Proceeds from sale of equity interest Proceeds from Divestiture of Businesses Intangible assets, accumulated amortization Less accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Commodity contracts Commodities Commodity Contract [Member] Entity Listings, Exchange [Axis] Entity Listings, Exchange [Axis] Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Schedule of Expected Benefit Payments Schedule of Expected Benefit Payments [Table Text Block] 2030 Unrecorded Unconditional Purchase Obligation, to be Paid, Year Five Derivative instruments - Current liabilities Business Combination, Recognized Liability Assumed, Liability, Current Award Timing Predetermined Award Timing Predetermined [Flag] Indefinite-lived Intangible Assets [Axis] Indefinite-Lived Intangible Assets [Axis] Entity File Number Entity File Number Additional Paid-In Capital Additional Paid-in Capital [Member] Total operating revenue Operating Revenues [Member] Operating Revenues [Member] Tabular List, Table Tabular List [Table Text Block] Target allocation of pension plan assets (as percent) Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Lightning Term Loan Lightning Term Loan [Member] Lightning Term Loan Recent Accounting Developments New Accounting Pronouncements, Policy [Policy Text Block] Summary of NRG's material related-party transactions with affiliates Schedule of Related Party Transactions [Table Text Block] Secured Overnight Financing Rate (SOFR) Secured Overnight Financing Rate (SOFR) [Member] Estimated Carrying Amounts and Fair Values of Financial Instruments Not Carried at Fair Value Fair Value, by Balance Sheet Grouping [Table Text Block] Acquisition, liabilities assumed Business Combination, Consideration Transferred, Liabilities Incurred Customers served Customers Number of Customers Number of Customers Long-term incentive plans Share-Based Payment Arrangement Share-Based Payment Arrangement [Member] Goodwill [Line Items] Goodwill [Line Items] Position [Axis] Position [Axis] Measurement Basis [Axis] Measurement Basis [Axis] Adjustment to Compensation: Adjustment to Compensation [Axis] Related Party Transactions Related Party Transactions Disclosure [Text Block] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Purchases Finite-Lived Intangible Assets, Purchases This element represents the finite-lived intangible assets purchased during the period. Revenue Recognition Revenue from Contract with Customer [Text Block] Equity compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-Based Compensation Cost Senior Lien Senior Lien [Member] Stock, Class of Stock [Table] Stock, Class of Stock [Table] Shares issued under ESPP (in shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Emissions Emissions [Member] Details pertaining to the emission allowances, which is considered as a derivative commodity. Total — current Current Income Tax Expense (Benefit) Return to provision adjustments Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount 2027 Defined Benefit Plan, Expected Future Prescription Drug Subsidy Receipt, Year Two Adjustment to Compensation, Amount Adjustment to Compensation Amount Pension Benefits Benefit Payments Pension Plan [Member] LC Agreement LC Agreement [Member] LC Agreement Principles of Consolidation Consolidation, Policy [Policy Text Block] Amortization of unearned equity compensation Share-Based Payment Arrangement, Noncash Expense Vivint 6.750% Senior Secured Notes, due 2027 Vivint 6.750% Senior Secured Notes due 2027 [Member] Vivint 6.750% Senior Secured Notes due 2027 Commodity contracts - current Commodity Contract Current [Member] The current portion of a derivative instrument whose primary underlying risk is tied to commodity prices. Counterparty Risk by Investment Grade [Axis] Counterparty Risk by Investment Grade [Axis] The counter party risk exposure by investment grades. Employee Stock Option Share-Based Payment Arrangement, Option [Member] Balance outstanding at the beginning of the period, (in usd per share) Balance outstanding at the end of the period (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options Vested, Weighted Average Grant Date Fair Value The weighted-average fair value of vested awards on equity-based plans excluding option plans. Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] 6.000% Senior Notes due 2036 6.000% Senior Notes due 2036 [Member] 6.000% Senior Notes due 2036 Term Loan Facility Term Loan Facility [Member] Term Loan Facility Percent Effective Income Tax Rate Reconciliation, Percent [Abstract] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Health care trend rate Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Common stock dividends and dividend equivalents declared Dividends, Common Stock, Cash Impairment losses Asset impairment losses Asset Impairment Charges Insider Trading Policies and Procedures [Line Items] New York NEW YORK Major Classes of Property, Plant and Equipment Property, Plant and Equipment [Table Text Block] Common stock, shares authorized (in shares) Common Stock, Shares Authorized Schedule of Stock by Class, Equity [Roll Forward] Schedule of Stock by Class, Equity [Roll Forward] Schedule of Stock by Class, Equity [Roll Forward] Issuance of Series A Preferred Stock (in shares) Stock Issued During Period, Shares, New Issues Loss Contingency Loss Contingency [Abstract] Concentrations of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Derivatives Deferred Tax Liabilities, Derivatives LIABILITIES AND STOCKHOLDERS' EQUITY Liabilities and Equity [Abstract] State and Local Jurisdiction U.S. state and local: State and Local Jurisdiction [Member] Redemption Period Prior to November 1 2027 Redemption Period Prior to November 1 2027 [Member] Redemption Period Prior to November 1 2027 Cover [Abstract] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Maximum High Maximum [Member] Rate of compensation increase Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Bridge Loan Bridge Loan [Member] Pennsylvania PENNSYLVANIA Intangible assets, net Net carrying amount Finite-Lived Intangible Assets, Net Taxes receivable and payable Income Tax Contingency [Line Items] Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Debt Instrument [Line Items] Debt Instrument [Line Items] New Secured Notes New Secured Notes [Member] New Secured Notes Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Retirement Benefits [Abstract] Retirement Benefits [Abstract] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Gross receipts taxes Gross Receipts Tax Gross Receipts Tax East East Segment [Member] East Segment Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Income/(Loss) Before Income Taxes Income/(Loss) before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block] Income Tax Paid, State and Local, after Refund Received [Abstract] Income Tax Paid, State and Local, after Refund Received [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Proceeds from sale of land and related generation assets Proceeds from Sale of Property, Plant, and Equipment Energy Revenue Energy revenue Energy Revenue [Member] Energy Revenue [Member] Business Interruption Insurance Business Interruption Insurance Policy [Policy Text Block] Business Interruption Insurance Policy Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Operating Segments Operating Segments [Member] Partnerships/joint ventures Partnership [Member] Reconciliation of Cash, Cash Equivalents, and Restricted Cash and Cash Equivalents Summary of Income Taxes Paid Details of Supplemental Disclosures of Cash Flow and Non-cash Investing and Financing Information Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Line of Credit Facility [Table] Line of Credit Facility [Table] Asset Retirement Obligations Asset Retirement Obligation [Policy Text Block] Prior service credit Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax Usage/Sales/Retirements/Transfers Finite-Lived Intangible Assets, Usage And Retirements The usage and retirement of finite-lived intangible assets during the period. Letter of Credit Letter of Credit [Member] Jointly Owned Utility Plant Interests Jointly Owned Utility Plant Interests [Line Items] Texas TEXAS U.S.  Income (Loss) from Continuing Operations before Income Taxes, Domestic Current portion of operating lease liabilities Operating Lease, Liability, Current February 15, 2027 to February 14, 2028 Redemption Period February 15, 2027 to February 14, 2028 [Member] Redemption Period February 15, 2027 to February 14, 2028 Interest on lease liabilities Finance Lease, Interest Expense Software Software and Software Development Costs [Member] Document Fiscal Period Focus Document Fiscal Period Focus Rate of compensation increase Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Period of estimated counterparty credit risk exposure under certain long term agreements, including California tolling agreements, South Central load obligations and solar power purchase agreements (in years) Estimated Counterparty Credit Risk Exposure to Certain Counterparties, Period Estimated Counterparty Credit Risk Exposure to Certain Counterparties, Period Award Timing Method Award Timing Method [Text Block] Litigation Case [Domain] Litigation Case [Domain] NRG Indian River Power 2020, tax exempt bonds, due 2045 Indian River Power 2020 Tax Exempt Bonds Due 2045 [Member] Indian River Power 2020 Tax Exempt Bonds Due 2045 Award Type [Axis] Award Type [Axis] Deferred revenue non-current Contract with Customer, Liability, Noncurrent Alexander Funding Trust II Alexander Funding Trust II [Member] Alexander Funding Trust II Stock-Based Compensation Share-Based Payment Arrangement [Policy Text Block] Investment, Name [Domain] Investment, Name [Domain] Investment, Name [Domain] Trading Symbol Trading Symbol 2029 Lessee, Operating Lease, Liability, to be Paid, Year Four Business Combinations Business Combination [Policy Text Block] Derivatives by Underlying Assets [Axis] Derivatives by Underlying Assets [Axis] Derivatives by the underlying asset from which its value is derived. Derivatives by Underlying Assets [Domain] Derivatives by Underlying Assets [Domain] Derivatives by Underlying Assets [Domain] Shares issued under LTIPs (in shares) Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture Gross Amounts of Recognized Assets / Liabilities Fair Value of Gross Derivative Assets/(Liabilities), Net Fair value of gross derivative assets less fair value of gross derivative liabilities. Environmental Remediation Obligations [Abstract] Entity Address, City or Town Entity Address, City or Town Short-Term Debt, Type [Domain] Short-Term Debt, Type [Domain] Asset Impairment Charges [Abstract] Asset Impairment Charges [Abstract] Total property, plant, and equipment Public Utilities, Property, Plant and Equipment, Plant in Service Weighted average discount rate Finance Lease, Weighted Average Discount Rate, Percent Gain on proceeds from insurance recoveries for property, plant and equipment, net Gain (Loss) On Proceeds From Insurance Recoveries for Property Plant And Equipment, Net Gain (Loss) On Proceeds From Insurance Recoveries for Property Plant And Equipment, Net Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Foreign exchange translation Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss) Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Restricted Stock Units RSUs Restricted Stock Units (RSUs) [Member] Statement of Income Location, Balance [Domain] Statement of Income Location, Balance [Domain] Credit Losses Credit Loss, Financial Instrument [Policy Text Block] Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Damages awarded Loss Contingency, Damages Awarded, Value Total consideration Total Consideration Business Combination, Consideration Transferred Settlements, payments and statute closure Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Permanent differences Effective Income Tax Rate Reconciliation, Permanent Differences, Amount Effective Income Tax Rate Reconciliation, Permanent Differences, Amount Regulatory Agency [Axis] Regulatory Agency [Axis] Impairment losses on investments Impairment losses on investments Equity Method Investment, Other-than-Temporary Impairment Entity Emerging Growth Company Entity Emerging Growth Company Fort Bend County, tax exempt bonds, due 2038 Fort Bend County, tax exempt bonds, due 2038 [Member] Fort Bend County, tax exempt bonds, due 2038 [Member] 2028 Long-Term Debt, Maturity, Year Three Total/Net accumulated OCI Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax October 15, 2032 and thereafter Redemption Period From 15 October 2032 and Thereafter [Member] Redemption Period From 15 October 2032 and Thereafter Weighted average remaining lease term (in years) Finance Lease, Weighted Average Remaining Lease Term Cash Collateral (Held)/Posted Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Not Offset Other Vivint Smart Home, Inc. equity instruments (Cash out RSUs and PSUs, Stock Appreciation Rights, Private Placement Warrants) Payments To Acquire Businesses, Acquiree, Other Equity Instruments, Cash Out, Share-based Payment Arrangements, Stock Appreciation Rights, And Private Placement Warrants Payments To Acquire Businesses, Acquiree, Other Equity Instruments, Cash Out, Share-based Payment Arrangements, Stock Appreciation Rights, And Private Placement Warrants Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Less debt issuance costs Debt Issuance Costs, Net Target allocation, return to shareholders, percent of cash available Capital Allocation Policy, Target Allocation, Return To Shareholders, Percentage Of Net Cash Available, Minimum Capital Allocation Policy, Target Allocation, Return To Shareholders, Percentage Of Net Cash Available 2026 Defined Benefit Plan, Expected Future Benefit Payment, Year One Carrying value Indefinite-Lived Intangible Assets (Excluding Goodwill) Environmental proceedings, disclosure threshold Environmental Proceedings, Disclosure Threshold Environmental Proceedings, Disclosure Threshold Common stock, shares outstanding (in shares) Beginning balance, common shares outstanding (in shares) Ending balance, common shares outstanding (in shares) Common Stock, Shares, Outstanding (Loss)/Gain on sale of assets Gain (Loss) on Disposition of Other Assets Provision for credit losses Provision for credit losses Accounts Receivable, Credit Loss Expense (Reversal) Allowance for credit losses, deducted from accounts receivable and other non-current assets SEC Schedule, 12-09, Allowance, Credit Loss [Member] Contract with customer, term Contract With Customer, Term Contract With Customer, Term Weighted-Average Assumptions Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract] Power Power [Member] Details pertaining to the power, which is considered as a derivative commodity. Capitalized Contract Cost Capitalized Contract Cost [Abstract] Other changes in plan assets and benefit obligations recognized in other comprehensive income Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax [Abstract] Accretion of asset retirement obligations Accretion Expense, Including Asset Retirement Obligations Direct Energy vs. Burk and Dickson Litigation Direct Energy vs. Burk and Dickson Litigation [Member] Direct Energy vs. Burk and Dickson Litigation Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Adequate Assurance Clauses Adequate Assurance Clauses [Member] Adequate Assurance Clauses [Member] Changes in NRG's Common Shares Issued and Outstanding Schedule of Common Stock Outstanding Roll Forward [Table Text Block] Excess executive compensation Effective Income Tax Rate Reconciliation Nondeductible Expense Excess Executive Compensation, Amount Effective Income Tax Rate Reconciliation Nondeductible Expense Excess Executive Compensation, Amount Ivanpah Ivanpah [Member] Ivanpah [Member] Current Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Proceeds from issuance of long-term debt Proceeds from Issuance of Senior Long-Term Debt Current taxes payable Accrued Income Taxes, Current Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] California property tax indemnity Guarantor Obligations, Current Carrying Value Nature of Operation, Product Information, Concentration of Risk [Table] Nature of Operation, Product Information, Concentration of Risk [Table] Schedule of Estimated Amortization of Intangible Assets for Next Five Years Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Pension and other post retirement benefit obligations Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Prepayments and other current assets Prepaid Expense and Other Assets, Current Units Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Contracts added from Texas Generation Portfolio acquisition Fair Value, Net Derivative Asset (Liability) Measured On Recurring Basis, Unobservable Inputs Reconciliation, Acquisition Fair Value, Net Derivative Asset (Liability) Measured On Recurring Basis, Unobservable Inputs Reconciliation, Acquisition Total other assets Regulated Entity, Other Assets, Noncurrent Income tax expense/(benefit) Income tax expense (benefit) Income tax expense/(benefit) Income Tax Expense (Benefit) Receivables Facility Receivables Facility [Member] Receivables Facility Basis spread on variable rate (as a percent) Debt Instrument, Basis Spread on Variable Rate Emission Allowances Emission Allowances Emission Allowances [Member] An asset acquired in a business combination representing an entity's emission allowances. Over 5 Years Guarantee Maturity, Greater than Five Years Maximum potential amount of future payments that the guarantor could be required to make after five years of the balance sheet date under the guarantee. Units Share-Based Compensation Arrangement By Share-Based Payment Award, Equity Instruments Other Than Options, Vested Number [Roll Forward] Share-Based Compensation Arrangement By Share-Based Payment Award, Equity Instruments Other Than Options, Vested Number [Roll Forward] Company's contributions to 401(k) plans Defined Contribution Plans [Abstract] Defined Contribution Plans Document Information [Line Items] Document Information [Line Items] Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Net purchases of emissions allowances Payments For Proceeds From Intangible Assets Payments For Proceeds From Intangible Assets Discontinued Operations and Disposal Groups [Abstract] Discontinued Operations and Disposal Groups [Abstract] Senior Note Redemptions Debt Instrument Redemption [Table Text Block] Guarantor Obligation [Table] Guarantor Obligation [Table] Airtron Airtron [Member] Airtron Commodity contracts - long-term Commodity Contract Non Current [Member] The noncurrent portion of a derivative instrument whose primary underlying risk is tied to commodity prices. Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Income tax valuation allowance, deducted from deferred tax assets SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] Changes in current and deferred income taxes and liability for uncertain tax benefits Increase (Decrease) in Income Taxes Equity, Class of Treasury Stock [Line Items] Equity, Class of Treasury Stock [Line Items] Equity, Class of Treasury Stock [Line Items] Dividends payable quarterly (in usd per share) Dividends Payable, Amount Per Share Cash consideration (inclusive of preliminary working capital and certain other adjustments of $479 million) Payments to Acquire Businesses, Including Working Capital Adjustments, Gross Payments to Acquire Businesses, Including Working Capital Adjustments, Gross Acquisitions and Dispositions Mergers, Acquisitions and Dispositions Disclosures [Text Block] Accelerated share repurchases, agreement amount Accelerated Share Repurchases, Agreement Amount Accelerated Share Repurchases, Agreement Amount Derivative, Other Assets Derivative, Other Assets [Member] Derivative, Other Assets All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Redemption percentage Redemption Percentage Debt Instrument, Redemption Price, Percentage Accrued expenses and other current liabilities Total accrued expenses and other current liabilities Accrued Liabilities, Current U.S. Federal net operating loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards, Domestic Less: Cumulative dividends attributable to Series A Preferred Stock Less: Cumulative dividends attributable to Series A Preferred Stock Preferred Stock Dividends, Income Statement Impact Class of Treasury Stock [Table] Class of Treasury Stock [Table] Class of Treasury Stock [Table] Deferred tax liabilities: Deferred Tax Liabilities, Gross [Abstract] Non-vested at beginning of period (in shares) Non-vested at end of period (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Schedule of Performance Benchmarks Schedule of Performance Benchmarks [Table Text Block] Tabular disclosure of the major categories of plan assets and their related performance benchmark. Eligible compensation withholding, minimum, percentage Employee Stock Purchase Plan, Minimum Percentage of Compensation Eligible Employee Stock Purchase Plan, Minimum Percentage of Compensation Eligible Number of company's retail suppliers notified Number Of Company's Retail Suppliers Notified Number Of Company's Retail Suppliers Notified Foreign net operating loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards, Foreign Transmission and distribution charges not yet billed Cost of Services Energy Services Unbilled The estimated transmission and distribution charges not yet billed by the transmission and distribution utilities for the period. Cash provided/(used) by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Amounts recognized in balance sheet Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract] Effective Income Tax Rate Reconciliation [Table] Effective Income Tax Rate Reconciliation [Table] Equity Method Investments and Joint Ventures [Abstract] Equity Method Investments and Joint Ventures [Abstract] Retirement of treasury stock Carrying value of treasury shares retired Treasury Stock, Retired, Cost Method, Amount Proceeds from the sale of nuclear decommissioning trust fund securities Proceeds from Sale of Debt Securities, Available-for-Sale Depreciable lives (in years) Property, Plant and Equipment, Useful Life Subsequent Event Subsequent Event [Member] Settlement loss Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement Gain (Loss), before Tax Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement Gain (Loss), before Tax Investments Accounted for by the Equity Method Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Income Tax Paid, Foreign, after Refund Received [Abstract] Income Tax Paid, Foreign, after Refund Received [Abstract] Senior Secured First Lien Notes, due 2030 4.734% Senior Secured First Lien Notes Due 2030 [Member] 4.734% Senior Secured First Lien Notes Due 2030 Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Depreciation of property, plant and equipment Depreciation Depreciation Derivative liability Derivative Liability, Measurement Input Derivative liabilities Derivative Liabilities Derivative liabilities Derivative Liability, Subject to Master Netting Arrangement, before Offset Aon Hewitt above median yield curve discount rate (in years) Aon Hewitt Above Median Yield Curve Discount Rate Years Aon Hewitt Above Median Yield Curve Discount Rate Years Texas Generation Portfolio Texas Generation Portfolio [Member] Texas Generation Portfolio Equity Components [Axis] Equity Components [Axis] Equity Components [Axis] Property, Plant and Equipment Property, Plant and Equipment [Line Items] Sublease income Sublease Income Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Asset Impairments Impaired Long-Lived Assets Held and Used [Line Items] Operating Costs and Expenses Operating Costs and Expenses [Abstract] Discounts Total discounts Debt Instrument, Unamortized Discount (Premium), Net Senior Notes, due 2031 3.625% Senior Unsecured Notes Due 2031 [Member] 3.625% Senior Unsecured Notes Due 2031 Operating revenue Sales [Member] Fort Bend County, tax exempt bonds, due 2042 Fort Bend County, tax exempt bonds, due 2042 [Member] Fort Bend County, tax exempt bonds, due 2042 [Member] Marketing and Advertising Costs Advertising Cost [Policy Text Block] Entity Address, State or Province Entity Address, State or Province Financing cash flows from finance leases Finance Lease, Principal Payments Antidilutive Security, Excluded EPS Calculation [Table] Antidilutive Security, Excluded EPS Calculation [Table] 2029 Defined Benefit Plan, Expected Future Benefit Payment, Year Four Capacity Revenue Capacity revenue Capacity Revenue [Member] Capacity Revenue [Member] Total current liabilities Current liabilities Liabilities, Current Acquisition-related transaction and integration costs Business Combination Acquisition and Integration Costs Business Combination Acquisition and Integration Costs Inventory obsolescence Deferred Tax Assets, Inventory Individual: Individual [Axis] Company contributions to defined contribution plans Defined Contribution Plan, Cost Income Tax Jurisdiction [Domain] Income Tax Jurisdiction [Domain] West/Other West and Other Segment [Member] West and Other Segment Working capital adjustments Working Capital Adjustments,, Sale of Business Working Capital Adjustments,, Sale of Business Right-of-use assets obtained in exchange for new finance lease liabilities Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Payments of dividends to preferred and common stockholders Payments of Ordinary Dividends, Common Stock Document Annual Report Document Annual Report Property, Plant & Equipment Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service Acquisition, shares outstanding (in shares) Business Acquisition, Shares Outstanding Business Acquisition, Shares Outstanding Number of states challenging the EPA's rule Number Of States Challenging The Environmental Protection Agency's Mercury And Air Toxics Standards Number Of States Challenging The Environmental Protection Agency's Mercury And Air Toxics Standards Payments for legal settlements accrued interest Payment For Legal Settlement, Accrued Interest Payment For Legal Settlement, Accrued Interest Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Repayment of debt Repayments of Long-Term Debt Entity Interactive Data Current Entity Interactive Data Current Finance lease cost Finance Lease, Cost Finance Lease, Cost October 15, 2031 to October 14, 2032 Redemption Period From 15 October 2031 to 14 October 2032 [Member] Redemption Period From 15 October 2031 to 14 October 2032 Interest crediting rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Interest Crediting Rate Deferred revenues Deferred Tax Assets, Deferred Income Funded status at December 31 — excess of obligation over assets Defined Benefit Plan, Funded (Unfunded) Status of Plan Retail revenue Products And Services, Retail Revenue [Member] Products And Services, Retail [Member] Contract and Emission Credit Amortization Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Stock compensation Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-Based Payment Arrangement, Amount Minimum Commitments Under Outstanding Agreements Long-Term Purchase Commitment [Table Text Block] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Current portion of long-term debt and finance leases Less current maturities Long-Term Debt and Lease Obligation, Current Lien Category [Axis] Lien Category [Axis] Derivative, nonmonetary notional amount, mass (ton) Derivative, Nonmonetary Notional Amount, Mass Long-Lived Tangible Asset [Axis] Long-Lived Tangible Asset [Axis] Senior Notes, due 2031 3.625% Senior Unsecured Notes Due February 2031 [Member] 3.625% Senior Unsecured Notes Due February 2031 Ownership [Domain] Ownership [Domain] 2030 and thereafter 12 months beginning February 15, 2030 and thereafter [Member] 12 months beginning February 15, 2030 and thereafter Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Balance at Beginning of Period Balance at End of Period SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount Customer repayment terms Finance Provider Loans Issued, Customer Repayment Term Finance Provider Loans Issued, Customer Repayment Term 2027 Defined Benefit Plan, Expected Future Benefit Payment, Year Two Reversal of acquired loss positions related to economic hedges Reversal Previously Recognized, Unrealized Gains (Losses) Acquired as Part of Acquisition Economic Hedges Amount reversed into entity's statement of operations for previously recognized unrealized (gains) losses on settled positions related to acquired economic hedges. Other non-current assets Other Assets, Noncurrent Accrued interest Interest Payable, Current Customer [Domain] Customer [Domain] Entity Central Index Key Entity Central Index Key PEO Name PEO Name Balance as of December 31, 2024 Balance as of December 31, 2025 Asset Retirement Obligation Cumulative translation adjustment Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Annual Payments Based on the Maturities of NRG's Debt Schedule of Maturities of Long-Term Debt [Table Text Block] Revenue Revenues Revenues Net unrealized gains/(losses) on open positions related to economic hedges Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Curtailment expense Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment Fair Value, Balance Sheet Grouping, Financial Statement Captions Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Land and improvements Land and Land Improvements [Member] Natural Gas Contracts Natural Gas Contract [Member] Natural Gas Contract Other Comprehensive Income/(Loss), net of tax Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Defined Benefit Plan [Table] Defined Benefit Plan [Table] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Gross Receipts and Sales Taxes Gross Receipts and Sales Taxes [Policy Text Block] Describes an entity's accounting policy for gross receipts and sales taxes, which may include its accounting policies, disclosure of the amount recognized in consolidated statement of operations, and method of recognition. Share-based Payment Arrangement, Tranche One Share-Based Payment Arrangement, Tranche One [Member] Excess executive compensation Effective Income Tax Rate Reconciliation Nondeductible Expense Excess Executive Compensation, Percentage Effective Income Tax Rate Reconciliation Nondeductible Expense Excess Executive Compensation, Percentage SOFR, Floor Secured Overnight Financing Rate (SOFR), Floor [Member] Secured Overnight Financing Rate (SOFR), Floor Deferred revenue current Contract with Customer, Liability, Current Prepayments and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Senior Notes, due 2034 6.250% Senior Notes Due 2034 [Member] 6.250% Senior Notes Due 2034 Exercise Price Award Exercise Price Coal Energy Related Inventory, Coal Entity Filer Category Entity Filer Category Class of Stock [Domain] Class of Stock [Domain] Derivative, nonmonetary notional amount, energy measure in (millions of btu) and (megawatt hours) Derivative, Nonmonetary Notional Amount, Energy Measure Benefit payments Defined Benefit Plan, Benefit Obligation, Benefits Paid Effective income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Subsequent Event Type [Axis] Subsequent Event Type [Axis] Long Long [Member] Number of power generating facilities acquired Acquisition, Number Of Power Generating Facilities Acquired Acquisition, Number Of Power Generating Facilities Acquired Non Recourse Debt Non Recourse Debt [Member] Represents the non-recourse debt. Proceeds from sale Disposal Group, Including Discontinued Operation, Consideration Target allocations Defined Benefit Plan, Plan Assets, Allocations [Abstract] Senior Secured Bridge Facility Senior Secured Bridge Facility [Member] Senior Secured Bridge Facility 2028 Finite-Lived Intangible Asset, Expected Amortization, Year Three Vesting [Domain] Vesting [Domain] NRG's net deferred tax position Deferred Tax Assets, Net [Abstract] Balance at beginning of period Balance at end of period Finite-Lived Intangible Assets, Gross Foreign exchange contracts - current Foreign Exchange Contract Current [Member] Foreign Exchange Contract Current Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] States where entity is located Number of States in which Entity Operates Entity Address, Address Line One Entity Address, Address Line One Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] Conversion of Convertible Senior Notes (in shares) Stock Issued During Period, Shares, Conversion of Convertible Securities Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract] Ownership [Axis] Ownership [Axis] Accounting for Derivative Instruments and Hedging Activities Derivative Instruments and Hedging Activities Disclosure [Text Block] Amortization of unrecognized prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Cash paid to acquire business excluding working capital adjustments Payments To Acquire Business , Excluding Working Capital Adjustments, Gross Payments To Acquire Business , Excluding Working Capital Adjustments, Gross Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Fair Value as of Grant Date Award Grant Date Fair Value Accounts receivable, net - Accounted for under topics other than ASC 606 Non ASC 606 [Member] Non ASC 606 Counterparty Risk by Institution [Axis] Counterparty Risk by Institution [Axis] The counter party risk exposure by institutions involved. November 1, 2029 to October 31, 2030 November 1, 2029 to October 31, 2030 [Member] November 1, 2029 to October 31, 2030 Schedule of Interest Expense, Convertible Senior Notes Schedule of Debt Instrument, Interest Expense [Table Text Block] Schedule of Debt Instrument, Interest Expense Operating loss carryforwards Operating Loss Carryforwards Changes in prior year unrecognized tax benefit Effective Income Tax Rate Reconciliation, Tax Contingency, Amount Total Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] Schedule of Tax Exempt Bonds Schedule of Long-Term Debt Instruments [Table Text Block] Mark-to-market for economic hedging activities Total unrealized mark-to-market (losses)/gains for economic hedging activities Unrealized Gain (Loss) on Derivatives, Mark To Market, Economic Hedging Activities Unrealized Gain (Loss) on Derivatives, Mark To Market, Economic Hedging Activities Amortization of nuclear fuel Amortization of Nuclear Fuel The current period expense charged against earnings for the periodic recognition of the entity's ownership in nuclear fuel based on units of production over the estimated useful life. As a noncash (income) expense, this element is added back to net income when calculating cash provided by (used in) operations using the indirect method. Incremental shares attributable to the issuance of equity compensation (treasury stock method) (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Counterparty credit risk exposure to certain counterparties, threshold (as a percent) Counterparty Credit Risk Exposure, Percentage Threshold Represents the threshold percentage for disclosure of counterparty credit exposure. Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Customer, short-term financing term Contract With Customer, Customer, Short-term Financing Term Contract With Customer, Customer, Short-term Financing Term Total operating costs and expenses Costs and Expenses Unrecognized Total Cost Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Forfeited (in shares) Forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Fuel oil Energy Related Inventory, Petroleum Related Party Transaction [Line Items] Related Party Transaction [Line Items] Equity Awards Pre-combination Service Equity Awards Pre-combination Service [Member] Equity Awards Pre-combination Service Derivative asset, NPNS Derivative Asset, Normal Purchase Normal Sale Scope Election Derivative Asset, Normal Purchase Normal Sale Scope Election Schedule of Significant Unobservable Inputs used in Developing Fair Value of Level 3 Positions Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Counterparty Risk by Investment Grade [Domain] Counterparty Risk by Investment Grade [Domain] Represents the counter party risk exposure by investment grades. Counterparty Name [Domain] Counterparty Name [Domain] 2027 Lessee, Operating Lease, Liability, to be Paid, Year Two Guarantees Guarantees [Text Block] Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] Accrued RECs Accrued Liabilities, RECs, Current Accrued Liabilities, RECs, Current Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration] Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration] Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount 2028 Defined Benefit Plan, Expected Future Benefit Payment, Year Three Amortization of net actuarial (gain)/loss Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Total Cash Consideration Payments to Acquire Businesses, Gross Non-PEO NEO Non-PEO NEO [Member] Letter of credit Letters of Credit Outstanding, Amount Shares reissuance for ESPP Stock Issued During Period, Value, Employee Stock Purchase Plan Payments for acquisitions of businesses and assets, net of cash acquired Payments To Acquire Assets And Businesses, Net Of Cash Acquired Payments To Acquire Assets And Businesses, Net Of Cash Acquired Position [Domain] Position [Domain] Retail Energy Customer Retail Energy Customer [Member] Retail Energy Customer Preferred stock, dividend rate (as percent) Preferred Stock, Dividend Rate, Percentage Other intangible assets, net Other Intangible Assets [Member] Undistributed Earnings by Equity Investment Schedule of Equity Method Investments, Undistributed Earnings [Table Text Block] Disclosure of details relating to undistributed earnings by equity method investments. Award Type [Domain] Equity Award [Domain] Award Type [Domain] Payments for debt extinguishment costs Payment for Debt Extinguishment or Debt Prepayment Cost 2026 Lessee, Operating Lease, Liability, to be Paid, Year One Equity Awards Adjustments Equity Awards Adjustments [Member] Advertising expense Advertising Expense Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Reversal of previously recognized unrealized losses/(gains) on settled positions related to trading activity Reversal Previously Unrecognized, Unrealized Gains (Losses) Settled Positions Trading Activity Amount reversed into entity's statement of operations for previously recognized unrealized (gains) losses on settled positions related to trading activities. Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Jointly Owned Plant Jointly Owned Plants [Text Block] Describes that the entity has a proportionate interest in a jointly owned plant. Should include a table showing separately for each interest the amount of plant in service; the accumulated provision for depreciation; the balance of property plant and equipment; the amount of plant under construction; and the proportionate share. Should include statements that the amounts represent the entity's share in each joint plant and that it must provide its own financing. Information concerning two or more generating plants on the same site may be combined. Should state that the entity's share of direct expenses of the joint plants is included in the corresponding operating expenses on its income statement (for example, fuel, maintenance of plant, other operating expense). Benefit Plans and Other Postretirement Benefits Defined Benefit Plan Disclosure [Line Items] Compensation Amount Outstanding Recovery Compensation Amount Thereafter Unrecorded Unconditional Purchase Obligation, to be Paid, after Year Five Deferred Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Foreign exchange contract Foreign exchange Foreign Exchange Contract [Member] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Fair Value Estimate of Fair Value Measurement [Member] Revenue recognized Contract with Customer, Liability, Revenue Recognized Retirement Plan Type [Domain] Retirement Plan Type [Domain] Charged to Costs and Expenses SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense Accounts Receivable, Allowance for Credit Loss Accounts Receivable, Allowance for Credit Loss [Table Text Block] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Other foreign jurisdictions Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent Fair Value, Option, Quantitative Disclosures [Line Items] Fair Value, Option, Quantitative Disclosures [Line Items] Schedule of Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Open market repurchases Capital Allocation Plan, Open Market Repurchases [Member] Capital Allocation Plan, Open Market Repurchases [Member] Revenue Revenues [Abstract] Documents Incorporated by Reference Documents Incorporated by Reference [Text Block] Net Period Benefit Cost/Credit Net Period Benefit Cost/Credit [Member] Net Period Benefit Cost/Credit [Member] NYSE Texas NYSE Texas [Member] NYSE Texas Common stock, annual dividends increase, percentage Common Stock, Annual Dividends Increase (Decrease), Percentage Common Stock, Annual Dividends Increase (Decrease), Percentage Acquisition working capital and other adjustments Business Combination, Consideration, Working Capital And Other Adjustments Business Combination, Consideration, Working Capital And Other Adjustments Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Long-term debt and finance leases Total long-term debt and finance leases Long-Term Debt and Lease Obligation Derivative assets, excluding NPNS elected Derivative Asset, Excluding NPNS Elected, Subject to Master Netting Arrangement, Before Offset Derivative Asset, Excluding NPNS Elected, Subject to Master Netting Arrangement, Before Offset 2026 Long-Term Debt, Maturity, Year One Financial Instruments [Domain] Financial Instruments [Domain] Partial settlement of Capped Call Options (in shares) Settlement of capped call options (in shares) Settlement Or Partial Settlement Of Capped Call Options, Shares Settlement Or Partial Settlement Of Capped Call Options, Shares Total deferred tax liabilities Deferred Tax Liabilities, Gross 2030 Long-Term Debt, Maturity, Year Five Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Other Accounts Receivable, Allowance For Credit Loss, Other Accounts Receivable, Allowance For Credit Loss, Other Other Nondeductible loss on Convertible Senior Notes repurchases Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Amount Convertible Senior Notes, due 2048 2.750 convertible Senior Notes Due 2048 [Member] 2.750 convertible Senior Notes Due 2048 Jointly Owned Plants Disclosure [Abstract] Jointly Owned Plants Disclosure [Abstract] -- None. No documentation exists for this element. -- Inventory Total Inventory Inventory, Net Annuity purchase settlement Defined Benefit Plan, Benefit Obligation, Payment for Settlement Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Minimum Low Minimum [Member] Year Health care cost trend rate reaches ultimate trend rate Year Health care cost trend rate reaches ultimate trend rate Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate Derivative liabilities, NPNS Derivative Liabilities, Normal Purchase Normal Sale Scope Exception Derivative Liabilities, Normal Purchase Normal Sale Scope Exception Company Selected Measure Name Company Selected Measure Name Fair Value Measurement [Domain] Fair Value Measurement [Domain] Vivint Smart Home Flex Pay Cost of Goods and Service [Policy Text Block] Senior Secured First Lien Notes, due 2035 5.407% Senior Secured First Lien Notes due 2035 [Member] 5.407% Senior Secured First Lien Notes due 2035 Asset Retirement Obligations Asset Retirement Obligation Disclosure [Text Block] Long-term Debt and Finance Leases Debt Disclosure [Text Block] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Decreases to fixed assets for accrued capital expenditures Increase (Decrease) Capital Expenditures Incurred but Not yet Paid Increase (Decrease) Capital Expenditures Incurred but Not yet Paid Accounts payable  Accounts Payable, Current Operating cash flows from operating leases Operating Lease, Payments Capitalized contract cost, amortization period Capitalized Contract Cost, Amortization Period Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Net Income/(Loss) Available for Common Stockholders Net Income (Loss) Available to Common Stockholders, Diluted June 15, 2027 and thereafter Redemption Period From June 15, 2027 And Thereafter [Member] Redemption Period From June 15, 2027 And Thereafter Cash paid Cash Paid Repayments of Senior Debt Foreign Current Foreign Tax Expense (Benefit) Senior Secured First Lien Notes, due 2027 2.450% Senior Secured Notes Due 2027 [Member] 2.450% Senior Secured Notes Due 2027 Goodwill [Roll Forward] Goodwill [Roll Forward] Goodwill Deferred Tax Liabilities, Goodwill Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Share-based Payment Arrangement, Tranche Two Share-Based Payment Arrangement, Tranche Two [Member] Senior Notes, due 2029 5.750% Senior Notes Due 2029 [Member] 5.750% Senior Notes Due 2029 Other Assets Other Assets, Noncurrent [Abstract] Weighted average number of common shares outstanding — diluted (in shares) Weighted average number of common shares outstanding — diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Derivative [Table] Derivative [Table] PRSUs Phantom Restricted Stock Units, PRSUs [Member] Phantom Restricted Stock Units, PRSUs Net Amount Derivative Asset, Fair Value, Amount Offset Against Collateral Net Of Derivative Liability, Fair Value, Amount Offset Against Collateral Derivative Asset, Fair Value, Amount Offset Against Collateral Net Of Derivative Liability, Fair Value, Amount Offset Against Collateral Entity Small Business Entity Small Business Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] 2027 12 months beginning February 15, 2027 [Member] 12 months beginning February 15, 2027 Preferred stock, dividend rate, floor Preferred Stock, Dividend Rate, Floor, Percentage Preferred Stock, Dividend Rate, Floor, Percentage Capitalization, Equity [Table] Capitalization, Equity [Table] Preferred stock, shares outstanding (in shares) Preferred shares, outstanding, beginning balance (in shares) Preferred shares, outstanding , ending balance (in shares) Preferred Stock, Shares Outstanding Vivint LTIP Vivint LTIP [Member] Vivint LTIP State Current State and Local Tax Expense (Benefit) Document Transition Report Document Transition Report Derivative instruments - Other assets Business Combination, Recognized Asset Acquired, Other Asset, Noncurrent Total derivative liabilities valued with prices provided by models and other valuation techniques, percentage Derivative Liability, Fair Value Determined Using Valuation Techniques, Percentage Derivative Liability, Fair Value Determined Using Valuation Techniques, Percentage 1-3 Years Guarantee Maturity, Between One to Three Years Maximum potential amount of future payments that the guarantor could be required to make between one to three years of the balance sheet date under the guarantee. Underlying Securities Award Underlying Securities Amount Defined Contribution Plan Contributions Defined Contribution Plan Disclosures [Table Text Block] Equity Component [Domain] Equity Component [Domain] Audit Information [Abstract] Audit Information [Abstract] Audit Information Document Period End Date Document Period End Date Income Taxes Income Tax Disclosure [Text Block] Proceeds from credit facility Proceeds from Lines of Credit Beginning balance Ending balance Accounts Receivable, Allowance for Credit Loss Consumer Financing Program - long-term Consumer Financing Program Noncurrent [Member] Consumer Financing Program Noncurrent Number of gas-fired facilities acquired Business Combination, Number Of Gas-Fired Facilities Acquired Business Combination, Number Of Gas-Fired Facilities Acquired Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Collateral required contracts with credit rating contingent features in a net liability position Derivative, Net Liability Position, Aggregate Fair Value Derivative liabilities: Derivative Liability, Subject to Master Netting Arrangement, before Offset of Collateral [Abstract] Short-term lease cost Short-Term Lease, Cost Deferred gains/losses on NPNS contracts - current Derivative Contract-NPNS Current [Member] Derivative Contract-NPNS Current Net Amount Derivative Asset, Including Not Subject to Master Netting Arrangement, after Offset and Deduction New Unsecured Notes New Unsecured Notes [Member] New Unsecured Notes Total Stockholders' Equity Beginning balance Ending balance Equity, Including Portion Attributable to Noncontrolling Interest Average price per share (in usd shares) Shares Acquired, Average Cost Per Share July 15, 2026 and thereafter Redemption Period July 15, 2026 And Thereafter [Member] Redemption Period July 15, 2026 And Thereafter 3-5 Years Guarantee Maturity, Between Three to Five Years Maximum potential amount of future payments that the guarantor could be required to make between three to five years of the balance sheet date under the guarantee. Document Type Document Type Capital Allocation Plan [Domain] Capital Allocation Plan [Domain] Explains details pertaining to the different capital allocation plans. Acquisitions Asset Retirement Obligations, Acquisitions Asset Retirement Obligations, Acquisitions Level 3 Fair Value, Inputs, Level 3 [Member] Income/(Loss) Per Share Earnings Per Share [Text Block] Name Outstanding Recovery, Individual Name Loss Contingencies [Table] Loss Contingencies [Table] Asset Impairments Asset Impairment Charges [Text Block] Hardware and office equipment and furnishings Office Equipment [Member] Product and Service [Axis] Product and Service [Axis] City of Texas City, tax exempt bonds, due 2045 Fort Bend County, tax exempt bonds, due 2045 [Member] Fort Bend County, tax exempt bonds, due 2045 [Member] Variable lease cost Variable Lease, Cost Revenue from contract with customer Revenue from Contract with Customer, Excluding Assessed Tax Litigation Status [Domain] Litigation Status [Domain] Accumulated depreciation Public Utilities, Property, Plant and Equipment, Accumulated Depreciation Proceeds from insurance recoveries for property, plant and equipment, net Proceeds From Insurance Recoveries For Property, Plant And Equipment, Net Proceeds From Insurance Recoveries For Property, Plant And Equipment, Net Summary of Significant Accounting Policies [Line Items] Summary of Significant Accounting Policies [Line Items] Summary of Significant Accounting Policies [Line Items] Company's exposure before collateral expected to roll off (as a percent) Counterparty Credit Risk Exposure Percentage Of Credit Risk Roll Off The percentage of net counterparty credit exposure that rolls-off by the end of 2012. Total current assets Assets, Current 4.000% Indian River Power 2020 Tax Exempt Bonds Due 2045 4.000% Indian River Power 2020 Tax Exempt Bonds Due 2045 [Member] 4.000% Indian River Power 2020 Tax Exempt Bonds Due 2045 Acquisition of businesses Finite-Lived Intangible Assets Acquired Range [Axis] Statistical Measurement [Axis] LS Power Portfolio LS Power Portfolio [Member] LS Power Portfolio Payment for settlement of capped call options Payments for (Proceeds from) Hedge, Financing Activities Stock repurchase program, authorized amount Share Repurchase Program, Authorized, Amount Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Disposal Group Name [Axis] Disposal Group Name [Axis] Equivalent shares purchased in lieu of tax withholdings Minimum tax withholdings Payment, Tax Withholding, Share-Based Payment Arrangement Home Home Customer [Member] Home Customer Eligible compensation withholding, maximum, percentage Employee Stock Purchase Plan, Maximum Percentage of Compensation Eligible This element represents the maximum percentage of eligible compensation, which can be withheld by employees to purchase shares of the entity. Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Net Income/(Loss) Available for Common Stockholders Net Income (Loss) Available to Common Stockholders, Basic Share Repurchase Program [Domain] Share Repurchase Program [Domain] Current Liabilities Liabilities, Current [Abstract] October 15, 2028 to October 14, 2029 Redemption Period From 15 October 2028 to 14 October 2029 [Member] Redemption Period From 15 October 2028 to 14 October 2029 Utilities, energy merchants, marketers and other Utilities Energy Merchants Marketers And Other [Member] Represents the information pertaining to utilities, energy, merchants, marketers and other. Total guarantees Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Derivative, Current Liabilities Derivative, Current Liabilities [Member] Derivative, Current Liabilities Acquisition, share price (in usd per share) Business Combination, Price Per Share Borrowings outstanding Long-Term Line of Credit Level 1 Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Net loss/(gain) on sale of assets and disposal of assets Gain (Loss) on Disposition of Assets Changes in collateral deposits in support of risk management activities Changes in Collateral Deposits Supporting Energy Risk Management Activities Changes in cash collateral deposits for contracts supporting energy risk management activities. Pre-Capitalized Trust Securities Redeemable July 2028 Pre-Capitalized Trust Securities Redeemable July 2028 [Member] Pre-Capitalized Trust Securities Redeemable July 2028 NRG Indian River Power 2020, tax exempt bonds, due 2040 1.250% Indian River Power2020 Tax Exempt Bonds Due 2040 [Member] 1.250% Indian River Power2020 Tax Exempt Bonds Due 2040 Related Party Transaction [Table] Related Party Transaction [Table] Income/(Loss) per weighted average common share — diluted (in usd per share) Earnings Per Share, Diluted Accounts receivable, net Accounts Receivable, after Allowance for Credit Loss, Current Schedule of Assumptions Used to Calculate Benefit Expense Defined Benefit Plan, Assumptions [Table Text Block] Excise tax accrued on share repurchases Share Repurchase Program, Excise Tax, Payable Series A Preferred Stock dividends Preferred stock, dividends Dividends, Preferred Stock, Cash Gross Receipts and Sales Taxes Gross Receipts and Sales Taxes [Abstract] Treasury stock, shares (in shares) Beginning balance, treasury shares (in shares) Ending balance, treasury shares (in shares) Treasury Stock, Common, Shares CPI Security Systems, Inc. CPI Security Systems, Inc. [Member] CPI Security Systems, Inc. U.S. state and local: Income Tax Paid, State and Local, after Refund Received Foreign exchange contracts - long-term Foreign Exchange Contract Noncurrent [Member] Foreign Exchange Contract Noncurrent Convertible Senior Notes Senior Debt Obligations [Member] Consolidation Items [Domain] Consolidation Items [Domain] Auditor Location Auditor Location Cash Collateral (Held) / Posted Derivative, Collateral, Obligation to Return Cash Net Of Derivative, Collateral, Right to Reclaim Cash Derivative, Collateral, Obligation to Return Cash Net Of Derivative, Collateral, Right to Reclaim Cash Investments Accounted for by the Equity Method and Variable Interest Entities Equity Method Investments and Joint Ventures Disclosure [Text Block] Funds deposited by counterparties Funds Deposited by Counterparties The amount of cash collateral received from hedge counterparties in support of energy risk management activities for which there is an offsetting liability within current liabilities. These amounts are segregated into separate accounts that are not contractually restricted but, based on the entity's intention, are not available for the payment of the entity's general corporate obligations. Depending on market fluctuations and the settlement of the underlying contracts, the entity will refund this collateral to the counterparties pursuant to the terms and conditions of the underlying trades. Amortization of customer acquisition costs Amortization of Deferred Sales Commissions Actuarial gain (loss) Actuarial loss/(gain) Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Vivint Smart Home, Inc. common shares outstanding as of March 10, 2023 of 216,901,639 at $12.00 per share Payments to Acquire Businesses, Equity Interest In Acquiree, Outstanding Shares Payments to Acquire Businesses, Equity Interest In Acquiree, Outstanding Shares Domestic Federal Tax Authority Domestic Tax Jurisdiction [Member] Common/collective trust investment — non-core assets Emerging Market Equities [Member] Emerging Market Equities [Member] Employee and retiree contributions Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant Balance Sheet Components Accounts Payable and Accrued Liabilities Disclosure [Text Block] Total gains/(losses) realized/unrealized included in earnings Total losses included in earnings Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings Less present value adjustment Lessee, Operating Lease, Liability, Undiscounted Excess Amount Commodity Commodity [Member] Cash collateral paid in support of energy risk management activities Derivative Liability, Not Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Not Offset Derivative Liability, Not Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Not Offset Remaining defendants Loss Contingency, Number of Defendants Total Income Taxes Paid, Net Other Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent Environmental Matters Environmental Loss Contingency Disclosure [Text Block] November 1, 2031 and thereafter November 1, 2031 and thereafter [Member] November 1, 2031 and thereafter Valuation Technique Option Model Valuation Technique Option Model [Member] Valuation Technique Option Model Senior Notes, due 2033 6.000% Senior Notes Due 2033 [Member] 6.000% Senior Notes Due 2033 2027 Finite-Lived Intangible Asset, Expected Amortization, Year Two Summary of NRG's net deferred tax position Schedule of Deferred Tax Component [Table Text Block] Disclosure of the current and non-current portion of net deferred tax assets and liabilities. Redemption Period Prior to October 15, 2030 Redemption Period Prior to October 15, 2030 [Member] Redemption Period Prior to October 15, 2030 Redemption Percentage (If Sustainability Performance Target has been satisfied and confirmed by External Verifier) Debt Instrument, Redemption Price, Percentage, Sustainability Performance Target Satisfied and Confirmed by External Verifier Debt Instrument, Redemption Price, Percentage, Sustainability Performance Target Satisfied and Confirmed by External Verifier Loan disbursements Borrowings outstanding Long-Term Debt, Gross Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Accrued compensation and employee benefits Employee-related Liabilities, Current Property, Plant and Equipment Property, Plant and Equipment Disclosure [Text Block] Total undiscounted lease payments Lessee, Operating Lease, Liability, to be Paid Collateral Prepayment Rates Measurement Input, Collateral Prepayment Rate [Member] Measurement Input, Collateral Prepayment Rate Net unrealized gains on open positions related to trading activity Derivative Unrealized Gains on Open Positions Related to Trading Activity, Net This element represents the amount recorded in the entity's statement of operations for net unrealized gains (losses) on open positions related to trading activities. Total recognized in OCI Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax Trade Names Trade Names [Member] Punitive damages awarded Loss Contingency, Punitive Damages Awarded, Value Loss Contingency, Punitive Damages Awarded, Value Less: Realized and unrealized ASC 815 revenue Gain (Loss) on Derivative Instruments, Net, Pretax Corporate/Eliminations Eliminations Intersegment Eliminations [Member] Expiration Date Trading Arrangement Expiration Date Schedule of Amounts Recognized in OCI Not Yet Recognized as Components of Net Periodic Benefit Costs Schedule of Net Periodic Benefit Cost Not yet Recognized [Table Text Block] STP South Texas Project Electric Generating Station [Member] South Texas Project Electric Generating Station 2030 Finite-Lived Intangible Asset, Expected Amortization, Year Five Product Information [Line Items] Product Information [Line Items] Summary NRG's Equity Method Investments Equity Method Investments [Table Text Block] Undistributed earnings from equity investment Retained Earnings, Undistributed Earnings from Equity Method Investees Derivative Instruments Derivative Asset Fair Value Gross Liability Net Of Derivative Liability Fair Value Gross Asset Derivative Asset Fair Value Gross Liability Net Of Derivative Liability Fair Value Gross Asset 2026 Unrecorded Unconditional Purchase Obligation, to be Paid, Year One Interest Interest [Member] Details pertaining to interest rate swaps which are considered a derivative commodity. Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Accounts receivable - trade Increase (Decrease) in Accounts Receivable Inventory Inventory, Policy [Policy Text Block] Series A Preferred Stock Series A Preferred Stock [Member] Entity Current Reporting Status Entity Current Reporting Status July 15, 2025 to July 14, 2026 Redemption Period July 15, 2025 to July 14, 2026 [Member] Redemption Period July 15, 2025 to July 14, 2026 Derivative [Line Items] Derivative [Line Items] Other Other Finite Lived Intangible Assets [Member] All other assets acquired in a business combination not specified elsewhere in the taxonomy. Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Consolidated Entities [Domain] Consolidated Entities [Domain] Tax at federal statutory tax rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Gain on sale of land and related generation assets Gain (Loss) on Disposition of Property Plant Equipment Non-Investment grade/Non-Rated External Credit Rating Not Rated [Member] Represents underlying referenced credits or entities, with respect to guarantees, for which ratings are not available. Financial Instrument [Axis] Financial Instrument [Axis] Financial Instrument [Axis] Deferred tax assets: Deferred Tax Assets, Gross [Abstract] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Executive Category: Executive Category [Axis] Vivint Vivint [Member] Vivint Stock compensation Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-Based Payment Arrangement, Percent Other Finite-Lived Intangible Assets, Other Changes This element represents other additions or reductions to finite-lived intangible assets during the period. Number of facilities Number Of Facilities Number Of Facilities SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract] SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract] State and local income taxes, net of federal effect Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Accumulated benefit obligation Defined Benefit Plan, Accumulated Benefit Obligation Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Current Fiscal Year End Date Current Fiscal Year End Date Health care trend rate Health care trend rate Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year Technology Technology-Based Intangible Assets [Member] Expected term (in years) Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Share repurchases additional authorized Share Repurchase Program Increase Amount Authorized Share Repurchase Program Increase Amount Authorized Insurance settlement Proceeds from Insurance Settlement, Operating Activities Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Weighted Average Grant-Date Fair Value per Unit Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Number of shares available for grant under plan (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant Marketing Partnerships Marketing Partnerships [Member] Marketing Partnerships [Member] Summary of maximum potential exposure that can be estimated by NRG's guarantees, indemnity, and other contingent liability Schedule of Guarantor Obligations [Table Text Block] Derivative Liabilities Derivative Liability Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Amortization of prior service cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Interest rate contracts Consumer Financing Program Interest Rate Contract [Member] West/Other West, Services and Other Segment [Member] West, Services and Other Segment Assets and Liabilities Measured and Recorded at Fair Value Measured on a Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Issuance of Series A Preferred Stock Stock Issued During Period, Value, Acquisitions Uncertain tax benefits Balance as of January 1 Uncertain tax benefits as of December 31 Unrecognized Tax Benefits Texas Generation Portfolio Purchase Price Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less) Impairment losses Asset Impairment Charges Including Equity Method Investments Asset Impairment Charges Including Equity Method Investments Antidilutive securities (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Total Unrecorded Unconditional Purchase Obligation Proceeds from issuance of preferred stock, net of fees Proceeds from issuance of preferred stock Proceeds from Issuance of Preferred Stock and Preference Stock Capacity Contracts Capacity Contracts [Member] Capacity Contracts Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] 2027 Long-Term Debt, Maturity, Year Two Regulated Operation, Jointly Owned Utility Plant [Table] Regulated Operation, Jointly Owned Utility Plant [Table] Leases Lessee, Operating Leases [Text Block] Cash provided/(used) by financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Investment grade External Credit Rating, Investment Grade [Member] Measure: Measure [Axis] Number of qualified pension plans Number Of Defined Benefit Plans Number Of Defined Benefit Plans Liability for uncertainty in income taxes, noncurrent Liability for Uncertainty in Income Taxes, Noncurrent Summary of NRG's proportionate ownership interest in the company's jointly-owned facilities Schedule of Jointly Owned Utility Plants [Table Text Block] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Axis] 2027 Unrecorded Unconditional Purchase Obligation, to be Paid, Year Two Generation capacity (in MW) Generation capacity (in MW) Power Generation Capacity, Megawatts The generation capacity of the entity's power generation facilities as of the balance sheet date, expressed in megawatts. Net recognized in net periodic pension (credit)/cost and OCI Defined Benefit Plan, Amount Recognized in Net Periodic Benefit Cost (Credit) and Other Comprehensive (Income) Loss, before Tax Long-Lived Tangible Asset [Domain] Long-Lived Tangible Asset [Domain] Cost of operations (excluding depreciation and amortization shown below) Cost of Goods and Service, Excluding Depreciation, Depletion, and Amortization Disposal Group Classification [Domain] Disposal Group Classification [Domain] Derivative, non-monetary notional amount (in shares) Derivative, Non-monetary Notional Amount, Other Derivative, Non-monetary Notional Amount, Other Total unrealized mark-to-market gains for trading activity Unrealized Gain (Loss) on Derivatives, Mark To Market, Trading Activities Unrealized Gain (Loss) on Derivatives, Mark To Market, Trading Activities Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Operating Expenses Segment, Operating Expenses Segment, Operating Expenses Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Risk free rate Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Entity Tax Identification Number Entity Tax Identification Number Customer and Supply Contracts Customer and Supply Contracts [Member] Customer and Supply Contracts Valuation Technique, Discounted Cash Flow Valuation Technique, Discounted Cash Flow [Member] Schedule of Contract Assets and Liabilities [Table] Schedule Of Contract Assets And Liabilities [Table] Schedule Of Contract Assets And Liabilities [Table] Summary of Financial Information for Consolidated VIEs Schedule of Variable Interest Entities [Table Text Block] Derivative Derivative [Member] Balance sheet Segment Reporting Information, Additional Information [Abstract] Derivative Fair Value Meaurements and Concentration of Credit Risk Fair Value, Concentration of Risk, Financial Statement Captions [Line Items] Restricted Stock Units-Rollover Restricted Stock Units-Rollover [Member] Restricted Stock Units-Rollover Short Short [Member] Purchased Energy and Other Cost of Sales for Customer Operations Cost of Energy for Retail Operations [Abstract] Common stock, shares issued (in shares) Beginning balance, common shares issued (in shares) Ending balance, common shares issued (in shares) Common Stock, Shares, Issued Credit Risk Related Contingent Features [Abstract] Credit Risk Related Contingent Features [Abstract] -- None. No documentation exists for this element. -- Derivative Asset, Statement of Financial Position [Extensible Enumeration] Derivative Asset, Statement of Financial Position [Extensible Enumeration] 2029 Long-Term Debt, Maturity, Year Four Weighted average remaining lease term (in years) Operating Lease, Weighted Average Remaining Lease Term Pre-tax Effects of Economic Hedges That Have Not Been Designated as Cash Flow Hedges, Ineffectiveness on Cash Flow Hedges and Trading Activity on the Company's Statement of Operations Derivatives Not Designated as Hedging Instruments [Table Text Block] Incremental Term Loan B Facility Incremental Term Loan B Facility [Member] Incremental Term Loan B Facility Goodwill and Other Intangibles Goodwill and Intangible Assets Disclosure [Text Block] Number of months beyond which company can not predict the holding of collateral (in months) Period Beyond which Comapny Can Not Predict Holding of Collateral This element represents the period beyond which company can not predict the holding of collateral. Entity Public Float Entity Public Float Schedule of Goodwill Schedule of Goodwill [Table Text Block] Interest expense Interest expense Interest Expense, Nonoperating Trading Arrangement: Trading Arrangement [Axis] Total Shareholder Return Amount Total Shareholder Return Amount Premium percentage of principal amount of note discount factor (as percent) Premium Percentage of Principal of Senior Notes, Discount Factor Percentage above the Treasury rate over the principal amount of the note used as a discount factor in determining the redemption price of Senior Notes prior to maturity. Estimated counterparty credit risk exposure under certain long term agreements, including California tolling agreements, South Central load obligations and solar power purchase agreements for the next 5 years Estimated Counterparty Credit Risk Exposure to Certain Counterparties This element represents the estimated amount of the counterparty credit risk exposure. Loss Contingencies [Line Items] Loss Contingencies [Line Items] Net loss/(gain) Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax Corporate Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] Security Exchange Name Security Exchange Name Jointly Owned Utility Plant [Domain] Jointly Owned Utility Plant [Domain] Foreign: Income Tax Paid, Foreign, after Refund Received Proceeds from sale of, net of working capital adjustments Proceeds From Divestiture Of Businesses, Net Of Working Capital Adjustments Proceeds From Divestiture Of Businesses, Net Of Working Capital Adjustments Total other liabilities Liabilities, Noncurrent Revolving credit facility Credit facility Line of Credit Facility, Maximum Borrowing Capacity Business Combination, Consideration Transferred, Equity Interest, Type [Domain] Business Combination, Consideration Transferred, Equity Interest, Type [Domain] 2031-2035 Defined Benefit Plan, Expected Future Prescription Drug Subsidy Receipt, after Year Five Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] New York State Public Service Commission New York State Public Service Commission [Member] New York State Public Service Commission Shares repurchased (in shares) Stock Repurchased During Period, Shares Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-Lived Intangible Assets, Major Class Name [Domain] Employee Stock Purchase Plan Employee Stock Purchase Plan [Member] Employee Stock Purchase Plan Employee and retiree contributions Defined Benefit Plan, Plan Assets, Contributions by Plan Participant Discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Capped call, convertible debt, conversion, premium Capped Call, Convertible Debt, Conversion, Premium Capped Call, Convertible Debt, Conversion, Premium Debt Instrument Redemption [Table] Debt Instrument Redemption [Table] Other non-current liabilities Liability, Defined Benefit Plan, Noncurrent Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid Offsetting Assets and Liabilities [Line Items] [Line Items] for Offsetting Assets and Liabilities [Table] Proceeds from sales of assets, net of cash disposed Proceeds from Sale of Other Productive Assets Statement [Line Items] Statement [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Cash and cash equivalents Cash and Cash Equivalent Additions Oil and Gas, Cost Incurred, Asset Retirement Obligation Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] Settlement of Capped Call Options Adjustments to Additional Paid in Capital, Settlement Of Capped Call Options Adjustments to Additional Paid in Capital, Settlement Of Capped Call Options Common Stock Common Stock [Member] Vested (in shares) Converted to Common Stock (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Intangible Assets Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block] Net Increase/(Decrease) in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Derivative instruments - Current assets Business Combination, Recognized Asset Acquired, Asset, Current Letters of credit and surety bonds, maximum expiration period (in years) Guarantee Obligations, Letters of Credit and Surety Bonds, Maximum Expiration Period This element represents the maximum expiration period of letters of credit and surety bonds for entity is contingently obliged. Dividends paid per share (in usd per share) Dividends paid per share (in usd per share) Common Stock, Dividends, Per Share, Cash Paid Guarantor Obligations Guarantor Obligations [Line Items] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Working capital and other adjustments, net Divestiture Of Business, Working Capital And Other Adjustments, Net Divestiture Of Business Working Capital And Other Adjustments Range [Domain] Statistical Measurement [Domain] Property, plant and equipment Business Combination, Recognized Asset Acquired, Property, Plant, and Equipment Business Combination [Abstract] Thereafter Lessee, Operating Lease, Liability, to be Paid, after Year Five Net Notional Volume Buy/(Sell) of NRG's Open Derivative Transactions Broken Out by Commodity Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Capitalized Contract Cost [Axis] Capitalized Contract Cost [Axis] Underlying Asset Class [Axis] Underlying Asset Class [Axis] Settled Litigation Settled Litigation [Member] Vivint 5.750% Senior Secured Notes, due 2029 Vivint 5.750% Senior Secured Notes due 2029 [Member] Vivint 5.750% Senior Secured Notes due 2029 Auction Prices ($ per MWh) Measurement Input, Auction Price [Member] Measurement Input, Auction Price Accumulated Depreciation Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Interest Rate Swap Interest Rate Swap [Member] Valuation Approach and Technique [Domain] Valuation Approach and Technique [Domain] Debt Issuance Costs Debt, Policy [Policy Text Block] Asset Impairments Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block] Equity in earnings of unconsolidated affiliates Equity in earnings of unconsolidated affiliates Income (Loss) from Equity Method Investments Lessor Accounting Leases [Abstract] Basic income/(loss) per share: Earnings Per Share, Basic [Abstract] Senior Notes, due 2028 Senior Notes due 2028 [Member] Senior Notes due 2028 Unbilled revenues (included within Accounts receivable, net - Contracts with customers) Unbilled Contracts Receivable Acquisition, shares issued (in shares) Business Combination, Consideration Transferred, Equity Interest, Share Issued, Number of Shares Accounts payable Increase (Decrease) in Accounts Payable Operating leases: Operating Leases [Abstract] Operating Leases Shares purchased in lieu of tax withholding on equity compensation issuances Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation Deferred gains/losses on NPNS contracts - long-term Derivative Contract-NPNS , Long-Term [Member] Derivative Contract-NPNS , Long-Term Transfers into Level 3 Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 3 Share-based Compensation [Abstract] Share-Based Payment Arrangement, Noncash Expense [Abstract] Common/collective trust investment — fixed income Common Trust Investment Fixed Income Securities [Member] Represents the investments in common/collective trust in fixed income securities. Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Fed Funds Rate Fed Funds Effective Rate Overnight Index Swap Rate [Member] Income/(Loss) per Weighted Average Common Share - Basic (in usd per share) Income /(Loss)/per weighted average common share — basic (in usd per share) Earnings Per Share, Basic Power Options Power Options [Member] Power Options Liabilities Liabilities, Fair Value Disclosure [Abstract] Long-term incentive plans (in shares) Common Stock, Capital Shares Reserved for Future Issuance Additional collateral required Additional Collateral, Aggregate Fair Value Changes in prior year unrecognized tax benefit Effective Income Tax Rate Reconciliation, Tax Contingency, Percent Total deferred tax assets Deferred Tax Assets, Gross Discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Other comprehensive income/(loss) Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Inventory Disclosure [Abstract] Inventory Disclosure [Abstract] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Axis] Estimated future fixed fee performance obligation Revenue, Remaining Performance Obligation, Amount Measurement Input Type [Domain] Measurement Input Type [Domain] Revisions in estimates for current obligations Asset Retirement Obligation, Revision of Estimate Capitalized Contract Cost [Domain] Capitalized Contract Cost [Domain] Accounts receivable, net - Affiliate Affiliated Entity [Member] Impaired Long-Lived Asset, Held and Used [Table] Impaired Long-Lived Asset, Held and Used [Table] Derivative instruments Derivative Instruments and Hedges, Assets Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Coal Coal [Member] Details pertaining to the coal, which is considered as a derivative commodity. Excise tax paid Share Repurchase Program, Excise Tax Variable Interest Entity, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Compensation Expense Share-Based Payment Arrangement, Expense February 15, 2029 and thereafter Redemption Period February 15, 2029 and thereafter [Member] Redemption Period February 15, 2029 and thereafter Hedging Designation [Domain] Hedging Designation [Domain] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Current Assets Assets, Current [Abstract] Fair Value Measurement Inputs and Valuation Techniques [Abstract Fair Value Measurement Inputs and Valuation Techniques [Abstract] Total Liabilities and Stockholders' Equity Liabilities and Equity Foreign Currency Translation and Transaction Gains and Losses Foreign Currency Transactions and Translations Policy [Policy Text Block] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Equity method investments Deferred Tax Liabilities, Investment in Noncontrolled Affiliates Shares issued for the acquisition of the LSP Portfolio (in shares) Stock Issued During Period, Shares, Acquisitions Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statements of cash flows Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Including Discontinued Operation Other Deferred Tax Assets, Other Equity Method Investment [Table] Equity Method Investment [Table] RPSUs Relative Performance Stock Units [Member] Relative Performance Stock Units Capital expenditures Segment, Expenditure, Addition to Long-Lived Assets Guarantees [Abstract] Guarantees [Abstract] Accounting Policies [Abstract] Accounting Policies [Abstract] Schedule of Annual Payments Based on Maturities of Leases Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] Senior Notes, due 2032 3.875% Senior Notes due 2032 [Member] 3.875% Senior Notes due 2032 Treasury Stock Treasury Stock, Common [Member] Vested in period, fair value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Vivint Smart Home Vivint Smart Home Inc. [Member] Vivint Smart Home Inc. Pay vs Performance Disclosure [Line Items] Forward Market Price (perMMBtu) or (per MWh) Measurement Input, Commodity Forward Price [Member] Operating lease liability Operating Lease, Liability Changes in derivative instruments Increase (Decrease) in Derivative Assets and Liabilities Preferred stock, liquidation preference (in usd per share) Preferred Stock, Liquidation Preference Per Share Guarantees by Remaining Maturity, Total Guarantee obligation Guarantee Obligations, Estimated Exposure The estimated amount of future payments the guarantor could be required to make under guarantees, indemnities and other contingent liability obligations. Amortization of right-of-use assets Finance Lease, Right-of-Use Asset, Amortization Capital Allocation Plan [Axis] Capital Allocation Plan [Axis] Explains the different capital allocation plans. Convertible Senior Notes Capped Calls Convertible Senior Notes Capped Calls [Member] Convertible Senior Notes Capped Calls Redemption percentage of principal Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed Other non-current liabilities Other Liabilities, Noncurrent Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Goodwill impairment losses Impairment Goodwill, Impairment Loss Accounts receivable, net and Other current assets Accounts Receivable, after Allowance for Credit Loss, And Other Assets, Current Accounts Receivable, after Allowance for Credit Loss, And Other Assets, Current P-Cap Secured Notes P-Cap Senior Secured First Lien Notes due 2028 [Member] P-Cap Senior Secured First Lien Notes due 2028 Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount Employer contributions Defined Benefit Plan, Plan Assets, Contributions by Employer 2028 Lessee, Operating Lease, Liability, to be Paid, Year Three Under 1 Year Guarantee Maturity, Less than One Year Maximum potential amount of future payments that the guarantor could be required to make within one year of the balance sheet date under the guarantee. Measurement Input Type [Axis] Measurement Input Type [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] Name Measure Name Change in credit reserve Derivative, Increase (Decrease) In Fair Value, Due to Change in Credit Reserve Derivative, Increase (Decrease) In Fair Value, Due to Change in Credit Reserve Domestic and foreign components of income/(loss) before income tax (benefit)/expense Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Capital Allocation Plan Capital Allocation Plan [Member] Capital Allocation Plan [Member] Secured Debt Secured Debt [Member] Reconciliation of Contractual Obligations of Consumer Financing Program Recognized at Fair Value Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Cedar Bayou Unit 4, Baytown, TX Cedar Bayou Unit 4 [Member] This element represents the information pertaining to Cedar Bayou Unit 4, Baytown, TX. Finite-lived Intangible Assets [Roll Forward] Finite-Lived Intangible Assets [Roll Forward] Senior Note Repurchases Schedule of Extinguishment of Debt [Table Text Block] Class of Stock [Line Items] Class of Stock [Line Items] Deferred income taxes Deferred tax liability Deferred Income Tax Liabilities, Net Expected return on plan assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-Term Rate of Return on Plan Assets Payment terms Contract With Customer, Payment Term, Period Contract With Customer, Payment Term, Period Sierra Club Et Al v. Midwest Generation L L C Sierra Club Et Al V. Midwest Generation L L C [Member] Sierra Club Et Al V. Midwest Generation L L C Unsecured Debt Unsecured Debt [Member] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] Income Tax Contingency [Table] Income Tax Contingency [Table] Long-term debt Long-term debt Borrowings outstanding Long-Term Debt Redemption Period Prior to November 1, 2029 Redemption Period Prior to November 1, 2029 [Member] Redemption Period Prior to November 1, 2029 Legal Entity [Axis] Legal Entity [Axis] Total Assets Total assets Assets 2026 Finite-Lived Intangible Asset, Expected Amortization, Year One Vested (in usd per share) Converted to Common Stock (in usd per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Restricted Cash Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Credit Derivatives Contract Type [Axis] Credit Derivatives Contract Type [Axis] Fair Value, Concentration of Risk [Table] Fair Value, Concentration of Risk [Table] Lightning Senior Secured Notes due 2032 Lightning Senior Secured Notes due 2032 [Member] Lightning Senior Secured Notes due 2032 Income Taxes Income Tax, Policy [Policy Text Block] Plan modification, incremental cost, expense recognized Share-Based Payment Arrangement, Plan Modification, Incremental Cost, Expense Recognized, Amount Share-Based Payment Arrangement, Plan Modification, Incremental Cost, Expense Recognized, Amount Company's deferred tax assets and liabilities Components of Deferred Tax Assets and Liabilities [Abstract] Cash Flows from Operating Activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Receivable Type [Axis] Receivable Type [Axis] 2029 12 months beginning February 15, 2029 [Member] 12 months beginning February 15, 2029 Weighted average useful life, years Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life Total deferred tax assets less deferred tax liabilities Deferred tax asset, net (before valuation allowance) Deferred Tax Asset, Net of Deferred Tax Liability (Before Valuation Allowance) Deferred Tax Asset, Net of Deferred Tax Liability (Before Valuation Allowance) Inventory Inventory Disclosure [Text Block] Total value cap, percentage Share-Based Payment Arrangement, Total Value Cap, Limit To Payout, Percentage Share-Based Payment Arrangement, Total Value Cap, Limit To Payout, Percentage Assets Assets, Fair Value Disclosure [Abstract] 2029 Finite-Lived Intangible Asset, Expected Amortization, Year Four Capitalized Contract Cost [Table] Capitalized Contract Cost [Table] Dividends per common share (in usd per share) Common Stock, Dividends, Per Share, Declared Consumer Financing Program Consumer Financing Program [Member] Consumer Financing Program Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Capitalized contract costs Capitalized Contract Cost, Net Right-of-use assets obtained in exchange for new operating lease liabilities Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Lease, Cost [Abstract] Lease, Cost [Abstract] Level 2 Significant Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Document Financial Statement Error Correction [Flag] Document Financial Statement Error Correction [Flag] State and local income taxes, net of federal effect State taxes Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Equity investments in affiliates Equity Method Investments Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Business Combination [Domain] Business Combination [Domain] Gain on sale Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal Related Party Related Party [Member] Lease Term and Discount Rate for leases: Leases, Weighted Average Discount Rate [Abstract] Leases, Weighted Average Discount Rate Contract Cost, Acquisitions Contract Cost, Acquisitions [Member] Contract Cost, Acquisitions Charged to Other Accounts SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Other Account Derivative asset/ liability measurement input Derivative Asset (Liability) Net, Measurement Input Fair value of plan assets for pension and other post retirement benefit Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Income tax provision from continuing operations Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Allowance for credit losses Deferred Tax Asset, Tax Deferred Expense, Reserve and Accrual, Accounts Receivable, Allowance for Credit Loss Plan Name [Axis] Plan Name [Axis] Property, Plant and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Total retail revenue Products And Services, Total Retail [Member] Products And Services, Total Retail [Member] Document Information [Table] Document Information [Table] PEO PEO [Member] Regulatory Matters Regulatory Matters [Text Block] Describes all of the specific regulatory matters that are pending, including the regulatory authorities involved and the potential impacts. Number of class action lawsuits Loss Contingency, Pending Claims, Number Midway-Sunset Cogeneration Company Midway-Sunset Cogeneration Company [Member] Midway-Sunset Cogeneration Company [Member] Intangibles amortization (excluding goodwill) Deferred Tax Liabilities, Intangible Assets 2028 12 months beginning February 15, 2028 [Member] 12 months beginning February 15, 2028 NumberOfReportableSegmentsNotDisclosedFlag NumberOfReportableSegmentsNotDisclosedFlag NumberOfReportableSegmentsNotDisclosedFlag Guarantees and Product Warranties [Abstract] Capped call cap price (in usd per share) Capped Call Options, Cap Price Capped Call Options, Cap Price United States UNITED STATES 6.625% Senior Notes Due 2027 6.625% Senior Notes Due 2027 [Member] 6.625% Senior Notes Due 2027 Changes in state valuation allowances Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount Expected volatility Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate Retained Earnings Retained Earnings [Member] Income Tax Jurisdiction [Axis] Income Tax Jurisdiction [Axis] Derivative revenue Products And Services, Derivative Revenue [Member] Products And Services, Derivative Revenue [Member] Components of Accrued Expenses and Other Current Liabilities Schedule of Accrued Liabilities [Table Text Block] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Share-Based Payment Arrangement [Abstract] Lightning Credit Agreement Lightning Credit Agreement [Member] Lightning Credit Agreement Income Statement Income Statement [Abstract] Derivative Assets Derivative Asset Preferred stock, dividends (in usd per share) Preferred stock, dividends (in usd per share) Preferred Stock, Dividends, Per Share, Cash Paid Texas Texas Segment [Member] Texas Segment Derivative instruments Derivative Liability, Noncurrent Equity securities Investments, Fair Value Disclosure Transaction fees on disposal Disposal Group, Including Discontinued Operation, Disposal Transaction Fees Disposal Group, Including Discontinued Operation, Disposal Transaction Fees Product and Service [Domain] Product and Service [Domain] Transfers out of Level 3 Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3 Contractual interest expense Interest Expense, Debt, Excluding Amortization Asset Retirement Obligation Disclosure [Abstract] Asset Retirement Obligation Disclosure [Abstract] Net Income/(Loss) Net Income/(Loss) Net Income/(Loss) Net income/(loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Total liabilities Liabilities, Fair Value Disclosure Business Combination [Table] Business Combination [Table] Spending for current obligations Asset Retirement Obligation, Liabilities Incurred Derivative, notional amount Derivative, notional amount Sale pre-capitalized trust securities Derivative, Notional Amount Business Combination, Consideration Transferred, Equity Interest, Type [Axis] Business Combination, Consideration Transferred, Equity Interest, Type [Axis] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] 2023 Capital Allocation Plan Capital Allocation Plan, 2023 [Member] Capital Allocation Plan, 2023 Long-term Incentive Plan Long-term Incentive Plan [Member] Long-term Incentive Plan 2026 Defined Benefit Plan, Expected Future Prescription Drug Subsidy Receipt, Year One Schedule of Purchase Price Allocation Business Combination, Recognized Asset Acquired and Liability Assumed [Table Text Block] City Area Code City Area Code Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Tax-exempt bonds Tax-exempt Bonds [Member] Tax-exempt Bonds [Member] Proceeds from credit facilities Proceeds from Long-Term Lines of Credit Contract Assets and Liabilities Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] Cash Flows from Investing Activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Senior Notes, due 2029 3.375% Senior Unsecured Notes Due 2029 [Member] 3.375% Senior Unsecured Notes Due 2029 Account Type [Axis] Account Type [Axis] Account Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] Disposal Group, Disposed of by Sale, Not Discontinued Operations Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Related Party Transactions [Abstract] Related Party Transactions [Abstract] Amortization of unrecognized net loss Defined Benefit Plan, Amortization of Gain 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Credit Derivatives Contract Type [Domain] Credit Derivatives Contract Type [Domain] Senior Notes, due 2029 5.250% Senior Notes, due 2029 5.250% Senior Notes Due 2029 [Member] 5.250% Senior Notes Due 2029 [Member] ASSETS Assets [Abstract] Measured using net asset value practical expedient: Measured Using Net Asset Value Practical Expedient [Abstract] Measured Using Net Asset Value Practical Expedient Credit Facility [Axis] Credit Facility [Axis] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Construction in Progress Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress Annual periodic pension cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] Debt Instrument, Redemption [Line Items] Debt Instrument, Redemption [Line Items] Senior Secured First Lien Notes, Due 2027, 2029 And 2033 Senior Secured First Lien Notes, Due 2027, 2029 And 2033 [Member] Senior Secured First Lien Notes, Due 2027, 2029 And 2033 Debt Instrument [Axis] Debt Instrument [Axis] Forfeited (in usd per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Benefit Plans and Other Postretirement Benefits Retirement Benefits [Text Block] Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Business Combination [Line Items] Business Combination [Line Items] (Loss)/Gain on debt extinguishment Gain (loss) on extinguishment of debt Loss on debt extinguishment Gain on debt extinguishment Gain (Loss) on Extinguishment of Debt Credit Facility [Domain] Credit Facility [Domain] Stockholders' Equity Equity, Attributable to Parent [Abstract] Derivative instruments Derivative Liability, Current Award vesting right, percentage Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage Weighted Average Grant Date Fair Value per Unit Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options Vested, Weighted Average Grant Date Fair Value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options Vested, Weighted Average Grant Date Fair Value [Abstract] Renewables Energy Certificates Renewable Energy Certificates [Member] Renewable Energy Certificates [Member] Cash (used)/provided by changes in other working capital: Cash Provided Used by Changes in Other Working Capital [Abstract] Consumer Financing Program - current Consumer Financing Program Current [Member] Consumer Financing Program Current Share repurchases Shares repurchased recorded in treasury Amounts paid for shares purchased (in millions) Treasury Stock, Value, Acquired, Cost Method 2029 Defined Benefit Plan, Expected Future Prescription Drug Subsidy Receipt, Year Four Amortization rate Debt Instrument, Amortization Rate Debt Instrument, Amortization Rate Interest rate, stated percentage Debt Instrument, Interest Rate, Stated Percentage Investment, Name [Axis] Investment, Name [Axis] Non-current operating lease liabilities Operating Lease, Liability, Noncurrent Entity Voluntary Filers Entity Voluntary Filers Aggregate intrinsic value for DSUs outstanding Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested, Aggregate Intrinsic Value As of the balance sheet date, the total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices of fully vested equity awards other than options. Volatilities Measurement Input, Option Volatility [Member] 2030 Defined Benefit Plan, Expected Future Prescription Drug Subsidy Receipt, Year Five Derivative assets Derivative Assets Derivative Asset, Subject to Master Netting Arrangement, before Offset Effect of changes in tax laws or rates enacted in the current period Effective Income Tax Rate Reconciliation, Tax Settlement, Foreign, Amount Depreciation of property, plant and equipment and amortization of customer relationships and other intangible assets Depreciation and amortization expense Depreciation, Amortization and Accretion, Net Accounts receivable, net Accounts Receivable, after Allowance for Credit Loss Property, Plant and Equipment Property, Plant and Equipment [Abstract] Entity Registrant Name Entity Registrant Name Recourse Debt Recourse Debt [Member] Recourse Debt [Member] SB IP Holdings LLC (Skybell) v. Vivint Smart Home, Inc. SB IP Holdings LLC (Skybell) v. Vivint Smart Home, Inc. [Member] SB IP Holdings LLC (Skybell) v. Vivint Smart Home, Inc. Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Aggregate intrinsic values for DSUs converted to common stock during the period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Conversions, Aggregate Intrinsic Value The total accumulated difference between fair values of underlying shares on dates of conversion and conversion price on units which were converted into shares during the reporting period under the plan. Net periodic benefit cost/(credit) Net periodic benefit cost/(credit) Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Treasury Lock Treasury Lock [Member] Foreign exchange translation Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss) New York Stock Exchange NEW YORK STOCK EXCHANGE, INC. 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Related Party [Axis] Related and Nonrelated Parties [Axis] Granted (in usd per share) Weighted average grant date fair value (in usd per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Interest cost on benefit obligation Interest cost Defined Benefit Plan, Interest Cost Amounts recognized in accumulated OCI Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract] Summary of the Components of Intangible Assets Subject to Amortization Schedule of Finite-Lived Intangible Assets [Table Text Block] Repayments to credit facilities Repayments of Long-Term Lines of Credit Restatement Determination Date: Restatement Determination Date [Axis] Cash paid for amounts included in the measurement of lease liabilities: Cash Flow, Lessee [Abstract] Cash Flow, Lessee Foreign Deferred Foreign Income Tax Expense (Benefit) Repayments of long-term debt and finance leases Repayments of Other Debt November 1, 2029 and thereafter November 1, 2029 and thereafter [Member] November 1, 2029 and thereafter Income tax provision from continuing operations Income Tax Expense (Benefit), Continuing Operations [Abstract] Total Interest Expense, Debt Deferred compensation, accrued vacation and other reserves Deferred Tax Assets, Tax Deferred Expense Compensation and Benefits Deferred Compensation, Accrued Vacation and Other Reserves The tax effect as of the balance sheet date of the amount of the estimated future tax deductions arising from deferred compensation, accrued vacation and other reserves, which can only be deducted for tax purposes when actual costs are incurred, and which can only be realized if sufficient tax-basis income is generated in future periods to enable the deduction to be taken. Convertible Senior Notes, due 2048 Convertible Senior Notes Due 2048 [Member] Convertible Senior Notes due 2048 [Member] August 15, 2029 and Thereafter August 15, 2029 and Thereafter [Member] August 15, 2029 and Thereafter Deferred impact of state tax rate changes Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount Name Trading Arrangement, Individual Name Underlying Asset Class [Domain] Underlying Asset Class [Domain] Jointly Owned Utility Plant [Axis] Jointly Owned Utility Plant [Axis] Accrued expenses and other current liabilities Increase (Decrease) Accrued Expenses and Other Current Liabilities Operating The sum of the net change during the reporting period of accrued expenses and other current liabilities. Accrued expenses is the net change during the reporting period in the aggregate amount of expenses incurred but not yet paid. Other current liabilities is the net change during the reporting period in other expenses incurred but not yet paid. Emissions allowances Deferred Tax Liabilities, Emissions Allowances The amount as of the balance sheet date of the estimated future tax effects arising on emissions allowances. August 15, 2028 to August 14, 2029 August 15, 2028 to August 14, 2029 [Member] August 15, 2028 to August 14, 2029 Debt redemption amount Tender amount Debt Instrument, Repurchase Amount Exercise price as a percentage of fair value (as a percent) Employee Stock Purchase Plan, Exercise Price as Percentage of Fair Value This element represents the exercise price under employee stock purchase plan as a percentage of fair value. October 15, 2030 to October 14, 2031 Redemption Period From 15 October 2030 to 14 October 2031 [Member] Redemption Period From 15 October 2030 to 14 October 2031 Aggregate principal amount Debt instrument, aggregate principal Debt Instrument, Face Amount Summary of Company's DSU awards and non-vested PSU Awards changes during the year Share-Based Payment Arrangement, Activity [Table Text Block] February 15, 2028 to February 14, 2029 Redemption Period February 15, 2028 to February 14, 2029 [Member] Redemption Period February 15, 2028 to February 14, 2029 November 1, 2030 to October 31, 2031 November 1, 2030 to October 31, 2031 [Member] November 1, 2030 to October 31, 2031 Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Difference between book and tax basis of property Deferred Tax Assets, Property, Plant and Equipment Payment for shares related to exercise of the Capped Call Options Payments for Hedge, Financing Activities Share Repurchase Program [Axis] Share Repurchase Program [Axis] Stock consideration Fair value of acquired Vivint Smart Home, Inc. equity awards attributable to pre-combination service Business Combination, Consideration Transferred, Equity Interest Preferred Stock Preferred Stock [Member] Acquired balance Accounts Receivable, Allowance for Credit Loss Acquired in Acquisition Accounts Receivable, Allowance for Credit Loss Acquired in Acquisition Schedule of Assumptions used in Fair Value Model Schedule of Share-based Payment Awards, Market Unit Valuation Assumptions [Table Text Block] Schedule of Share-based Payment Awards, Market Unit Valuation Assumptions [Table Text Block] Conversion of Convertible Senior Notes Adjustments to Additional Paid in Capital, Convertible Debt with Conversion Feature Significant assumptions used to calculate NRG's benefit expense Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] Name Awards Close in Time to MNPI Disclosures, Individual Name Domestic and foreign components of income from continuing operations before income tax expense Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest [Abstract] Schedule of Capitalization, Equity [Line Items] Schedule of Capitalization, Equity [Line Items] Non-vested at beginning of period (in usd per share) Non-vested at end of period (in usd per share) Nonvested, weighted average fair value (in usd per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag NRG Dunkirk 2020, tax exempt bonds, due 2042 NRG Dunkirk 2020, tax exempt bonds, due 2042 [Member] NRG Dunkirk 2020, tax exempt bonds, due 2042 Amortization of customer relationships and other intangible assets Amortization Of Customer Relationships And Other Intangible Assets Amortization Of Customer Relationships And Other Intangible Assets Equity-based awards activity, net APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Treasury stock, at cost; 9,452,008 and 6,460,055 shares at December 31, 2025 and 2024, respectively Treasury Stock, Value Generation capacity (MMBTU) annually Power Generation Capacity, Million Dekatherms Power Generation Capacity, Million Dekatherms Amortization of in-the-money contracts and emissions allowances Amortization of Intangibles, In-the-Money Contracts, and Retirement of RECs Amortization of Intangibles, In-the-Money Contracts, and Retirement of RECs Spare parts Other Inventories, Spare Parts, Gross Commodity and foreign exchange Commodity and Foreign Exchange Contracts [Member] Commodity and Foreign Exchange Contracts Litigation Case [Axis] Litigation Case [Axis] Cedar Bayou 5 TEF loan, due 2045 3.000% Cedar Bayou 5 TEF Loan Due 2045 [Member] 3.000% Cedar Bayou 5 TEF Loan Due 2045 Foreign Foreign: Foreign Tax Jurisdiction [Member] Auditor Firm ID Auditor Firm ID State net operating loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards, State and Local Segments [Domain] Segments [Domain] Segments [Domain] Statement of Income Location, Balance [Axis] Statement of Income Location, Balance [Axis] Foreign Income (Loss) from Continuing Operations before Income Taxes, Foreign Remaining borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Benefit obligation at January 1 Benefit obligation at December 31 Projected benefit obligation Defined Benefit Plan, Benefit Obligation Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] November 1, 2028 to October 31, 2029 November 1, 2028 to October 31, 2029 [Member] November 1, 2028 to October 31, 2029 Facilities and equipment Facilities And Equipment [Member] Represents long-lived, depreciable assets of facilities and equipment. Borrowings outstanding Line of Credit, Current Inventory Increase (Decrease) in Inventories Natural Gas Natural Gas Natural Gas [Member] Details pertaining to the natural gas, which is considered as a derivative commodity. Amortization of financing costs and debt discounts Amortization of discount and deferred finance costs Amortization of Debt Issuance Costs and Discounts Derivative assets: Derivative Asset [Abstract] Cash Collateral (Held)/Posted Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Cash Not Offset Accretion Asset Retirement Obligation, Accretion Expense Number Of new states where EPA FIP was stayed Number Of New States Where EPA FIP Was Stayed Number Of New States Where EPA FIP Was Stayed Gregory Gregory [Member] Gregory Counterparty credit exposure, net Net Credit Exposure Represents the net exposure of the entity determined as total credit exposure to all counterparties less collateral (cash and letters of credit) held against those positions as of the reporting date. Derivative Instruments Derivative Liability, Subject to Master Netting Arrangement, Asset Offset Senior Notes Senior Notes [Member] Investments in nuclear decommissioning trust fund securities Payments to Acquire Debt Securities, Available-for-Sale Redemption Percentage (If Sustainability Performance Target has not been satisfied and/or confirmed by External Verifier) Debt Instrument, Redemption Price, Percentage, Sustainability Performance Target Not Satisfied and/or Confirmed by External Verifier Debt Instrument, Redemption Price, Percentage, Sustainability Performance Target Not Satisfied and/or Confirmed by External Verifier Schedule of Amortization and Retirements of Intangible Expense Finite-Lived Intangible Assets Amortization Expense [Table Text Block] Preferred stock; 10,000,000 shares authorized; 650,000 Series A shares issued and outstanding at December 31, 2025 and 2024 (aggregate liquidation preference $650) Preferred Stock, Value, Issued Accrued interest Interest Payable June 15, 2026 to June 14, 2027 Redemption Period From 15 June 2026 to 14 June 2027 [Member] Redemption Period From 15 June 2026 to 14 June 2027 Greens Bayou 6 TEF loan, due 2045 3.000% Greens Bayou 6 TEF Loan Due 2045 [Member] 3.000% Greens Bayou 6 TEF Loan Due 2045 Number of performance obligations Number Of Performance Obligations Number Of Performance Obligations Residential Customer Residential Customer [Member] Residential Customer All Executive Categories All Executive Categories [Member] Company's deferred tax assets and liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of Benefit Obligations Significant Components Defined Benefit Plan, Plan with Projected Benefit Obligation in Excess of Plan Assets [Table Text Block] Common stock; $0.01 par value; 500,000,000 shares authorized; 199,828,615 and 205,064,058 shares issued; and 190,376,607 and 198,604,003 shares outstanding at December 31, 2025 and 2024, respectively Common Stock, Value, Issued Equity in and distributions from earnings of unconsolidated affiliates Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Commitments and Contingencies Commitments and Contingencies Preferred stock, liquidation preference Preferred Stock, Liquidation Preference, Value October 15, 2029 to October 14, 2030 Redemption Period From 15 October 2029 to 14 October 2030 [Member] Redemption Period From 15 October 2029 to 14 October 2030 Operations and Maintenance and Other Costs of Operations Cost of Operations, Maintenance and Other Costs of Operations [Policy Text Block] Cost of Operations, Maintenance and Other Costs of Operations Summary of NRG's total compensation expense recognized and total non-vested compensation costs not yet recognized and the period over which this expense is expected to be recognized Schedule of Share-based Payment Compensation, Allocation of Share-based Compensation Costs by Plan Unrecognized Compensation Cost and Weighted-Average Recognition Period [Table Text Block] Disclosure of the amount of total share-based compensation cost, including amounts attributable to each share-based compensation plan and any related tax benefits. Disclosure of the total compensation cost related to nonvested awards not yet recognized and the weighted average period over which it is expected to be recognized. Net Asset Value Fair Value Measured at Net Asset Value Per Share [Member] Business Combination [Axis] Business Combination [Axis] Comprehensive Income/(Loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: Revenues accounted for under topics other than ASC 606 and ASC 815 Revenue Not from Contract with Customer, Other Asset sales guarantee obligations Asset Sales Guarantee Obligations [Member] The entity's estimated guarantees under asset sales guarantee obligations. Marketing and Advertising Costs Marketing and Advertising Expense [Abstract] Schedule of Retirement of Treasury Stock Schedule Of Retirement Of Treasury Stock [Table Text Block] Schedule Of Retirement Of Treasury Stock Vivint Credit Agreement Vivint Credit Agreement [Member] Vivint Credit Agreement Capitalized contract costs Deferred Tax Liabilities, Deferred Expense, Other Capitalized Costs Investments Accounted for by the Equity Method Equity Method Investments [Policy Text Block] Short-term investment fund Short-Term Investments [Member] Ownership percentage Economic interest in equity method investments (as a percent) Equity Method Investment, Ownership Percentage Net deferred tax asset Deferred tax asset Deferred Tax Assets, Net CPI Security Systems, Inc. v. Vivint Smart Home, Inc. CPI Security Systems, Inc. v. Vivint Smart Home, Inc. [Member] CPI Security Systems, Inc. v. Vivint Smart Home, Inc. PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount October 15, 2030 and thereafter Redemption Period From 15 October 2030 and Thereafter [Member] Redemption Period From 15 October 2030 and Thereafter Account Type [Domain] Account Type [Domain] [Domain] for Account Type [Axis] Diluted income/(loss) per share: Earnings Per Share, Diluted [Abstract] SCHEDULE II — VALUATION AND QUALIFYING ACCOUNTS SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Expected period of benefit Revenue, Performance Obligation, Description of Timing Revenue from Contract with Customer [Abstract] Hedging Designation [Axis] Hedging Designation [Axis] Fair Value Within the Derivative Instrument Valuation on the Balance Sheet Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position, Location [Table Text Block] Scenario [Axis] Scenario [Axis] Significant components of NRG's domestic pension plan Significant Components of Defined Benefit Pension Plan [Abstract] Reconciliation of total amounts of uncertain tax benefits Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Net Counterparty Credit Exposure by Industry Sector and by Counterparty Credit Quality Schedule of Net Exposure to Counter Party Credit Exposure [Table Text Block] Disclosure of the net exposure to counterparty credit risk by category. Foreign Currency Translation and Transaction Gains and Losses Foreign Currency Translation and Transaction [Abstract] Gladstone Gladstone Power Station [Member] Represents the information pertaining to Gladstone Power Station. Funds Deposited by Counterparties Funds Deposited by Counterparties [Abstract] Defined benefit plans Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax California CALIFORNIA Net Amount Derivative Liability, Including Not Subject to Master Netting Arrangement, after Offset and Deduction Derivative Contract [Domain] Derivative Contract [Domain] 2030 Defined Benefit Plan, Expected Future Benefit Payment, Year Five FTRs Financial Transmission Rights [Member] Financial Transmission Rights [Member] Quarterly dividends per share (usd per share) Common Stock, Quarterly Dividends, Per Share, Cash Paid Common Stock, Quarterly Dividends, Per Share, Cash Paid All Individuals All Individuals [Member] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Capital expenditures Payments to Acquire Property, Plant, and Equipment Name Forgone Recovery, Individual Name Derivative revenue Total impact to statement of operations Unrealized Gain (Loss) on Derivatives Regulatory Agency [Domain] Regulatory Agency [Domain] 2029 Unrecorded Unconditional Purchase Obligation, to be Paid, Year Four Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Deferred revenue from contract with customers Contract with Customer, Liability, Increase For Cash Payments Received Contract with Customer, Liability, Increase For Cash Payments Received Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid Schedule of Offsetting Assets and Liabilities [Table Text Block] Schedule of Offsetting Assets and Liabilities [Table Text Block] Loss/(gain) on debt extinguishment Gains Losses on Extinguishment of Debt, Non Cash Portion Gains Losses on Extinguishment of Debt, Non-cash Portion Disposal Group Classification [Axis] Disposal Group Classification [Axis] Weighted average interest rate Debt, Weighted Average Interest Rate Foreign Exchange Foreign Exchange [Member] Sale of Airtron Finite-Lived Intangible Assets, Disposal Of Intangible Assets Of Equity Method Investment Finite-Lived Intangible Assets, Disposal Of Intangible Assets Of Equity Method Investment Term Loan B, due 2031 Term Loan Due 2031 [Member] Term Loan Due 2031 Foreign currency translation adjustments Goodwill, Foreign Currency Translation, Gain (Loss) Common/collective trust investment — U.S. equity Common Trust Investment US Equity Securities [Member] Represents the investments in common/collective trust in U.S. equity securities. Derivative instruments Derivative Instruments and Hedges, Noncurrent Other guarantees Guarantee Type, Other [Member] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Intangible Asset, Finite-Lived [Table] Intangible Asset, Finite-Lived [Table] Accelerated repurchase agreements Capital Allocation Plan, Accelerated Repurchase Agreements [Member] Capital Allocation Plan, Accelerated Repurchase Agreements Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Debt conversion, shares Issued (in shares) Debt Conversion, Converted Instrument, Shares Issued Other assets and liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Present value of note (as percentage) Debt Instrument, Present Value Of Note, Rate Debt Instrument, Present Value Of Note, Rate Federal tax credit carryforwards Deferred Tax Assets, Tax Credit Carryforwards Restricted Stock Units -Excluding Rollovers Restricted Stock Units -Excluding Rollovers [Member] Restricted Stock Units -Excluding Rollovers Valuation and Qualifying Accounts Disclosure SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] U.S. capital loss Deferred Tax Assets, Capital Loss Carryforwards Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] February 15, 2026 to February 14, 2027 Redemption Period February 15, 2026 to February 14, 2027 [Member] Redemption Period February 15, 2026 to February 14, 2027 Title of 12(b) Security Title of 12(b) Security Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Amortization of capitalized contract costs Amortization of capitalized contract costs Contract amortization Capitalized Contract Cost, Amortization Redemption Period Prior to October 15, 2028 Redemption Period Prior to October 15, 2028 [Member] Redemption Period Prior to October 15, 2028 Interest rate contracts long-term Interest Rate Contract Non Current [Member] The noncurrent portion of a derivative instrument whose primary underlying risk is tied to the right to receive or pay a sum of money at a given interest rate. 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] Other, including current and non-current working capital Business Combination, Recognized Assets Acquired And Liabilities Assumed, Other, Working Capital, Net Business Combination, Recognized Assets Acquired And Liabilities Assumed, Other, Working Capital, Net Vivint Home Services Retail Revenue Vivint Home Services [Member] Vivint Home Services Bilateral Letter of Credit Facilities Bilateral Letter of Credit Facilities [Member] Bilateral Letter of Credit Facilities Supplemental Statement of Income Disclosures Supplemental Statement Of Income Disclosures [Table Text Block] Supplemental Statement Of Income Disclosures Income/(Loss) Per Share Earnings Per Share [Abstract] 2030 Lessee, Operating Lease, Liability, to be Paid, Year Five Total other expense Nonoperating Income (Expense) Ownership percentage, parent Subsidiary, Ownership Percentage, Parent Gains/(Losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of year-end Fair Value, Net Derivative Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss) Medicare prescription drug reimbursements Defined Benefit Plan, Postretirement Medical Plan with Prescription Drug Benefits [Abstract] Sale of Airtron Goodwill, Written off Related to Sale of Business Unit November 2023 Accelerated Share Repurchase Agreements November 2023 Accelerated Share Repurchase Agreements [Member] November 2023 Accelerated Share Repurchase Agreements Short-Term Debt, Type [Axis] Short-Term Debt, Type [Axis] Interest rate contracts - current Interest Rate Contract Current [Member] The current portion of a derivative instrument whose primary underlying risk is tied to the right to receive or pay a sum of money at a given interest rate. Increase in existing borrowing commitments Line of Credit Facility, Increase in Borrowing Capacity Line of Credit Facility, Increase in Borrowing Capacity Net actuarial gain Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax Shares, repurchased (in shares) Total number of shares purchased (in shares) Treasury Stock, Shares, Acquired Scenario, Plan Scenario, Plan [Member] Award Timing Disclosures [Line Items] Schedule of ARO Obligations and Related Additions, Reductions and Accretion Schedule of Change in Asset Retirement Obligation [Table Text Block] Schedule of Inventory Schedule of Inventory, Current [Table Text Block] Service cost benefits earned Service cost Defined Benefit Plan, Service Cost Recoveries collected Accounts Receivable, Allowance for Credit Loss, Recovery Net exposure (as a percent) Credit Derivative, Maximum Net Exposure, Percentage Represents the percentage of net counterparty credit exposure of the entity. Credit Loss Rates Measurement Input, Loss Severity [Member] Payments for legal settlement Payments for Legal Settlements Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Table] Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Table] Capital Structure Equity [Text Block] Debt Instrument, Unamortized Discount [Abstract] Debt Instrument, Unamortized Discount [Abstract] State Deferred State and Local Income Tax Expense (Benefit) T.H. Wharton TEF loan, due 2045 3.000% T.H. Wharton TEF Loan Due 2045 [Member] 3.000% T.H. Wharton TEF Loan Due 2045 4.00% Indian River Power 2020 Tax Exempt Bonds Due 2040 4.00% Indian River Power 2020 Tax Exempt Bonds Due 2040 [Member] 4.00% Indian River Power 2020 Tax Exempt Bonds Due 2040 Net income (loss) Net Income (Loss) Attributable to Parent Effective Interest Rate Debt Instrument, Interest Rate During Period Property, plant and equipment, net Property, plant and equipment, net Public Utilities, Property, Plant and Equipment, Net Construction in progress Construction in Progress [Member] Other Other Accrued Liabilities, Current Reconciliation of the U.S. federal statutory rate to NRG's effective rate Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Award vesting period Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period Accounts Receivable, Allowance for Credit Loss [Roll Forward] Accounts Receivable, Allowance for Credit Loss [Roll Forward] Deductions SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction Segment Reporting Information Segment Reporting Information [Line Items] Fair Value Inputs, Sensitivity Analysis Fair Value Inputs, Sensitivity Analysis [Table Text Block] Fair Value Inputs, Sensitivity Analysis [Table Text Block] Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Payments for share repurchase activity and excise tax Payments for Repurchase of Common Stock Adoption Date Trading Arrangement Adoption Date Reclassifications Reclassification, Comparability Adjustment [Policy Text Block] Closing, share price (in usd per share) Shares Issued, Price Per Share Treasury stock reserved for issuance under the ESPP (in shares) Common Stock, Capital Shares Reserved For Employee Stock Purchase Plan Aggregate number of common shares reserved for employee stock purchase plan. Customer [Axis] Customer [Axis] Customer relationships, net Customer Relationships Customer Relationships [Member] Operating Income Operating income/(loss) Operating Income (Loss) Line of Credit Line of Credit [Member] Retained earnings Retained Earnings (Accumulated Deficit) Summary of Shares Repurchased Class of Treasury Stock [Table Text Block] Schedule of Comparison of Pension Benefit Obligation, Other Postretirement Benefit Obligations and Related Plan Assets on a Combined Basis Schedule of Net Funded Status [Table Text Block] Collateral Default Rates Measurement Input, Collateral Default Rate [Member] Measurement Input, Collateral Default Rate August 15, 2027 to August 14, 2028 August 15, 2027 to August 14, 2028 [Member] August 15, 2027 to August 14, 2028 Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Short-term commitments Unrecorded Unconditional Purchase Obligation, Less Than One Year Unrecorded Unconditional Purchase Obligation, Less Than One Year Total derivative assets valued with prices provided by models and other valuation techniques percentage Derivative Asset, Fair Value Determined Using Valuation Techniques, Percentage This element represents the portion of total fair value of all derivative assets, which are valued using various valuation techniques including internal models based on a fundamental analysis of the market and extrapolation of observable market data with similar characteristics. Plan modification, incremental cost Share-Based Payment Arrangement, Plan Modification, Incremental Cost Class of Stock [Axis] Class of Stock [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Share-based Payment Arrangement, Tranche Five Share-based Payment Arrangement, Tranche Five [Member] Share-based Payment Arrangement, Tranche Five Intangible Assets Finite-Lived Intangible Assets, Net [Abstract] Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Payables and Accruals [Abstract] Statement [Table] Statement [Table] Other income, net Other income, net Other Nonoperating Income (Expense) Actual return on plan assets Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Schedule of Total Consideration Business Combination [Table Text Block] Total — deferred Deferred Income Tax Expense (Benefit) Adjustments to reconcile net income/(loss) to cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Cash Flows from Financing Activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Other Foreign Tax Jurisdiction, Other [Member] Federal Trade Commissions Federal Trade Commission [Member] Federal Trade Commission Disposal Group, Not Discontinued Operation, Gain Loss on Disposal Statement of Income Extensible List Not Disclosed Flag Disposal Group Not Discontinued Operation Gain Loss On Disposal Statement Of Income Extensible List Not Disclosed Flag Disposal Group Not Discontinued Operation Gain Loss On Disposal Statement Of Income Extensible List Not Disclosed Flag [Extensible Enumeration] Variable Rate [Domain] Variable Rate [Domain] Deferred revenue Contract with Customer, Liability Sale-Leaseback Arrangements Lessor, Leases [Policy Text Block] Payments for legal settlements, judgement Payments For Legal Settlements, Judgement Payments For Legal Settlements, Judgement Minimum purchase commitment Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract] Preferred stock, dividend rate, basis spread on variable rate Preferred Stock, Dividend Rate, Basis Spread on Variable Rate Preferred Stock, Dividend Rate, Basis Spread on Variable Rate Reconciliation of Beginning and Ending Balances for Financial Instruments that are Recognized at Fair Value using Significant Unobservable Inputs Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] All Adjustments to Compensation All Adjustments to Compensation [Member] Retirement of treasury stock (in shares) Total number of treasury shares retired (in shares) Retirement of treasury stock (in shares) Treasury Stock, Shares, Retired Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Amendment Flag Amendment Flag Tax (benefit)/detriment recognized Share-Based Payment Arrangement, Expense, Tax Benefit Share-based Payment Arrangement, Tranche Four Share-based Payment Arrangement, Tranche Four [Member] Share-based Payment Arrangement, Tranche Four Number of shares authorized for issuance under plan (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized Other Postretirement Benefits Plan Other Postretirement Benefits Plan [Member] Schedule of Target Allocation of Pension Plan Assets Schedule of Allocation of Plan Assets [Table Text Block] Capped Call Options Capped call options Adjustment To Additional Paid In Capital, Purchase Of Capped Call Options Adjustment To Additional Paid In Capital, Purchase Of Capped Call Options Pension and other postretirement benefits Deferred Tax Assets, Tax Deferred Expense Compensation and Benefits Pensions and Other Postretirement Benefits The tax effect as of the balance sheet date of the amount of the estimated future tax deductions arising from pension and other post retirement costs, which can only be deducted for tax purposes when actual costs are incurred, and which can only be realized if sufficient tax-basis income is generated in future periods to enable the deduction to be taken. Termination Date Trading Arrangement Termination Date Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] DSUs Deferred Stock Units [Member] Represents details pertaining to deferred stock units. Cash and Cash Equivalents Cash and Cash Equivalents, Unrestricted Cash and Cash Equivalents, Policy [Policy Text Block] Receivable [Domain] Receivable [Domain] Share-based Payment Arrangement, Tranche Three Share-Based Payment Arrangement, Tranche Three [Member] Net assets Net Assets Weighted average discount rate Operating Lease, Weighted Average Discount Rate, Percent Accrued interest and penalties related to unrecognized tax benefits Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Schedule of Fair Value of Pension Plan Assets by Asset Category and Level within the Fair Value Hierarchy Fair Value, Assets Measured on Recurring Basis [Table Text Block] Weighted average number of common shares outstanding — basic (in shares) Weighted average number of common shares outstanding — basic (in shares) Weighted Average Number of Shares Outstanding, Basic Cash Flow Information Cash Flow, Supplemental Disclosures [Text Block] Recognition of uncertain tax benefits Effective Income Tax Rate Reconciliation, Reversal of Uncertain Tax Positions Reserves Effective Income Tax Rate Reconciliation, Reversal of Uncertain Tax Positions Reserves Reconciliation of NRG's Basic and Diluted Income per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Common/collective trust investment — non-U.S. equity Common Trust Investment Non US Equity Securities [Member] Represents the investments in common/collective trust in non-US equity securities. Capitalized Contract Cost [Line Items] Capitalized Contract Cost [Line Items] Segment Reporting [Abstract] Segment Reporting [Abstract] Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Counterparty credit exposure, collateral held (cash and letters of credit) against positions Collateral Held Cash and Letters of Credit Carrying amount as of the balance sheet date of cash collateral and letters of credit received by the entity on deposit from third parties in support of energy risk management. Commercial And industrial Virtual Power Plant Platform Commercial And industrial Virtual Power Plant Platform [Member] Commercial And industrial Virtual Power Plant Platform Debt Disclosure [Abstract] Debt Disclosure [Abstract] Defined Benefit Plan by Plan Asset Categories [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Scenario [Domain] Scenario [Domain] Other Income/(Expense) Costs and Expenses [Abstract] Write-offs Accounts Receivable, Allowance for Credit Loss, Writeoff Variable Interest Entities Disclosure [Abstract] -- None. No documentation exists for this element. -- Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Stock-Based Compensation Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Consolidated Entities [Axis] Consolidated Entities [Axis] Common stock, par or value (in usd per share) Common Stock, Par or Stated Value Per Share Acquisition, working capital adjustments Business Acquisition, Working Capital Adjustments, Net Business Acquisition, Working Capital Adjustments, Net Current net federal tax receivable Income Taxes Receivable, Current 2031-2035 Defined Benefit Plan, Expected Future Benefit Payment, after Year Five for Next Five Years Senior Secured First Lien Notes, due 2033 7.000% Senior Secured First Lien Notes due 2033 [Member] 7.000% Senior Secured First Lien Notes due 2033 Use of Estimates Use of Estimates, Policy [Policy Text Block] Income tax valuation allowance, deducted from deferred tax assets SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Other current liabilities Liability, Defined Benefit Plan, Current Net receipts/(payments) from settlement of acquired derivatives that include financing elements Payments for (Proceeds from) Derivative Instrument, Financing Activities November 1, 2027 to October 31, 2028 November 1, 2027 to October 31, 2028 [Member] November 1, 2027 to October 31, 2028 Derivative Instruments Derivative Asset, Subject to Master Netting Arrangement, Liability Offset Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Insider Trading Arrangements [Line Items] Equity securities Equity Securities [Member] Total Liabilities Liabilities Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Settlements Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Increase due to current year positions Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Derivative, Other Liabilities Derivative, Other Liabilities [Member] Derivative, Other Liabilities Aggregate principal repaid Principal Repurchased Principal repurchased Debt Instrument, Repurchased Face Amount Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Federal benefit on state uncertain tax positions Deferred Tax Assets, Federal Benefit on State Unrecognized Tax Benefits The tax effect as of the balance sheet date of the amount of the estimated future tax reductions attributable to the difference between the tax basis and the generally accepted accounting principles basis of a federal benefit on state unrecognized tax benefits which will decrease future taxable income when such basis difference reverses. Ownership Interest (as a percent) Jointly Owned Utility Plant, Proportionate Ownership Share Expects to contribute to the pension plans Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year Derivative liabilities, excluding NPNS elected Derivative Liability, Excluding NPNS Elected, Subject to Master Netting Arrangement, before Offset Derivative Liability, Excluding NPNS Elected, Subject to Master Netting Arrangement, before Offset Finance leases: Finance Lease [Abstract] Finance Lease Other revenue Products And Services, Other [Member] Products And Services, Other [Member] Counterparty Risk by Institution [Domain] Counterparty Risk by Institution [Domain] Represents the counter party risk exposure by institutions involved. Capped calls, strike price (in usd per share) Capped Call Options, Strike Price Capped Call Options, Strike Price Variable Rate [Axis] Variable Rate [Axis] Consolidation Items [Axis] Consolidation Items [Axis] Natural gas Energy Related Inventory, Natural Gas in Storage Derivative, Current Assets Derivative, Current Assets [Member] Derivative, Current Assets Counterparty Name [Axis] Counterparty Name [Axis] Summary of Company's non-vested RSU awards and changes during the year Share-Based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block] Write-off of fully amortized balances Finite-Lived Intangible Assets, Write-off of Fully Amortized Intangible Assets Write-off of fully amortized intangible assets during the period. Contract Cost, Fulfillment Contract Cost Fulfillment [Member] Contract Cost Fulfillment Investments in securities (classified within other current and non-current assets) Debt Securities, Available-for-Sale Schedule of Contract Assets and Liabilities [Line Items] Schedule Of Contract Assets And Liabilities [Line Items] [Line Items] for Schedule Of Contract Assets And Liabilities [Table] Unrealized Mark To Market Results [Abstract] Unrealized Mark To Market Results [Abstract] -- None. No documentation exists for this element. -- Accounts receivable, net - Contracts with customers Customer Contracts [Member] Net income (loss) Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Non-NEOs Non-NEOs [Member] Collateral required for contracts in net liability positions that have adequate assurance clauses Collateral Already Posted, Aggregate Fair Value