Business Combinations [Abstract] Schedule of Purchase Price Allocation Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block] Leases [Abstract] Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Westar Energy Westar Energy Inc [Member] Utility operating in Kansas. KCP&L KCPL [Member] Kansas City Power & Light Company [Member] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] 2019 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2020 Operating Leases, Future Minimum Payments, Due in Two Years 2021 Operating Leases, Future Minimum Payments, Due in Three Years 2022 Operating Leases, Future Minimum Payments, Due in Four Years 2023 Operating Leases, Future Minimum Payments, Due in Five Years After 2023 Operating Leases, Future Minimum Payments, Due Thereafter Total operating lease payments Operating Leases, Future Minimum Payments Due Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] GMO Kcpl Greater Missouri Operations Member Information on KCPL Greater Missouri Operations. Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Unsecured Debt Unsecured Debt [Member] Senior Notest Senior Notes [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Senior Notes due 2023 KCPL Senior Notes due 2023 KCPL [Member] 3.15% Series Senior Notes due 2023 KCPL [Member] Senior Notes due 2025 KCPL Senior Notes due 2025 KCPL [Member] Senior Notes due 2025 KCPL [Member] Senior notes due 2035 KCPL Senior notes due 2035 KCPL [Member] Senior notes due 2035 KCPL. Senior Notes Due 2041 KCPL Senior Notes Due 2041 KCPL [Member] Senior Notes Due 2041 KCPL. Senior Notes Due 2047 KCPL Senior Notes Due 2047 KCPL [Member] Senior Notes Due 2047. Senior Notes Due 2048 KCPL Senior Notes Due 2048 KCPL [Member] Senior Notes Due 2048 KCPL [Member] Senior Notes Due 2049 KCPL Senior Notes Due 2049 KCPL [Member] Senior Notes Due 2049 KCPL [Member] Senior Notes Due 2019 KCPL Senior Notes Due 2019 KCPL [Member] Senior notes due 2019 KCPL [Member] Senior Notes Due June 2019 Senior Notes Due June 2019 [Member] Senior Notes Due June 2019 [Member] Senior Notes Due 2022 GMO Senior Notes Due 2022 GMO [Member] Senior Notes Due 2022 GMO [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Long-term debt gross Long-term Debt, Gross Interest rates (in hundredths) Debt Instrument, Interest Rate, Stated Percentage Repayments of long-term debt Repayments of Debt Finance lease costs Lease, Cost [Abstract] Amortization of right-of-use assets Finance Lease, Right-of-Use Asset, Amortization Interest on lease liabilities Finance Lease, Interest Expense Operating lease costs Operating Lease, Cost Short-term lease costs Short-term Lease, Cost Variable lease costs for renewable purchase power agreements Variable Lease, Cost Total lease costs Lease, Cost Statement of Financial Position [Abstract] Common stock - shares authorized (in shares) Common Stock, Shares Authorized Common stock - shares issued (in shares) Common Stock, Shares, Issued Statement of Cash Flows [Abstract] Statement [Table] Statement [Table] Statement [Line Items] Statement [Line Items] CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Adjustments to reconcile income to net cash from operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Amortization of nuclear fuel Amortization of Nuclear fuel The noncash expense, not otherwise specified in the taxonomy, charged against earnings in the period to allocate the cost of nuclear fuel over the operating cycle of the nuclear plant. Amortization of deferred refueling outage Amortization Of Deferred Refueling Outage Costs Amortization Of Deferred Refueling Outage Costs Amortization of corporate-owned life insurance Amortization Of Corporate Owned Life Insurance Amortization Of Corporate Owned Life Insurance Non-cash compensation Share-based Payment Arrangement, Noncash Expense Net deferred income taxes and credits Deferred Income Taxes and Tax Credits Allowance for equity funds used during construction Increase (Decrease) in Allowance for Equity Funds Used During Construction Payments for asset retirement obligations Payments For Asset Retirement Obligations Payments For Asset Retirement Obligations Equity in earnings of equity method investees, net of income taxes Income (Loss) from Equity Method Investments Income from corporate-owned life insurance Income From Corporate Owned Life Insurance Income From Corporate Owned Life Insurance Other Other Noncash Income (Expense) Changes in working capital items: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Accounts receivable pledged as collateral Increase Decrease In Accounts Receivable Pledged As Collateral The increase (decrease) during the reporting period in the amount due within one year (or one business cycle) from customers for the credit sale of goods and services where those amounts have been pledged as collateral. Fuel inventory and supplies Increase (Decrease) In Energy Related Inventory Increase (Decrease) In Energy Related Inventory Prepaid expenses and other current assets 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 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 Investments to be Held in Decommissioning Trust Fund Sale of securities - trusts Proceeds from Decommissioning Trust Fund Assets Investment in corporate-owned life insurance Payment to Acquire Life Insurance Policy, Investing Activities Proceeds from investment in corporate-owned life insurance Proceeds from Life Insurance Policy Other investing activities Payments for (Proceeds from) Other Investing Activities Cash Flows from (used) in Investing Activities Net Cash Provided by (Used in) Investing Activities 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 Collateralized short-term debt, net Payments For Issuance Of Collateralized Debt Payments For Issuance Of Collateralized Debt Retirements of long-term debt Repayments of Long-term Debt Retirements of long-term debt of variable interest entities Retirements of Long Term Debt Of VIEs Retirements of Long Term Debt Of VIEs Borrowings against cash surrender value of corporate-owned life insurance Proceeds From Borrowings Against Corporate Owned Life Insurance Proceeds From Borrowings Against Corporate Owned Life Insurance Repayment of borrowings against cash surrender value of corporate-owned life insurance Repayments Of Borrowings Against Corporate Owned Life Insurance Repayments Of Borrowings Against Corporate Owned Life Insurance Cash dividends paid Payments of Dividends Other financing activities Proceeds from (Payments for) Other Financing Activities Cash Flows (used in) from Financing Activities Net Cash Provided by (Used in) Financing Activities NET CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect CASH, CASH EQUIVALENTS AND RESTRICTED CASH: Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect [Abstract] Beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents End of period Restricted cash Restricted Cash and Cash Equivalents Income Tax Disclosure [Abstract] Schedule of Components of Income Tax Expense (Benefit) Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of Effective Income Tax Rate Reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Accounting Policies [Abstract] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable Interest Entities Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member] Cash paid for (received from): Supplemental Cash Flow Information [Abstract] Interest, net of amounts capitalized Interest Paid, Including Capitalized Interest, Operating and Investing Activities Income taxes, net of refunds Income Taxes Paid, Net Non-cash investing transactions: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Property, plant and equipment additions (reductions) Non Cash Property Plant And Equipment Additions (Reductions) Non-cash property, plant and equipment additions (reductions) Non-cash financing transactions: Other Noncash Investing and Financing Items [Abstract] Issuance of stock for compensation and reinvested dividends Stock Issued Stockholders' Equity Note [Abstract] Line of Credit Facility [Table] Line of Credit Facility [Table] Share Repurchase Program [Axis] Share Repurchase Program [Axis] Share Repurchase Program [Domain] Share Repurchase Program [Domain] November 2018 ASR Agreement November 2018 ASR Agreement [Member] November 2018 ASR Agreement [Member] March 2019 ASR Agreement March 2019 ASR Agreement [Member] March 2019 ASR Agreement [Member] June 2019 ASR Agreement June 2019 ASR Agreement [Member] June 2019 ASR Agreement [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Cash Borrowings Revolving Credit Facility [Member] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Number of shares authorized to be repurchased (in shares) Stock Repurchase Program, Number of Shares Authorized to be Repurchased Stock repurchased and retired during period under repurchase plan, value Stock Repurchased And Retired During Period Under Repurchase Plan Value Equity impact of the value of stock that has been repurchased and retired during the period under the repurchase plan. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital). Stock repurchased and retired during period (in shares) Stock Repurchased and Retired During Period, Shares Stock repurchase program, authorized amount Stock Repurchase Program, Authorized Amount Partial settlement of accelerated share repurchase agreement (in shares) Partial Settlement Of Accelerated Share Repurchase Agreement, Shares Partial Settlement Of Accelerated Share Repurchase Agreement, Shares Accelerated share repurchases, payment Accelerated Share Repurchases, Settlement (Payment) or Receipt Restriction on payment of dividends, minimum ratio of total capitalization Restriction on Payment Of Dividends, Minimum Ratio Of Equity To Capitalization Restriction on Payment of Dividends, Minimum Ratio of Equity to Capitalization Debt instrument, debt to capitalization ratio (no more than) Debt Instrument, Covenant, Debt To Capitalization Ratio, Maximum Debt Instrument, Covenant, Debt to Capitalization Ratio, Maximum Retained earnings restrictions Equity Restrictions Restricted net assets of subsidiaries Amount of Restricted Net Assets for Consolidated and Unconsolidated Subsidiaries Related Party Transactions [Abstract] Schedule of Related Party Receivables and Payables Schedule of Related Party Transactions [Table Text Block] Cash paid for amounts included in the measurement of lease liabilities: Cash Flow, Lessee [Abstract] Cash Flow, Lessee [Abstract] Operating cash flows from operating leases Operating Lease, Payments Operating cash flows from finance leases Finance Lease, Interest Payment on Liability Financing cash flows from finance leases Finance Lease, Principal Payments Right-of-use assets obtained in exchange for new operating lease liabilities Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Right-of-use assets obtained in exchange for new finance lease liabilities Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Variable Interest Entities Variable Interest Entity, Primary Beneficiary [Member] ASSETS Assets [Abstract] CURRENT ASSETS: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Receivables, net Receivables, Net, Current Accounts receivable pledged as collateral Transfers Accounted for as Secured Borrowings, Assets, Carrying Amount Fuel inventory and supplies Energy Related Inventory Income taxes receivable Income Taxes Receivable, Current Regulatory assets Regulatory Assets, Current Prepaid expenses and other assets Prepaid Expense and Other Assets, Current Total Current Assets Assets, Current PROPERTY, PLANT AND EQUIPMENT, NET Property, Plant and Equipment, Net OTHER ASSETS: Investments And Other Assets [Abstract] Regulatory assets Regulatory Assets, Noncurrent Nuclear decommissioning trust fund Decommissioning Fund Investments Goodwill Goodwill Other Other Assets, Noncurrent Total Other Assets Assets, Noncurrent TOTAL ASSETS Assets LIABILITIES AND EQUITY Liabilities and Equity [Abstract] CURRENT LIABILITIES: Liabilities, Current [Abstract] Current maturities of long-term debt Long-term Debt, Current Maturities Notes payable and commercial paper Short-term Bank Loans and Notes Payable Collateralized note payable Transfers Accounted for as Secured Borrowings, Associated Liabilities, Carrying Amount Accounts payable Accounts Payable, Current Accrued taxes Taxes Payable, Current Accrued interest Interest Payable, Current Regulatory liabilities Regulatory Liability, Current Asset retirement obligations Asset Retirement Obligation, Current Other Other Liabilities, Current Total Current Liabilities Liabilities, Current LONG-TERM LIABILITIES: Liabilities, Noncurrent [Abstract] Long-term debt, net Long-term Debt, Excluding Current Maturities Deferred income taxes Deferred Income Tax Liabilities, Net Unamortized investment tax credits Accumulated Deferred Investment Tax Credit Regulatory liabilities Regulatory Liability, Noncurrent Pension and post-retirement liability Liability, Defined Benefit Plan, Noncurrent Asset retirement obligations Asset Retirement Obligations, Noncurrent Other Other Liabilities, Noncurrent Total Long-Term Liabilities Liabilities, Noncurrent Commitments and Contingencies (Note 11) Commitments and Contingencies EQUITY: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Evergy, Inc. Shareholders' Equity: Stockholders' Equity Attributable to Parent [Abstract] Common stock Common Stock, Value, Issued Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total Shareholders' Equity Stockholders' Equity Attributable to Parent Noncontrolling Interests Stockholders' Equity Attributable to Noncontrolling Interest Total Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest TOTAL LIABILITIES AND EQUITY Liabilities and Equity Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Jointly Owned Utility Plant [Axis] Jointly Owned Utility Plant [Axis] Jointly Owned Utility Plant [Domain] Jointly Owned Utility Plant [Domain] Jointly Owned Electricity Generation Plant Iatan No 1 And 2 Jointly Owned Electricity Generation Plant Iatan No 1 And 2 [Member] Jointly Owned Electricity Generation Plant Iatan No 1 And 2 [Member] Jeffrey Energy Center Jeffrey Energy Center [Member] Jeffrey Energy Center [Member] La Cygne Station La Cygne Station [Member] La Cygne Station [Member] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Evergy Evergy [Member] Evergy [Member] Subsidiary of Common Parent Subsidiary of Common Parent [Member] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Operating Expenses and Capital Costs Billed Operating Expenses And Capital Costs Billed [Member] Operating Expenses and Capital Costs Billed [Member] Money Pool Money Pool [Member] Transactions related to the Great Plains Energy Money Pool, an internal financing arrangement between Great Plains Energy, KCP&L and GMO. Income Tax Receivable Income Tax Receivable [Member] Income Tax Receivable [Member] Income Taxes Payable Income Taxes Payable [Member] Income Taxes Payable [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Jointly owned utility plant, proportionate ownership share Jointly Owned Utility Plant, Proportionate Ownership Share Related party transaction Related Party Transaction, Amounts of Transaction Due from (to) related parties Related Party Transaction, Due from (to) Related Party, Current Operating lease, right-of-use asset Operating Lease, Right-of-Use Asset Less: current portion Operating Lease, Liability, Current Total long-term obligations under operating leases Operating Lease, Liability, Noncurrent Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Great Plains Energy Great Plains Energy [Member] Information on Great Plains Energy. Business Acquisition [Line Items] Business Acquisition [Line Items] Current assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets Property, plant and equipment, net Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Goodwill Other long-term assets, excluding goodwill Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets Total assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets Current liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities Long-term liabilities, excluding long-term debt Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other Long-term debt, net Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt Total liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Total purchase price Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net Equity Interest Type [Axis] Equity Interest Type [Axis] Equity Interest Issued or Issuable, Type [Domain] Equity Interest Issued or Issuable, Type [Domain] Share-based Payment Arrangement Share-based Payment Arrangement [Member] Anticipated Merger With Westar Energy, Inc. [Line Items] Anticipated Acquisition Of Westar Energy, Inc. [Line Items] Anticipated Acquisition Of Westar Energy, Inc. Conversion ratio Business Acquisition, Conversion Ratio Business Acquisition, Conversion Ratio Purchase price Business Combination, Consideration Transferred Fair value of shares issued Business Combination, Consideration Transferred, Equity Interests Issued and Issuable Goodwill decrease from recognition of deferred tax assets Goodwill, Subsequent Recognition of Deferred Tax Asset Statement of Comprehensive Income [Abstract] OPERATING REVENUES Revenues OPERATING EXPENSES: Costs and Expenses [Abstract] Fuel and purchased power FuelAndPurchasedPower Amount of operating expense for fuel and purchased power used by regulated operation Operating and maintenance Utilities Operating Expense, Maintenance and Operations Taxes other than income tax Taxes, Miscellaneous Total Operating Expenses Costs and Expenses INCOME FROM OPERATIONS Operating Income (Loss) OTHER INCOME (EXPENSE): Other Income and Expenses [Abstract] Investment earnings Investment Income, Nonoperating Other income Other Nonoperating Income Other expense Other Nonoperating Expense Total Other Expense, Net Nonoperating Income (Expense) Interest expense Interest Expense INCOME BEFORE INCOME TAXES Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Income tax expense Income Tax Expense (Benefit) Net income attributable to Evergy, Inc. Net Income (Loss) Attributable to Parent COMPREHENSIVE INCOME Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Derivative hedging activity Other Comprehensive Income (Loss), Net of Tax [Abstract] Reclassification to expenses, net of tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax Derivative hedging activity, net of tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Total other comprehensive loss Other Comprehensive Income (Loss), Net of Tax COMPREHENSIVE INCOME Comprehensive Income (Loss), Net of Tax, Attributable to Parent Retirement Benefits [Abstract] Schedule of Net Benefit Costs Schedule of Net Benefit Costs [Table Text Block] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Wolf Creek Jointly Owned Nuclear Power Plant [Member] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Pension Benefits Pension Plan [Member] Post-Retirement Benefits Other Postretirement Benefits Plan [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Components of net periodic benefit costs Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [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 (Loss) on Plan Assets Prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Recognized net actuarial (gain)/loss Defined Benefit Plan, Amortization of Gain (Loss) Net periodic benefit costs before regulatory adjustment and intercompany allocations Net Period Benefit Costs Before Regulatory Adjustment And Intercompany Allocations The total amount of net periodic benefit cost for defined benefit plans for the period before regulatory adjustment and intercompany allocations. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments. Regulatory adjustment Defined Benefit Plan Regulatory Adjustment Increase (decrease) in net periodic benefit costs related to regulatory adjustments. Intercompany allocations Defined Benefit Plans Intercompany Allocations Increase (decrease) in net periodic benefit costs related to intercompany allocations. Net periodic benefit costs (income) Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Contributions by employer Defined Benefit Plan, Plan Assets, Contributions by Employer Contributions by employer, remainder of fiscal year Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year Common stock - par value (in dollars per share) Common Stock, Par or Stated Value Per Share Goodwill and Intangible Assets Disclosure [Abstract] GOODWILL Goodwill and Intangible Assets Disclosure [Text Block] PENSION PLANS AND POST-RETIREMENT BENEFITS Pension and Other Postretirement Benefits Disclosure [Text Block] RELATED PARTY TRANSACTIONS AND RELATIONSHIPS Related Party Transactions Disclosure [Text Block] MERGER OF GREAT PLAINS ENERGY AND WESTAR ENERGY Business Combination Disclosure [Text Block] Income Statement [Abstract] SPP network transmission costs SPPNetworkTransmissionCosts Cost incurred for SPP transmission costs Investment earnings Income tax expense (benefit) Equity in earnings of equity method investees, net of income taxes NET INCOME Less: Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest BASIC AND DILUTED EARNINGS PER AVERAGE COMMON SHARE OUTSTANDING ATTRIBUTABLE TO EVERGY (see Note 1) Earnings Per Share, Basic and Diluted [Abstract] Basic earnings per common share (in dollars per share) Earnings Per Share, Basic Diluted earnings per common share (in dollars per share) Earnings Per Share, Diluted AVERAGE COMMON SHARES OUTSTANDING Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Derivative hedging activity Derivative Hedging Activity [Abstract] Derivative Hedging Activity [Abstract] Loss on derivative hedging instruments Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax Income tax benefit Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax Derivative hedging activity, net of tax COMPREHENSIVE INCOME Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: comprehensive income attributable to noncontrolling interest Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest Commitments and Contingencies Disclosure [Abstract] COMMITMENTS AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] 2019 Capital Leases, Future Minimum Payments Due, Next Twelve Months 2020 Capital Leases, Future Minimum Payments Due in Two Years 2021 Capital Leases, Future Minimum Payments Due in Three Years 2022 Capital Leases, Future Minimum Payments Due in Four Years 2023 Capital Leases, Future Minimum Payments Due in Five Years After 2023 Capital Leases, Future Minimum Payments Due Thereafter Total finance lease payments Capital Leases, Future Minimum Payments Due Amounts representing imputed interest Capital Leases, Future Minimum Payments, Interest Included in Payments Present value of net minimum lease payments under finance leases Capital Lease Obligations Less: current portion Capital Lease Obligations, Current Total long-term obligations under finance leases Capital Lease Obligations, Noncurrent Schedule of Short-term Debt [Table] Schedule of Short-term Debt [Table] Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] Term Loan Secured Debt [Member] Line of Credit Line of Credit [Member] Short-term Debt [Line Items] Short-term Debt [Line Items] Line of credit, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Debt instrument, debt default, threshold Debt Instrument, Debt Default, Threshold Debt Instrument, Debt Default, Threshold Debt Instrument, debt to capitalization ratio (no more than) Debt instrument, term Debt Instrument, Term Number of loans Debt Instrument, Number Of Loans Debt Instrument, Number Of Loans Proceeds from lines of credit Proceeds from Lines of Credit Number of remaining loans Debt Instrument, Number of Loans Available For Borrowing Debt Instrument, Number of Loans Available For Borrowing Available borrowings Line of Credit Facility, Remaining Borrowing Capacity Long-term line of credit Short-term Debt Interest rate during period Short-term Debt, Weighted Average Interest Rate, at Point in Time Fair Value Disclosures [Abstract] Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Table] Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Table] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Nuclear decommissioning trust - equity securities Decommissioning Trust Assets - Equity [Member] Decommissioning Trust Assets - Equity [Member] Rabbi trusts Rabbi Trusts [Member] Rabbi Trusts [Member] Nuclear decommissioning trust - debt securities Decommissioning Trust Assets - Debt [Member] Decommissioning Trust Assets - Debt [Member] Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items] Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items] Unrealized gain (losses) Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss) Statement of Stockholders' Equity [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock Common Stock [Member] Retained earnings Retained Earnings [Member] Non-controlling interests Noncontrolling Interest [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning balance (in shares) Shares, Outstanding Beginning balance Issuance of stock for compensation and reinvested dividends, net of tax withholding (in shares) Stock Issued During Period, Shares, Dividend Reinvestment Plan And Share-Based Compensation Stock Issued During Period, Shares, Dividend Reinvestment Plan And Share-Based Compensation Issuance of stock for compensation and reinvested dividends, net of tax withholding Stock Issued During Period, Value, Dividend Reinvestment Plan And Share-Based Compensation Stock Issued During Period, Value, Dividend Reinvestment Plan And Share-Based Compensation Stock cancelled pursuant to Amended Merger Agreement Stock Canceled During Period Shares Stock Canceled During Period Shares Dividends declared on common stock Dividends, Common Stock, Cash Stock compensation expense APIC, Share-based Payment Arrangement, Increase for Cost Recognition Other Stockholders' Equity, Other Consolidation of noncontrolling interests Noncontrolling Interest, Increase From Consolidation Noncontrolling Interest, Increase From Consolidation Distributions to shareholders of noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Ending balance (in shares) Ending balance July 2019 through December 2019 Finance Lease, Liability, Payments, Remainder of Fiscal Year 2020 Finance Lease, Liability, Payments, Due Year Two 2021 Finance Lease, Liability, Payments, Due Year Three 2022 Finance Lease, Liability, Payments, Due Year Four 2023 Finance Lease, Liability, Payments, Due Year Five After 2023 Finance Lease, Liability, Payments, Due after Year Five Total finance lease payments Finance Lease, Liability, Payment, Due Amounts representing imputed interest Finance Lease, Liability, Undiscounted Excess Amount Present value of lease payments Finance Lease, Liability Less: current portion Finance Lease, Liability, Current Total long-term obligations under finance leases Finance Lease, Liability, Noncurrent Weighted-average remaining lease term (years) Finance Lease, Weighted Average Remaining Lease Term Weighted-average discount rate Finance Lease, Weighted Average Discount Rate, Percent SHAREHOLDERS' EQUITY Stockholders' Equity Note Disclosure [Text Block] Cover page. Entities [Table] Entities [Table] WESTAR ENERGY INC /KS KANSAS CITY POWER & LIGHT CO Entity Information [Line Items] Entity Information [Line Items] Document Type Document Type Document Quarterly Report Document Quarterly Report Document Period End Date Document Period End Date Document Transition Report Document Transition Report Entity File Number Entity File Number Entity Registrant Name Entity Registrant Name Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line One Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province Entity Address, Postal Zip Code Entity Address, Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Entity Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag AOCI AOCI Including Portion Attributable to Noncontrolling Interest [Member] Issuance of stock to Great Plains Energy shareholders (in shares) Stock Issued During Period, Shares, Acquisitions Issuance of stock to Great Plains Energy shareholders Stock Issued During Period, Value, Acquisitions Issuance of restricted common stock (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Gross Issuance of stock for compensation and reinvested dividends (in shares) Issuance of stock for compensation and reinvested dividends Dividend equivalents declared Dividends, Paid-in-kind Repurchase of common stock under repurchase plan (in shares) Stock Repurchased During Period, Shares Repurchase of common stock under repurchase plan Stock Repurchased During Period, Value Consolidation of noncontrolling interests Non-service cost component of net benefit cost Non Service Cost Component Of Net Benefit Cost Non Service Cost Component Of Net Benefit Cost Other Other Expenses Other expense Income from corporate-owned life insurance Accounts receivable pledged as collateral Cash acquired from the merger with Great Plains Energy Cash Acquired from Acquisition Proceeds from settlement of interest rate swap Proceeds from Derivative Instrument, Investing Activities Collateralized short-term borrowings, net Proceeds From Issuance Of Collateralized Debt Proceeds From Issuance Of Collateralized Debt Proceeds from long-term debt Proceeds from Issuance of Long-term Debt Repurchase of common stock under repurchase plan Payments for Repurchase of Common Stock LEASES Lessee, Operating Leases [Text Block] LEASES Lessee, Finance Leases [Text Block] Receivables [Abstract] RECEIVABLES Loans Notes Trade And Other Receivables Disclosure And Transfers And Servicing Of Financial Asset [Text Block] Includes disclosure of claims held for amounts due a company. Examples include trade accounts receivables, notes receivables, loans receivables. Also provides the disclosures pertaining to a transferor's continuing involvement in financial assets that it has transferred in a securitization or asset-backed financing arrangements. Schedule of Short-term Debt Schedule of Short-term Debt [Table Text Block] Summary Of Accounting Policies [Table] Summary Of Accounting Policies [Table] Summary Of Accounting Policies [Table] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Transource Energy, LLC Transource Energy, LLC [Member] Transource Energy, LLC Prairie Wind Transmission, LLC Prairie Wind Transmission, LLC [Member] Prairie Wind Transmission, LLC [Member] Ownership [Axis] Ownership [Axis] Ownership [Domain] Ownership [Domain] Kansas Gas And Electric Company Kansas Gas And Electric Company [Member] Kansas Gas And Electric Company [Member] GPE Transmission Holding Company, LLC GPE Transmission Holding Company, LLC [Member] GPE Transmission Holding Company, LLC AEP Transmission Holding Company, LLC AEP Transmission Holding Company, LLC [Member] AEP Transmission Holding Company, LLC Summary Of Accounting Policies [Line Items] Summary Of Accounting Policies [Line Items] [Line Items] for Summary Of Accounting Policies [Table] Number of active wholly owned subsidiaries Number Of Wholly Owned Subsidiaries Number Of Wholly Owned Subsidiaries Ownership percentage Equity Method Investment, Ownership Percentage Transmission line length Transmission Line Length Transmission Line Length Transmission line electrical potential Transmission Line Electrical Potential Transmission Line Electrical Potential Ownership interest Noncontrolling Interest, Ownership Percentage by Parent Owned generating capacity and renewable purchased power Owned Generating Capacity And Renewable Purchased Power Owned Generating Capacity and Renewable Purchased Power Number of customers served Number Of Customers Served Number Of Customers Served Number of shares issued (in shares) Business Acquisition, Equity Interest Issued or Issuable, Number of Shares Number of segments Number of Reportable Segments Class of Financing Receivable [Axis] Class of Financing Receivable [Axis] Class of Financing Receivable [Domain] Class of Financing Receivable [Domain] Borrowings From Mid December Through Mid January Borrowings From Mid December Through Mid January [Member] Borrowings From Mid December Through Mid January [Member] Borrowings From Mid January Through Mid February Borrowings From Mid January Through Mid February [Member] Borrowings From Mid January Through Mid February [Member] Borrowings From Mid February Through Mid July Borrowings From Mid February Through Mid July [Member] Borrowings From Mid February Through Mid July [Member] Borrowings From Mid July To Thereafter Borrowings From Mid July To Thereafter [Member] Borrowings From Mid July To Thereafter [Member] Borrowings From Mid November Through Mid June Borrowings From Mid November Through Mid June [Member] Borrowings From Mid November Through Mid June [Member] Borrowings From Mid June Through Expiration Borrowings From Mid June Through Expiration [Member] Borrowings From Mid June Through Expiration [Member] Other receivables, contracts with customers Other Receivables, Contracts With Customers The amount of other receivables resulting from contracts with customers. Sale Of Accounts Receivable - KCPL and GMO Sale Of Accounts Receivable - KCPL and GMO [Line Items] [Abstract] Sale Of Accounts Receivable - KCPL and GMO [Line Items] [Abstract] Maximum amount of outstanding principal under receivables agreement Maximum Amount Of Outstanding Principal Under Receivables Agreement Maximum amount of outstanding principal under receivables agreement Statistical Measurement [Axis] Statistical Measurement [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Remaining lease term Lease, Remaining Lease Term Lease, Remaining Lease Term Schedule of Fuel Inventory and Supplies Schedule of Inventory, Current [Table Text Block] Summary of Property, Plant and Equipment Property, Plant and Equipment [Table Text Block] Schedule of Other Nonoperating Income (Expense) Schedule of Other Nonoperating Income (Expense) [Table Text Block] Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Supplemental Cash Flow Information Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Accounts, Notes, Loans and Financing Receivable by Receivable Type [Axis] Receivable Type [Axis] Receivable [Domain] Receivable [Domain] Customer accounts receivable Trade Accounts Receivable [Member] Accounts, Notes, Loans and Financing Receivable by Billing Status, Type [Axis] Billing Status, Type [Axis] Receivables Billing Status [Domain] Receivables Billing Status [Domain] Billed Billed Revenues [Member] Unbilled Unbilled Revenues [Member] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Customer accounts receivable Accounts Receivable, before Allowance for Credit Loss, Current Other receivables Other Receivables, Gross, Current Allowance for doubtful accounts Accounts Receivable, Allowance for Credit Loss, Current Total July 2019 through December 2019 Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year 2020 Lessee, Operating Lease, Liability, Payments, Due Year Two 2021 Lessee, Operating Lease, Liability, Payments, Due Year Three 2022 Lessee, Operating Lease, Liability, Payments, Due Year Four 2023 Lessee, Operating Lease, Liability, Payments, Due Year Five After 2023 Lessee, Operating Lease, Liability, Payments, Due after Year Five Total operating lease payments Lessee, Operating Lease, Liability, Payments, Due Amounts representing imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Present value of lease payments Operating Lease, Liability Less: current portion Weighted-average remaining lease term (years) Operating Lease, Weighted Average Remaining Lease Term Weighted-average discount rate Operating Lease, Weighted Average Discount Rate, Percent Inventory, Current [Table] Inventory, Current [Table] Inventory [Line Items] Inventory [Line Items] Fuel inventory Energy Related Inventory, Coal Supplies Energy Related Inventory, Supplies Energy Related Inventory, Supplies Fuel inventory and supplies Commercial Paper Commercial Paper [Member] Letters of Credit Standby Letters of Credit [Member] Evergy, Inc. Credit Facility Line of Credit Facility, Current Borrowing Capacity Long-term line of credit Long-term Line of Credit Letters of Credit Letters of Credit Outstanding, Amount Available Borrowings Weighted Average Interest Rate on Short-Term Borrowings Line of Credit Facility, Interest Rate at Period End Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Other Evergy Other Evergy [Member] Other Evergy [Member] Geographic Distribution [Axis] Geographic Distribution [Axis] Geographic Distribution [Domain] Geographic Distribution [Domain] Domestic Geographic Distribution, Domestic [Member] International Geographic Distribution, Foreign [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Measurement Frequency [Domain] Measurement Frequency [Domain] Fair Value, Measurements, Recurring Fair Value, Recurring [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Level 1 Fair Value, Inputs, Level 1 [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Level 3 Fair Value, Inputs, Level 3 [Member] NAV Fair Value Measured at Net Asset Value Per Share [Member] Equity securities Equity Securities [Member] Core bond fund Core Bond Fund [Member] Core Bond Fund [Member] High-yield bond fund High-Yield Bond Fund [Member] High-Yield Bond Fund [Member] Emerging markets bond fund Emerging Markets Bond Fund [Member] Emerging Markets Bond Fund [Member] Combination debt/equity/other fund Debt Equity Other Fund [Member] Debt Equity Other Fund [Member] Alternative investments fund Alternative Investment Fund [Member] Alternative Investment Fund [Member] Real estate securities fund Real Estate Funds [Member] Cash equivalents Cash Equivalents [Member] U.S. Treasury US Treasury and Government [Member] U.S. Agency US Government Corporations and Agencies Securities [Member] State and local obligations US States and Political Subdivisions Debt Securities [Member] Corporate bonds Corporate Debt Securities [Member] Foreign governments Debt Security, Government, Non-US [Member] Other Other Trust Assets [Member] Other assets within the trust fund. Debt securities Debt Securities [Member] Cash and cash equivalents Cash and Cash Equivalents [Member] Fixed income fund Fixed Income Funds [Member] Liability Class [Axis] Liability Class [Axis] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Interest rate swaps Derivative Financial Instruments, Liabilities [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Assets Assets, Fair Value Disclosure [Abstract] Total nuclear decommissioning trust Decommissioning Fund Investments, Fair Value Total rabbi trust Rabbi Trust, Fair Value Disclosure Rabbi Trust, Fair Value Disclosure Total self-insured health plan trust Self Insured Health Plan Trust Fair Value Disclosure The fair value of investments held in a trust for KCP&L's self-insurance health plan. Total Assets Assets, Fair Value Disclosure Liabilities Liabilities, Fair Value Disclosure [Abstract] Interest rate swaps Derivative Liability Total Financial Liabilities Fair Value Disclosure Dividends declared on common stock (in dollars per share) Common Stock, Dividends, Per Share, Declared SHORT-TERM BORROWINGS AND SHORT-TERM BANK LINES OF CREDIT Short-term Debt [Text Block] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] ASU 2016-02 Accounting Standards Update 2016-02 [Member] Lease asset Lessee, Lease, Asset Lessee, Lease, Asset Lease liability Lessee, Lease, Liability Lessee, Lease, Liability LONG-TERM DEBT Long-term Debt [Text Block] TAXES Income Tax Disclosure [Text Block] Basis of Presentation Basis of Presentation and Significant Accounting Policies [Text Block] Principles of Consolidation Consolidation, Policy [Policy Text Block] Fuel Inventory and Supplies Inventory, Policy [Policy Text Block] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] New Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Carrying Value and Fair Value of Debt Instruments Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] Fair Value of Assets and Liabilities Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Fair Value Investments, Entities that Calculate NAV Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table Text Block] Fair Value Recurring Gain (Loss) Included in Earnings Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Table Text Block] Schedule of Receivables Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Summary of Bad Debt Expense Impaired Financing Receivables [Table Text Block] Schedule of Lease Expense Lease, Cost [Table Text Block] Schedule of Payments for Finance Leases Finance Lease, Liability, Maturity [Table Text Block] Schedule of Future Commitments Under Finance Leases Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block] Schedule of Lease Payments for Operating Leases Lessee, Operating Lease, Liability, Maturity [Table Text Block] Schedule of Future Commitments Under Operating Leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] FAIR VALUE MEASUREMENTS Fair Value Disclosures [Text Block] Investment earnings Regulated Operations [Abstract] Regulatory Proceedings [Table] Public Utilities General Disclosures [Table] Public Utilities, Regulatory Proceeding [Axis] Public Utilities, Regulatory Proceeding [Axis] Public Utilities, Regulatory Proceeding [Domain] Public Utilities, Regulatory Proceeding [Domain] Transmission Delivery Charge Transmission Delivery Charge [Member] Transmission Delivery Charge [Member] 2018 Rate Case Proceedings 2018 Rate Case Proceedings [Member] 2018 Rate Case Proceedings [Member] FERC 2019 TFR Proceeding FERC2019TFRProceeding [Member] FERC 2019 TFR Proceeding Regulatory Agency [Axis] Regulatory Agency [Axis] Regulatory Agency [Domain] Regulatory Agency [Domain] Kansas Corporation Commission Kansas Corporation Commission [Member] Information related to the State Corporation Commission of the State of Kansas. Federal Energy Regulatory Commission Federal Energy Regulatory Commission [Member] Federal Energy Regulatory Commission [Member] Regulatory Proceedings [Line Items] Public Utilities, General Disclosures [Line Items] Annual revenue decrease approved Public Utilities, Approved Rate Increase (Decrease), Amount Annual transmissions revenue estimated amount of decrease over prior year Public Utilities Estimated Annual Transmissions Revenue Increase (Decrease) Over Prior Year Amount Public utilities, estimated annual transmissions revenue amount of increase (decrease) over prior year Refund percent on earnings over approved return on equity Public Utilities, Refund Percent On Earnings Over Approved Return On Equity Public Utilities, Refund Percent On Earnings Over Approved Return On Equity Approved return on equity, percentage Public Utilities, Approved Return on Equity, Percentage SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] SEC Schedule, 12-09, Allowance, Credit Loss SEC Schedule, 12-09, Allowance, Credit Loss [Member] Receivable Type [Axis] Customer Contracts Customer Contracts [Member] Impairment losses recognized on receivables SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense Revenue from Contract with Customer [Abstract] Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Related party receivables Accounts Receivable, Related Parties, Current Related party payables Accounts Payable, Related Parties, Current Income Earnings Per Share Reconciliation [Abstract] Common Shares Outstanding Weighted average equivalent common shares outstanding - basic (in shares) Add: effect of dilutive securities (in shares) Weighted Average Number Diluted Shares Outstanding Adjustment Diluted average number of common shares outstanding (in shares) Basic and Diluted EPS (in dollars per share) Earnings Per Share, Basic and 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] Performance Shares Performance Shares [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive securities excluded from computation of earnings per share, amount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Income Tax Contingency [Table] Income Tax Contingency [Table] Income Tax Contingency [Line Items] Income Tax Contingency [Line Items] Components of Income Tax Expense (Benefit), Continuing Operations [Abstract] Components of Income Tax Expense (Benefit), Continuing Operations [Abstract] Current income taxes Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Current Federal Tax Expense (Benefit) State Current State and Local Tax Expense (Benefit) Total Current Income Tax Expense (Benefit) Deferred income taxes Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Deferred Federal Income Tax Expense (Benefit) State Deferred State and Local Income Tax Expense (Benefit) Total Deferred Income Tax Expense (Benefit) Investment tax credit amortization Investment Tax Credit Amortization The amount deducted from an entities' taxes, reflecting a percentage of an amount invested in certain assets spread over the useful life of those assets; the part related to the amortization of investment tax credits. Income tax expense (benefit) Effective Income Tax Rate Reconciliation, Percent [Abstract] Effective Income Tax Rate Reconciliation, Percent [Abstract] Federal statutory income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Effect of: Effect Of [Abstract] Effect Of [Abstract] COLI policies Effective Income Tax Rate Reconciliation, Nondeductible Expense, Life Insurance, Percent State income taxes Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Flow through depreciation for plant-related differences EffectiveIncomeTaxRateReconciliationEffectOfRegulatoryTreatmentBookTaxDifferences Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to the effect of regulatory treatment of book and tax differences. Federal tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent Non-controlling interest Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Percent AFUDC equity EffectiveIncomeTaxRateReconciliationAFUDCEquity Effective Income Tax Rate Reconciliation, AFUDC Equity Amortization of federal investment tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Investment, Percent State tax rate change Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent Valuation allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Stock compensation Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Payment Arrangement, Percent Officer compensation limitation Officer Compensation Limitation Officer compensation limitation Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Dividends Payable [Table] Dividends Payable [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Dividends Payable [Line Items] Dividends Payable [Line Items] Dividends payable Dividends Payable Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table] Nuclear decommissioning trust: Decommissioning Trust Assets [Member] Decommissioning Trust Assets [Member] Rabbi trust: Equity Securities - Fourth Fund Equity Securities - Fourth Fund [Member] Equity Securities - Fourth Fund [Member] Equity Securities - Fifth Fund Equity Securities - Fifth Fund [Member] Equity Securities - Fifth Fund [Member] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] Unfunded Commitments Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments Length of Settlement Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Liquidating Investment, Remaining Period NAV, Number of funds Fair Value, Investments, Entities That Calculate Net Asset Value Per Share, Number Of Funds Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Number Of Funds NAV, Number of funds making distributions Fair Value, Investments, Entities That Calculate Net Asset Value Per Share, Number Of Funds Making Distributions Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Number Of Funds Making Distributions NAV, Number of extensions Fair Value, Investments, Entities That Calculate Net Asset Value Per Share, Number Of Extensions Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Number Of Extensions NAV, Extension term Fair Value, Investments, Entities That Calculate Net Asset Value Per Share, Extension Term Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Extension Term Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Electric plant in service Electric Plant In Service [Member] Electric Plant In Service [Member] Construction work in progress Construction in Progress [Member] Nuclear fuel, net Nuclear Fuel [Member] Plant to be retired, net Plant To Be Retired [Member] Plant To Be Retired [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Property, plant and equipment, gross Property, Plant and Equipment, Gross Property, plant and equipment, adjustment Property, Plant And Equipment, Adjustment Property, Plant And Equipment, Adjustment Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property, plant and equipment, net Schedule of Goodwill [Table] Schedule of Goodwill [Table] Goodwill [Line Items] Goodwill [Line Items] Number of reporting units Number of Reporting Units ORGANIZATION AND BASIS OF PRESENTATION Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block] RATE MATTERS AND REGULATION Public Utilities Disclosure [Text Block] REVENUE Revenue from Contract with Customer [Text Block] Long-Term debt fair value adjustment Long-TermDebtFairValueAdjustment [Member] Long-Term debt fair value adjustment recorded in association with the merger. Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Book Value Reported Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] Notional contract amount Derivative, Notional Amount Fair value adjustments Derivative, Fair Value, Net Loss on derivative hedging instruments Long-term debt Long-term Debt, Fair Value AOCI - Net gains (losses) on cash flow hedges Prepaid expenses Prepaid Expense, Current Other assets Other Assets, Current Accrued compensation benefits Employee-related Liabilities, Current Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Residential Electric Utility Customer Class Residential [Member] Residential customer class from which revenues are generated by the regulated sale of electricity [Member] Commercial Electric Utility Customer Class Commercial [Member] Commercial customer class from which revenues are generated by the regulated sale of electricity [Member] Industrial Electric Utility Customer Class Industrial [Member] Industrial customer class from which revenues are generated by the regulated sale of electricity [Member] Other retail Electric Utility Customer Class Other Retail [Member] Other retail customer class from which revenues are generated by the regulated sale of electricity [Member] Total electric retail Electric Utility Customer Class Total Electric Retail [Member] Total electric retail customer class from which revenues are generated by the regulated sale of electricity [Member] Wholesale Electric Utility Customer Class Wholesale [Member] Wholesale customer class from which revenues are generated by the sale of wholesale power and capacity when the power is not required for customers within service territory [Member] Transmission Electric Utility Customer Class Transmission [Member] Transmission customer class from which revenues are generated by the use of KCP&L's and GMO's transmission network by the SPP on behalf of other power providers [Member] Industrial steam and other Electric Utility Customer Class Industrial Steam [Member] Industrial steam customer class from which revenues are generated by the regulated sale of industrial steam to GMO's steam customers [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Total revenue from contracts with customers Revenue from Contract with Customer, Excluding Assessed Tax Other Other Revenue Revenue other than from contracts with customers. Revenues