2
Liabilities
Derivative instruments ^(c)		3.3			2.4			0.1			0.8
Total		$	3.3		$	2.4		$	0.1		$	0.8
Great Plains Energy
Assets
Nuclear decommissioning trust ^(a)		$	199.0		$	162.3		$	36.7		$	—
Self-insured health plan trust ^(b)		15.1			7.5			7.6			—
Derivative instruments ^(c)		8.6			—			3.4			5.2
SERP rabbi trusts ^(d)		17.9			0.1			17.8			—
Total		240.6			169.9			65.5			5.2
Liabilities
Derivative instruments ^(c)		4.2			2.4			0.1			1.7
Total		$	4.2		$	2.4		$	0.1		$	1.7


^(a)	Fair value is based on quoted market prices of the investments held by the fund and/or valuation models.


^(b)	Fair value is based on quoted market prices of the investments held by the trust. Debt securities classified as Level 2 are comprised of corporate bonds, U.S. Agency, state and local obligations, and other asset-backed securities.

^(c)

The fair value of derivative instruments is estimated using market quotes, over-the-counter forward price and volatility curves and correlations among fuel prices, net of estimated credit risk. Derivative instruments classified as Level 1 represent exchange traded derivative instruments. Derivative instruments classified as Level 2 represent non-exchange traded derivative instruments traded in over-the-counter markets. Derivative instruments classified as Level 3 represent non-exchange traded derivatives traded in over-the-counter markets for which observable market data is not available to corroborate the valuation inputs and TCRs valued at the most recent auction price in the SPP Integrated Marketplace.


^(d)	Fair value is based on quoted market prices for equity securities and Net Asset Value (NAV) per share for fixed income funds. The fixed income fund invests primarily in intermediate and long-term debt securities, can be redeemed immediately and is not subject to any restrictions on redemptions.

The following tables reconcile the beginning and ending balances for all Level 3 assets and liabilities measured at fair value on a recurring basis.



Great Plains Energy
Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
	Derivative Instruments
	2015			2014
	(millions)
Net asset at July 1	$	0.8		$	0.6
Total realized/unrealized gains (losses):
included in electric revenue	(0.2		)	(10.0		)
included in purchased power expense	(0.2		)	(4.8		)
included in non-operating income	3.2			2.2
included in regulatory (asset) liability	(0.1		)	3.4
Purchases	(0.2		)	1.7
Settlements	(2.9		)	9.9
Net asset at September 30	$	0.4		$	3.0
Total unrealized gains (losses) relating to assets and liabilities still on the consolidated balance sheet at September 30:
included in electric revenue	$	(0.1	)	$	1.9
included in non-operating income	—			(0.2		)
included in regulatory (asset) liability	(0.1		)	3.4

Great Plains Energy
Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
	Derivative Instruments
	2015			2014
	(millions)
Net asset at January 1	$	3.5		$	3.3
Total realized/unrealized gains (losses):
included in electric revenue	(7.9		)	(12.3		)
included in purchased power expense	(1.4		)	(4.4		)
included in non-operating income	6.9			13.3
included in regulatory asset	(0.1		)	(0.7		)
Purchases	0.4			15.1
Settlements	(1.0		)	(11.3		)
Net asset at September 30	$	0.4		$	3.0
Total unrealized losses relating to assets and liabilities still on the consolidated balance sheet at September 30:
included in electric revenue	$	(0.1	)	$	(0.6	)
included in non-operating income	(0.1		)	—
included in regulatory asset	(0.1		)	(0.7		)



KCP&L
Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
	Derivative Instruments
	2015			2014
	(millions)
Net asset at July 1	$	0.1		$	0.9
Total realized/unrealized gains (losses):
included in electric revenue	(0.2		)	(10.0		)
included in regulatory (asset) liability	(0.1		)	1.7
Purchases	(0.2		)	1.3
Settlements	0.2			8.8
Net asset (liability) at September 30	$	(0.2	)	$	2.7
Total unrealized gains (losses) relating to assets and liabilities still on the consolidated balance sheet at September 30:
included in electric revenue	$	(0.1	)	$	1.9
included in regulatory (asset) liability	(0.1		)	1.7

KCP&L
Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
	Derivative Instruments
	2015			2014
	(millions)
Net asset at January 1	$	3.1		$	1.1
Total realized/unrealized gains (losses):
included in electric revenue	(7.9		)	(12.3		)
included in regulatory asset	(0.1		)	(0.5		)
Purchases	(0.4		)	13.1
Settlements	5.1			1.3
Net asset (liability) at September 30	$	(0.2	)	$	2.7
Total unrealized losses relating to assets and liabilities still on the consolidated balance sheet at September 30:
included in electric revenue	$	(0.1	)	$	(0.6	)
included in regulatory asset	(0.1		)	(0.5		)

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References+ Details

Accumulated Other Comprehensive Income (Loss)

9 Months Ended

Sep. 30, 2015

Accumulated Other Comprehensive Income (Loss) [Text Block]

17. ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

The following tables reflect the change in the balances of each component of accumulated other comprehensive loss for Great Plains Energy and KCP&L.



Great Plains Energy
	Gains and Losses on Cash Flow Hedges^(a)				Defined Benefit Pension Items^(a)				Total^(a)
	(millions)
Year to Date September 30, 2015
Beginning balance January 1		$	(15.8	)		$	(2.9	)	$	(18.7	)
Amounts reclassified from accumulated other comprehensive loss		4.2				0.3			4.5
Net current period other comprehensive income		4.2				0.3			4.5
Ending balance September 30		$	(11.6	)		$	(2.6	)	$	(14.2	)
Year to Date September 30, 2014
Beginning balance January 1		$	(23.8	)		$	(1.5	)	$	(25.3	)
Amounts reclassified from accumulated other comprehensive loss		6.6				0.3			6.9
Net current period other comprehensive income		6.6				0.3			6.9
Ending balance September 30		$	(17.2	)		$	(1.2	)	$	(18.4	)

^(a) Net of tax



KCP&L
	Gains and Losses on Cash Flow Hedges^(a)
	(millions)
Year to Date September 30, 2015
Beginning balance January 1		$	(14.9	)
Amounts reclassified from accumulated other comprehensive loss		4.0
Net current period other comprehensive income		4.0
Ending balance September 30		$	(10.9	)
Year to Date September 30, 2014
Beginning balance January 1		$	(20.2	)
Amounts reclassified from accumulated other comprehensive loss		3.9
Net current period other comprehensive income		3.9
Ending balance September 30		$	(16.3	)

^(a) Net of tax

The following tables reflect the effect on certain line items of net income from amounts reclassified out of each component of accumulated other comprehensive loss for Great Plains Energy and KCP&L.



Great Plains Energy
Details about Accumulated Other Comprehensive Loss Components	Amount Reclassified from Accumulated Other Comprehensive Loss						Affected Line Item in the Income Statement
Three Months Ended September 30	2015			2014
	(millions)
Gains and (losses) on cash flow hedges (effective portion)
Interest rate contracts	$	(2.3	)	$	(2.3	)	Interest charges
	(2.3		)	(2.3		)	Income before income tax expense and income from equity investments
	0.9			1.0			Income tax benefit
	$	(1.4	)	$	(1.3	)	Net income
Amortization of defined benefit pension items
Net losses included in net periodic benefit costs	$	(0.1	)	$	(0.1	)	Utility operating and maintenance expenses
	(0.1		)	(0.1		)	Income before income tax expense and income from equity investments
	0.1			—			Income tax benefit
	$	—		$	(0.1	)	Net income

Total reclassifications, net of tax	$	(1.4	)	$	(1.4	)	Net income

Great Plains Energy
Details about Accumulated Other Comprehensive Loss Components	Amount Reclassified from Accumulated Other Comprehensive Loss						Affected Line Item in the Income Statement
Year to Date September 30	2015			2014
	(millions)
Gains and (losses) on cash flow hedges (effective portion)
Interest rate contracts	$	(6.9	)	$	(10.9	)	Interest charges
	(6.9		)	(10.9		)	Income before income tax expense and income from equity investments
	2.7			4.3			Income tax benefit
	$	(4.2	)	$	(6.6	)	Net income
Amortization of defined benefit pension items
Net losses included in net periodic benefit costs	$	(0.5	)	$	(0.4	)	Utility operating and maintenance expenses
	(0.5		)	(0.4		)	Income before income tax expense and income from equity investments
	0.2			0.1			Income tax benefit
	$	(0.3	)	$	(0.3	)	Net income

Total reclassifications, net of tax	$	(4.5	)	$	(6.9	)	Net income



KCP&L
Details about Accumulated Other Comprehensive Loss Components	Amount Reclassified from Accumulated Other Comprehensive Loss						Affected Line Item in the Income Statement
Three Months Ended September 30	2015			2014
	(millions)
Gains and (losses) on cash flow hedges (effective portion)
Interest rate contracts	$	(2.2	)	$	(2.1	)	Interest charges
	(2.2		)	(2.1		)	Income before income tax expense
	0.9			0.9			Income tax benefit
Total reclassifications, net of tax	$	(1.3	)	$	(1.2	)	Net income

KCP&L
Details about Accumulated Other Comprehensive Loss Components	Amount Reclassified from Accumulated Other Comprehensive Loss						Affected Line Item in the Income Statement
Year to Date September 30	2015			2014
	(millions)
Gains and (losses) on cash flow hedges (effective portion)
Interest rate contracts	$	(6.6	)	$	(6.5	)	Interest charges
	(6.6		)	(6.5		)	Income before income tax expense
	2.6			2.6			Income tax benefit
Total reclassifications, net of tax	$	(4.0	)	$	(3.9	)	Net income

The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income.

Income Tax Disclosure [Text Block]

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Taxes

9 Months Ended

Sep. 30, 2015

Income Tax Disclosure [Abstract]

18. TAXES

Components of income tax expense are detailed in the following tables.



	Three Months Ended September 30						Year to Date September 30
Great Plains Energy	2015			2014			2015			2014
Current income taxes	(millions)
Federal	$	(0.8	)	$	(0.7	)	$	(0.3	)	$	(0.6	)
State	0.5			(0.1		)	0.4			—
Total	(0.3		)	(0.8		)	0.1			(0.6		)
Deferred income taxes
Federal	66.4			69.0			91.8			100.6
State	12.4			12.9			18.3			19.7
Total	78.8			81.9			110.1			120.3
Noncurrent income taxes
Federal	—			—			—			(2.4		)
State	—			—			—			(0.3		)
Foreign	—			(6.2		)	—			(6.2		)
Total	—			(6.2		)	—			(8.9		)
Investment tax credit
Deferral	0.5			—			0.5			—
Amortization	(0.4		)	(0.2		)	(1.1		)	(1.0		)
Total	0.1			(0.2		)	(0.6		)	(1.0		)
Income tax expense	$	78.6		$	74.7		$	109.6		$	109.8



	Three Months Ended September 30						Year to Date September 30
KCP&L	2015			2014			2015			2014
Current income taxes	(millions)
Federal	$	43.9		$	33.8		$	42.4		$	34.5
State	7.1			5.9			6.7			6.1
Total	51.0			39.7			49.1			40.6
Deferred income taxes
Federal	(1.6		)	10.9			14.6			26.2
State	0.8			2.9			5.2			6.8
Total	(0.8		)	13.8			19.8			33.0
Investment tax credit
Deferral	0.5			—			0.5			—
Amortization	(0.2		)	(0.2		)	(0.7		)	(0.7		)
Total	0.3			(0.2		)	(0.2		)	(0.7		)
Income tax expense	$	50.5		$	53.3		$	68.7		$	72.9

Effective Income Tax Rates

Effective income tax rates reflected in the financial statements and the reasons for their differences from the statutory federal rates are detailed in the following tables.



	Three Months Ended September 30				Year to Date September 30
Great Plains Energy	2015		2014		2015		2014
Federal statutory income tax rate	35.0	%	35.0	%	35.0	%	35.0	%
Differences between book and tax depreciation not normalized	0.3		(0.3	)	0.4		(0.5	)
Amortization of investment tax credits	(0.2	)	(0.1	)	(0.4	)	(0.3	)
Federal income tax credits	(1.2	)	(1.8	)	(2.6	)	(3.0	)
State income taxes	4.2		3.7		4.0		3.7
Changes in uncertain tax positions, net	—		(2.8	)	—		(1.8	)
Other	0.2		(0.1	)	0.2		(0.2	)
Effective income tax rate	38.3	%	33.6	%	36.6	%	32.9	%



	Three Months Ended September 30				Year to Date September 30
KCP&L	2015		2014		2015		2014
Federal statutory income tax rate	35.0	%	35.0	%	35.0	%	35.0	%
Differences between book and tax depreciation not normalized	0.4		(0.2	)	0.6		(0.7	)
Amortization of investment tax credits	(0.2	)	(0.2	)	(0.4	)	(0.4	)
Federal income tax credits	(1.8	)	(2.4	)	(3.9	)	(4.3	)
State income taxes	3.9		3.9		3.9		3.8
Other	0.1		—		(0.1	)	(0.1	)
Effective income tax rate	37.4	%	36.1	%	35.1	%	33.3	%

Segments and Related Information

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References+ Details

Segments and Related Information

9 Months Ended

Sep. 30, 2015

Segment Reporting [Abstract]

19. SEGMENTS AND RELATED INFORMATION

Great Plains Energy has one reportable segment based on its method of internal reporting, which segregates reportable segments based on products and services, management responsibility and regulation. The one reportable business segment is electric utility, consisting of KCP&L, GMO's regulated utility operations and GMO Receivables Company. Other includes GMO activity other than its regulated utility operations, GPETHC and unallocated corporate charges. The summary of significant accounting policies applies to the reportable segment. Segment performance is evaluated based on net income.

The following tables reflect summarized financial information concerning Great Plains Energy's reportable segment.



Three Months Ended September 30, 2015	Electric Utility				Other				Eliminations			Great Plains Energy
		(millions)
Operating revenues		$	781.4			$	—			$	—		$	781.4
Depreciation and amortization		(82.4		)		—				—			(82.4		)
Interest (charges) income		(48.9		)		(10.2		)		8.1			(51.0		)
Income tax (expense) benefit		(78.5		)		(0.1		)		—			(78.6		)
Net income (loss)		129.1				(2.3		)		—			126.8

Year to Date September 30, 2015	Electric Utility				Other				Eliminations			Great Plains Energy
		(millions)
Operating revenues		$	1,939.5			$	—			$	—		$	1,939.5
Depreciation and amortization		(245.7		)		—				—			(245.7		)
Interest (charges) income		(142.1		)		(30.3		)		24.1			(148.3		)
Income tax (expense) benefit		(112.0		)		2.4				—			(109.6		)
Net income (loss)		196.4				(6.3		)		—			190.1



Three Months Ended September 30, 2014	Electric Utility				Other				Eliminations			Great Plains Energy
		(millions)
Operating revenues		$	782.5			$	—			$	—		$	782.5
Depreciation and amortization		(76.6		)		—				—			(76.6		)
Interest (charges) income		(44.9		)		(6.8		)		8.1			(43.6		)
Income tax (expense) benefit		(81.0		)		6.3				—			(74.7		)
Net income (loss)		140.3				7.1				—			147.4

Year to Date September 30, 2014	Electric Utility				Other				Eliminations			Great Plains Energy
		(millions)
Operating revenues		$	2,016.0			$	—			$	—		$	2,016.0
Depreciation and amortization		(226.7		)		—				—			(226.7		)
Interest (charges) income		(137.9		)		(31.1		)		27.7			(141.3		)
Income tax (expense) benefit		(118.8		)		9.0				—			(109.8		)
Net income (loss)		221.1				2.2				—			223.3



	Electric Utility			Other			Eliminations				Great Plains Energy
September 30, 2015		(millions)
Assets		$	11,053.9		$	163.6		$	(373.4	)		$	10,844.1
Capital expenditures ^(a)		520.9			—			—				520.9
December 31, 2014
Assets		$	10,746.1		$	33.1		$	(303.5	)		$	10,475.7
Capital expenditures ^(a)		773.7			—			—				773.7

^(a) Capital expenditures reflect year to date amounts for the periods presented.

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 40

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9031-108599

Reference 13: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 33

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8971-108599

Reference 14: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8595-108599

+ Details

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2015

Accounting Policies [Abstract]

Organization


•	KCP&L is an integrated, regulated electric utility that provides electricity to customers primarily in the states of Missouri and Kansas. KCP&L has one active wholly owned subsidiary, Kansas City Power & Light Receivables Company (KCP&L Receivables Company).

•

Each of Great Plains Energy's and KCP&L's consolidated financial statements includes the accounts of their subsidiaries. Intercompany transactions have been eliminated.

Great Plains Energy's sole reportable business segment is electric utility. See Note 19 for additional information.

Basic and Diluted Earnings per Common Share Calculation [Policy Text Block]

Basic and Diluted Earnings per Common Share Calculation

New Accounting Pronouncements, Policy [Policy Text Block]

New Accounting Standards

Disclosure of accounting policy regarding (1) the principles it follows in consolidating or combining the separate financial statements, including the principles followed in determining the inclusion or exclusion of subsidiaries or other entities in the consolidated or combined financial statements and (2) its treatment of interests (for example, common stock, a partnership interest or other means of exerting influence) in other entities, for example consolidation or use of the equity or cost methods of accounting. The accounting policy may also address the accounting treatment for intercompany accounts and transactions, noncontrolling interest, and the income statement treatment in consolidation for issuances of stock by a subsidiary.

+ References+ Details

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

Disclosure of accounting policy for computing basic and diluted earnings or loss per share for each class of common stock and participating security. Addresses all significant policy factors, including any antidilutive items that have been excluded from the computation and takes into account stock dividends, splits and reverse splits that occur after the balance sheet date of the latest reporting period but before the issuance of the financial statements.

+ References+ Details

Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2015

Accounting Policies [Abstract]

The following table reconciles Great Plains Energy's basic and diluted EPS.



	Three Months Ended September 30				Year to Date September 30
	2015		2014		2015		2014
Income	(millions, except per share amounts)
Net income	$	126.8	$	147.4	$	190.1	$	223.3
Less: preferred stock dividend requirements	0.4		0.4		1.2		1.2
Earnings available for common shareholders	$	126.4	$	147.0	$	188.9	$	222.1
Common Shares Outstanding
Average number of common shares outstanding	154.2		153.9		154.1		153.8
Add: effect of dilutive securities	0.6		0.4		0.7		0.4
Diluted average number of common shares outstanding	154.8		154.3		154.8		154.2
Basic EPS	$	0.82	$	0.96	$	1.23	$	1.44
Diluted EPS	$	0.82	$	0.95	$	1.22	$	1.44

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

Anti-dilutive shares excluded from the computation of diluted EPS are detailed in the following table.



	Three Months Ended September 30		Year to Date September 30
	2015	2014	2015	2014
Performance shares	—	108,832	—	108,832
Restricted stock shares	—	73,671	—	71,860

Supplemental Cash Flow Information (Tables)

9 Months Ended

Sep. 30, 2015

Supplemental Cash Flow Elements [Abstract]

Schedule of Cash Flow, Supplemental Disclosures [Table Text Block]



Great Plains Energy Other Operating Activities
Year to Date September 30	2015			2014
Cash flows affected by changes in:	(millions)
Receivables	$	(13.2	)	$	(70.4	)
Accounts receivable pledged as collateral	(19.0		)	4.0
Fuel inventories	(10.8		)	23.3
Materials and supplies	(2.9		)	1.7
Accounts payable	(121.9		)	(75.2		)
Accrued taxes	89.2			91.2
Accrued interest	16.9			11.4
Deferred refueling outage costs	(12.8		)	15.8
Pension and post-retirement benefit obligations	48.8			24.8
Allowance for equity funds used during construction	(3.8		)	(13.2		)
Fuel recovery mechanism	36.6			(21.3		)
Solar rebates paid	(7.3		)	(43.9		)
Other	9.9			(10.0		)
Total other operating activities	$	9.7		$	(61.8	)
Cash paid during the period:
Interest	$	121.2		$	115.6
Income taxes	$	0.2		$	0.1
Non-cash investing activities:
Liabilities accrued for capital expenditures	$	23.4		$	50.5



KCP&L Other Operating Activities
Year to Date September 30	2015			2014
Cash flows affected by changes in:	(millions)
Receivables	$	(6.2	)	$	(70.5	)
Fuel inventories	(11.6		)	18.3
Materials and supplies	(4.0		)	0.5
Accounts payable	(83.1		)	(34.7		)
Accrued taxes	162.3			118.2
Accrued interest	12.3			10.8
Deferred refueling outage costs	(12.8		)	15.8
Pension and post-retirement benefit obligations	48.8			23.6
Allowance for equity funds used during construction	(2.9		)	(12.3		)
Fuel recovery mechanism	1.8			1.4
Solar rebates paid	(6.0		)	(14.8		)
Other	5.0			(23.9		)
Total other operating activities	$	103.6		$	32.4
Cash paid during the period:
Interest	$	79.1		$	72.9
Non-cash investing activities:
Liabilities accrued for capital expenditures	$	15.7		$	44.4

Receivables (Tables)

9 Months Ended

Sep. 30, 2015

Receivables [Abstract]

Schedule of receivables [Table Text Block]

Great Plains Energy's and KCP&L's receivables are detailed in the following table.



	September 30				December 31
		2015				2014
Great Plains Energy		(millions)
Customer accounts receivable - billed		$	28.1			$	1.1
Customer accounts receivable - unbilled		81.4				75.3
Allowance for doubtful accounts - customer accounts receivable		(4.1		)		(2.8		)
Other receivables		68.0				86.7
Total		$	173.4			$	160.3
KCP&L
Customer accounts receivable - billed		$	27.6			$	0.6
Customer accounts receivable - unbilled		59.3				49.7
Allowance for doubtful accounts - customer accounts receivable		(1.9		)		(1.2		)
Other receivables		61.8				79.8
Total		$	146.8			$	128.9

Schedule of accounts receivable sold [Table Text Block]

Information regarding KCP&L's sale of accounts receivable to KCP&L Receivables Company and GMO's sale of accounts receivable to GMO Receivables Company is reflected in the following tables.



Three Months Ended September 30, 2015	KCP&L				KCP&L Receivables Company				Consolidated KCP&L				GMO				GMO Receivables Company				Consolidated Great Plains Energy
	(millions)
Receivables (sold) purchased		$	(495.5	)		$	495.5			$	—			$	(267.4	)		$	267.4			$	—
Gain (loss) on sale of accounts receivable ^(a)		(6.3		)		6.1				(0.2		)		(3.4		)		3.4				(0.2		)
Servicing fees received (paid)		0.8				(0.8		)		—				0.4				(0.4		)		—
Fees paid to outside investor		—				(0.3		)		(0.3		)		—				(0.2		)		(0.5		)
Cash from customers (transferred) received		(489.5		)		489.5				—				(267.7		)		267.7				—
Cash received from (paid for) receivables purchased		483.4				(483.4		)		—				264.4				(264.4		)		—
Interest on intercompany note received (paid)		0.1				(0.1		)		—				—				—				—



Year to Date September 30, 2015	KCP&L				KCP&L Receivables Company				Consolidated KCP&L				GMO				GMO Receivables Company				Consolidated Great Plains Energy
	(millions)
Receivables (sold) purchased		$	(1,234.0	)		$	1,234.0			$	—			$	(656.7	)		$	656.7			$	—
Gain (loss) on sale of accounts receivable ^(a)		(15.6		)		15.1				(0.5		)		(8.3		)		8.1				(0.7		)
Servicing fees received (paid)		2.0				(2.0		)		—				1.0				(1.0		)		—
Fees paid to outside investor		—				(0.7		)		(0.7		)		—				(0.4		)		(1.1		)
Cash from customers (transferred) received		(1,205.6		)		1,205.6				—				(646.0		)		646.0				—
Cash received from (paid for) receivables purchased		1,190.5				(1,190.5		)		—				638.0				(638.0		)		—
Interest on intercompany note received (paid)		0.2				(0.2		)		—				0.1				(0.1		)		—



Three Months Ended September 30, 2014	KCP&L				KCP&L Receivables Company				Consolidated KCP&L				GMO				GMO Receivables Company				Consolidated Great Plains Energy
	(millions)
Receivables (sold) purchased		$	(472.9	)		$	472.9			$	—			$	(251.3	)		$	251.3			$	—
Gain (loss) on sale of accounts receivable ^(a)		(6.0		)		5.9				(0.1		)		(3.1		)		3.2				—
Servicing fees received (paid)		0.8				(0.8		)		—				0.4				(0.4		)		—
Fees paid to outside investor		—				(0.3		)		(0.3		)		—				(0.2		)		(0.5		)
Cash from customers (transferred) received		(471.5		)		471.5				—				(253.2		)		253.2				—
Cash received from (paid for) receivables purchased		465.6				(465.6		)		—				250.0				(250.0		)		—
Interest on intercompany note received (paid)		0.1				(0.1		)		—				—				—				—



Year to Date September 30, 2014	KCP&L				KCP&L Receivables Company				Consolidated KCP&L				GMO				GMO Receivables Company				Consolidated Great Plains Energy
	(millions)
Receivables (sold) purchased		$	(1,206.9	)		$	1,206.9			$	—			$	(643.0	)		$	643.0			$	—
Gain (loss) on sale of accounts receivable ^(a)		(15.3		)		14.9				(0.4		)		(8.1		)		7.9				(0.6		)
Servicing fees received (paid)		2.0				(2.0		)		—				1.0				(1.0		)		—
Fees paid to outside investor		—				(0.9		)		(0.9		)		—				(0.5		)		(1.4		)
Cash from customers (transferred) received		(1,187.3		)		1,187.3				—				(630.5		)		630.5				—
Cash received from (paid for) receivables purchased		1,172.4				(1,172.4		)		—				622.6				(622.6		)		—
Interest on intercompany note received (paid)		0.2				(0.2		)		—				—				—				—

Nuclear Plant (Tables)

9 Months Ended

Sep. 30, 2015

Nuclear Plant [Abstract]

Changes in nuclear decommissioning trust fund

The following table summarizes the change in Great Plains Energy's and KCP&L's nuclear decommissioning trust fund.



	September 30 2015				December 31 2014
Decommissioning Trust		(millions)
Beginning balance January 1		$	199.0			$	183.9
Contributions		2.5				3.3
Earned income, net of fees		2.4				3.6
Net realized gains		0.9				0.4
Net unrealized gains (losses)		(11.7		)		7.8
Ending balance		$	193.1			$	199.0

Detail of assets held in nuclear decommissioning trust fund

The nuclear decommissioning trust is reported at fair value on the balance sheets and is invested in assets as detailed in the following table.



	September 30, 2015													December 31, 2014
	Cost Basis		Unrealized Gains			Unrealized Losses				Fair Value			Cost Basis			Unrealized Gains			Unrealized Losses				Fair Value
	(millions)
Equity securities	$	89.4		$	42.2		$	(3.2	)		$	128.4		$	87.2		$	50.6		$	(0.7	)		$	137.1
Debt securities	59.0			3.2			(0.3		)		61.9			55.4			3.8			(0.1		)		59.1
Other	2.8			—			—				2.8			2.8			—			—				2.8
Total	$	151.2		$	45.4		$	(3.5	)		$	193.1		$	145.4		$	54.4		$	(0.8	)		$	199.0

Gains and losses from the sale of securities by the nuclear decommissioning trust fund

The following table summarizes the realized gains and losses from the sale of securities in the nuclear decommissioning trust fund.



	Three Months Ended September 30						Year to Date September 30
	2015			2014			2015			2014
	(millions)
Realized gains	$	0.6		$	0.3		$	3.2		$	1.0
Realized losses	(0.5		)	(0.1		)	(2.3		)	(0.7		)

Asset Retirement Obligations (Tables)

9 Months Ended

Sep. 30, 2015

Asset Retirement Obligation Disclosure [Abstract]

Schedule of Change in Asset Retirement Obligation [Table Text Block]

The following table summarizes the change in Great Plains Energy's and KCP&L's AROs.



		Great Plains Energy						KCP&L
	September 30			December 31			September 30			December 31
		2015			2014			2015			2014
		(millions)
Beginning balance		$	195.9		$	158.8		$	177.7		$	141.7
Additions		54.5			—			34.6			—
Revision in timing and/or estimates		15.0			26.8			16.7			26.8
Accretion		9.4			10.3			8.5			9.2
Ending balance		$	274.8		$	195.9		$	237.5		$	177.7

Pension Plans and Other Employee Benefits (Tables)

9 Months Ended

Sep. 30, 2015

Defined Benefit Plan Disclosure [Line Items]

Schedule of Net Benefit Costs [Table Text Block]

The following tables provide Great Plains Energy's components of net periodic benefit costs prior to the effects of capitalization and sharing with joint owners of power plants.



	Pension Benefits						Other Benefits
Three Months Ended September 30	2015			2014			2015			2014
Components of net periodic benefit costs	(millions)
Service cost	$	11.4		$	9.1		$	0.8		$	0.9
Interest cost	12.5			12.7			1.7			2.0
Expected return on plan assets	(13.0		)	(12.7		)	(0.7		)	(0.7		)
Prior service cost	0.2			0.2			0.7			0.8
Recognized net actuarial loss	12.9			12.4			0.1			—
Transition obligation	—			—			0.1			—
Net periodic benefit costs before regulatory adjustment	24.0			21.7			2.7			3.0
Regulatory adjustment	(3.5		)	(0.6		)	1.4			1.1
Net periodic benefit costs	$	20.5		$	21.1		$	4.1		$	4.1

	Pension Benefits						Other Benefits
Year to Date September 30	2015			2014			2015			2014
Components of net periodic benefit costs	(millions)
Service cost	$	34.0		$	27.2		$	2.5		$	2.7
Interest cost	37.7			38.1			5.1			6.0
Expected return on plan assets	(38.8		)	(38.1		)	(2.2		)	(2.1		)
Prior service cost	0.6			0.6			2.3			2.4
Recognized net actuarial loss	38.5			37.2			0.2			—
Transition obligation	—			—			0.1			0.1
Net periodic benefit costs before regulatory adjustment	72.0			65.0			8.0			9.1
Regulatory adjustment	(9.3		)	(1.4		)	4.2			3.3
Net periodic benefit costs	$	62.7		$	63.6		$	12.2		$	12.4

Equity Compensation (Tables)

9 Months Ended

Sep. 30, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Equity compensation expense and associated income tax benefits

The following table summarizes Great Plains Energy's and KCP&L's equity compensation expense and the associated income tax benefit.



	Three Months Ended September 30				Year to Date September 30
	2015		2014		2015		2014
Great Plains Energy	(millions)
Equity compensation expense	$	3.7	$	1.0	$	4.6	$	6.4
Income tax benefit	1.4		0.3		1.7		2.3
KCP&L
Equity compensation expense	$	2.5	$	0.6	$	3.1	$	4.4
Income tax benefit	0.9		0.1		1.1		1.5

Performance share activity



	Performance Shares			Grant Date Fair Value*
Beginning balance January 1, 2015		534,016			$	25.11
Granted		232,838			24.03
Earned		(25,844	)		19.48
Forfeited		(46,927	)		25.68
Performance adjustment		(77,515	)		19.48
Ending balance September 30, 2015		616,568			25.60

* weighted-average

Restricted stock activity



	Nonvested Restricted Stock			Grant Date Fair Value*
Beginning balance January 1, 2015		267,390			$	22.31
Granted and issued		91,880			25.88
Vested		(109,246	)		19.68
Forfeited		(15,644	)		24.81
Ending balance September 30, 2015		234,380			24.76

* weighted-average

Long-Term Debt (Tables)

9 Months Ended

Sep. 30, 2015

Debt Disclosure [Abstract]

Schedule of Debt [Table Text Block]

Great Plains Energy's and KCP&L's long-term debt is detailed in the following table.



		September 30				December 31
	Year Due	2015				2014
KCP&L			(millions)
General Mortgage Bonds
2.47% EIRR bonds^(a)	2017-2035		$	110.5			$	146.4
7.15% Series 2009A (8.59% rate)^(b)	2019		400.0				400.0
4.65% EIRR Series 2005	2035		—				50.0
Senior Notes
5.85% Series (5.72% rate)^(b)	2017		250.0				250.0
6.375% Series (7.49% rate)^(b)	2018		350.0				350.0
3.15% Series	2023		300.0				300.0
3.65% Series	2025		350.0				—
6.05% Series (5.78% rate)^(b)	2035		250.0				250.0
5.30% Series	2041		400.0				400.0
EIRR Bonds
0.02% Series 2007A and 2007B^(c)	2035		146.5				146.5
2.875% Series 2008	2038		23.4				23.4
Current maturities			—				(14.0		)
Unamortized discount			(4.9		)		(3.8		)
Total KCP&L excluding current maturities^(d)			2,575.5				2,298.5
Other Great Plains Energy
GMO First Mortgage Bonds 9.44% Series	2016-2021		6.8				7.9
GMO Senior Notes
8.27% Series	2021		80.9				80.9
3.49% Series A	2025		125.0				125.0
4.06% Series B	2033		75.0				75.0
4.74% Series C	2043		150.0				150.0
GMO Medium Term Notes
7.33% Series	2023		3.0				3.0
7.17% Series	2023		7.0				7.0
Great Plains Energy Senior Notes
6.875% Series (7.33% rate)^(b)	2017		100.0				100.0
4.85% Series	2021		350.0				350.0
5.292% Series	2022		287.5				287.5
Current maturities			(1.1		)		(1.1		)
Unamortized discount and premium, net			3.9				4.3
Total Great Plains Energy excluding current maturities^(d)			$	3,763.5			$	3,488.0


^(a)	Weighted-average interest rates at September 30, 2015


^(b)	Rate after amortizing gains/losses recognized in OCI on settlements of interest rate hedging instruments


^(c)	Variable rate


^(d)	Does not include $50.0 million and $21.9 million EIRR Series 2005 bonds because the bonds were repurchased in September 2015 and are held by KCP&L.

Derivative Instruments (Tables)

9 Months Ended

Sep. 30, 2015

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Values of open positions for derivative instruments [Table Text Block]



	September 30					December 31
	2015					2014
	Notional Contract Amount		Fair Value			Notional Contract Amount		Fair Value
Great Plains Energy	(millions)
Futures contracts
Non-hedging derivatives	$	26.7	$	(4.5	)	$	14.9	$	(2.4	)
Forward contracts
Non-hedging derivatives	19.3		3.5			29.7		4.1
Transmission congestion rights
Non-hedging derivatives	9.2		(0.2		)	28.3		2.6
Option contracts
Non-hedging derivatives	—		—			1.7		0.1
KCP&L
Futures contracts
Non-hedging derivatives	$	1.5	$	0.1		$	—	$	—
Transmission congestion rights
Non-hedging derivatives	6.8		(0.2		)	23.6		3.1

Fair value of open derivative positions, gross values before netting agreements and netting of cash collatral [Table Text Block]

Great Plains Energy

Balance Sheet

Asset Derivatives

Liability Derivatives

September 30, 2015

Classification

Fair Value

Derivatives Not Designated as Hedging Instruments

(millions)

Commodity contracts

Other

4.0

5.2

December 31, 2014

Derivatives Not Designated as Hedging Instruments

Commodity contracts

Other

8.6

4.2

KCP&L

Balance Sheet

Asset Derivatives

Liability Derivatives

September 30, 2015

Classification

Fair Value

Derivatives Not Designated as Hedging Instruments

(millions)

Commodity contracts

Other

0.4

0.5

December 31, 2014

Derivatives Not Designated as Hedging Instruments

Commodity contracts

Other

4.0

0.9

Offsetting Derivative Assets and Liabilities [Table Text Block]

The following tables provide information regarding Great Plains Energy's and KCP&L's offsetting of derivative assets and liabilities.



Great Plains Energy
											Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts Recognized			Gross Amounts Offset in the Statement of Financial Position				Net Amounts Presented in the Statement of Financial Position			Financial Instruments			Cash Collateral			Net Amount
September 30, 2015	(millions)
Derivative assets		$	4.0		$	(0.4	)		$	3.6		$	—		$	—		$	3.6
Derivative liabilities		5.2			(5.0		)		0.2			—			—			0.2
December 31, 2014
Derivative assets		$	8.6		$	(1.2	)		$	7.4		$	—		$	—		$	7.4
Derivative liabilities		4.2			(3.5		)		0.7			—			—			0.7



KCP&L
											Gross Amounts Not Offset in the Statement of Financial Position
Description	Gross Amounts Recognized			Gross Amounts Offset in the Statement of Financial Position				Net Amounts Presented in the Statement of Financial Position			Financial Instruments			Cash Collateral			Net Amount
September 30, 2015	(millions)
Derivative assets		$	0.4		$	(0.3	)		$	0.1		$	—		$	—		$	0.1
Derivative liabilities		0.5			(0.4		)		0.1			—			—			0.1
December 31, 2014
Derivative assets		$	4.0		$	(0.9	)		$	3.1		$	—		$	—		$	3.1
Derivative liabilities		0.9			(0.9		)		—			—			—			—

Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]



Great Plains Energy
	Three Months Ended September 30						Year to Date September 30
Derivatives Not Designated as Hedging Instruments	2015			2014			2015			2014
Location of Gain (Loss)	(millions)
Electric revenues	$	(0.2	)	$	(10.0	)	$	(7.9	)	$	(12.3	)
Fuel	(0.1		)	0.8			(1.2		)	1.8
Purchased power	(0.2		)	(4.8		)	(1.4		)	(4.4		)
Regulatory asset	(1.9		)	3.2			(5.1		)	(0.9		)
Regulatory liability	—			(0.2		)	—			—
Total	$	(2.4	)	$	(11.0	)	$	(15.6	)	$	(15.8	)



KCP&L
	Three Months Ended September 30						Year to Date September 30
Derivatives Not Designated as Hedging Instruments	2015			2014			2015			2014
Location of Gain (Loss)	(millions)
Electric revenues	$	(0.2	)	$	(10.0	)	$	(7.9	)	$	(12.3	)
Fuel	1.1			1.0			1.3			1.1
Regulatory asset	(0.1		)	1.7			(0.1		)	(0.5		)
Total	$	0.8		$	(7.3	)	$	(6.7	)	$	(11.7	)

Tabular disclosure of pertinent information about a derivative or group of derivatives on a disaggregated basis, such as for individual instruments, or small groups of similar instruments. May include a combination of the type of instrument, risks being hedged, notional amount, hedge designation, related hedged item, inception date, maturity date, or other relevant item.

Fair value of assets and liabilities

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+ Details

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2015

Fair Value Disclosures [Abstract]



Description	September 30 2015			Level 1		Level 2			Level 3
KCP&L		(millions)
Assets
Nuclear decommissioning trust ^(a)
Equity securities		$	128.4	$	128.4		$	—		$	—
Debt securities
U.S. Treasury		27.4		27.4			—			—
U.S. Agency		1.8		—			1.8			—
State and local obligations		4.0		—			4.0			—
Corporate bonds		28.4		—			28.4			—
Foreign governments		0.3		—			0.3			—
Cash equivalents		2.8		2.8			—			—
Total nuclear decommissioning trust		193.1		158.6			34.5			—
Self-insured health plan trust ^(b)
Equity securities		1.1		1.1			—			—
Debt securities		7.2		—			7.2			—
Cash and cash equivalents		6.4		6.4			—			—
Total self-insured health plan trust		14.7		7.5			7.2			—
Derivative instruments ^(c)		0.4		0.1			—			0.3
Total		$	208.2	$	166.2		$	41.7		$	0.3
Liabilities
Derivative instruments ^(c)		0.5		—			—			0.5
Total		$	0.5	$	—		$	—		$	0.5
Other Great Plains Energy
Assets
Derivative instruments ^(c)		$	3.6	$	—		$	2.9		$	0.7
SERP rabbi trusts ^(d)
Equity securities		0.1		0.1			—			—
Fixed income funds		16.9		—			16.9			—
Total SERP rabbi trusts		17.0		0.1			16.9			—
Total		20.6		0.1			19.8			0.7
Liabilities
Derivative instruments ^(c)		4.7		4.6			—			0.1
Total		$	4.7	$	4.6		$	—		$	0.1
Great Plains Energy
Assets
Nuclear decommissioning trust ^(a)		$	193.1	$	158.6		$	34.5		$	—
Self-insured health plan trust ^(b)		14.7		7.5			7.2			—
Derivative instruments ^(c)		4.0		0.1			2.9			1.0
SERP rabbi trusts ^(d)		17.0		0.1			16.9			—
Total		228.8		166.3			61.5			1.0
Liabilities
Derivative instruments ^(c)		5.2		4.6			—			0.6
Total		$	5.2	$	4.6		$	—		$	0.6



Description	December 31 2014			Level 1			Level 2			Level 3
KCP&L		(millions)
Assets
Nuclear decommissioning trust ^(a)
Equity securities		$	137.1		$	137.1		$	—		$	—
Debt securities
U.S. Treasury		22.9			22.9			—			—
U.S. Agency		3.5			—			3.5			—
State and local obligations		4.1			—			4.1			—
Corporate bonds		28.1			—			28.1			—
Foreign governments		0.5			—			0.5			—
Cash equivalents		2.3			2.3			—			—
Other		0.5			—			0.5			—
Total nuclear decommissioning trust		199.0			162.3			36.7			—
Self-insured health plan trust ^(b)
Equity securities		1.3			1.3			—			—
Debt securities		7.6			—			7.6			—
Cash and cash equivalents		6.2			6.2			—			—
Total self-insured health plan trust		15.1			7.5			7.6			—
Derivative instruments ^(c)		4.0			—			—			4.0
Total		$	218.1		$	169.8		$	44.3		$	4.0
Liabilities
Derivative instruments ^(c)		0.9			—			—			0.9
Total		$	0.9		$	—		$	—		$	0.9
Other Great Plains Energy
Assets
Derivative instruments ^(c)		$	4.6		$	—		$	3.4		$	1.2
SERP rabbi trusts ^(d)
Equity securities		0.1			0.1			—			—
Fixed income funds		17.8			—			17.8			—
Total SERP rabbi trusts		17.9			0.1			17.8			—
Total		22.5			0.1			21.2			1.2
Liabilities
Derivative instruments ^(c)		3.3			2.4			0.1			0.8
Total		$	3.3		$	2.4		$	0.1		$	0.8
Great Plains Energy
Assets
Nuclear decommissioning trust ^(a)		$	199.0		$	162.3		$	36.7		$	—
Self-insured health plan trust ^(b)		15.1			7.5			7.6			—
Derivative instruments ^(c)		8.6			—			3.4			5.2
SERP rabbi trusts ^(d)		17.9			0.1			17.8			—
Total		240.6			169.9			65.5			5.2
Liabilities
Derivative instruments ^(c)		4.2			2.4			0.1			1.7
Total		$	4.2		$	2.4		$	0.1		$	1.7


^(a)	Fair value is based on quoted market prices of the investments held by the fund and/or valuation models.


^(b)	Fair value is based on quoted market prices of the investments held by the trust. Debt securities classified as Level 2 are comprised of corporate bonds, U.S. Agency, state and local obligations, and other asset-backed securities.

^(c)


^(d)	Fair value is based on quoted market prices for equity securities and Net Asset Value (NAV) per share for fixed income funds. The fixed income fund invests primarily in intermediate and long-term debt securities, can be redeemed immediately and is not subject to any restrictions on redemptions.

Unobservable inputs reconciliation

The following tables reconcile the beginning and ending balances for all Level 3 assets and liabilities measured at fair value on a recurring basis.



Great Plains Energy
Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
	Derivative Instruments
	2015			2014
	(millions)
Net asset at July 1	$	0.8		$	0.6
Total realized/unrealized gains (losses):
included in electric revenue	(0.2		)	(10.0		)
included in purchased power expense	(0.2		)	(4.8		)
included in non-operating income	3.2			2.2
included in regulatory (asset) liability	(0.1		)	3.4
Purchases	(0.2		)	1.7
Settlements	(2.9		)	9.9
Net asset at September 30	$	0.4		$	3.0
Total unrealized gains (losses) relating to assets and liabilities still on the consolidated balance sheet at September 30:
included in electric revenue	$	(0.1	)	$	1.9
included in non-operating income	—			(0.2		)
included in regulatory (asset) liability	(0.1		)	3.4

Great Plains Energy
Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
	Derivative Instruments
	2015			2014
	(millions)
Net asset at January 1	$	3.5		$	3.3
Total realized/unrealized gains (losses):
included in electric revenue	(7.9		)	(12.3		)
included in purchased power expense	(1.4		)	(4.4		)
included in non-operating income	6.9			13.3
included in regulatory asset	(0.1		)	(0.7		)
Purchases	0.4			15.1
Settlements	(1.0		)	(11.3		)
Net asset at September 30	$	0.4		$	3.0
Total unrealized losses relating to assets and liabilities still on the consolidated balance sheet at September 30:
included in electric revenue	$	(0.1	)	$	(0.6	)
included in non-operating income	(0.1		)	—
included in regulatory asset	(0.1		)	(0.7		)



KCP&L
Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
	Derivative Instruments
	2015			2014
	(millions)
Net asset at July 1	$	0.1		$	0.9
Total realized/unrealized gains (losses):
included in electric revenue	(0.2		)	(10.0		)
included in regulatory (asset) liability	(0.1		)	1.7
Purchases	(0.2		)	1.3
Settlements	0.2			8.8
Net asset (liability) at September 30	$	(0.2	)	$	2.7
Total unrealized gains (losses) relating to assets and liabilities still on the consolidated balance sheet at September 30:
included in electric revenue	$	(0.1	)	$	1.9
included in regulatory (asset) liability	(0.1		)	1.7

KCP&L
Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
	Derivative Instruments
	2015			2014
	(millions)
Net asset at January 1	$	3.1		$	1.1
Total realized/unrealized gains (losses):
included in electric revenue	(7.9		)	(12.3		)
included in regulatory asset	(0.1		)	(0.5		)
Purchases	(0.4		)	13.1
Settlements	5.1			1.3
Net asset (liability) at September 30	$	(0.2	)	$	2.7
Total unrealized losses relating to assets and liabilities still on the consolidated balance sheet at September 30:
included in electric revenue	$	(0.1	)	$	(0.6	)
included in regulatory asset	(0.1		)	(0.5		)

Accumulated Other Comprehensive Income (Loss) (Tables)

9 Months Ended

Sep. 30, 2015

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]

The following tables reflect the change in the balances of each component of accumulated other comprehensive loss for Great Plains Energy and KCP&L.



Great Plains Energy
	Gains and Losses on Cash Flow Hedges^(a)				Defined Benefit Pension Items^(a)				Total^(a)
	(millions)
Year to Date September 30, 2015
Beginning balance January 1		$	(15.8	)		$	(2.9	)	$	(18.7	)
Amounts reclassified from accumulated other comprehensive loss		4.2				0.3			4.5
Net current period other comprehensive income		4.2				0.3			4.5
Ending balance September 30		$	(11.6	)		$	(2.6	)	$	(14.2	)
Year to Date September 30, 2014
Beginning balance January 1		$	(23.8	)		$	(1.5	)	$	(25.3	)
Amounts reclassified from accumulated other comprehensive loss		6.6				0.3			6.9
Net current period other comprehensive income		6.6				0.3			6.9
Ending balance September 30		$	(17.2	)		$	(1.2	)	$	(18.4	)

^(a) Net of tax



KCP&L
	Gains and Losses on Cash Flow Hedges^(a)
	(millions)
Year to Date September 30, 2015
Beginning balance January 1		$	(14.9	)
Amounts reclassified from accumulated other comprehensive loss		4.0
Net current period other comprehensive income		4.0
Ending balance September 30		$	(10.9	)
Year to Date September 30, 2014
Beginning balance January 1		$	(20.2	)
Amounts reclassified from accumulated other comprehensive loss		3.9
Net current period other comprehensive income		3.9
Ending balance September 30		$	(16.3	)

^(a) Net of tax

Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]

The following tables reflect the effect on certain line items of net income from amounts reclassified out of each component of accumulated other comprehensive loss for Great Plains Energy and KCP&L.



Great Plains Energy
Details about Accumulated Other Comprehensive Loss Components	Amount Reclassified from Accumulated Other Comprehensive Loss						Affected Line Item in the Income Statement
Three Months Ended September 30	2015			2014
	(millions)
Gains and (losses) on cash flow hedges (effective portion)
Interest rate contracts	$	(2.3	)	$	(2.3	)	Interest charges
	(2.3		)	(2.3		)	Income before income tax expense and income from equity investments
	0.9			1.0			Income tax benefit
	$	(1.4	)	$	(1.3	)	Net income
Amortization of defined benefit pension items
Net losses included in net periodic benefit costs	$	(0.1	)	$	(0.1	)	Utility operating and maintenance expenses
	(0.1		)	(0.1		)	Income before income tax expense and income from equity investments
	0.1			—			Income tax benefit
	$	—		$	(0.1	)	Net income

Total reclassifications, net of tax	$	(1.4	)	$	(1.4	)	Net income

Great Plains Energy
Details about Accumulated Other Comprehensive Loss Components	Amount Reclassified from Accumulated Other Comprehensive Loss						Affected Line Item in the Income Statement
Year to Date September 30	2015			2014
	(millions)
Gains and (losses) on cash flow hedges (effective portion)
Interest rate contracts	$	(6.9	)	$	(10.9	)	Interest charges
	(6.9		)	(10.9		)	Income before income tax expense and income from equity investments
	2.7			4.3			Income tax benefit
	$	(4.2	)	$	(6.6	)	Net income
Amortization of defined benefit pension items
Net losses included in net periodic benefit costs	$	(0.5	)	$	(0.4	)	Utility operating and maintenance expenses
	(0.5		)	(0.4		)	Income before income tax expense and income from equity investments
	0.2			0.1			Income tax benefit
	$	(0.3	)	$	(0.3	)	Net income

Total reclassifications, net of tax	$	(4.5	)	$	(6.9	)	Net income



KCP&L
Details about Accumulated Other Comprehensive Loss Components	Amount Reclassified from Accumulated Other Comprehensive Loss						Affected Line Item in the Income Statement
Three Months Ended September 30	2015			2014
	(millions)
Gains and (losses) on cash flow hedges (effective portion)
Interest rate contracts	$	(2.2	)	$	(2.1	)	Interest charges
	(2.2		)	(2.1		)	Income before income tax expense
	0.9			0.9			Income tax benefit
Total reclassifications, net of tax	$	(1.3	)	$	(1.2	)	Net income

KCP&L
Details about Accumulated Other Comprehensive Loss Components	Amount Reclassified from Accumulated Other Comprehensive Loss						Affected Line Item in the Income Statement
Year to Date September 30	2015			2014
	(millions)
Gains and (losses) on cash flow hedges (effective portion)
Interest rate contracts	$	(6.6	)	$	(6.5	)	Interest charges
	(6.6		)	(6.5		)	Income before income tax expense
	2.6			2.6			Income tax benefit
Total reclassifications, net of tax	$	(4.0	)	$	(3.9	)	Net income

Taxes (Tables)

9 Months Ended

Sep. 30, 2015

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

Components of income tax expense are detailed in the following tables.



	Three Months Ended September 30						Year to Date September 30
Great Plains Energy	2015			2014			2015			2014
Current income taxes	(millions)
Federal	$	(0.8	)	$	(0.7	)	$	(0.3	)	$	(0.6	)
State	0.5			(0.1		)	0.4			—
Total	(0.3		)	(0.8		)	0.1			(0.6		)
Deferred income taxes
Federal	66.4			69.0			91.8			100.6
State	12.4			12.9			18.3			19.7
Total	78.8			81.9			110.1			120.3
Noncurrent income taxes
Federal	—			—			—			(2.4		)
State	—			—			—			(0.3		)
Foreign	—			(6.2		)	—			(6.2		)
Total	—			(6.2		)	—			(8.9		)
Investment tax credit
Deferral	0.5			—			0.5			—
Amortization	(0.4		)	(0.2		)	(1.1		)	(1.0		)
Total	0.1			(0.2		)	(0.6		)	(1.0		)
Income tax expense	$	78.6		$	74.7		$	109.6		$	109.8



	Three Months Ended September 30						Year to Date September 30
KCP&L	2015			2014			2015			2014
Current income taxes	(millions)
Federal	$	43.9		$	33.8		$	42.4		$	34.5
State	7.1			5.9			6.7			6.1
Total	51.0			39.7			49.1			40.6
Deferred income taxes
Federal	(1.6		)	10.9			14.6			26.2
State	0.8			2.9			5.2			6.8
Total	(0.8		)	13.8			19.8			33.0
Investment tax credit
Deferral	0.5			—			0.5			—
Amortization	(0.2		)	(0.2		)	(0.7		)	(0.7		)
Total	0.3			(0.2		)	(0.2		)	(0.7		)
Income tax expense	$	50.5		$	53.3		$	68.7		$	72.9

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]



	Three Months Ended September 30				Year to Date September 30
Great Plains Energy	2015		2014		2015		2014
Federal statutory income tax rate	35.0	%	35.0	%	35.0	%	35.0	%
Differences between book and tax depreciation not normalized	0.3		(0.3	)	0.4		(0.5	)
Amortization of investment tax credits	(0.2	)	(0.1	)	(0.4	)	(0.3	)
Federal income tax credits	(1.2	)	(1.8	)	(2.6	)	(3.0	)
State income taxes	4.2		3.7		4.0		3.7
Changes in uncertain tax positions, net	—		(2.8	)	—		(1.8	)
Other	0.2		(0.1	)	0.2		(0.2	)
Effective income tax rate	38.3	%	33.6	%	36.6	%	32.9	%



	Three Months Ended September 30				Year to Date September 30
KCP&L	2015		2014		2015		2014
Federal statutory income tax rate	35.0	%	35.0	%	35.0	%	35.0	%
Differences between book and tax depreciation not normalized	0.4		(0.2	)	0.6		(0.7	)
Amortization of investment tax credits	(0.2	)	(0.2	)	(0.4	)	(0.4	)
Federal income tax credits	(1.8	)	(2.4	)	(3.9	)	(4.3	)
State income taxes	3.9		3.9		3.9		3.8
Other	0.1		—		(0.1	)	(0.1	)
Effective income tax rate	37.4	%	36.1	%	35.1	%	33.3	%

Segments and Related Information (Tables)

9 Months Ended

Sep. 30, 2015

Segment Reporting [Abstract]

Segment Financial Information [Table Text Block]



Three Months Ended September 30, 2015	Electric Utility				Other				Eliminations			Great Plains Energy
		(millions)
Operating revenues		$	781.4			$	—			$	—		$	781.4
Depreciation and amortization		(82.4		)		—				—			(82.4		)
Interest (charges) income		(48.9		)		(10.2		)		8.1			(51.0		)
Income tax (expense) benefit		(78.5		)		(0.1		)		—			(78.6		)
Net income (loss)		129.1				(2.3		)		—			126.8

Year to Date September 30, 2015	Electric Utility				Other				Eliminations			Great Plains Energy
		(millions)
Operating revenues		$	1,939.5			$	—			$	—		$	1,939.5
Depreciation and amortization		(245.7		)		—				—			(245.7		)
Interest (charges) income		(142.1		)		(30.3		)		24.1			(148.3		)
Income tax (expense) benefit		(112.0		)		2.4				—			(109.6		)
Net income (loss)		196.4				(6.3		)		—			190.1



Three Months Ended September 30, 2014	Electric Utility				Other				Eliminations			Great Plains Energy
		(millions)
Operating revenues		$	782.5			$	—			$	—		$	782.5
Depreciation and amortization		(76.6		)		—				—			(76.6		)
Interest (charges) income		(44.9		)		(6.8		)		8.1			(43.6		)
Income tax (expense) benefit		(81.0		)		6.3				—			(74.7		)
Net income (loss)		140.3				7.1				—			147.4

Year to Date September 30, 2014	Electric Utility				Other				Eliminations			Great Plains Energy
		(millions)
Operating revenues		$	2,016.0			$	—			$	—		$	2,016.0
Depreciation and amortization		(226.7		)		—				—			(226.7		)
Interest (charges) income		(137.9		)		(31.1		)		27.7			(141.3		)
Income tax (expense) benefit		(118.8		)		9.0				—			(109.8		)
Net income (loss)		221.1				2.2				—			223.3



	Electric Utility			Other			Eliminations				Great Plains Energy
September 30, 2015		(millions)
Assets		$	11,053.9		$	163.6		$	(373.4	)		$	10,844.1
Capital expenditures ^(a)		520.9			—			—				520.9
December 31, 2014
Assets		$	10,746.1		$	33.1		$	(303.5	)		$	10,475.7
Capital expenditures ^(a)		773.7			—			—				773.7

Tabular disclosure of the profit or loss and total assets for each reportable segment. An entity discloses certain information on each reportable segment if the amounts (a) are included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) are otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.

+ References+ Details

Summary of Significant Accounting Policies Equity Method Investment (Details) (Transource Energy, LLC [Member])	9 Months Ended
	Sep. 30, 2015
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Description of Principal Activities	Transource is focused on the development of competitive electric transmission projects.
GPE Transmission Holding Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	13.50%
AEP Transmission Holding Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage of Majority Owner	86.50%

Summary of Significant Accounting Policies Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accounting Policies [Abstract]
Net income (loss)	$ 126.8	$ 147.4	$ 190.1	$ 223.3
Income [Abstract]
Less: preferred stock dividend requirements	0.4	0.4	1.2	1.2
Earnings (loss) available for common shareholders	$ 126.4	$ 147.0	$ 188.9	$ 222.1
Common Shares Outstanding [Abstract]
Average number of common shares outstanding (in shares)	154.2	153.9	154.1	153.8
Add: effect of dilutive securities (in shares)	0.6	0.4	0.7	0.4
Diluted average number of common shares outstanding (in shares)	154.8	154.3	154.8	154.2
Earnings Per Share, Basic	$ 0.82	$ 0.96	$ 1.23	$ 1.44
Earnings Per Share, Diluted	$ 0.82	$ 0.95	$ 1.22	$ 1.44

Summary of Significant Accounting Policies Antidilutive Securities (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Performance Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	108,832	0	108,832
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	73,671	0	71,860

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References+ Details

Summary of Significant Accounting Policies Subsequent Events (Details) (Subsequent Event [Member], USD $)	1 Months Ended
	Nov. 30, 2015
Common Stock [Member]
Dividends Declared [Abstract]
Dividends Payable, Date Declared, Month and Year	2015-11
Dividends Payable, Amount Per Share	$ 0.2625
Dividends Payable, Date to be Paid	Dec. 21, 2015
Dividends Payable, Date of Record	Nov. 30, 2015
Preferred Stock [Member]
Dividends Declared [Abstract]
Dividends Payable, Date Declared, Month and Year	2015-11
Dividends Payable, Date to be Paid	Mar. 01, 2016
Dividends Payable, Date of Record	Feb. 08, 2016

Supplemental Cash Flow Information (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash flows affected by changes in:
Receivables	$ (13.2)	$ (70.4)
Accounts receivable pledged as collateral	(19.0)	4.0
Fuel inventories	(10.8)	23.3
Materials and supplies	(2.9)	1.7
Accounts payable	(121.9)	(75.2)
Accrued taxes	89.2	91.2
Accrued interest	16.9	11.4
Deferred refueling outage costs	(12.8)	15.8
Pension and post-retirement benefit obligations	48.8	24.8
Allowance for equity funds used during construction	(3.8)	(13.2)
Fuel recovery mechanism	36.6	(21.3)
Solar rebates paid	(7.3)	(43.9)
Other operating activities	9.9	(10.0)
Total other operating activities	9.7	(61.8)
Cash paid during the period:
Interest Paid, Net	121.2	115.6
Income Taxes Paid	0.2	0.1
Non-cash investing activities:
Liabilities accrued for capital expenditures	23.4	50.5
Kansas City Power and Light Company [Member]
Cash flows affected by changes in:
Receivables	(6.2)	(70.5)
Fuel inventories	(11.6)	18.3
Materials and supplies	(4.0)	0.5
Accounts payable	(83.1)	(34.7)
Accrued taxes	162.3	118.2
Accrued interest	12.3	10.8
Deferred refueling outage costs	(12.8)	15.8
Pension and post-retirement benefit obligations	48.8	23.6
Allowance for equity funds used during construction	(2.9)	(12.3)
Fuel recovery mechanism	1.8	1.4
Solar rebates paid	(6.0)	(14.8)
Other operating activities	5.0	(23.9)
Total other operating activities	103.6	32.4
Cash paid during the period:
Interest Paid, Net	79.1	72.9
Non-cash investing activities:
Liabilities accrued for capital expenditures	$ 15.7	$ 44.4

Receivables (Details) (USD $)
In Millions, unless otherwise specified

3 Months Ended

9 Months Ended

Sep. 30, 2015

Sep. 30, 2014

Sep. 30, 2015

Sep. 30, 2014

$ 0

(0.2)

^[1]

(0.7)

^[1]

(0.6)

^[1]

(0.5)

(1.1)

(1.4)

Cash received from (paid for) receivables purchased

Kansas City Power and Light Company [Member]

(0.2)

^[1]

(0.1)

^[1]

(0.5)

^[1]

(0.4)

^[1]

(0.3)

(0.7)

(0.9)

Cash received from (paid for) receivables purchased

Kansas City Power And Light Company Unconsolidated [Member]

(495.5)

(472.9)

(1,234.0)

(1,206.9)

(6.3)

^[1]

(6.0)

^[1]

(15.6)

^[1]

(15.3)

^[1]

0.8

2.0

Cash received from (paid for) receivables purchased

(489.5)

(471.5)

(1,205.6)

(1,187.3)

483.4

465.6

1,190.5

1,172.4

0.1

0.2

KCPL Receivables Company [Member]

495.5

472.9

1,234.0

1,206.9

6.1

^[1]

5.9

^[1]

15.1

^[1]

14.9

^[1]

(0.8)

(2.0)

(0.3)

(0.7)

(0.9)

Cash received from (paid for) receivables purchased

489.5

471.5

1,205.6

1,187.3

(483.4)

(465.6)

(1,190.5)

(1,172.4)

(0.1)

(0.2)

KCPL Greater Missouri Operations [Member]

(267.4)

(251.3)

(656.7)

(643.0)

(3.4)

^[1]

(3.1)

^[1]

(8.3)

^[1]

(8.1)

^[1]

0.4

1.0

Cash received from (paid for) receivables purchased

(267.7)

(253.2)

(646.0)

(630.5)

264.4

250.0

638.0

622.6

0.1

GMO Receivables Company Member

267.4

251.3

656.7

643.0

3.4

^[1]

3.2

^[1]

8.1

^[1]

7.9

^[1]

(0.4)

(1.0)

(0.2)

(0.4)

(0.5)

Cash received from (paid for) receivables purchased

267.7

253.2

646.0

630.5

(264.4)

(250.0)

(638.0)

(622.6)

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

$ 0

$ (0.1)

$ 0

[1]	Any net gain (loss) is the result of the timing difference inherent in collecting receivables and over the life of the agreement will net to zero.

Receivables Accounts, Notes, and Financing (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other Receivables, Gross, Current	$ 68.0	$ 86.7
Receivables, net	173.4	160.3
Kansas City Power and Light Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other Receivables, Gross, Current	61.8	79.8
Receivables, net	146.8	128.9
Trade Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for doubtful accounts	(4.1)	(2.8)
Trade Accounts Receivable [Member] \| Kansas City Power and Light Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for doubtful accounts	(1.9)	(1.2)
Trade Accounts Receivable [Member] \| Billed Revenues [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	28.1	1.1
Trade Accounts Receivable [Member] \| Billed Revenues [Member] \| Kansas City Power and Light Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	27.6	0.6
Trade Accounts Receivable [Member] \| Unbilled Revenues [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	81.4	75.3
Trade Accounts Receivable [Member] \| Unbilled Revenues [Member] \| Kansas City Power and Light Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	$ 59.3	$ 49.7

Receivables Narrative (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Accounts receivable pledged as collateral	$ 190.0	$ 171.0
Collateralized note payable	190.0	171.0
Kansas City Power and Light Company [Member]
Accounts receivable pledged as collateral	110.0	110.0
Collateralized note payable	110.0	110.0
Contractually Specified Servicing Fees Percentage Amount	1.50%
Maximum amount of outstanding principal under receivables agreement	110
KCPL Greater Missouri Operations [Member]
Contractually Specified Servicing Fees Percentage Amount	1.50%
Maximum amount of outstanding principal under receivables agreement from mid-November to mid-June	65
Maximum amount of outstanding principal under receivables agreement from mid-June to mid-November	$ 80

Nuclear Plant (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Investments in decommissioning trust fund [Line Items]
Cost Basis	$ 151.2		$ 151.2		$ 145.4
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	45.4		45.4		54.4
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(3.5)		(3.5)		(0.8)
Fair Value, Nuclear decommissioning trust fund	193.1		193.1		199.0	183.9
Weighted average maturity of debt securities (in years)			7 years 0 months
Realized gains on investments in decommissioning trust fund	0.6	0.3	3.2	1.0
Realized losses on investments in decommissioning trust fund	(0.5)	(0.1)	(2.3)	(0.7)
Equity Securities [Member]
Investments in decommissioning trust fund [Line Items]
Cost Basis	89.4		89.4		87.2
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	42.2		42.2		50.6
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	(3.2)		(3.2)		(0.7)
Fair Value, Nuclear decommissioning trust fund	128.4		128.4		137.1
Debt Securities [Member]
Investments in decommissioning trust fund [Line Items]
Cost Basis	59.0		59.0		55.4
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	3.2		3.2		3.8
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(0.3)		(0.3)		(0.1)
Fair Value, Nuclear decommissioning trust fund	61.9		61.9		59.1
Other Securities [Member]
Investments in decommissioning trust fund [Line Items]
Cost Basis	2.8		2.8		2.8
Fair Value, Nuclear decommissioning trust fund	$ 2.8		$ 2.8		$ 2.8

Nuclear Plant Decommissioning Trust (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Nuclear decommissioning trust fund [Roll Forward]
Nuclear decommissioning trust fund, beginning balance	$ 199.0	$ 183.9
Contributions to nuclear decommissioning trust fund	2.5	3.3
Earned income, net of fees	2.4	3.6
Net realized gains (losses) on nuclear decommissioning trust fund	0.9	0.4
Net unrealized gains (losses) on nuclear decommissioning trust fund	(11.7)	7.8
Nuclear decommissioning trust fund, ending balance	193.1	199.0
Wolf Creek [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership percentage in Wolf Creek, a nuclear generating unit (in hundredths)	47.00%
Kansas City Power and Light Company [Member]
Nuclear decommissioning trust fund [Roll Forward]
Nuclear decommissioning trust fund, beginning balance	199.0	183.9
Contributions to nuclear decommissioning trust fund	2.5	3.3
Earned income, net of fees	2.4	3.6
Net realized gains (losses) on nuclear decommissioning trust fund	0.9	0.4
Net unrealized gains (losses) on nuclear decommissioning trust fund	(11.7)	7.8
Nuclear decommissioning trust fund, ending balance	$ 193.1	$ 199.0
Kansas City Power and Light Company [Member] \| Wolf Creek [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership percentage in Wolf Creek, a nuclear generating unit (in hundredths)	47.00%

Regulatory Matters (Details) (Kansas City Power and Light Company [Member], USD $) In Millions, unless otherwise specified	1 Months Ended		9 Months Ended	1 Months Ended
	Sep. 30, 2015 Missouri Public Service Commission [Member]	Oct. 31, 2014 Missouri Public Service Commission [Member]	Sep. 30, 2015 Missouri Public Service Commission [Member]	Sep. 30, 2015 Kansas Corporation Commission [Member] Rate	Jan. 31, 2015 Kansas Corporation Commission [Member]
Regulatory Proceedings [Line Items]
Annual revenue increase, requested		$ 120.9			$ 67.3
Revised annual revenue increase, requested			112.7
Return on equity, requested (in hundredths)		10.30%			10.30%
Rate-making equity ratio, requested (in hundredths)		50.36%			50.48%
Annual revenue increase authorized	$ 89.7			$ 48.7
Return on equity, approved (in hundredths)	9.50%			9.30%
Ratemaking equity ratio, approved (in hundredths)	50.09%			50.48%

Asset Retirement Obligations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended	12 Months Ended
	Jun. 30, 2015	Sep. 30, 2015	Dec. 31, 2014
Increase in asset retirement obligations due to CCR regulations	$ 69.5
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation, Beginning Balance		195.9	158.8
Additions		54.5	0
Revision in timing and/or estimates		15.0	26.8
Accretion		9.4	10.3
Asset Retirement Obligation, Ending Balance		274.8	195.9
Asset Retirement Obligations, Liability Not Recognized		certain wiring used in Great Plains Energy's and KCP&L's generating stations include asbestos insulation, which would require special handling if disturbed. Due to the inability to reasonably estimate the quantities or the amount of disturbance that will be necessary during dismantlement at the end of the life of a plant, the fair value of this ARO cannot be reasonably estimated at this time. Management will continue to monitor the obligation and will recognize a liability in the period in which sufficient information becomes available to reasonably estimate its fair value.
Kansas City Power and Light Company [Member]
Asset Retirement Obligations, Description		KCP&L has AROs related to decommissioning Wolf Creek, site remediation of its Spearville Wind Energy Facilities, asbestos abatement, removal of storage tanks and closure and post-closure of ponds and landfills containing coal combustion residuals (CCRs).
Increase in asset retirement obligations due to CCR regulations	51.3
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation, Beginning Balance		177.7	141.7
Additions		34.6	0
Revision in timing and/or estimates		16.7	26.8
Accretion		8.5	9.2
Asset Retirement Obligation, Ending Balance		$ 237.5	$ 177.7
Asset Retirement Obligations, Liability Not Recognized		certain wiring used in Great Plains Energy's and KCP&L's generating stations include asbestos insulation, which would require special handling if disturbed. Due to the inability to reasonably estimate the quantities or the amount of disturbance that will be necessary during dismantlement at the end of the life of a plant, the fair value of this ARO cannot be reasonably estimated at this time. Management will continue to monitor the obligation and will recognize a liability in the period in which sufficient information becomes available to reasonably estimate its fair value.
KCPL Greater Missouri Operations [Member]
Asset Retirement Obligations, Description		GMO has AROs related to asbestos abatement, removal of storage tanks and closure and post-closure of ponds and landfills containing CCRs.

Pension Plans and Other Employee Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Contributions by Employer			$ 29.5
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year			49.4
Components of net periodic benefit costs [Abstract]
Defined Benefit Plan, Service Cost	11.4	9.1	34.0	27.2
Defined Benefit Plan, Interest Cost	12.5	12.7	37.7	38.1
Defined Benefit Plan, Expected Return on Plan Assets	(13.0)	(12.7)	(38.8)	(38.1)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0.2	0.2	0.6	0.6
Defined Benefit Plan, Amortization of (Gains) Losses	12.9	12.4	38.5	37.2
Defined Benefit Plan, Amortization of Transition Obligations (Assets)	0	0	0	0
Net periodic benefit costs before regulatory adjustment	24.0	21.7	72.0	65.0
Defined Benefit Plan, Regulatory Adjustment	(3.5)	(0.6)	(9.3)	(1.4)
Defined Benefit Plan, Net Periodic Benefit Cost	20.5	21.1	62.7	63.6
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year			10.2
Components of net periodic benefit costs [Abstract]
Defined Benefit Plan, Service Cost	0.8	0.9	2.5	2.7
Defined Benefit Plan, Interest Cost	1.7	2.0	5.1	6.0
Defined Benefit Plan, Expected Return on Plan Assets	(0.7)	(0.7)	(2.2)	(2.1)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0.7	0.8	2.3	2.4
Defined Benefit Plan, Amortization of (Gains) Losses	0.1	0	0.2	0
Defined Benefit Plan, Amortization of Transition Obligations (Assets)	0.1	0	0.1	0.1
Net periodic benefit costs before regulatory adjustment	2.7	3.0	8.0	9.1
Defined Benefit Plan, Regulatory Adjustment	1.4	1.1	4.2	3.3
Defined Benefit Plan, Net Periodic Benefit Cost	$ 4.1	$ 4.1	$ 12.2	$ 12.4
Wolf Creek [Member]
Defined Benefit Plan Disclosure [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	47.00%		47.00%
Wolf Creek [Member] \| Kansas City Power and Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	47.00%		47.00%

Equity Compensation (Details) (USD $)
In Millions, except Share data, unless otherwise specified

3 Months Ended

9 Months Ended

Sep. 30, 2015

Sep. 30, 2014

Sep. 30, 2015

Sep. 30, 2014

Equity compensation expense

$ 3.7

$ 1.0

$ 4.6

$ 6.4

Income tax benefit

1.4

0.3

1.7

2.3

Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Expected volatility, minimum (in hundredths)

16.00%

Expected volatility, maximum (in hundredths)

17.00%

Expected dividend yield range (in hundredths)

3.72%-4.03%

Risk-free interest rate, minimum (in hundredths)

0.86%

Risk-free interest rate, maximum (in hundredths)

1.02%

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]

Beginning balance (in shares)

534,016

Granted (in shares)

232,838

Earned (in shares)

(25,844)

Performance adjustment (in shares)

(77,515)

Forfeited (in shares)

(46,927)

Ending balance (in shares)

616,568

Weighted average beginning balance (in dollars per share)

$ 25.11

^[1]

Weighted average granted (in dollars per share)

$ 22.46

$ 28.78

$ 24.03

^[1]

$ 28.78

Weighted average earned (in dollars per share)

$ 19.48

^[1]

Weighted average forfeited (in dollars per share)

$ 25.68

^[1]

Weighted average performance adjustment (in dollars per share)

$ 19.48

^[1]

Weighted average ending balance (in dollars per share)

$ 25.60

^[1]

$ 25.60

^[1]

Total unrecognized compensation expense

7.8

Remaining weighted-average contractual term (in years)

1 year 4 months

Fair value of performance shares earned and paid

0.5

2.8

Restricted Stock [Member]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]

Beginning balance (in shares)

267,390

Granted (in shares)

91,880

Vested (in shares)

(109,246)

Forfeited (in shares)

(15,644)

Ending balance (in shares)

234,380

Weighted average beginning balance (in dollars per share)

$ 22.31

^[1]

Weighted average granted (in dollars per share)

$ 24.20

$ 25.10

$ 25.88

^[1]

$ 25.69

Weighted average vested (in dollars per share)

$ 19.68

^[1]

Weighted average forfeited (in dollars per share)

$ 24.81

^[1]

Weighted average ending balance (in dollars per share)

$ 24.76

^[1]

$ 24.76

^[1]

Total unrecognized compensation expense

2.9

Total fair value of shares vested

0.1

0.5

2.1

1.9

Remaining weighted-average contractual term (in years)

1 year 6 months

Kansas City Power and Light Company [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Equity compensation expense

2.5

0.6

3.1

4.4

Income tax benefit

$ 0.9

$ 0.1

$ 1.1

$ 1.5

[1]	weighted-average

Short-term Borrowings and Short-term Bank Lines of Credit (Details) (USD $)	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Short-term Debt [Line Items]
Amount of outstanding cash borrowings	$ 12,000,000	$ 4,000,000
Commercial paper outstanding	139,100,000	358,300,000
Parent Company [Member] \| Revolving Credit Facility [Member]
Short-term Debt [Line Items]
Amount of revolving credit facility	200,000,000
Revolving credit facility expiration date	Oct. 31, 2019
Maximum borrowing capacity with transfer of unused commitments	400,000,000
Line of Credit Facility, Covenant Terms	A default by Great Plains Energy or any of its significant subsidiaries on other indebtedness totaling more than $50.0 million is a default under the facility. Under the terms of this facility, Great Plains Energy is required to maintain a consolidated indebtedness to consolidated capitalization ratio, as defined in the facility, not greater than 0.65 to 1.00 at all times.
Line of Credit Facility, Covenant Compliance	in compliance
Amount of outstanding cash borrowings	12,000,000	4,000,000
Weighted-average interest rate from outstanding borrowings	1.75%	1.69%
Amount of letters of credit outstanding	200,000	0
Kansas City Power and Light Company [Member]
Short-term Debt [Line Items]
Commercial paper outstanding	82,100,000	358,300,000
Weighted-average interest rate from outstanding borrowings	0.43%	0.48%
Kansas City Power and Light Company [Member] \| Revolving Credit Facility [Member]
Short-term Debt [Line Items]
Amount of revolving credit facility	600,000,000
Revolving credit facility expiration date	Oct. 31, 2019
Maximum transfer of unused commitments	200,000,000
Line of Credit Facility, Covenant Terms	A default by KCP&L on other indebtedness totaling more than $50.0 million is a default under the facility. Under the terms of this facility, KCP&L is required to maintain a consolidated indebtedness to consolidated capitalization ratio, as defined in the facility, not greater than 0.65 to 1.00 at all times.
Line of Credit Facility, Covenant Compliance	in compliance
Amount of outstanding cash borrowings	0	0
Amount of letters of credit outstanding	2,700,000	2,700,000
KCPL Greater Missouri Operations [Member]
Short-term Debt [Line Items]
Commercial paper outstanding	57,000,000	0
Weighted-average interest rate from outstanding borrowings	0.43%
KCPL Greater Missouri Operations [Member] \| Revolving Credit Facility [Member]
Short-term Debt [Line Items]
Amount of revolving credit facility	450,000,000
Revolving credit facility expiration date	Oct. 31, 2019
Maximum transfer of unused commitments	200,000,000
Line of Credit Facility, Covenant Terms	A default by GMO or any of its significant subsidiaries on other indebtedness totaling more than $50.0 million is a default under the facility. Under the terms of this facility, GMO is required to maintain a consolidated indebtedness to consolidated capitalization ratio, as defined in the facility, not greater than 0.65 to 1.00 at all times.
Line of Credit Facility, Covenant Compliance	in compliance
Amount of outstanding cash borrowings	0	0
Amount of letters of credit outstanding	$ 2,500,000	$ 3,200,000

Long-Term Debt (Details) (USD $)
In Millions, unless otherwise specified

9 Months Ended

1 Months Ended

9 Months Ended

1 Months Ended

9 Months Ended

Sep. 30, 2015

Sep. 30, 2014

Dec. 31, 2014

Sep. 30, 2015

Kansas City Power and Light Company [Member]

Sep. 30, 2014

Kansas City Power and Light Company [Member]

Dec. 31, 2014

Kansas City Power and Light Company [Member]

Sep. 30, 2015

Kansas City Power and Light Company [Member]

Secured Debt [Member]

General Mortgage Bonds EIRR due 2017-2035 [Member]

Dec. 31, 2014

Kansas City Power and Light Company [Member]

Secured Debt [Member]

General Mortgage Bonds EIRR due 2017-2035 [Member]

Sep. 30, 2015

Kansas City Power and Light Company [Member]

Secured Debt [Member]

General Mortgage bonds Series 2009A due 2019 [Member]

Dec. 31, 2014

Kansas City Power and Light Company [Member]

Secured Debt [Member]

General Mortgage bonds Series 2009A due 2019 [Member]

Sep. 30, 2015

Kansas City Power and Light Company [Member]

Secured Debt [Member]

General Mortgage bonds EIRR series 2005 due 2035 [Member]

Dec. 31, 2014

Kansas City Power and Light Company [Member]

Secured Debt [Member]

General Mortgage bonds EIRR series 2005 due 2035 [Member]

Mar. 31, 2015

Kansas City Power and Light Company [Member]

Secured Debt [Member]

Secured EIRR Bonds Series 2005 [Member]

Sep. 30, 2015

Kansas City Power and Light Company [Member]

Senior Notes [Member]

Senior notes due 2017 KCPL [Member]

Dec. 31, 2014

Kansas City Power and Light Company [Member]

Senior Notes [Member]

Senior notes due 2017 KCPL [Member]

Sep. 30, 2015

Kansas City Power and Light Company [Member]

Senior Notes [Member]

Senior notes due 2018 KCPL [Member]

Dec. 31, 2014

Kansas City Power and Light Company [Member]

Senior Notes [Member]

Senior notes due 2018 KCPL [Member]

Sep. 30, 2015

Kansas City Power and Light Company [Member]

Senior Notes [Member]

Senior Notes due 2023 KCPL [Member]

Dec. 31, 2014

Kansas City Power and Light Company [Member]

Senior Notes [Member]

Senior Notes due 2023 KCPL [Member]

Aug. 31, 2015

Kansas City Power and Light Company [Member]

Senior Notes [Member]

Senior Notes due 2025 KCPL [Member]

Sep. 30, 2015

Kansas City Power and Light Company [Member]

Senior Notes [Member]

Senior Notes due 2025 KCPL [Member]

Dec. 31, 2014

Kansas City Power and Light Company [Member]

Senior Notes [Member]

Senior Notes due 2025 KCPL [Member]

Sep. 30, 2015

Kansas City Power and Light Company [Member]

Senior Notes [Member]

Senior notes due 2035 KCPL [Member]

Dec. 31, 2014

Kansas City Power and Light Company [Member]

Senior Notes [Member]

Senior notes due 2035 KCPL [Member]

Sep. 30, 2015

Kansas City Power and Light Company [Member]

Senior Notes [Member]

Senior Notes Due 2041 KCPL [Member]

Dec. 31, 2014

Kansas City Power and Light Company [Member]

Senior Notes [Member]

Senior Notes Due 2041 KCPL [Member]

Sep. 30, 2015

Kansas City Power and Light Company [Member]

Unsecured Debt [Member]

EIRR Bonds Series 2007A and 2007B due 2035 [Member]

Dec. 31, 2014

Kansas City Power and Light Company [Member]

Unsecured Debt [Member]

EIRR Bonds Series 2007A and 2007B due 2035 [Member]

Sep. 30, 2015

Kansas City Power and Light Company [Member]

Unsecured Debt [Member]

EIRR bonds 2.875 percent Series 2008 [Member]

Dec. 31, 2014

Kansas City Power and Light Company [Member]

Unsecured Debt [Member]

EIRR bonds 2.875 percent Series 2008 [Member]

Sep. 30, 2015

KCPL Greater Missouri Operations [Member]

Secured Debt [Member]

First Mortgage Bonds due through 2021 [Member]

Dec. 31, 2014

KCPL Greater Missouri Operations [Member]

Secured Debt [Member]

First Mortgage Bonds due through 2021 [Member]

Sep. 30, 2015

KCPL Greater Missouri Operations [Member]

Senior Notes [Member]

Senior notes 8.27 percent series due 2021 [Member]

Dec. 31, 2014

KCPL Greater Missouri Operations [Member]

Senior Notes [Member]

Senior notes 8.27 percent series due 2021 [Member]

Sep. 30, 2015

KCPL Greater Missouri Operations [Member]

Senior Notes [Member]

Senior Notes Series A due 2025 [Member]

Dec. 31, 2014

KCPL Greater Missouri Operations [Member]

Senior Notes [Member]

Senior Notes Series A due 2025 [Member]

Sep. 30, 2015

KCPL Greater Missouri Operations [Member]

Senior Notes [Member]

Senior Notes Series B due 2033 [Member]

Dec. 31, 2014

KCPL Greater Missouri Operations [Member]

Senior Notes [Member]

Senior Notes Series B due 2033 [Member]

Sep. 30, 2015

KCPL Greater Missouri Operations [Member]

Senior Notes [Member]

Senior Notes Series C due 2043 [Member]

Dec. 31, 2014

KCPL Greater Missouri Operations [Member]

Senior Notes [Member]

Senior Notes Series C due 2043 [Member]

Sep. 30, 2015

KCPL Greater Missouri Operations [Member]

Medium-term Notes [Member]

Medium term notes 7.33 percent series due 2023 [Member]

Dec. 31, 2014

KCPL Greater Missouri Operations [Member]

Medium-term Notes [Member]

Medium term notes 7.33 percent series due 2023 [Member]

Sep. 30, 2015

KCPL Greater Missouri Operations [Member]

Medium-term Notes [Member]

Medium term notes 7.17 percent series due 2023 [Member]

Dec. 31, 2014

KCPL Greater Missouri Operations [Member]

Medium-term Notes [Member]

Medium term notes 7.17 percent series due 2023 [Member]

Sep. 30, 2015

Parent Company [Member]

Senior Notes [Member]

Senior notes due 2017 [Member]

Dec. 31, 2014

Parent Company [Member]

Senior Notes [Member]

Senior notes due 2017 [Member]

Sep. 30, 2015

Parent Company [Member]

Senior Notes [Member]

Senior Notes Due 2021 [Member]

Dec. 31, 2014

Parent Company [Member]

Senior Notes [Member]

Senior Notes Due 2021 [Member]

Sep. 30, 2015

Parent Company [Member]

Senior Notes [Member]

Senior Notes Due 2022 [Member]

Dec. 31, 2014

Parent Company [Member]

Senior Notes [Member]

Senior Notes Due 2022 [Member]

Sep. 30, 2015

Other Consolidated Entities [Member]

Dec. 31, 2014

Other Consolidated Entities [Member]

Debt Instrument [Line Items]

Principal outstanding

$ 110.5

^[1]

$ 146.4

^[1]

$ 400.0

^[2]

$ 400.0

^[2]

$ 0

$ 50.0

$ 250.0

^[2]

$ 250.0

^[2]

$ 350.0

^[2]

$ 350.0

^[2]

$ 300.0

$ 350.0

$ 0

$ 250.0

^[2]

$ 250.0

^[2]

$ 400.0

$ 146.5

^[3]

$ 146.5

^[3]

$ 23.4

$ 6.8

$ 7.9

$ 80.9

$ 125.0

$ 75.0

$ 150.0

$ 3.0

$ 7.0

$ 100.0

^[2]

$ 100.0

^[2]

$ 350.0

$ 287.5

Debt Instrument, Maturity Date

Dec. 31, 2019

Dec. 31, 2035

Dec. 31, 2017

Dec. 31, 2018

Dec. 31, 2023

Dec. 31, 2025

Dec. 31, 2035

Dec. 31, 2041

Dec. 31, 2035

Dec. 31, 2038

Dec. 31, 2021

Dec. 31, 2025

Dec. 31, 2033

Dec. 31, 2043

Dec. 31, 2023

Dec. 31, 2017

Dec. 31, 2021

Dec. 31, 2022

Current maturities

(1.1)

(15.1)

(14.0)

(1.1)

Unamortized discount

(4.9)

(3.8)

Unarmortized discount and premium, net

3.9

4.3

Long-term debt excluding current maturities

3,763.5

^[4]

3,488.0

^[4]

2,575.5

^[4]

2,298.5

^[4]

Debt Instrument Maturity Date Range Start

Dec. 31, 2017

Dec. 31, 2016

Debt Instrument Maturity Date Range End

Dec. 31, 2035

Dec. 31, 2021

Interest rates (in hundredths)

7.15%

4.65%

5.85%

6.375%

3.15%

3.65%

6.05%

5.30%

2.875%

9.44%

8.27%

3.49%

4.06%

4.74%

7.33%

7.17%

6.875%

4.85%

5.292%

Long-term Debt, Weighted Average Interest Rate

2.47%

Variable rate (in hundredths)

0.02%

Rate after amortizing gains or losses in Other Comprehensive Income (in hundredths)

8.59%

5.72%

7.49%

5.78%

7.33%

Repayments of Long-term Debt

87.0

13.4

85.9

14.0

Bonds purchased in lieu of redemption

21.9

50.0

Proceeds from Issuance of Senior Long-term Debt

$ 350.0

[1]	Weighted-average interest rates at September 30, 2015
[2]	Rate after amortizing gains/losses recognized in OCI on settlements of interest rate hedging instruments
[3]	Variable rate
[4]	Does not include $50.0 million and $21.9 million EIRR Series 2005 bonds because the bonds were repurchased in September 2015 and are held by KCP&L.

Commitments and Contingencies Environmental Matters (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2015 MW T	Dec. 31, 2014
Estimated Environmental Capital Expenditures [Abstract]
Estimate Of Environmental Capital Expenditures Current	$ 119.1
Estimate Of Environmental Capital Expenditures In Two Years	62.2
Estimate Of Environmental Capital Expenditures In Three Years	158.4
Estimate Of Environmental Capital Expenditures In Four Years	103.4
Estimate Of Environmental Capital Expenditures In Five Years	99.9
Mercury and Air Toxics Standards Rule [Abstract]
Capacity of electric steam generating units that fall under MACT standards (in megawatts)	25
SO2 National Ambient Air Quality Standard (NAAQS) [Abstract]
Primary one-hour sulfur dioxide standard, as revised June 2010 (in parts per million)	0.075
Primary twenty-four hour sulfur dioxide standard, prior to June 2010 (in parts per million)	0.140
Primary one-year sulfur dioxide standard, prior to June 2010 (in parts per million)	0.030
Climate Change [Abstract]
CO2 produced per year (in tons)	22,000,000
EPA nationwide CO2 emission reductions by 2030	32.00%
Remediation [Abstract]
Accrued environmental remediation expenses	1.4	1.4
MISSOURI
Climate Change [Abstract]
EPA Interim Co2 Goal Rate Reduction	26.00%
EPA Co2 Emission Reductions By 2030 By State	37.00%
KANSAS
Climate Change [Abstract]
EPA Interim Co2 Goal Rate Reduction	34.00%
EPA Co2 Emission Reductions By 2030 By State	44.00%
LaCygne Station [Member]
Best Available Retrofit Technology Rule [Abstract]
Predetermination request for environmental equipment required at LaCygne Station to comply with BART	1,230
Final expected amount below predetermination request for environmental upgrades at LaCynge Station to comply with BART	75
Kansas City Power and Light Company [Member]
Estimated Environmental Capital Expenditures [Abstract]
Estimate Of Environmental Capital Expenditures Current	104.5
Estimate Of Environmental Capital Expenditures In Two Years	51.5
Estimate Of Environmental Capital Expenditures In Three Years	132.9
Estimate Of Environmental Capital Expenditures In Four Years	86.9
Estimate Of Environmental Capital Expenditures In Five Years	84.3
Climate Change [Abstract]
CO2 produced per year (in tons)	17,000,000
Remediation [Abstract]
Accrued environmental remediation expenses	0.3	0.3
Kansas City Power and Light Company [Member] \| LaCygne Station [Member]
Best Available Retrofit Technology Rule [Abstract]
Predetermination request for environmental equipment required at LaCygne Station to comply with BART	615
Entity's ownership percentage in facility (in hundredths)	50.00%
Cash capital expenditures for La Cygne environmental project	531
KCPL Greater Missouri Operations [Member]
Remediation [Abstract]
Estimated amount of insurance proceeds available to cover qualified remediation expenses	$ 1.4
KCPL Greater Missouri Operations [Member] \| Jeffrey Units Nos 1 and 2 [Member]
Best Available Retrofit Technology Rule [Abstract]
Entity's ownership percentage in facility (in hundredths)	8.00%
KCPL Greater Missouri Operations [Member] \| Iatan No. 1 [Member]
Best Available Retrofit Technology Rule [Abstract]
Entity's ownership percentage in facility (in hundredths)	18.00%

Legal Proceedings Loss Contingencies (Details) (MPS Merchant Services, Inc. [Member], USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2015
MPS Merchant Services, Inc. [Member]
Loss Contingencies [Line Items]
Approximate amount of refunds received as a net purchaser of power through settlements with sellers of power	$ 8
Estimated additional refunds entitled to receive	$ 12
Loss Contingency, Inestimable Loss	Due to the uncertainties remaining in the case, the potential refund or range of potential refunds owed by MPS Merchant are not reasonably estimable

Related Party Transactions and Relationships (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Kansas City Power and Light Company [Member] \| KCPL Greater Missouri Operations [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	$ 43.6		$ 43.6		$ 38.2
Operating expenses and capital costs billed from KCPL to GMO	45.5	41.4	137.7	128.6
KCPL net wholesale sales to GMO	0.1	1.6	0.2	12.6
Kansas City Power and Light Company [Member] \| KCPL Greater Missouri Operations [Member] \| Money Pool [Member]
Related Party Transaction [Line Items]
Payable to Related Party					12.6
Kansas City Power and Light Company [Member] \| Great Plains Energy [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	$ 13.4		$ 13.4		$ 18.0
Iatan No 1 And 2 [Member] \| KCPL Greater Missouri Operations [Member]
Related Party Transaction [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	18.00%		18.00%

Carrying amount as of the balance sheet date of obligations due all related parties. For classified balance sheets, represents the current portion of such liabilities (due within one year or within the normal operating cycle if longer).

+ References+ Details

Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2015	Dec. 31, 2014
Futures contracts [Member] \| Not Designated as Hedging Instrument [Member]
Price Risk Derivatives [Abstract]
Notional Contract Amount	$ 26.7	$ 14.9
Fair Value	(4.5)	(2.4)
Forward Contracts [Member] \| Not Designated as Hedging Instrument [Member]
Price Risk Derivatives [Abstract]
Notional Contract Amount	19.3	29.7
Fair Value	3.5	4.1
Option contracts [Member] \| Not Designated as Hedging Instrument [Member]
Price Risk Derivatives [Abstract]
Notional Contract Amount	0	1.7
Fair Value	0	0.1
Transmission Congestion Rights [Member] \| Not Designated as Hedging Instrument [Member]
Price Risk Derivatives [Abstract]
Notional Contract Amount	9.2	28.3
Fair Value	(0.2)	2.6
Kansas City Power and Light Company [Member] \| Futures contracts [Member] \| Not Designated as Hedging Instrument [Member]
Price Risk Derivatives [Abstract]
Notional Contract Amount	1.5	0
Fair Value	0.1	0
Kansas City Power and Light Company [Member] \| Transmission Congestion Rights [Member] \| Not Designated as Hedging Instrument [Member]
Price Risk Derivatives [Abstract]
Notional Contract Amount	6.8	23.6
Fair Value	$ (0.2)	$ 3.1
KCPL Greater Missouri Operations [Member]
Price Risk Derivatives [Abstract]
Percentage of expected on peak natural gas and natural gas equivalent purchased power price exposure hedged remainder of fiscal year	49.00%
Percentage of expected on peak natural gas and natural gas equivalent purchased power price exposure hedged year one	30.00%
Percentage of expected on peak natural gas and natural gas equivalent purchased power price exposure hedged year two	14.00%
Percentage of expected on peak natural gas and natural gas equivalent purchased power price exposure hedged year three	7.00%

Derivative Instruments Offsetting Assets (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2015	Dec. 31, 2014
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 4.0	$ 8.6
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	(0.4)	(1.2)
Derivative Asset	3.6	7.4
Derivative, Collateral, Obligation to Return Securities	0	0
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	3.6	7.4
Kansas City Power and Light Company [Member]
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset	0.4	4.0
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	(0.3)	(0.9)
Derivative Asset	0.1	3.1
Derivative, Collateral, Obligation to Return Securities	0	0
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	$ 0.1	$ 3.1

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References+ Details

Derivative Instruments Offsetting Liabilities (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2015	Dec. 31, 2014
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ 5.2	$ 4.2
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	(5.0)	(3.5)
Derivative Liability	0.2	0.7
Derivative, Collateral, Right to Reclaim Securities	0	0
Derivative, Collateral, Right to Reclaim Cash	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	0.2	0.7
Cash collateral posted with third parties as part of netting agreements	4.6	2.3
Kansas City Power and Light Company [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	0.5	0.9
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	(0.4)	(0.9)
Derivative Liability	0.1	0
Derivative, Collateral, Right to Reclaim Securities	0	0
Derivative, Collateral, Right to Reclaim Cash	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ 0.1	$ 0

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References+ Details

Derivative Instruments Fair Value (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 4.0	$ 8.6
Derivative Liability, Fair Value, Gross Liability	5.2	4.2
Kansas City Power and Light Company [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0.4	4.0
Derivative Liability, Fair Value, Gross Liability	0.5	0.9
Commodity Contract [Member] \| Not Designated as Hedging Instrument [Member] \| Other Balance Sheet Location [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	4.0	8.6
Derivative Liability, Fair Value, Gross Liability	5.2	4.2
Commodity Contract [Member] \| Not Designated as Hedging Instrument [Member] \| Other Balance Sheet Location [Member] \| Kansas City Power and Light Company [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0.4	4.0
Derivative Liability, Fair Value, Gross Liability	$ 0.5	$ 0.9

Derivative Instruments Gain and Losses (Details) (Not Designated as Hedging Instrument [Member], Commodity Contract [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) reflected in the income statement or regulatory account for changes in fair value of commodity contracts not designated as hedging	$ (2.4)	$ (11.0)	$ (15.6)	$ (15.8)
Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in regulatory account for changes in fair value of commodity contracts not designated as hedging	(1.9)	3.2	(5.1)	(0.9)
Regulatory Liability [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in regulatory account for changes in fair value of commodity contracts not designated as hedging	0	(0.2)	0	0
Kansas City Power and Light Company [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) reflected in the income statement or regulatory account for changes in fair value of commodity contracts not designated as hedging	0.8	(7.3)	(6.7)	(11.7)
Kansas City Power and Light Company [Member] \| Regulatory Asset [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in regulatory account for changes in fair value of commodity contracts not designated as hedging	(0.1)	1.7	(0.1)	(0.5)
Purchased Power Costs [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) reflected in the income statement for changes in fair value of commodity contracts not designated as hedging	(0.2)	(4.8)	(1.4)	(4.4)
Fuel Costs [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) reflected in the income statement for changes in fair value of commodity contracts not designated as hedging	(0.1)	0.8	(1.2)	1.8
Fuel Costs [Member] \| Kansas City Power and Light Company [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) reflected in the income statement for changes in fair value of commodity contracts not designated as hedging	1.1	1.0	1.3	1.1
Electric Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) reflected in the income statement for changes in fair value of commodity contracts not designated as hedging	(0.2)	(10.0)	(7.9)	(12.3)
Electric Revenues [Member] \| Kansas City Power and Light Company [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) reflected in the income statement for changes in fair value of commodity contracts not designated as hedging	$ (0.2)	$ (10.0)	$ (7.9)	$ (12.3)

Fair Value Measurements Level 3 (Details) (Derivative Financial Instruments, Assets [Member], Fair Value, Inputs, Level 3 [Member], Fair Value, Measurements, Recurring [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net asset (liability) beginning of period	$ 0.8	$ 0.6	$ 3.5	$ 3.3
Purchases	(0.2)	1.7	0.4	15.1
Settlements	(2.9)	9.9	(1.0)	(11.3)
Net asset (liability) end of period	0.4	3.0	0.4	3.0
Purchased Power Costs [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	(0.2)	(4.8)	(1.4)	(4.4)
Non-Operating Income [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	3.2	2.2	6.9	13.3
Total unrealized gains and (losses) relating to assets and liabilities still on the consolidated balance sheet at period end	0	(0.2)	(0.1)	0
Electric Revenues [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	(0.2)	(10.0)	(7.9)	(12.3)
Total unrealized gains and (losses) relating to assets and liabilities still on the consolidated balance sheet at period end	(0.1)	1.9	(0.1)	(0.6)
Regulatory (Asset) Liability [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Regulatory Account	(0.1)	3.4
Total unrealized gains and (losses) relating to assets and liabilities still on the consolidated balance sheet at period end	(0.1)	3.4
Regulatory Asset [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Regulatory Account			(0.1)	(0.7)
Total unrealized gains and (losses) relating to assets and liabilities still on the consolidated balance sheet at period end			(0.1)	(0.7)
Kansas City Power and Light Company [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net asset (liability) beginning of period	0.1	0.9	3.1	1.1
Purchases	(0.2)	1.3	(0.4)	13.1
Settlements	0.2	8.8	5.1	1.3
Net asset (liability) end of period	(0.2)	2.7	(0.2)	2.7
Kansas City Power and Light Company [Member] \| Electric Revenues [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	(0.2)	(10.0)	(7.9)	(12.3)
Total unrealized gains and (losses) relating to assets and liabilities still on the consolidated balance sheet at period end	(0.1)	1.9	(0.1)	(0.6)
Kansas City Power and Light Company [Member] \| Regulatory (Asset) Liability [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Regulatory Account	(0.1)	1.7
Total unrealized gains and (losses) relating to assets and liabilities still on the consolidated balance sheet at period end	(0.1)	1.7
Kansas City Power and Light Company [Member] \| Regulatory Asset [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Regulatory Account			(0.1)	(0.5)
Total unrealized gains and (losses) relating to assets and liabilities still on the consolidated balance sheet at period end			$ (0.1)	$ (0.5)

Fair Value Measurements Fair Value Long-Term Debt (Details) (USD $) In Billions, unless otherwise specified	Sep. 30, 2015	Dec. 31, 2014
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair value of financial instruments [Abstract]
Long-term Debt	$ 3.8	$ 3.5
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Kansas City Power and Light Company [Member]
Fair value of financial instruments [Abstract]
Long-term Debt	2.6	2.3
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member]
Fair value of financial instruments [Abstract]
Long-term debt fair value	4.1	3.8
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Kansas City Power and Light Company [Member]
Fair value of financial instruments [Abstract]
Long-term debt fair value	$ 2.8	$ 2.6

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References+ Details

Fair Value Measurements (Details) (USD $)
In Millions, unless otherwise specified

Sep. 30, 2015

Dec. 31, 2014

$ 4.0

$ 8.6

5.2

4.2

Kansas City Power and Light Company [Member]

0.4

4.0

0.5

0.9

Fair Value, Measurements, Recurring [Member]

4.0

^[1]

8.6

^[1]

193.1

^[2]

199.0

^[2]

Self Insured Health Plan Trust Fair Value Disclosure

14.7

^[3]

15.1

^[3]

17.0

^[4]

17.9

^[4]

228.8

240.6

5.2

^[1]

4.2

^[1]

5.2

4.2

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]

0.1

^[1]

158.6

^[2]

162.3

^[2]

Self Insured Health Plan Trust Fair Value Disclosure

7.5

^[3]

7.5

^[3]

0.1

^[4]

0.1

^[4]

166.3

169.9

4.6

^[1]

2.4

^[1]

4.6

2.4

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]

2.9

^[1]

3.4

^[1]

34.5

^[2]

36.7

^[2]

Self Insured Health Plan Trust Fair Value Disclosure

7.2

^[3]

7.6

^[3]

16.9

^[4]

17.8

^[4]

61.5

65.5

^[1]

0.1

^[1]

0.1

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]

1.0

^[1]

5.2

^[1]

^[2]

Self Insured Health Plan Trust Fair Value Disclosure

^[3]

^[4]

1.0

5.2

0.6

^[1]

1.7

^[1]

0.6

1.7

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member]

0.4

^[1]

4.0

^[1]

193.1

199.0

Self Insured Health Plan Trust Fair Value Disclosure

14.7

15.1

208.2

218.1

0.5

^[1]

0.9

^[1]

0.5

0.9

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Equity Securities [Member]

128.4

137.1

Self Insured Health Plan Trust Fair Value Disclosure

1.1

1.3

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Debt Securities [Member]

Self Insured Health Plan Trust Fair Value Disclosure

7.2

7.6

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | US Treasury and Government [Member]

27.4

22.9

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | US Government Corporations and Agencies Securities [Member]

1.8

3.5

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | US States and Political Subdivisions Debt Securities [Member]

4.0

4.1

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Corporate Debt Securities [Member]

28.4

28.1

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Foreign Government Debt Securities [Member]

0.3

0.5

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Cash Equivalents [Member]

2.8

2.3

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Cash and Cash Equivalents [Member]

Self Insured Health Plan Trust Fair Value Disclosure

6.4

6.2

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Other Trust Assets [Member]

0.5

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member]

0.1

^[1]

158.6

162.3

Self Insured Health Plan Trust Fair Value Disclosure

7.5

166.2

169.8

^[1]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member]

128.4

137.1

Self Insured Health Plan Trust Fair Value Disclosure

1.1

1.3

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member]

Self Insured Health Plan Trust Fair Value Disclosure

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | US Treasury and Government [Member]

27.4

22.9

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | US Government Corporations and Agencies Securities [Member]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Foreign Government Debt Securities [Member]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Cash Equivalents [Member]

2.8

2.3

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member]

Self Insured Health Plan Trust Fair Value Disclosure

6.4

6.2

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Other Trust Assets [Member]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member]

^[1]

34.5

36.7

Self Insured Health Plan Trust Fair Value Disclosure

7.2

7.6

41.7

44.3

^[1]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member]

Self Insured Health Plan Trust Fair Value Disclosure

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member]

Self Insured Health Plan Trust Fair Value Disclosure

7.2

7.6

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | US Treasury and Government [Member]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | US Government Corporations and Agencies Securities [Member]

1.8

3.5

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]

4.0

4.1

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]

28.4

28.1

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Foreign Government Debt Securities [Member]

0.3

0.5

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Cash Equivalents [Member]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Cash and Cash Equivalents [Member]

Self Insured Health Plan Trust Fair Value Disclosure

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Other Trust Assets [Member]

0.5

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member]

0.3

^[1]

4.0

^[1]

Self Insured Health Plan Trust Fair Value Disclosure

0.3

4.0

0.5

^[1]

0.9

^[1]

0.5

0.9

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]

Self Insured Health Plan Trust Fair Value Disclosure

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member]

Self Insured Health Plan Trust Fair Value Disclosure

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | US Treasury and Government [Member]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | US Government Corporations and Agencies Securities [Member]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Foreign Government Debt Securities [Member]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Cash Equivalents [Member]

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Cash and Cash Equivalents [Member]

Self Insured Health Plan Trust Fair Value Disclosure

Fair Value, Measurements, Recurring [Member] | Kansas City Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Other Trust Assets [Member]

Fair Value, Measurements, Recurring [Member] | Other Great Plains [Member]

3.6

^[1]

4.6

^[1]

17.0

17.9

20.6

22.5

4.7

^[1]

3.3

^[1]

4.7

3.3

Fair Value, Measurements, Recurring [Member] | Other Great Plains [Member] | Equity Securities [Member]

0.1

Fair Value, Measurements, Recurring [Member] | Other Great Plains [Member] | Fixed Income Funds [Member]

16.9

17.8

Fair Value, Measurements, Recurring [Member] | Other Great Plains [Member] | Fair Value, Inputs, Level 1 [Member]

^[1]

0.1

0.1

4.6

^[1]

2.4

^[1]

4.6

2.4

Fair Value, Measurements, Recurring [Member] | Other Great Plains [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member]

0.1

Fair Value, Measurements, Recurring [Member] | Other Great Plains [Member] | Fair Value, Inputs, Level 1 [Member] | Fixed Income Funds [Member]

Fair Value, Measurements, Recurring [Member] | Other Great Plains [Member] | Fair Value, Inputs, Level 2 [Member]

2.9

^[1]

3.4

^[1]

16.9

17.8

19.8

21.2

^[1]

0.1

^[1]

0.1

Fair Value, Measurements, Recurring [Member] | Other Great Plains [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member]

Fair Value, Measurements, Recurring [Member] | Other Great Plains [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed Income Funds [Member]

16.9

17.8

Fair Value, Measurements, Recurring [Member] | Other Great Plains [Member] | Fair Value, Inputs, Level 3 [Member]

0.7

^[1]

1.2

^[1]

0.7

1.2

0.1

^[1]

0.8

^[1]

0.1

0.8

Fair Value, Measurements, Recurring [Member] | Other Great Plains [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]

Fair Value, Measurements, Recurring [Member] | Other Great Plains [Member] | Fair Value, Inputs, Level 3 [Member] | Fixed Income Funds [Member]

Accumulated Other Comprehensive Income (Loss) [Line Items]

$ 0

[1]	The fair value of derivative instruments is estimated using market quotes, over-the-counter forward price and volatility curves and correlations among fuel prices, net of estimated credit risk. Derivative instruments classified as Level 1 represent exchange traded derivative instruments. Derivative instruments classified as Level 2 represent non-exchange traded derivative instruments traded in over-the-counter markets. Derivative instruments classified as Level 3 represent non-exchange traded derivatives traded in over-the-counter markets for which observable market data is not available to corroborate the valuation inputs and TCRs valued at the most recent auction price in the SPP Integrated Marketplace.
[2]	Fair value is based on quoted market prices of the investments held by the fund and/or valuation models.
[3]	Fair value is based on quoted market prices of the investments held by the trust. Debt securities classified as Level 2 are comprised of corporate bonds, U.S. Agency, state and local obligations, and other asset-backed securities.
[4]	Fair value is based on quoted market prices for equity securities and Net Asset Value (NAV) per share for fixed income funds. The fixed income fund invests primarily in intermediate and long-term debt securities, can be redeemed immediately and is not subject to any restrictions on redemptions.

Accumulated Other Comprehensive Income (Loss) (Details) (USD $)
In Millions, unless otherwise specified

3 Months Ended

9 Months Ended

Sep. 30, 2015

Sep. 30, 2014

Sep. 30, 2015

Sep. 30, 2014

Amounts reclassified from accumulated other comprehensive loss

$ (18.7)

^[1]

$ (25.3)

^[1]

4.5

^[1]

6.9

^[1]

1.4

4.5

^[1]

6.9

^[1]

Accumulated Other Comprehensive Income (Loss) [Line Items]

(14.2)

^[1]

(18.4)

^[1]

(14.2)

^[1]

(18.4)

^[1]

Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]

Amounts reclassified from accumulated other comprehensive loss

(15.8)

^[1]

(23.8)

^[1]

4.2

^[1]

6.6

^[1]

4.2

^[1]

6.6

^[1]

Accumulated Other Comprehensive Income (Loss) [Line Items]

(11.6)

^[1]

(17.2)

^[1]

(11.6)

^[1]

(17.2)

^[1]

Accumulated Defined Benefit Plans Adjustment [Member]

Amounts reclassified from accumulated other comprehensive loss

(2.9)

^[1]

(1.5)

^[1]

0.3

^[1]

0.3

^[1]

0.3

^[1]

0.3

^[1]

Accumulated Other Comprehensive Income (Loss) [Line Items]

(2.6)

^[1]

(1.2)

^[1]

(2.6)

^[1]

(1.2)

^[1]

Kansas City Power and Light Company [Member]

(14.9)

1.3

1.2

4.0

3.9

Accumulated Other Comprehensive Income (Loss) [Line Items]

(10.9)

Kansas City Power and Light Company [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]

Amounts reclassified from accumulated other comprehensive loss

(14.9)

^[1]

(20.2)

^[1]

4.0

^[1]

3.9

^[1]

4.0

^[1]

3.9

^[1]

$ (10.9)

^[1]

$ (16.3)

^[1]

$ (10.9)

^[1]

$ (16.3)

^[1]

[1]	Net of tax

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References+ Details

Accumulated Other Comprehensive Income (Loss) Reclassification (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest charges	$ (51.0)	$ (43.6)	$ (148.3)	$ (141.3)
Fuel	(124.5)	(142.3)	(332.0)	(392.9)
Utility operating and maintenance expenses	(182.5)	(164.1)	(537.4)	(528.2)
Income before income tax (expense) benefit and income (loss) from equity investments	205.2	222.2	298.8	333.0
Income tax (expense) benefit	(78.6)	(74.7)	(109.6)	(109.8)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	(1.4)	(1.4)	(4.5)	(6.9)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income tax (expense) benefit and income (loss) from equity investments	(2.3)	(2.3)	(6.9)	(10.9)
Income tax (expense) benefit	0.9	1.0	2.7	4.3
Net income (loss)	(1.4)	(1.3)	(4.2)	(6.6)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member] \| Interest Rate Contract [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest charges	(2.3)	(2.3)	(6.9)	(10.9)
Accumulated Defined Benefit Plans Adjustment [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Utility operating and maintenance expenses	(0.1)	(0.1)	(0.5)	(0.4)
Income before income tax (expense) benefit and income (loss) from equity investments	(0.1)	(0.1)	(0.5)	(0.4)
Income tax (expense) benefit	0.1	0	0.2	0.1
Net income (loss)	0	(0.1)	(0.3)	(0.3)
Kansas City Power and Light Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest charges	(34.8)	(31.1)	(100.4)	(92.8)
Fuel	(89.4)	(107.2)	(237.3)	(289.0)
Utility operating and maintenance expenses	(122.9)	(112.8)	(365.8)	(369.1)
Income before income tax (expense) benefit and income (loss) from equity investments	134.8	147.8	195.6	219.4
Income tax (expense) benefit	(50.5)	(53.3)	(68.7)	(72.9)
Kansas City Power and Light Company [Member] \| Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income tax (expense) benefit and income (loss) from equity investments	(2.2)	(2.1)	(6.6)	(6.5)
Income tax (expense) benefit	0.9	0.9	2.6	2.6
Net income (loss)	(1.3)	(1.2)	(4.0)	(3.9)
Kansas City Power and Light Company [Member] \| Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member] \| Interest Rate Contract [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest charges	$ (2.2)	$ (2.1)	$ (6.6)	$ (6.5)

Income Tax Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Current income taxes
Federal	$ (0.8)	$ (0.7)	$ (0.3)	$ (0.6)
State	0.5	(0.1)	0.4	0
Current Income Tax Expense (Benefit), Total	(0.3)	(0.8)	0.1	(0.6)
Deferred income taxes
Federal	66.4	69.0	91.8	100.6
State	12.4	12.9	18.3	19.7
Deferred Income Tax Expense (Benefit), Total	78.8	81.9	110.1	120.3
Noncurrent income taxes
Federal	0	0	0	(2.4)
State	0	0	0	(0.3)
Foreign	0	(6.2)	0	(6.2)
Noncurrent Income Tax Expense (Benefit), Total	0	(6.2)	0	(8.9)
Investment tax credit
Deferral	0.5	0	0.5	0
Investment tax credit amortization	(0.4)	(0.2)	(1.1)	(1.0)
Investment Tax Credit, Total	0.1	(0.2)	(0.6)	(1.0)
Total income tax expense	78.6	74.7	109.6	109.8
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory income tax (in hundredths)	35.00%	35.00%	35.00%	35.00%
Differences between book and tax depreciation not normalized (in hundredths)	0.30%	(0.30%)	0.40%	(0.50%)
Amortization of investments tax credits (in hundredths)	(0.20%)	(0.10%)	(0.40%)	(0.30%)
Federal income tax credits (in hundredths)	(1.20%)	(1.80%)	(2.60%)	(3.00%)
State income taxes (in hundredths)	4.20%	3.70%	4.00%	3.70%
Changes in uncertain tax positions, net (in hundredths)	0.00%	(2.80%)	0.00%	(1.80%)
Effective Income Tax Rate Reconciliation, Other Adjustments	0.20%	(0.10%)	0.20%	(0.20%)
Effective Income Tax Rate Reconciliation, Percent	38.30%	33.60%	36.60%	32.90%
Kansas City Power and Light Company [Member]
Current income taxes
Federal	43.9	33.8	42.4	34.5
State	7.1	5.9	6.7	6.1
Current Income Tax Expense (Benefit), Total	51.0	39.7	49.1	40.6
Deferred income taxes
Federal	(1.6)	10.9	14.6	26.2
State	0.8	2.9	5.2	6.8
Deferred Income Tax Expense (Benefit), Total	(0.8)	13.8	19.8	33.0
Investment tax credit
Deferral	0.5	0	0.5	0
Investment tax credit amortization	(0.2)	(0.2)	(0.7)	(0.7)
Investment Tax Credit, Total	0.3	(0.2)	(0.2)	(0.7)
Total income tax expense	$ 50.5	$ 53.3	$ 68.7	$ 72.9
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory income tax (in hundredths)	35.00%	35.00%	35.00%	35.00%
Differences between book and tax depreciation not normalized (in hundredths)	0.40%	(0.20%)	0.60%	(0.70%)
Amortization of investments tax credits (in hundredths)	(0.20%)	(0.20%)	(0.40%)	(0.40%)
Federal income tax credits (in hundredths)	(1.80%)	(2.40%)	(3.90%)	(4.30%)
State income taxes (in hundredths)	3.90%	3.90%	3.90%	3.80%
Effective Income Tax Rate Reconciliation, Other Adjustments	0.10%	0.00%	(0.10%)	(0.10%)
Effective Income Tax Rate Reconciliation, Percent	37.40%	36.10%	35.10%	33.30%

Segments and Related Information (Details) (USD $)
In Millions, unless otherwise specified

3 Months Ended

9 Months Ended

12 Months Ended

Sep. 30, 2015

Sep. 30, 2014

Sep. 30, 2015

Sep. 30, 2014

Dec. 31, 2014

$ 781.4

$ 782.5

$ 1,939.5

$ 2,016.0

(82.4)

(76.6)

(245.7)

(226.7)

(51.0)

(43.6)

(148.3)

(141.3)

(78.6)

(74.7)

(109.6)

(109.8)

126.8

147.4

190.1

223.3

10,844.1

10,475.7

520.9

^[1]

553.3

773.7

^[1]

Operating Segments [Member] | Electric Utility Segment [Member]

781.4

782.5

1,939.5

2,016.0

(82.4)

(76.6)

(245.7)

(226.7)

(48.9)

(44.9)

(142.1)

(137.9)

(78.5)

(81.0)

(112.0)

(118.8)

129.1

140.3

196.4

221.1

11,053.9

10,746.1

520.9

^[1]

773.7

^[1]

Other [Member]

(10.2)

(6.8)

(30.3)

(31.1)

(0.1)

6.3

2.4

9.0

(2.3)

7.1

(6.3)

2.2

163.6

33.1

^[1]

Eliminations [Member]

8.1

24.1

27.7

(373.4)

(303.5)

$ 0

^[1]

$ 0

^[1]

[1]	Capital expenditures reflect year to date amounts for the periods presented.