Regulated Operations [Abstract] RATE MATTERS AND REGULATION Public Utilities Disclosure [Text Block] Revenue from Contract with Customer [Abstract] Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Receivables [Abstract] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [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] 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] Receivable Type [Axis] Receivable [Domain] Receivable [Domain] Customer Contracts Customer Contracts [Member] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Impairment losses recognized on receivables SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common stock Common Stock [Member] Retained earnings Retained Earnings [Member] Derivative Hedging Instrument Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member] AOCI AOCI Including Portion Attributable to Noncontrolling Interest [Member] Non-controlling interests Noncontrolling Interest [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning balance (in shares) Shares, Outstanding Beginning balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Issuance of stock for compensation and reinvested dividends (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 Stock Issued During Period, Value, Dividend Reinvestment Plan And Share-Based Compensation Stock Issued During Period, Value, Dividend Reinvestment Plan And Share-Based Compensation Dividends declared on common stock Dividends, Common Stock, Cash Stock compensation expense Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Repurchase of common stock (in shares) Stock Repurchased During Period, Shares Repurchase of common stock under repurchase plan Stock Repurchased During Period, Value 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 Net current period other comprehensive income Other Comprehensive Income (Loss), Net of Tax Other Stockholders' Equity, Other Ending balance (in shares) Ending balance Retirement Benefits [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Jointly Owned Utility Plant [Axis] Jointly Owned Utility Plant [Axis] Jointly Owned Utility Plant [Domain] Jointly Owned Utility Plant [Domain] 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] Jointly owned utility plant, proportionate ownership share Jointly Owned Utility Plant, Proportionate Ownership Share Components of net periodic benefit costs [Abstract] 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 DefinedBenefitPlansIntercompanyAllocations Increase (decrease) in net periodic benefit costs related to intercompany allocations. Net periodic benefit costs 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 Debt Disclosure [Abstract] 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] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Commercial Paper Commercial Paper [Member] Letters of Credit Standby Letters of Credit [Member] Cash Borrowings Revolving Credit Facility [Member] Evergy, Inc. Evergy [Member] Evergy [Member] GMO Kcpl Greater Missouri Operations Member Information on KCPL Greater Missouri Operations. Short-term Debt [Line Items] Short-term Debt [Line Items] 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 Line of Credit Facility, Remaining Borrowing Capacity Weighted Average Interest Rate on Short-Term Borrowings Line of Credit Facility, Interest Rate at Period End Accounting Policies [Abstract] ORGANIZATION AND BASIS OF PRESENTATION Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block] Fair Value Disclosures [Abstract] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table] Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] NAV Fair Value Measured at Net Asset Value Per Share [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring Fair Value, Measurements, Recurring [Member] Geographic Distribution [Axis] Geographic Distribution [Axis] Geographic Distribution [Domain] Geographic Distribution [Domain] Domestic Geographic Distribution, Domestic [Member] Other Evergy Other Evergy [Member] Other Evergy [Member] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Equity securities Equity Securities [Member] Alternative investments fund Alternative Investment Fund [Member] Alternative Investment Fund [Member] Real estate securities fund Real Estate Funds [Member] Nuclear decommissioning trust: Decommissioning Trust Assets [Member] Decommissioning Trust Assets [Member] Core bond fund Core Bond Fund [Member] Core Bond Fund [Member] Combination debt/equity/other fund Debt Equity Other Fund [Member] Debt Equity Other Fund [Member] Rabbi trust: Rabbi Trusts [Member] Rabbi Trusts [Member] 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] Total nuclear decommissioning trust Decommissioning Fund Investments, Fair Value Total rabbi trust Rabbi Trust, Fair Value Disclosure Rabbi Trust, Fair Value Disclosure Total Assets Assets, Fair Value Disclosure 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, 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 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 Related Party Transactions [Abstract] Schedule of related party receivables and payables Schedule of Related Party Transactions [Table Text Block] Entities [Table] Entities [Table] 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] Entity Information [Line Items] Entity Information [Line Items] Lease asset Lessee, Lease, Asset Lessee, Lease, Asset Lease liability Lessee, Lease, Liability Lessee, Lease, Liability Schedule of Error Corrections and Prior Period Adjustment Restatement [Table] Schedule of Error Corrections and Prior Period Adjustment Restatement [Table] Restatement [Axis] Restatement [Axis] Restatement [Domain] Restatement [Domain] As Previously Filed Previously Reported [Member] As Recast Restatement Adjustment [Member] Error Corrections and Prior Period Adjustments Restatement [Line Items] Error Corrections and Prior Period Adjustments Restatement [Line Items] CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] 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] Amortization of other Amortization of Other Deferred Charges Amortization of deferred refueling outage Amortization Of Deferred Refueling Outage Costs Amortization Of Deferred Refueling Outage Costs Deferred income taxes, net 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. Net deferred income taxes and credits Deferred Income Taxes and Tax Credits Other Other Noncash Income (Expense) Changes in working capital items: Increase (Decrease) in Operating Capital [Abstract] Fuel inventory and supplies Increase (Decrease) In Energy Related Inventory Increase (Decrease) In Energy Related Inventory Fuel inventories Increase (Decrease) in Fuel Inventories Materials and supplies Increase (Decrease) in Raw Materials, Packaging Materials and Supplies Inventories Prepaid expenses and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Accrued interest Increase (Decrease) in Interest Payable, Net 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 Deferred refueling outage costs Increase Decrease In Deferred Refueling Outage Costs The increase (decrease) in deferred refueling outage costs. Pension and post-retirement benefit obligations Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits Fuel recovery mechanisms Increase (Decrease) in over (under) Energy Recovery 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 Utility capital expenditures Payments to Acquire Property, Plant, and Equipment, Utility Payments to Acquire Property, Plant, and Equipment, Utility Allowance for borrowed funds used during construction Allowance For Borrowed Funds Used During Construction The component of the allowance for funds used during construction during the period based on the interest rate on borrowed funds used in financing the construction of regulated assets. Other investing activities Payments for (Proceeds from) Other Investing Activities Cash Flows used in Investing Activities Net Cash Provided by (Used in) Investing Activities Statement of Financial Position [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 [Member] ASSETS Assets [Abstract] CURRENT ASSETS: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash Restricted Cash, Current 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 Tax Liabilities, Net, Noncurrent 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 9) 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 TOTAL LIABILITIES AND EQUITY Liabilities and Equity 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 OtherRevenue Revenue other than from contracts with customers. Revenues Revenues Schedule of short-term debt Schedule of Short-term Debt [Table Text Block] Statement of Cash Flows [Abstract] Restricted cash Restricted Cash and Cash Equivalents Line of Credit Line of Credit [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum Maximum [Member] Line of credit, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Credit facility expiration date Line of Credit Facility, Expiration Date 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, Covenant, Debt to Capitalization Ratio Debt Instrument, Covenant, Debt to Capitalization Ratio 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 Available borrowings Long-term line of credit Short-term Debt Interest rate during period Short-term Debt, Weighted Average Interest Rate, at Point in Time Income Statement [Abstract] OPERATING 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 SPP network transmission costs SPPNetworkTransmissionCosts Cost incurred for SPP transmission costs Operating and maintenance Utilities Operating Expense, Maintenance and Operations Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction 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 (loss) Investment Income, Nonoperating Other income Other Nonoperating Income Other expense Other Nonoperating Expense Total Other Income (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) Equity in earnings of equity method investees, net of income taxes Income (Loss) from Equity Method Investments NET INCOME Less: Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to Evergy, Inc. Net Income (Loss) Attributable to Parent 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 COMPREHENSIVE INCOME Comprehensive Income (Loss), Net of Tax, Attributable to Parent [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 Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Total other comprehensive loss 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 COMPREHENSIVE INCOME Comprehensive Income (Loss), Net of Tax, Attributable to Parent Statement of Comprehensive Income [Abstract] OTHER COMPREHENSIVE INCOME: 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 Total other comprehensive loss Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Leases [Abstract] Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] 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, Payments, 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 lease term (years) Finance Lease, Weighted Average Remaining Lease Term Weighted-average discount rate Finance Lease, Weighted Average Discount Rate, Percent Related party receivables Accounts Receivable, Related Parties, Current Related party payables Accounts Payable, Related Parties, Current 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 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 Commitments and Contingencies Disclosure [Abstract] COMMITMENTS AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] Common stock - shares authorized (in shares) Common Stock, Shares Authorized Common stock - par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock - shares issued (in shares) Common Stock, Shares, Issued 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 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. 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 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. Accounts payable Increase (Decrease) in Accounts Payable Accrued taxes Increase (Decrease) in Accrued Taxes Payable 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 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 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 Retirements of long-term debt Repayments of Long-term Debt Cash dividends paid Payments of Dividends Cash Flows used in 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 LONG-TERM DEBT Long-term Debt [Text Block] SHORT-TERM BORROWINGS AND SHORT-TERM BANK LINES OF CREDIT Short-term Debt [Text Block] 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 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] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] 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 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 Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Nonrecurring Adjustment [Axis] Nonrecurring Adjustment [Axis] Nonrecurring Adjustment [Domain] Nonrecurring Adjustment [Domain] Acquisition-related Costs Acquisition-related Costs [Member] 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] Operating revenues Business Acquisition, Pro Forma Revenue Net income attributable to Evergy, Inc. Business Acquisition, Pro Forma Net Income (Loss) Basic earnings per common share (in dollars per share) Business Acquisition, Pro Forma Earnings Per Share, Basic Diluted earnings per common share (in dollars per share) Business Acquisition, Pro Forma Earnings Per Share, Diluted Merger-related, after tax costs Business Combination Merger Related Costs After Tax Business Combination Merger Related Costs, AfterTax 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 NonCashPropertyPlantAndEquipmentAdditions(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 Income Tax Disclosure [Abstract] TAXES Income Tax Disclosure [Text Block] Amortization of corporate-owned life insurance Amortization Of Corporate Owned Life Insurance Amortization Of Corporate Owned Life Insurance Non-cash compensation Share-based Compensation Equity in earnings of equity method investees, net of income taxes Income from corporate-owned life insurance Income From Corporate Owned Life Insurance Income From Corporate Owned Life Insurance 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 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 Other financing activities Proceeds from (Payments for) Other Financing Activities 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 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] 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] 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 Investment tax credit amortization Income tax expense 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 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 Compensation Cost, 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 Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] 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] Level 2 Fair Value, Inputs, Level 2 [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] 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 FAIR VALUE MEASUREMENTS Fair Value Disclosures [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] 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. International Geographic Distribution, Foreign [Member] Level 1 Fair Value, Inputs, Level 1 [Member] Level 3 Fair Value, Inputs, Level 3 [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] 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] Other Other Assets [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] Assets Assets, Fair Value Disclosure [Abstract] 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. Liabilities Liabilities, Fair Value Disclosure [Abstract] Interest rate swaps Derivative Liability Total Financial Liabilities Fair Value Disclosure 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 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] 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 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] 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 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 segments Number of Reportable Segments Number of active wholly owned subsidiaries Number Of Wholly Owned Subsidiaries Number Of Wholly Owned Subsidiaries Ownership percentage Equity Method Investment, Ownership Percentage 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 Conversion ratio Business Acquisition, Conversion Ratio Business Acquisition, Conversion Ratio Number of shares issued (in shares) Business Acquisition, Equity Interest Issued or Issuable, Number of Shares Minimum Minimum [Member] Remaining lease term Lease, Remaining Lease Term Lease, Remaining Lease Term Summary of Reclassifications Schedule of Error Corrections and Prior Period Adjustments [Table Text Block] 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] Unaudited Pro Forma Financial Information Business Acquisition, Pro Forma Information [Table Text Block] Stockholders' Equity Note [Abstract] Line of Credit Facility [Table] Line of Credit Facility [Table] 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 (in shares) 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 Retained earnings restrictions Equity Restrictions Restricted net assets of subsidiaries Amount of Restricted Net Assets for Consolidated and Unconsolidated Subsidiaries PENSION PLANS AND POST-RETIREMENT BENEFITS Pension and Other Postretirement Benefits Disclosure [Text Block] 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 lease term (years) Operating Lease, Weighted Average Remaining Lease Term Weighted-average discount rate Operating Lease, Weighted Average Discount Rate, Percent Dividends declared on common stock (in dollars per share) Common Stock, Dividends, Per Share, Declared Finance lease costs Finance 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 Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Table] Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Table] Nuclear decommissioning trust - equity securities Decommissioning Trust Assets - Equity [Member] Decommissioning Trust Assets - Equity [Member] Rabbi trusts 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, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Accounts, Notes, Loans and Financing Receivable by Receivable Type [Axis] 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] Customer accounts receivable Accounts Receivable, Gross, Current Other receivables Other Receivables, Gross, Current Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Current Total SHAREHOLDERS' EQUITY Stockholders' Equity Note Disclosure [Text Block] AOCI - Net gains (losses) on cash flow hedges Regulatory Proceedings [Table] Public Utilities General Disclosures [Table] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Forecast Scenario, Forecast [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] 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 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 Annual transmissions revenue estimated amount of increase (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 Dividends Payable [Table] Dividends Payable [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Dividends Payable [Line Items] Dividends Payable [Line Items] Dividends payable Dividends Payable Schedule of Net Benefit Costs Schedule of Net Benefit Costs [Table 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 REVENUE Revenue from Contract with Customer [Text Block] 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] RELATED PARTY TRANSACTIONS AND RELATIONSHIPS Related Party Transactions Disclosure [Text Block] 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 from mid-Dec to mid-Jan MaximumAmountOfOutstandingPrincipalUnderReceivablesAgreementFromMid-DecToMid-Jan Maximum amount of outstanding principal under receivables agreement from mid-Dec to mid-Jan Maximum amount of outstanding principal under receivables agreement from mid-Jan to mid Feb MaximumAmountOfOutstandingPrincipalUnderReceivablesAgreementFromJanToMidFeb Maximum Amount Of Outstanding Principal Under Receivables Agreement From Jan To Mid Feb Maximum amount of outstanding principal under receivables agreement from mid February to mid July Maximum Amount Of Outstanding Principal Under Receivables Agreement From Mid February to Mid July Maximum Amount Of Outstanding Principal Under Receivables Agreement From Mid February to mid July. Maximum amount of outstanding principal under receivable agreement from mid-July to expiration MaximumAmountOfOutstandingPrincipalUnderReceivableAgreementFromMid-JulyToExpiration Maximum amount of outstanding principal under receivable agreement from mid-July to the expiration date of the facility. Maximum amount of outstanding principal under receivables agreement Maximum Amount Of Outstanding Principal Under Receivables Agreement Maximum amount of outstanding principal under receivables agreement Maximum amount of outstanding principal under receivables agreement from mid-November to mid-June MaximumAmountOfOutstandingPrincipalUnderReceivablesAgreementFromMidNovToMidJun MaximumAmountOfOutstandingPrincipalUnderReceivablesAgreementFromMidNovToMidJun Maximum amount of outstanding principal under receivables agreement from mid-June to expiration MaximumAmountOfOutstandingPrincipalUnderReceivablesAgreementFromMidJuneToExpiration Maximum Amount Of Outstanding Principal Under Receivables Agreement From Mid June To Expiration Entity information [Abstract] Entity information for DEI KANSAS CITY POWER & LIGHT CO WESTAR ENERGY INC /KS 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 Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business 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 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