Investments [Abstract] Financial Investments Investments Securities Disclosure [Text Block] Disclosure related to investments in certain debt and equity securities classified as either trading securities or available-for-sale securities. Regulated Operations [Abstract] Regulatory Proceedings [Table] Regulatory Proceedings [Table] Regulatory Proceedings [Table] Public Utilities, Rate Review, Type [Axis] Public Utilities, Rate Review, Type [Axis] Public Utilities, Rate Review, Type [Axis] Public Utilities, Inventory, Type [Domain] Inventory [Domain] Regulatory Proceedings [Line Items] Regulatory Proceedings [Line Items] Regulatory Proceedings [Line Items] Estimated Increase In Annual Retail Revenues For Transmission Costs Estimated Increase In Annual Retail Revenues For Transmission Costs Estimated Increase In Annual Retail Revenues For Transmission Costs Estimated Increase In Annual Retail Revenues For Environmental Costs Estimated Increase In Annual Retail Revenues For Environmental Costs Estimated Increase In Annual Retail Revenues For Environmental Costs Estimated Increase In Annual Revenues For Property Tax Estimated Increase In Annual Revenues For Property Tax Estimated Increase In Annual Revenues For Property Tax Estimated Increase In Annual Transmission Revenues Estimated Increase In Annual Transmission Revenues Estimated Increase In Annual Transmission Revenues Variable Interest Entities [Abstract] Schedule Of Variable Interest Entities [Abstract] Assets And Liabilities of VIEs Schedule of Variable Interest Entities [Table Text Block] Accounting Policies [Abstract] Principles Of Consolidation Consolidation, Policy [Policy Text Block] Use Of Management's Estimates Use of Estimates, Policy [Policy Text Block] Fuel Inventory And Supplies Inventory, Policy [Policy Text Block] Allowance For Funds Used During Construction Allowance for Funds Used During Construction, Policy [Policy Text Block] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Class of Stock Disclosures [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Class of Stock [Line Items] Class of Stock [Line Items] Common Stock Schedule of Stock by Class [Table Text Block] Summary Of Significant Accounting Policies Significant Accounting Policies [Text Block] Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract] Statement [Table] Statement [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Wolf Creek [Member] Wolf Creek Member Wolf Creek [Member] Wolf Creek Pension And Post-Retirement Benefit Plans [Line Items] Wolf Creek Interim Pension And Post-Retirement Benefit Disclosure [Line Items] Wolf Creek Interim Pension And Post-Retirement Benefit Disclosure [Line Items] Schedule of Net Periodic Benefit Costs [Table Text Block] Schedule of Net Benefit Costs [Table Text Block] Compensation and Retirement Disclosure [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plans Disclosures, Defined Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Pension Benefits [Member] Pension Plan [Member] Post-Retirement Benefits [Member] Other Postretirement Benefit Plan [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Components of Net Periodic Cost (Benefit): Defined Benefit Plan, Net Periodic Benefit Cost [Abstract] Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return on Plan Assets Transition obligation, net Defined Benefit Plan, Amortization of Transition Obligations (Assets) Prior service costs Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Actuarial loss, net Defined Benefit Plan, Amortization of Gains (Losses) Net periodic cost before regulatory adjustment Defined Benefit Plan Net Periodic Benefit Cost before Regulatory Adjustment The total amount of net periodic benefit cost for defined benefit plans for the period prior to regulatory adjustment. Regulatory adjustment Defined Benefit Plan Regulatory Adjustment Defined Benefit Plan Regulatory Adjustment Net periodic cost Defined Benefit Plan, Net Periodic Benefit Cost Pension Contributions Pension Contributions Statement of Cash Flows [Abstract] Scenario [Axis] Scenario, Unspecified [Domain] Variable Interest Entities by Classification of Entity [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable Interest Entity [Member] Variable Interest Entity, Primary Beneficiary [Member] 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 net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Amortization and Accretion, Net Amortization of nuclear fuel Amortization of nuclear fuel The current period expense charged against earnings for the amortization of capitalized nuclear fuel used to generate electricity. Amortization of deferred regulatory gain from sale leaseback Sale Leaseback Transaction, Current Period Gain Recognized Amortization of corporate-owned life insurance Amortization Of Corporate Owned Life Insurance The amortization of various items related to corporate-owned life insurance policies. Non-cash compensation Share-based Compensation Net deferred income taxes and credits Deferred Income Taxes and Tax Credits Stock-based compensation excess tax benefits Excess Tax Benefit from Share-based Compensation, Operating Activities Allowance for equity funds used during construction Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Changes in working capital items: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Fuel inventory and supplies Increase (Decrease) in Inventories Prepaid expenses and other Increase (Decrease) in Prepaid Expense and Other Assets Accounts payable Increase (Decrease) in Accounts Payable Accrued taxes Increase (Decrease) in Accrued Taxes Payable Other current liabilities Increase (Decrease) in Other Current Liabilities Changes in other assets Increase (Decrease) in Other Operating Assets Changes in other liabilities Increase (Decrease) in Other Operating Liabilities Cash Flows from Operating Activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations CASH FLOWS FROM (USED IN) INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities [Abstract] Additions to property, plant and equipment Payments to Acquire Property, Plant, and Equipment Purchase of securities - trusts Payments to Acquire Marketable Securities Sale of securities - trusts Proceeds from Sale and Maturity of Marketable Securities Investment in corporate-owned life insurance Life Insurance, Corporate or Bank Owned, Change in Value Proceeds from investment in corporate-owned life insurance Proceeds from Life Insurance Policies Proceeds from federal grant Proceeds From Federal Grant The cash inflow associated with non-repayable money awarded to an entity to carry out a specific project. Investment in affiliated company Payments to Acquire Businesses and Interest in Affiliates Other investing activities Payments for (Proceeds from) Other Investing Activities Cash Flows used in Investing Activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Short-term debt, net Proceeds from (Repayments of) Short-term Debt Proceeds from long-term debt Proceeds from Issuance of Long-term Debt Retirements of long-term debt Repayments of Long-term Debt Repayment of capital leases Repayments of Long-term Capital Lease Obligations Borrowings against cash surrender value of corporate-owned life insurance Proceeds From Borrowings Against Cash Surrender Value Of Corporate Owned Life Insurance The cash inflow from borrowings against the cash surrender value of corporate-owned life insurance polices. Repayment of borrowings against cash surrender value of corporate-owned life insurance Repayment of borrowings against cash surrender value of corporate-owned life insurance The cash outflow associated with the repayment of borrowings against the cash surrender value of corporate-owned life insurance polices. Stock-based compensation excess tax benefits Excess Tax Benefit from Share-based Compensation, Financing Activities Preferred stock redemption Proceeds from (Repayments of) Restricted Cash, Financing Activities Issuance of common stock Proceeds from Issuance of Common Stock Distributions to shareholders of noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Cash dividends paid Payments of Dividends Other financing activities Proceeds from (Payments for) Other Financing Activities Cash Flows from Financing Activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations NET CHANGE IN CASH AND CASH EQUIVALENTS Cash and Cash Equivalents, Period Increase (Decrease) CASH AND CASH EQUIVALENTS: Cash and Cash Equivalents, at Carrying Value [Abstract] Beginning of period Cash and Cash Equivalents, at Carrying Value End of period Long-term Debt, Unclassified [Abstract] Debt Financing Debt Disclosure [Text Block] Consolidated Balance Sheets Parenthetical [Abstract] Consolidated Balance Sheets Parenthetical [Abstract] Scenario [Axis] Scenario, Unspecified [Domain] CURRENT ASSETS: Assets, Current [Abstract] Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Current Westar Energy, Inc. Shareholders' Equity: Stockholders' Equity Attributable to Parent [Abstract] Common stock, par value Common Stock, Par or Stated Value Per Share Common stock, shares authorized Common Stock, Shares Authorized Common stock, shares issued Common Stock, Shares, Issued Common stock, shares outstanding Common Stock, Shares, Outstanding Financial And Derivative Instruments and Trading Securities [Abstract] Financial And Derivative Instruments and Trading Securities [Abstract] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Summary of Investments, Other than Investments in Related Parties, by Type [Axis] Summary of Investments, Other than Investments in Related Parties, by Type [Axis] Summary of Investments, by Type [Domain] Summary of Investments, by Type [Domain] Domestic Equity [Member] Domestic Equity Member Domestic Equity [Member] International Equity [Member] International Equity Member International Equity [Member] Core Bonds [Member] Core Bonds [Member] Core Bonds [Member] High-Yield Bonds [Member] High Yield Bonds Member High-yield Bonds [Member] Emerging Market Bonds [Member] Emerging Market Bonds Member Emerging Market Bonds [Member] Other Fixed Income [Member] Other Fixed Income [Member] Other Fixed Income [Member] Combination Debt Equity And Other Fund [Member] Combination Debt Equity And Other Fund [Member] Combination Debt Equity And Other Fund [Member] Combination Debt and Equity Fund [Member] Combination Debt and Equity Fund [Member] Combination Debt and Equity Fund [Member] Alternative Funds [Member] Alternative Funds [Member] Alternative Funds [Member] Real Estate Securities [Member] Real Estate Funds [Member] Cash Equivalents [Member] Cash Equivalents [Member] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Financial and Derivative Instruments and Trading Securities [Line Items] Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items] Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items] Nuclear decommissioning trust assets Decommissioning Fund Investments, Fair Value Trading securities Trading Securities Total assets measured at fair value Assets, Fair Value Disclosure Statement of Stockholders' Equity [Abstract] Statement, Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Cumulative Preferred Stock [Member] Preferred Stock [Member] Common Stock [Member] Common Stock [Member] Paid-In Capital [Member] Additional Paid-in Capital [Member] Retained Earnings [Member] Retained Earnings [Member] Noncontrolling Interests [Member] Noncontrolling Interest [Member] Beginning Balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Beginning Balance (Shares) Shares, Outstanding Issuance of stock Stock Issued During Period, Value, New Issues Issuance Of Stock For Comprensation And Reinvested Dividends, Shares Issuance Of Stock For Comprensation And Reinvested Dividends, Shares Issuance Of Stock For Comprensation And Reinvested Dividends, Shares Issuance of stock (shares) Stock Issued During Period, Shares, New Issues Issuance Of Stock For Compensation And Reinvested Dividends Issuance Of Stock For Compensation And Reinvested Dividends Issuance Of Stock For Compensation And Reinvested Dividends Stock redemption Stock Redeemed or Called During Period, Value Stock redemption (shares) Stock Redeemed or Called During Period, Shares Tax withholding related to stock compensation Adjustments Related to Tax Withholding for Share-based Compensation Preferred dividends Dividends, Preferred Stock Dividends on common stock Dividends, Common Stock Stock compensation expense Adjustments to Additional Paid in Capital, Share-based Compensation, Restricted Stock Unit or Restricted Stock Award, Requisite Service Period Recognition Tax Benefit on stock compensation Deconsolidation of variable interest entity Noncontrolling Interest, Decrease from Deconsolidation Ending Balance Ending Balance (Shares) Stockholders' Equity, Other Stockholders' Equity, Other Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Axis] KGE [Member] KGE Member KGE [Member] Subsidiary Interest in Defined Benefit Plans Subsidiary Interest in Defined Benefit Plans Subsidiary's interest in defined benefit plans. Net periodic cost before regulatory adjustment Net periodic cost Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Fixed Rate Debt Member Fixed Rate Debt [Member] Fixed Rate Debt Of Variable Interest Entities Member Fixed Rate Debt Of Variable Interest Entities Member Fixed Rate Debt of Variable Interest Entities [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Carrying Value Long-term Debt, Gross Fair Value Debt Instrument, Fair Value Disclosure Organization, Consolidation and Presentation of Financial Statements [Abstract] Number of customers in Kansas Number Of Customers Getting Electric Generation, Transmission And Distribution Services Number Of Customers Getting Electric Generation, Transmission And Distribution Services Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Line Items] Schedule of Available-for-sale Securities [Line Items] Trading Securities, Change in Unrealized Holding Gain (Loss) Trading Securities, Change in Unrealized Holding Gain (Loss) Fair Value, Less than 12 Months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Gross Unrealized Losses, Less than 12 Months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss Fair Value, 12 Months or Greater Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Gross Unrealized Losses, 12 Months or Greater Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss Fair Value, Total Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value Gross Unrealized Losses, Total Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Cash and cash equivalents Restricted cash Restricted Cash and Cash Equivalents, Current Accounts receivable, net of allowance for doubtful accounts of $4,503 and $4,596, respectively Accounts Receivable, Net, Current Fuel inventory and supplies Inventory, Net Deferred Tax Assets, Net of Valuation Allowance, Current Deferred Tax Assets, Net of Valuation Allowance, Current Prepaid expenses Prepaid Expense, Current Regulatory assets Regulatory Assets, Current Other Other Assets, Current Total Current Assets Assets, Current Property, plant and equipment, net Property, Plant and Equipment, Net OTHER ASSETS: Other Assets, Noncurrent [Abstract] Regulatory assets Regulatory Assets, Noncurrent Nuclear decommissioning trust Other Other Assets, Noncurrent Total Other Assets Total Other Assets Total Other Assets TOTAL ASSETS Assets LIABILITIES AND EQUITY Liabilities and Equity [Abstract] CURRENT LIABILITIES: Liabilities, Current [Abstract] Current maturities of long-term debt Long-term Debt, Current Maturities Short-term debt Short-term Debt Accounts payable Accounts Payable, Current Accrued dividends Dividends Payable, Current Accrued taxes Taxes Payable, Current Accrued interest Interest Payable, Current Regulatory liabilities Regulatory Liability, Current Other Other Liabilities, Current Total Current Liabilities Liabilities, Current LONG-TERM LIABILITIES: Liabilities, Noncurrent [Abstract] Long-term debt, net 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 Accrued employee benefits Accrued Employee Benefits Noncurrent The noncurrent liability recognized in the balance sheet associated with defined benefit pension plans, other post-retirement benefit plans and other general benefit plans. Asset retirement obligations Asset Retirement Obligations, Noncurrent Other Other Liabilities, Noncurrent Total Long-Term Liabilities Liabilities, Noncurrent COMMITMENTS AND CONTINGENCIES (See Notes 10 and 11) Commitments and Contingencies EQUITY: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Common stock, par value $5 per share; authorized 275,000,000 shares; issued and outstanding 129,272,835 shares and 128,254,229 shares, respective to each date Common Stock, Value, Issued Paid-in capital Additional Paid in Capital, Common Stock Retained earnings Retained Earnings (Accumulated Deficit) Total Westar Energy, Inc. Shareholders' Equity Stockholders' Equity Attributable to Parent Noncontrolling Interests Stockholders' Equity Attributable to Noncontrolling Interest Total Equity TOTAL LIABILITIES AND EQUITY Liabilities and Equity Carrying Values And Fair Values Of Financial Instruments Schedule of Carrying Value and Fair Values of Financial Instruments [Table Text Block] Schedule of Carrying Value and Fair Values of Financial Instruments. Fair Value Of Assets And Liabilities Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Reconciliations Of Assets And Liabilities At Fair Value Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Unrealized Gains And Losses On Fair Value Assets And Liabilities Schedule Of Unrealized Gains And Losses Of Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input [Table Text Block] Schedule of unrealized gains and losses recorded for assets and liabilities measured at fair value on a recurring basis using unobservable inputs. Investments In Financial Instruments Fair Value Investments Entities That Calculate Net Asset Value per Share Disclosure [Table Text Block] This item represents the disclosure regarding the investments in certain entities that calculate net asset value per share that enables users to understand the nature and risks of the investments and whether the investments are probable of being sold at amounts different from net asset value per share. Such disclosure may include (1) the fair value of the investments in the major category, and a description of the significant investment strategies of the investee(s) in the major category; (2) for each major category of investment that includes investments that can never be redeemed with the investees, but the reporting entity receives distributions through the liquidation of the underlying assets of the investees, the reporting entity's estimate of the period of time over which the underlying assets are expected to be liquidated by the investees; (3) the amount of the entity's unfunded commitments related to investments in the major category; (4) a general description of the terms and conditions upon which the investor may redeem investments in the major category; (5) the circumstances in which an otherwise redeemable investment in the major category might not be redeemable; (6) for those otherwise redeemable investments that are restricted from redemption as of the reporting entity's measurement date, the entity's best estimate of when the restriction from redemption might lapse; if an estimate cannot be made, the entity shall disclose that fact and how long the restriction has been in effect; (7) any other significant restriction on the ability to sell investments in the major category at the measurement date; (8) total fair value of held for sale investments and any remaining actions required to complete the sale when the reporting entity determines that it is probable that it will sell the investments for an amount different from net asset value per share; and (9) disclosure of an entity's plans to sell and any remaining actions required to complete the sale when the entity intends to sell a group of investments, but the individual investments to be sold have not been identified. Wolf Creek Pension And Post-Retirement Benefit Plans Entity Share Of Affiliate Pension And Other Postretirement Benefits Disclosure Text Block Includes disclosure of the entity's share of an affiliate's pension and other post-retirement benefits. Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Jeffrey Energy Center [Member] Jeffrey Energy Center Member Jeffrey Energy Center [Member] La Cygne Generating Station [Member] La Cygne Generating Station Member La Cygne Generating Station [Member] Railroad Transportation Equipment [Member] Railroad Transportation Equipment [Member] Railroad Transportation Equipment 2 [Member] Railroad Transportation Equipment 2 [Member] Railroad Transportation Equipment 2 [Member] Variable Interest Entity, Primary Beneficiary [Member] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Variable interest entity percentage of asset held Variable Interest Entity Percentage of Asset Held The percentage of an asset held by a variable interest entity that is consolidated by the entity. Agreement expiration date Lease Expiration Date Gain or loss upon deconsolidation of VIE Deconsolidation, Gain (Loss), Amount Income Tax Disclosure [Abstract] Income Tax Contingency [Table] Income Tax Contingency [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Income Tax Contingency [Line Items] Income Tax Contingency [Line Items] Income tax expense Income Tax Expense (Benefit) Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Liability for unrecognized income tax benefits Unrecognized Tax Benefits Interest on liability related to unrecognized income tax benefits Unrecognized Tax Benefits, Interest on Income Taxes Accrued Penalties accrued for unrecognized income tax benefits Unrecognized Tax Benefits, Income Tax Penalties Accrued Accrual for taxes other than income taxes Accrual for Taxes Other than Income Taxes Public Utilities, Inventory [Table] Inventory [Axis] Fuel Inventory [Member] Public Utilities, Inventory, Fuel [Member] Supplies [Member] Supplies [Member] Public Utilities, Inventory [Line Items] Public Utility Inventory Public Utilities, Inventory Total Summary of Investments, Other than Investments in Related Parties [Table] Summary of Investments, Other than Investments in Related Parties [Table] Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items] Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items] Unrealized gain (loss) included in regulatory liabilities Fair Value Measurement with Unobservable Inputs Recurring Basis Asset and Liability Unrealized Gain Loss Included In Regulatory Liabilities This element represents total unrealized gains or losses for the period arising from assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in regulatory liabilities on the statement of financial position. Legal Proceedings [Abstract] LEGAL PROCEEDINGS [Abstract] Legal Proceedings Legal Proceedings Text Block Open legal proceedings in the normal course of business, including product liability and other litigation and contingencies. Less: Preferred dividends Participating Securities, Distributed and Undistributed Earnings (Loss), Basic Participating Securities, Distributed and Undistributed Earnings (Loss), Basic Net income allocated to common stock Common Stock Distributed And Undistributed Earnings Earnings distributed and earnings allocated to common stock under the two-class method. Weighted Average Number of Shares Outstanding , Basic Weighted Average Number of Shares Outstanding, Basic RSUs Incremental Common Shares Attributable to Dilutive Effect of Nonvested Shares with Forfeitable Dividends Forward sale agreements Incremental Common Shares Attributable To Equity Forward Sale Agreements Additional common shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of equity forward sale agreements using the treasury stock method. Weighted average equivalent common shares outstanding - diluted Weighted Average Number of Shares Outstanding, Diluted Earnings Per Share, Basic Earnings Per Share, Basic Earnings Per Share, Diluted Earnings Per Share, Diluted Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive securities Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Commitments and Contingencies Disclosure [Abstract] Loss Contingencies [Table] Loss Contingencies [Table] Unrecorded Unconditional Purchase Obligation by Category of Item Purchased [Axis] Unrecorded Unconditional Purchase Obligation by Category of Item Purchased [Axis] Unconditional Purchase Obligation, Category of Goods or Services Acquired [Domain] Unconditional Purchase Obligation, Category of Goods or Services Acquired [Domain] Transmission Service Agreement One [Member] Transmission Service Agreement One [Member] First agreement between a transmission customer and the transmission provider for service. Loss Contingencies by Nature of Contingency [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Potential GHG Emissions Restrictions 1 [Member] Potential GHG Emissions Restrictions1 Member More than (or equal to) the amount. Potential GHG Emissions Restrictions 2 [Member] Potential GHG Emissions Restrictions2 Member More than (or equal to) the amount. Report Date [Axis] Report Date [Axis] Financial Statements Date [Domain] Financial Statement Filing Date [Domain] 2011 Through 2015 Generation Capacity Peak Demand [Member] Two Thousand Eleven Through Two Thousand Fifteen Generation Capacity Peak Demand Member Two Thousand Eleven Through Two Thousand Fifteen Generation Capacity Peak Demand [Member] 2016 Through 2019 Generation Capacity Peak Demand [Member] Two Thousand Sixteen Through Two Thousand Nineteen Generation Capacity Peak Demand Member Two Thousand Sixteen Through Two Thousand Nineteen Generation Capacity Peak Demand [Member] 2020 And Thereafter Generation Capacity Peak Demand [Member] Two Thousand Twenty And Thereafter Generation Capacity Peak Demand Member Two Thousand Twenty And Thereafter Generation Capacity Peak Demand [Member] Commitments And Contingencies [Line Items] Commitments And Contingencies [Line Items] Commitments And Contingencies [Line Items] Environmental Projects [Abstract] Environmental Projects [Abstract] Environmental Projects [Abstract] Environmental upgrades jointly owned utility plant entity share Proposed Environmental Upgrades Jointly Owned Utility Plant Entity Share Entity's share of the total amount of proposed environmental upgrades at a jointly owned utility plant. Environmental upgrades jointly owned utility plant Proposed Increase In Annual Retail Revenues Proposed Increase In Annual Retail Revenues Greenhouse Gases [Abstract] Greenhouse Gases [Abstract] Greenhouse Gases [Abstract] GHG emission GHG Emission GHG Emission Renewable Energy Standard [Abstract] Renewable Energy Standard [Abstract] Renewable Energy Standard [Abstract] Renewable energy generation capacity, percentage Renewable Energy Generation Capacity Renewable Energy Generation Capacity Net Capacity, in MW Net Capacity, in MW Net capacity, in megawatts EPA Consent Decree [Abstract] EPA Lawsuit [Abstract] EPA Lawsuit [Abstract] Preliminary estimate of the cost of selective catalytic reduction (SCR) equipment Estimate of Cost of Environmental Equipment The estimated cost to install environmental equipment on a power plant. Cost And Fair Value Of Investments Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Fair Value And Gross Unrealized Losses Of Available-For-Sale Securities Schedule of Temporary Impairment Losses, Investments [Table Text Block] Document And Entity Information [Abstract] Document and Entity Information [Abstract] Entities [Table] Entities [Table] Entity Information [Line Items] Entity Information [Line Items] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Income Statement [Abstract] REVENUES Revenues OPERATING EXPENSES: Operating Costs and Expenses [Abstract] Fuel and purchased power Cost Electric Fuel Purchased Power Fuel and purchased power expense incurred that are directly related to goods produced and sold. Network Transmission Cost Network Transmission Cost Network Transmission Cost Operating and maintenance Utilities Operating Expense, Maintenance and Operations Selling, general and administrative Selling, General and Administrative Expense Taxes, Miscellaneous Taxes, Miscellaneous Total Operating Expenses Costs and Expenses INCOME FROM OPERATIONS Operating Income (Loss) OTHER INCOME (EXPENSE): Nonoperating Income (Expense) [Abstract] Investment earnings (losses) Investment Income, Nonoperating Other income Other Nonoperating Income Other expense Other Nonoperating Expense Total Other Income Nonoperating Income (Expense) Interest expense Interest Expense INCOME BEFORE INCOME TAXES Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest NET INCOME Less: Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest NET INCOME ATTRIBUTABLE TO WESTAR ENERGY, INC. Net Income (Loss) Attributable to Parent Earnings Per Share [Abstract] Earnings Per Share [Abstract] AVERAGE EQUIVALENT COMMON SHARES OUTSTANDING Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Weighted Average Number of Shares Outstanding, Diluted DIVIDENDS DECLARED PER COMMON SHARE Common Stock, Dividends, Per Share, Declared Borrowed funds Allowance for Funds Used During Construction, Capitalized Interest Equity funds Total Public Utilities, Allowance for Funds Used During Construction, Additions Average AFUDC rates Public Utilities, Allowance for Funds Used During Construction, Rate Pension And Post-Retirement Benefit Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Forward Contract Indexed To Issuers Equity, Indexed Shares For Period Forward Contract Indexed To Issuers Equity, Indexed Shares For Period Forward Contract Indexed To Issuers Equity,Indexed Shares For Period Forward Contract Indexed to Issuer's Equity, Settlement Period Forward Contract Indexed to Issuer's Equity, Settlement Period Forward Contract Indexed to Issuer's Equity, Settlement Period Forward Contract Indexed to Issuer's Equity, Indexed Shares Forward Contract Indexed to Issuer's Equity, Indexed Shares Forward Contract Indexed to Issuer's Equity, Estimated Proceeds Forward Contract Indexed to Issuer's Equity, Estimated Proceeds Forward Contract Indexed to Issuer's Equity, Estimated Proceeds Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share Forward Contract Indexed to Issuer's Equity, Proceeds Forward Contract Indexed to Issuer's Equity, Proceeds Forward Contract Indexed to Issuer's Equity, Proceeds Variable Interest Entities Variable Interest Entities Disclosure [Text Block] Variable Interest Entities Disclosure [Text Block] Investment Type [Axis] Investment Type [Axis] Investment Type Categorization [Domain] Investments [Domain] Decommissioning Trust Assets [Member] Decommissioning Trust Assets [Member] Decommissioning Trust Assets [Member] Trading Securities [Member] Trading Securities [Member] Fair Value by Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value [Member] Fair Value, Measurements, Recurring [Member] Total Unfunded commitments Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments Investment redemption frequency Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency Investment redemption length of settlement Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period KGE Member Westar Energy [Member] Westar Energy [Member] Westar Energy [Member] Debt Instrument 8880 [Member] Debt Instrument 8880 [Member] Debt Instrument 8880 [Member] Debt Instruments 8820 [Member] Debt Instruments 8820 [Member] Debt Instruments 8820 [Member] Debt Instruments 8640 and 8660 [Member] Debt Instruments 8640 and 8660 [Member] Debt Instruments 8640 and 8660 [Member] Debt Instruments 8640, 8660 and 8820 [Member] Debt Instruments 8640, 8660 and 8820 [Member] Debt Instrument 8640 [Member] Debt Instrument 8860 [Member] Debt Instrument 8860 [Member] Debt Instrument 8860 [Member] Debt Instrument 8620 [Member] Debt Instrument 8620 [Member] Debt Instrument 8620 [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Secured Debt [Member] Secured Debt [Member] Pollution Control Bond Series [Member] Pollution Control Bond Series [Member] Pollution Control Bond Series [Member] Lender Name [Axis] Lender Name [Axis] Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] Revolving Credit Facility Lender Two [Member] Revolving Credit Facility Lender Two [Member] Revolving Credit Facility Lender Two [Member] Long-term Line of Credit Long-term Line of Credit Long-term Debt, Gross Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year Line of Credit Facility, Maximum Borrowing Capacity Line of Credit Facility, Maximum Borrowing Capacity Line of Credit Facility, Increase(Decrease) in Maximum Borrowing Capacity Line of Credit Facility, Increase(Decrease) in Maximum Borrowing Capacity Line of Credit Facility, Increase(Decrease) in Maximum Borrowing Capacity Stated interest rate on first mortgage bonds Line Of Credit Facility Potential Maximum Aggregate Borrowings The potential maximum aggregate borrowings available under the credit facility if option to increase is exercised. Commitments And Contingencies Commitments and Contingencies Disclosure [Text Block] Consolidated Statements of Changes in Equity Parenthetical [Abstract] Consolidated Statements of Changes in Equity Parenthetical [Abstract] Financial And Derivative Instruments And Trading Securities Financial And Derivative Instruments And Trading Securities [Text Block] Financial And Derivative Instruments And Trading Securities [Text Block] Summary Of Significant Accounting Policies [Line Items] Summary Of Significant Accounting Policies [Line Items] Summary Of Significant Accounting Policies [Line Items] Cash Paid For (Received From) Supplemental Cash Flow Information [Abstract] Interest on financing activities Interest Paid Income taxes, net of refunds Income Taxes Paid, Net Noncash Investing and Financing Transactions Noncash Investing and Financing Items [Abstract] Property, plant and equipment Noncash or Part Noncash Acquisition, Fixed Assets Acquired Issuance of common stock for reinvested dividends and compensation plans Stock Issued Deconsolidation of VIE Assets acquired through capital leases Capital Lease Obligations Incurred Regulatory assets Regulatory Assets Long-term debt, net Investment Holdings [Table] Investment Holdings [Table] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Cost Available-for-sale Securities, Amortized Cost Basis Available-for-sale Securities, Gross Unrealized Gain Available-for-sale Securities, Gross Unrealized Gain Available-for-sale Securities, Gross Unrealized Loss Available-for-sale Securities, Gross Unrealized Loss Available-for-sale Securities Available-for-sale Securities Allocation Available-for-sale Securities, Security Type Allocation Percentage Available-for-sale Securities, Security Type Allocation Percentage Balance at period start Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Regulatory liabilities Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Regulatory Liabilities This element represents total gains or losses for the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in regulatory liabilities on the statement of financial position. Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Balance at period end Rate Matters And Regulation Public Utilities Disclosure [Text Block] Taxes Income Tax Disclosure [Text Block] Description Of Business Nature of Operations [Text Block] Trading securities Unrealized gains losses Fair value of available-for-sale bond funds Available-for-sale Securities, Debt Securities Realized gains on available-for-sale-securities Available-for-sale Securities, Gross Realized Gain (Loss) Schedule of Utility Inventory Schedule of Utility Inventory [Table Text Block] Allowance For Funds Used During Construction Schedule of Allowance for Funds Used During Construction [Table Text Block] Tabular disclosure of an entity's allowance for funds used during construction. Reconciliation Of Basic And Diluted EPS Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Supplemental Cash Flow Information Schedule of Cash Flow, Supplemental Disclosures [Table Text Block]