Variable Interest Entities [Abstract] Schedule Of Variable Interest Entities [Abstract] Assets And Liabilities of VIEs Schedule of Variable Interest Entities [Table Text Block] Income Tax Disclosure [Abstract] Taxes Income Tax Disclosure [Text Block] Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract] Statement [Table] Statement [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Pension Benefits [Member] Pension Plan [Member] Post-Retirement Benefits [Member] Other Postretirement Benefit Plan [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Wolf Creek [Member] Wolf Creek Member Wolf Creek [Member] KGE [Member] KGE Member KGE [Member] Statement [Line Items] Statement [Line Items] Subsidiary Interest in Defined Benefit Plans Subsidiary Interest in Defined Benefit Plans Subsidiary's interest in defined benefit plans. Components of Net Periodic Cost (Benefit): Defined Benefit Plan, Net Periodic Benefit Cost [Abstract] Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return on Plan Assets Prior service costs Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Actuarial loss, net Defined Benefit Plan, Amortization of Gains (Losses) Net periodic cost before regulatory adjustment Defined Benefit Plan Net Periodic Benefit Cost before Regulatory Adjustment The total amount of net periodic benefit cost for defined benefit plans for the period prior to regulatory adjustment. Regulatory adjustment Defined Benefit Plan Regulatory Adjustment Defined Benefit Plan Regulatory Adjustment Net periodic cost Defined Benefit Plan, Net Periodic Benefit Cost Pension Contributions Pension Contributions Compensation and Retirement Disclosure [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Schedule of Net Periodic Benefit Costs [Table Text Block] Schedule of Net Benefit Costs [Table Text Block] Consolidated Statements of Changes in Equity Parenthetical [Abstract] Consolidated Statements of Changes in Equity Parenthetical [Abstract] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] DIVIDENDS DECLARED PER COMMON SHARE Common Stock, Dividends, Per Share, Declared Investments [Abstract] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Summary of Investments, Other than Investments in Related Parties, by Type [Axis] Summary of Investments, Other than Investments in Related Parties, by Type [Axis] Summary of Investments, by Type [Domain] Summary of Investments, by Type [Domain] Schedule of Available-for-sale Securities [Line Items] Schedule of Available-for-sale Securities [Line Items] Trading Securities Trading Securities Unrealized gains losses Trading Securities, Change in Unrealized Holding Gain (Loss) Realized gains on available-for-sale-securities Available-for-sale Securities, Gross Realized Gain (Loss) Accounting Policies [Abstract] Summary Of Significant Accounting Policies Significant Accounting Policies [Text Block] Long-term Debt, Unclassified [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Variable Interest Entities by Classification of Entity [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] La Cygne Generating Station [Member] La Cygne Generating Station Member La Cygne Generating Station [Member] Variable Interest Entity, Primary Beneficiary [Member] Variable Interest Entity, Primary Beneficiary [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Debt Instrument La Cygne [Member] [Domain] [Domain] Debt Instrument La Cygne [Member] [Domain] [Domain] Debt Instrument La Cygne VIE [Member] KGE Member [Domain] KGE Member [Domain] KGE Member [Domain] Debt Instrument [Line Items] Debt Instrument [Line Items] Long-term Debt, Gross Long-term Debt, Gross Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage debt instrument, interest rate, refunded stated percentage debt instrument, interest rate, refunded stated percentage debt instrument, interest rate, refunded stated percentage Variable Interest Entities Variable Interest Entities Disclosure [Text Block] Variable Interest Entities Disclosure [Text Block] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Jeffrey Energy Center [Member] Jeffrey Energy Center Member Jeffrey Energy Center [Member] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Variable interest entity percentage of asset held Variable Interest Entity Percentage of Asset Held The percentage of an asset held by a variable interest entity that is consolidated by the entity. Agreement expiration date Lease Expiration Date Debt Financing Debt Disclosure [Text Block] Property, plant and equipment, net Property, Plant and Equipment, Net Regulatory assets Regulatory Assets Current maturities of long-term debt Long-term Debt, Current Maturities Accrued interest Interest Payable, Current Long-term debt, net Long-term Debt, Excluding Current Maturities Wolf Creek Pension And Post-Retirement Benefit Plans [Line Items] Wolf Creek Interim Pension And Post-Retirement Benefit Disclosure [Line Items] Wolf Creek Interim Pension And Post-Retirement Benefit Disclosure [Line Items] Statement of Stockholders' Equity [Abstract] Statement, Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock [Member] Common Stock [Member] Paid-In Capital [Member] Additional Paid-in Capital [Member] Retained Earnings [Member] Retained Earnings [Member] Noncontrolling Interest [Member] Noncontrolling Interest [Member] Beginning Balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Beginning Balance (Shares) Shares, Outstanding Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Issuance of stock Stock Issued During Period, Value, New Issues Issuance Of Stock For Compensation And Reinvested Dividends, Shares Issuance Of Stock For Compensation And Reinvested Dividends, Shares Issuance Of Stock For Compensation And Reinvested Dividends, Shares Issuance of stock (shares) Stock Issued During Period, Shares, New Issues Issuance Of Stock For Compensation And Reinvested Dividends Issuance Of Stock For Compensation And Reinvested Dividends Issuance Of Stock For Compensation And Reinvested Dividends Tax withholding related to stock compensation Adjustments Related to Tax Withholding for Share-based Compensation Dividends on common stock Dividends, Common Stock Stock compensation expense Adjustments to Additional Paid in Capital, Share-based Compensation, Restricted Stock Unit or Restricted Stock Award, Requisite Service Period Recognition Tax Benefit on stock compensation Excess Tax Benefit from Share-based Compensation, Financing Activities Distributions to shareholders of noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets Ending Balance Ending Balance (Shares) Stockholders' Equity, Other Stockholders' Equity, Other Organization, Consolidation and Presentation of Financial Statements [Abstract] Description Of Business Nature of Operations [Text Block] Commitments and Contingencies Disclosure [Abstract] Commitments And Contingencies Commitments and Contingencies Disclosure [Text Block] Borrowed funds Allowance for Funds Used During Construction, Capitalized Interest Equity funds Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Total Public Utilities, Allowance for Funds Used During Construction, Additions Average AFUDC rates Public Utilities, Allowance for Funds Used During Construction, Rate Legal Proceedings [Abstract] LEGAL PROCEEDINGS [Abstract] Legal Proceedings Legal Proceedings Text Block Open legal proceedings in the normal course of business, including product liability and other litigation and contingencies. Financial And Derivative Instruments and Trading Securities [Abstract] Financial And Derivative Instruments and Trading Securities [Abstract] Summary of Investments, Other than Investments in Related Parties [Table] Summary of Investments, Other than Investments in Related Parties [Table] Investment Type [Axis] Investment Type [Axis] Investment Type Categorization [Domain] Investments [Domain] Decommissioning Trust Assets [Member] Decommissioning Trust Assets [Member] Decommissioning Trust Assets [Member] Fair Value by Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value [Member] Fair Value, Measurements, Recurring [Member] Domestic Equity Funds [Member] Domestic Equity Member Domestic Equity [Member] Alternative Funds [Member] Alternative Funds [Member] Alternative Funds [Member] Real Estate Securities Fund [Member] Real Estate Funds [Member] Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items] Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Excess Tax Benefit from Share-based Compensation Excess Tax Benefit from Share-based Compensation Excess Tax Benefit from Share-based Compensation Financial And Derivative Instruments And Trading Securities Financial And Derivative Instruments And Trading Securities [Text Block] Financial And Derivative Instruments And Trading Securities [Text Block] Cost And Fair Value Of Investments Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Fair Value And Gross Unrealized Losses Of Available-For-Sale Securities Schedule of Temporary Impairment Losses, Investments [Table Text Block] Schedule of Utility Inventory Schedule of Utility Inventory [Table Text Block] Allowance For Funds Used During Construction Schedule of Allowance for Funds Used During Construction [Table Text Block] Tabular disclosure of an entity's allowance for funds used during construction. Reconciliation Of Basic And Diluted EPS Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Supplemental Cash Flow Information Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Regulated Operations [Abstract] Rate Matters And Regulation Public Utilities Disclosure [Text Block] Consolidated Balance Sheets Parenthetical [Abstract] Consolidated Balance Sheets Parenthetical [Abstract] CURRENT ASSETS: Assets, Current [Abstract] Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Current Westar Energy, Inc. Shareholders' Equity: Stockholders' Equity Attributable to Parent [Abstract] Common stock, par value Common Stock, Par or Stated Value Per Share Common stock, shares authorized Common Stock, Shares Authorized Common stock, shares issued Common Stock, Shares, Issued Common stock, shares outstanding Common Stock, Shares, Outstanding Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Inputs Valuation Techniques [Axis] Fair Value Inputs Valuation Techniques [Axis] Fair Value Inputs Valuation Techniques [Axis] Fair Value Inputs Valuation Techniques [Domain] Fair Value Inputs Valuation Techniques [Domain] Fair Value Inputs Valuation Techniques [Domain] Fair Value, Inputs, Net Asset Value [Member] Fair Value, Inputs, Net Asset Value [Member] Fair Value, Inputs, Net Asset Value [Member] International Equity Funds [Member] International Equity Member International Equity [Member] Core Bonds Fund [Member] Core Bonds [Member] Core Bonds [Member] High-Yield Bonds Fund [Member] High Yield Bonds Member High-yield Bonds [Member] Emerging Market Bonds Fund [Member] Emerging Market Bonds Member Emerging Market Bonds [Member] Combination Debt Equity And Other Fund [Member] Combination Debt Equity And Other Fund [Member] Combination Debt Equity And Other Fund [Member] Cash Equivalents [Member] Cash Equivalents [Member] Fair Value, Measurements, Fair Value Hierarchy [Domain] Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Financial and Derivative Instruments and Trading Securities [Line Items] Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items] Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items] Nuclear decommissioning trust assets Decommissioning Fund Investments, Fair Value Trading securities Total assets measured at fair value Assets, Fair Value Disclosure Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Redemption Restriction Period Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Redemption Restriction Period Total Investment redemption frequency Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency Regulatory Proceedings [Table] Regulatory Proceedings [Table] Regulatory Proceedings [Table] Return On Equity Components [Axis] Return On Equity Components [Axis] Return On Equity Components [Axis] return on equity components [Domain] return on equity components [Domain] [Domain] for return on equity components [Axis] Incentive Return on Equity [Member] Incentive Return on Equity [Member] Incentive Return on Equity [Member] Base Return on Equity [Member] Base Return on Equity [Member] Base Return on Equity [Member] Regulatory Agency [Axis] Regulatory Agency [Axis] Regulatory Agency [Domain] Regulatory Agency [Domain] Kansas Corporation Commission [Member] Kansas Corporation Commission [Member] Kansas Corporation Commission [Member] Public Utilities, Regulatory Proceeding [Axis] Public Utilities, Regulatory Proceeding [Axis] Public Utilities, Regulatory Proceeding [Domain] Public Utilities, Regulatory Proceeding [Domain] Electric Transmission [Member] Electric Transmission [Member] Ad Valorem Tax [Member] Ad Valorem Tax [Member] Ad Valorem Tax [Member] FERC 206 [Member] FERC 206 [Member] Proceedings with FERC under Section 206 of the Federal Power Act [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Regulatory Proceedings [Line Items] Regulatory Proceedings [Line Items] Regulatory Proceedings [Line Items] Public Utilities, Approved Rate Increase (Decrease), Amount Public Utilities, Approved Rate Increase (Decrease), Amount Public Utilities, Requested Rate Increase (Decrease), Amount Public Utilities, Requested Rate Increase (Decrease), Amount Public Utilities, Approved Return on Equity, Percentage Public Utilities, Approved Return on Equity, Percentage Loss Contingency Accrual Loss Contingency Accrual Investment Holdings [Table] Investment Holdings [Table] Available-for-sale Securities, Amortized Cost Basis Available-for-sale Securities, Amortized Cost Basis Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax Available-for-sale Securities Available-for-sale Securities Allocation Available-for-sale Securities, Security Type Allocation Percentage Available-for-sale Securities, Security Type Allocation Percentage Wolf Creek Pension And Post-Retirement Benefit Plans Entity Share Of Affiliate Pension And Other Postretirement Benefits Disclosure Text Block Includes disclosure of the entity's share of an affiliate's pension and other post-retirement benefits. Financial Investments Investments Securities Disclosure [Text Block] Disclosure related to investments in certain debt and equity securities classified as either trading securities or available-for-sale securities. Summary Of Significant Accounting Policies [Line Items] Summary Of Significant Accounting Policies [Line Items] Summary Of Significant Accounting Policies [Line Items] Cash Paid For (Received From) Supplemental Cash Flow Information [Abstract] Interest on financing activities Interest Paid Income Taxes Paid, Net Income Taxes Paid, Net Noncash Investing and Financing Transactions Noncash Investing and Financing Items [Abstract] Property, plant and equipment Noncash or Part Noncash Acquisition, Fixed Assets Acquired Issuance of common stock for reinvested dividends and compensation plans Stock Issued Assets acquired through capital leases Capital Lease Obligations Incurred New Accounting Pronouncements, Policy [Policy Text Block] New Accounting Pronouncements, Policy [Policy Text Block] Principles Of Consolidation Consolidation, Policy [Policy Text Block] Use Of Management's Estimates Use of Estimates, Policy [Policy Text Block] Fuel Inventory And Supplies Inventory, Policy [Policy Text Block] Allowance For Funds Used During Construction Allowance for Funds Used During Construction, Policy [Policy Text Block] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Supplemental Cash Flow Information Cash Flow, Supplemental Disclosures [Text Block] Income Statement [Abstract] REVENUES Revenues OPERATING EXPENSES: Operating Costs and Expenses [Abstract] Fuel and purchased power Cost Electric Fuel Purchased Power Fuel and purchased power expense incurred that are directly related to goods produced and sold. Network Transmission Cost Network Transmission Cost Network Transmission Cost Operating and maintenance Utilities Operating Expense, Maintenance and Operations Depreciation and amortization Depreciation, Amortization and Accretion, Net Selling, general and administrative Selling, General and Administrative Expense Taxes, Miscellaneous Taxes, Miscellaneous Total Operating Expenses Costs and Expenses INCOME FROM OPERATIONS Operating Income (Loss) OTHER INCOME (EXPENSE): Nonoperating Income (Expense) [Abstract] Investment earnings (losses) Investment Income, Nonoperating Other income Other Nonoperating Income Other expense Other Nonoperating Expense Total Other Income Nonoperating Income (Expense) Interest expense Interest Expense INCOME BEFORE INCOME TAXES Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Income tax expense Income Tax Expense (Benefit) NET INCOME Less: Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest NET INCOME ATTRIBUTABLE TO WESTAR ENERGY, INC. Net Income (Loss) Attributable to Parent Earnings Per Share [Abstract] Earnings Per Share [Abstract] Earnings Per Share, Basic Earnings Per Share, Basic Earnings Per Share, Diluted Earnings Per Share, Diluted AVERAGE EQUIVALENT COMMON SHARES OUTSTANDING Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Weighted Average Number of Shares Outstanding , Basic Weighted Average Number of Shares Outstanding, Basic Weighted Average Number of Shares Outstanding, Diluted Weighted Average Number of Shares Outstanding, Diluted Income Tax Contingency [Table] Income Tax Contingency [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Income Tax Contingency [Line Items] Income Tax Contingency [Line Items] Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Liability for unrecognized income tax benefits Unrecognized Tax Benefits Interest on liability related to unrecognized income tax benefits Unrecognized Tax Benefits, Interest on Income Taxes Accrued Penalties accrued for unrecognized income tax benefits Unrecognized Tax Benefits, Income Tax Penalties Accrued Accrual for taxes other than income taxes Accrual for Taxes Other than Income Taxes Pension And Post-Retirement Benefit Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Fixed Rate Debt Member Fixed Rate Debt [Member] Fixed Rate Debt Of Variable Interest Entities Member Fixed Rate Debt Of Variable Interest Entities Member Fixed Rate Debt of Variable Interest Entities [Member] Carrying Value Fair Value Debt Instrument, Fair Value Disclosure Net Income Allocated to RSUs Participating Securities, Distributed and Undistributed Earnings (Loss), Diluted Net income allocated to common stock Common Stock Distributed And Undistributed Earnings Earnings distributed and earnings allocated to common stock under the two-class method. RSUs Incremental Common Shares Attributable to Dilutive Effect of Nonvested Shares with Forfeitable Dividends Forward sale agreements Incremental Common Shares Attributable To Equity Forward Sale Agreements Additional common shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of equity forward sale agreements using the treasury stock method. Weighted average equivalent common shares outstanding - diluted Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive securities Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Defined Benefit Plans Disclosures, Defined Benefit Plans [Axis] Net periodic cost before regulatory adjustment Net periodic cost Statement of Cash Flows [Abstract] Variable Interest Entity [Member] CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Amortization of nuclear fuel Amortization of nuclear fuel The current period expense charged against earnings for the amortization of capitalized nuclear fuel used to generate electricity. Amortization of deferred regulatory gain from sale leaseback Sale Leaseback Transaction, Current Period Gain Recognized Amortization of corporate-owned life insurance Amortization Of Corporate Owned Life Insurance The amortization of various items related to corporate-owned life insurance policies. Non-cash compensation Share-based Compensation Net deferred income taxes and credits Deferred Income Taxes and Tax Credits Allowance for equity funds used during construction Changes in working capital items: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Fuel inventory and supplies Increase (Decrease) in Inventories Prepaid expenses and other Increase (Decrease) in Prepaid Expense and Other Assets Accounts payable Increase (Decrease) in Accounts Payable Accrued taxes Increase (Decrease) in Accrued Taxes Payable Other current liabilities Increase (Decrease) in Other Current Liabilities Changes in other assets Increase (Decrease) in Other Operating Assets Changes in other liabilities Increase (Decrease) in Other Operating Liabilities Cash Flows from Operating Activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations CASH FLOWS FROM (USED IN) INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities [Abstract] Additions to property, plant and equipment Payments to Acquire Property, Plant, and Equipment Purchase of securities - trusts Payments to Acquire Marketable Securities Sale of securities - trusts Proceeds from Sale and Maturity of Marketable Securities Proceeds from investment in corporate-owned life insurance Proceeds from Life Insurance Policies Investment in affiliated company Payments to Acquire Businesses and Interest in Affiliates Other investing activities Payments for (Proceeds from) Other Investing Activities Cash Flows used in Investing Activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Short-term debt, net Proceeds from (Repayments of) Short-term Debt Proceeds from long-term debt Proceeds from Issuance of Long-term Debt Retirements of long-term debt Repayments of Long-term Debt Repayment of capital leases Repayments of Long-term Capital Lease Obligations Borrowings against cash surrender value of corporate-owned life insurance Proceeds From Borrowings Against Cash Surrender Value Of Corporate Owned Life Insurance The cash inflow from borrowings against the cash surrender value of corporate-owned life insurance polices. Repayment of borrowings against cash surrender value of corporate-owned life insurance Repayment of borrowings against cash surrender value of corporate-owned life insurance The cash outflow associated with the repayment of borrowings against the cash surrender value of corporate-owned life insurance polices. Issuance of common stock Proceeds from Issuance of Common Stock Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Cash dividends paid Payments of Dividends Other financing activities Proceeds from (Payments for) Other Financing Activities Cash Flows from Financing Activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations NET CHANGE IN CASH AND CASH EQUIVALENTS Cash and Cash Equivalents, Period Increase (Decrease) CASH AND CASH EQUIVALENTS: Cash and Cash Equivalents, at Carrying Value [Abstract] Beginning of period Cash and Cash Equivalents, at Carrying Value End of period Public Utilities, Inventory [Table] Inventory [Axis] Inventory [Domain] Fuel Inventory [Member] Public Utilities, Inventory, Fuel [Member] Supplies [Member] Supplies [Member] Public Utilities, Inventory [Line Items] Public Utilities Inventory Public Utilities, Inventory Total Inventory, Net Carrying Values And Fair Values Of Financial Instruments Schedule of Carrying Value and Fair Values of Financial Instruments [Table Text Block] Schedule of Carrying Value and Fair Values of Financial Instruments. Fair Value Of Assets And Liabilities Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Reconciliations Of Assets And Liabilities At Fair Value Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Unrealized Gains And Losses On Fair Value Assets And Liabilities Schedule Of Unrealized Gains And Losses Of Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input [Table Text Block] Schedule of unrealized gains and losses recorded for assets and liabilities measured at fair value on a recurring basis using unobservable inputs. Investments In Financial Instruments Fair Value Investments Entities That Calculate Net Asset Value per Share Disclosure [Table Text Block] This item represents the disclosure regarding the investments in certain entities that calculate net asset value per share that enables users to understand the nature and risks of the investments and whether the investments are probable of being sold at amounts different from net asset value per share. Such disclosure may include (1) the fair value of the investments in the major category, and a description of the significant investment strategies of the investee(s) in the major category; (2) for each major category of investment that includes investments that can never be redeemed with the investees, but the reporting entity receives distributions through the liquidation of the underlying assets of the investees, the reporting entity's estimate of the period of time over which the underlying assets are expected to be liquidated by the investees; (3) the amount of the entity's unfunded commitments related to investments in the major category; (4) a general description of the terms and conditions upon which the investor may redeem investments in the major category; (5) the circumstances in which an otherwise redeemable investment in the major category might not be redeemable; (6) for those otherwise redeemable investments that are restricted from redemption as of the reporting entity's measurement date, the entity's best estimate of when the restriction from redemption might lapse; if an estimate cannot be made, the entity shall disclose that fact and how long the restriction has been in effect; (7) any other significant restriction on the ability to sell investments in the major category at the measurement date; (8) total fair value of held for sale investments and any remaining actions required to complete the sale when the reporting entity determines that it is probable that it will sell the investments for an amount different from net asset value per share; and (9) disclosure of an entity's plans to sell and any remaining actions required to complete the sale when the entity intends to sell a group of investments, but the individual investments to be sold have not been identified. Trading Securities, Change in Unrealized Holding Gain (Loss) Fair Value, Less than 12 Months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Gross Unrealized Losses, Less than 12 Months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss Fair Value, 12 Months or Greater Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Gross Unrealized Losses, 12 Months or Greater Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss Fair Value, Total Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value Gross Unrealized Losses, Total Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss Number of customers in Kansas Number Of Customers Getting Electric Generation, Transmission And Distribution Services Number Of Customers Getting Electric Generation, Transmission And Distribution Services Document And Entity Information [Abstract] Document and Entity Information [Abstract] Entities [Table] Entities [Table] Entity Information [Line Items] Entity Information [Line Items] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Cash and cash equivalents Accounts receivable, net of allowance for doubtful accounts Accounts Receivable, Net, Current Fuel inventory and supplies Prepaid expenses Prepaid Expense, Current Regulatory assets Regulatory Assets, Current Other Other Assets, Current Total Current Assets Assets, Current OTHER ASSETS: Other Assets, Noncurrent [Abstract] Regulatory assets Regulatory Assets, Noncurrent Nuclear decommissioning trust Other Other Assets, Noncurrent Total Other Assets Total Other Assets Total Other Assets TOTAL ASSETS Assets LIABILITIES AND EQUITY Liabilities and Equity [Abstract] CURRENT LIABILITIES: Liabilities, Current [Abstract] Short-term debt Short-term Debt Accounts payable Accounts Payable, Current Accrued dividends Dividends Payable, Current Accrued taxes Taxes Payable, Current Regulatory liabilities Regulatory Liability, Current Other Other Liabilities, Current Total Current Liabilities Liabilities, Current LONG-TERM LIABILITIES: Liabilities, Noncurrent [Abstract] Long-term debt, net Deferred income taxes Deferred Tax Liabilities, Net, Noncurrent Unamortized investment tax credits Accumulated Deferred Investment Tax Credit Regulatory liabilities Regulatory Liability, Noncurrent Accrued employee benefits Accrued Employee Benefits Noncurrent The noncurrent liability recognized in the balance sheet associated with defined benefit pension plans, other post-retirement benefit plans and other general benefit plans. Asset retirement obligations Asset Retirement Obligations, Noncurrent Other Other Liabilities, Noncurrent Total Long-Term Liabilities Liabilities, Noncurrent COMMITMENTS AND CONTINGENCIES (See Notes 10 and 11) Commitments and Contingencies EQUITY: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Common stock, par value $5 per share Common Stock, Value, Issued Paid-in capital Additional Paid in Capital, Common Stock Retained earnings Retained Earnings (Accumulated Deficit) Total Westar Energy, Inc. Shareholders' Equity Stockholders' Equity Attributable to Parent Noncontrolling Interests Stockholders' Equity Attributable to Noncontrolling Interest Total Equity TOTAL LIABILITIES AND EQUITY Liabilities and Equity