NRG Energy (NRG) 10-Q 4 Nov 21 2021 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2021	Nov. 04, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-15891
Entity Registrant Name	NRG Energy, Inc
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	41-1724239
Entity Address, Address Line One	910 Louisiana Street
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77002
City Area Code	713
Local Phone Number	537-3000
Title of 12(b) Security	Common Stock, par value $0.01
Trading Symbol	NRG
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		244,838,651
Entity Central Index Key	0001013871
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating Revenues
Total operating revenues	$ 6,609	$ 2,809	$ 19,943	$ 7,066
Operating Costs and Expenses
Cost of operations (excluding depreciation and amortization shown below)	3,692	2,034	13,496	4,925
Depreciation and amortization	199	99	569	318
Impairment losses	0	29	306	29
Selling, general and administrative costs	318	216	973	592
Provision for credit losses	64	26	715	74
Acquisition-related transaction and integration costs	17	12	81	13
Total operating costs and expenses	4,290	2,416	16,140	5,951
Gain on sale of assets	0	0	17	6
Operating Income	2,319	393	3,820	1,121
Other Income/(Expense)
Equity in earnings of unconsolidated affiliates	15	36	23	37
Impairment losses on investments	0	0	0	(18)
Other income, net	8	11	42	52
Loss on debt extinguishment, net	(57)	0	(57)	(1)
Interest expense	(122)	(99)	(374)	(292)
Total other expense	(156)	(52)	(366)	(222)
Income Before Income Taxes	2,163	341	3,454	899
Income tax expense	545	92	840	216
Net Income	$ 1,618	$ 249	$ 2,614	$ 683
Income per Share
Weighted average number of common shares outstanding — basic (in shares)	245	244	245	246
Income per Weighted Average Common Share — Basic (in usd per share)	$ 6.60	$ 1.02	$ 10.67	$ 2.78
Weighted average number of common shares outstanding — diluted (in shares)	245	245	245	247
Income per weighted average common share — diluted (in usd per share)	$ 6.60	$ 1.02	$ 10.67	$ 2.77

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net Income	$ 1,618	$ 249	$ 2,614	$ 683
Other Comprehensive (Loss)/Income
Foreign currency translation adjustments	(11)	4	(6)	2
Defined benefit plans	1	0	20	0
Other comprehensive (loss)/income	(10)	4	14	2
Comprehensive Income	$ 1,608	$ 253	$ 2,628	$ 685

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Current Assets
Cash and cash equivalents	$ 259	$ 3,905
Funds deposited by counterparties	1,748	19
Restricted cash	14	6
Accounts receivable, net	3,096	904
Inventory	445	327
Derivative instruments	8,528	560
Cash collateral paid in support of energy risk management activities	21	50
Prepayments and other current assets	461	257
Total current assets	14,572	6,028
Property, plant and equipment, net	1,976	2,547
Other Assets
Equity investments in affiliates	167	346
Operating lease right-of-use assets, net	293	301
Goodwill	1,801	579
Intangible assets, net	2,915	668
Nuclear decommissioning trust fund	957	890
Derivative instruments	2,671	261
Deferred income taxes	1,994	3,066
Other non-current assets	619	216
Total other assets	11,417	6,327
Total Assets	27,965	14,902
Current Liabilities
Current portion of long-term debt and finance leases	504	1
Current portion of operating lease liabilities	79	69
Accounts payable	1,967	649
Derivative instruments	6,032	499
Cash collateral received in support of energy risk management activities	1,748	19
Accrued expenses and other current liabilities	1,679	678
Total current liabilities	12,009	1,915
Other Liabilities
Long-term debt and finance leases	7,957	8,691
Non-current operating lease liabilities	257	278
Nuclear decommissioning reserve	316	303
Nuclear decommissioning trust liability	619	565
Derivative instruments	1,489	385
Deferred income taxes	74	19
Other non-current liabilities	1,166	1,066
Total other liabilities	11,878	11,307
Total Liabilities	23,887	13,222
Commitments and Contingencies
Stockholders' Equity
Common stock; $0.01 par value; 500,000,000 shares authorized; 423,545,261 and 423,057,848 shares issued and 244,779,313 and 244,231,933 shares outstanding at September 30, 2021 and December 31, 2020, respectively	4	4
Additional paid-in-capital	8,525	8,517
Retained earnings/(accumulated deficit)	971	(1,403)
Treasury stock, at cost 178,765,948 and 178,825,915 shares at September 30, 2021 and December 31, 2020, respectively	(5,230)	(5,232)
Accumulated other comprehensive loss	(192)	(206)
Total Stockholders' Equity	4,078	1,680
Total Liabilities and Stockholders' Equity	$ 27,965	$ 14,902

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Common stock, par or value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	423,545,261	423,057,848
Common stock, shares outstanding (in shares)	244,779,313	244,231,933
Treasury stock, shares (in shares)	178,765,948	178,825,915

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash Flows from Operating Activities
Net Income	$ 2,614	$ 683
Adjustments to reconcile net income to cash provided by operating activities:
Distributions from and equity in earnings of unconsolidated affiliates	8	6
Depreciation and amortization	569	318
Accretion of asset retirement obligations	21	46
Provision for credit losses	715	74
Amortization of nuclear fuel	39	40
Amortization of financing costs and debt discounts	30	23
Loss on debt extinguishment, net	57	1
Amortization of in-the-money contracts, emissions allowances and retirements of RECs	111	60
Amortization of unearned equity compensation	16	17
Net gain on sale and disposal of assets	(29)	(22)
Impairment losses	306	47
Changes in derivative instruments	(4,419)	(7)
Changes in deferred income taxes and liability for uncertain tax benefits	782	202
Changes in collateral deposits in support of energy risk management activities	1,970	96
Changes in nuclear decommissioning trust liability	38	39
Oil lower of cost or market adjustment	0	29
Changes in other working capital	(973)	(266)
Cash provided by operating activities	1,855	1,386
Cash Flows from Investing Activities
Payments for acquisitions of businesses, net of cash acquired	(3,534)	(277)
Capital expenditures	(219)	(167)
Net sales/(purchases) of emission allowances	6	(15)
Investments in nuclear decommissioning trust fund securities	(460)	(360)
Proceeds from the sale of nuclear decommissioning trust fund securities	424	318
Proceeds from sale of assets, net of cash disposed	198	15
Changes in investments in unconsolidated affiliates	0	2
Cash used by investing activities	(3,585)	(484)
Cash Flows from Financing Activities
Payments of dividends to common stockholders	(239)	(221)
Payments for share repurchase activity	(9)	(229)
Net receipts/(payments) from settlement of acquired derivatives that include financing elements	396	(6)
Repayments of long-term debt and finance leases	(1,360)	(62)
Proceeds from issuance of long-term debt	1,100	59
Payments for debt extinguishment costs	(48)	0
Payments of debt issuance costs	(18)	(24)
Proceeds from issuance of common stock	1	1
Net repayments of Revolving Credit Facility and Receivables Securitization Facilities	0	(83)
Purchase of and distributions to noncontrolling interests from subsidiaries	0	(2)
Net Cash Used by Financing Activities	(177)	(567)
Effect of exchange rate changes on cash and cash equivalents	(2)	(2)
Net (Decrease)/Increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash	(1,909)	333
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period	3,930	385
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	$ 2,021	$ 718

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions		Total	Common Stock	Additional Paid-In Capital	Retained Earnings/ (Accumulated Deficit)	Treasury Stock	Accumulated Other Comprehensive Loss
Beginning balance at Dec. 31, 2019		$ 1,658	$ 4	$ 8,501	$ (1,616)	$ (5,039)	$ (192)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income		121			121
Other comprehensive income (loss)		(15)					(15)
Repurchase of partners' equity interest in VIE		18		18
Share repurchases		(150)				(150)
Equity-based awards activity, net	[1]	(21)		(21)
Common stock dividends and dividend equivalents declared	[2]	(75)			(75)
Ending balance at Mar. 31, 2020		1,536	4	8,498	(1,570)	(5,189)	(207)
Beginning balance at Dec. 31, 2019		1,658	4	8,501	(1,616)	(5,039)	(192)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income		683
Other comprehensive income (loss)		2
Ending balance at Sep. 30, 2020		1,934	4	8,511	(1,157)	(5,234)	(190)
Beginning balance at Mar. 31, 2020		1,536	4	8,498	(1,570)	(5,189)	(207)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income		313			313
Other comprehensive income (loss)		13					13
Shares reissuance for ESPP		2				2
Share repurchases		(47)				(47)
Equity-based awards activity, net		6		6
Issuance of common stock		1		1
Common stock dividends and dividend equivalents declared		(74)			(74)
Ending balance at Jun. 30, 2020		1,750	4	8,505	(1,331)	(5,234)	(194)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income		249			249
Other comprehensive income (loss)		4					4
Equity-based awards activity, net		6		6
Common stock dividends and dividend equivalents declared		(75)			(75)
Ending balance at Sep. 30, 2020		1,934	4	8,511	(1,157)	(5,234)	(190)
Beginning balance at Dec. 31, 2020		1,680	4	8,517	(1,403)	(5,232)	(206)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income		(82)			(82)
Other comprehensive income (loss)		3					3
Equity-based awards activity, net	[1]	(5)		(5)
Issuance of common stock		1		1
Common stock dividends and dividend equivalents declared	[2]	(80)			(80)
Ending balance at Mar. 31, 2021		1,517	4	8,513	(1,565)	(5,232)	(203)
Beginning balance at Dec. 31, 2020		1,680	4	8,517	(1,403)	(5,232)	(206)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income		2,614
Other comprehensive income (loss)		14
Ending balance at Sep. 30, 2021		4,078	4	8,525	971	(5,230)	(192)
Beginning balance at Mar. 31, 2021		1,517	4	8,513	(1,565)	(5,232)	(203)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income		1,078			1,078
Other comprehensive income (loss)		21					21
Shares reissuance for ESPP		2				2
Equity-based awards activity, net		6		6
Common stock dividends and dividend equivalents declared		(80)			(80)
Ending balance at Jun. 30, 2021		2,544	4	8,519	(567)	(5,230)	(182)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income		1,618			1,618
Other comprehensive income (loss)		(10)					(10)
Equity-based awards activity, net		6		6
Common stock dividends and dividend equivalents declared		(80)			(80)
Ending balance at Sep. 30, 2021		$ 4,078	$ 4	$ 8,525	$ 971	$ (5,230)	$ (192)
[1]	Includes $(9) million and $(27) million of equivalent shares purchased in lieu of tax withholding on equity compensation issuances for the quarters ended March 31, 2021 and 2020, respectively
[2]	Dividends per common share were $0.325 for the quarters ended September 30, June 30 and March 31, 2021 and $0.30 for the quarters ended September 30, June 30 and March 31, 2020

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares shares in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Shares purchased for tax withholding obligation (in shares)	(9)	(27)
Dividends per common share (in usd per share)	$ 0.325	$ 0.30

Nature of Business and Basis of

Nature of Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business and Basis of Presentation	Nature of Business and Basis of Presentation General NRG Energy, Inc., or NRG or the Company, is a consumer services company built on dynamic retail brands with diverse generation assets. NRG brings the power of energy to customers by producing and selling energy and related products and services, nation-wide in the U.S. and Canada in a manner that delivers value to all of NRG's stakeholders. The Company sells energy, services, and innovative, sustainable solutions and advisory services to approximately 6 million Home customers under the names NRG, Reliant, Direct Energy, Green Mountain Energy, Stream, and XOOM Energy, as well as other brand names owned by NRG, supported by approximately 23,000 MW of generation, including approximately 4,850 MW of fossil generation assets held for sale as of September 30, 2021 and approximately 1,600 MW of its PJM coal fleet with a retirement date of June 2022. On January 5, 2021, the Company acquired Direct Energy, which is a leading retail provider of electricity, natural gas, and home and business energy related products and services, as well as a participant in the wholesale gas and power markets, in the U.S. and Canada. Refer to Note 4, Acquisitions and Dispositions, for further discussion of the acquisition of Direct Energy. The acquired operations of Direct Energy are integrated into the existing NRG segment structure. Domestic customer and market operations are combined into the corresponding geographical segments of Texas, East and West/Services/Other. The West/Services/Other segment includes activity related to the Canadian operations as well as the services businesses. The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with the SEC's regulations for interim financial information and with the instructions to Form 10-Q. Accordingly, they do not include all of the information and notes required by generally accepted accounting principles for complete financial statements. The following notes should be read in conjunction with the accounting policies and other disclosures as set forth in the notes to the consolidated financial statements in the Company's 2020 Form 10-K. Interim results are not necessarily indicative of results for a full year. In the opinion of management, the accompanying unaudited interim condensed consolidated financial statements contain all material adjustments consisting of normal and recurring accruals necessary to present fairly the Company's consolidated financial position as of September 30, 2021, and the results of operations, comprehensive income, cash flows and statements of stockholders' equity for the three and nine months ended September 30, 2021 and 2020. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates. Reclassifications Certain prior period amounts have been reclassified for comparative purposes. The reclassifications did not affect consolidated results from operations, net assets or consolidated cash flows.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Other Balance Sheet Information The following table presents the accumulated depreciation included in property, plant and equipment, net and accumulated amortization included in intangible assets, net: (In millions) September 30, 2021 December 31, 2020 Property, plant and equipment accumulated depreciation $ 1,543 $ 1,936 Intangible assets accumulated amortization 1,542 1,357 Credit Losses On January 1, 2020, the Company adopted ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , or ASU No. 2016-13, using the modified retrospective approach. Following the adoption of the new standard, the Company’s process of estimating expected credit losses remains materially consistent with its historical practice. Retail trade receivables are reported on the balance sheet net of the allowance for credit losses. The Company accrues a provision for current expected credit losses based on (i) estimates of uncollectible revenues by analyzing accounts receivable aging and current and reasonable forecasts of expected economic factors including, but not limited to, unemployment rates and weather-related events, (ii) historical collections and delinquencies, and (iii) counterparty credit ratings for commercial and industrial customers. The following table represents the activity in the allowance for credit losses for the three and nine months ended September 30, 2021 and 2020: Three months ended September 30, Nine months ended September 30, (In millions) 2021 2020 2021 2020 Beginning balance $ 761 $ 47 $ 67 $ 43 Acquired balance from Direct Energy — — 112 — Provision for credit losses 64 26 715 74 Write-offs (41) (19) (124) (71) Recoveries collected 8 3 22 11 Ending balance $ 792 $ 57 $ 792 $ 57 The increase in the provision for credit losses during the three months ended September 30, 2021, compared to the same period in 2020 was primarily due to the impact of Winter Storm Uri on counterparty credit risk. The increase in the provision for credit losses during the nine months ended September 30, 2021, compared to the same period in 2020 was primarily due to the impacts of Winter Storm Uri on bilateral finance hedging risk of $403 million, counterparty credit risk of $152 million and ERCOT default shortfall payments of $83 million. Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash The following table provides a reconciliation of cash and cash equivalents, restricted cash and funds deposited by counterparties reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the statements of cash flows: (In millions) September 30, 2021 December 31, 2020 Cash and cash equivalents $ 259 $ 3,905 Funds deposited by counterparties 1,748 19 Restricted cash 14 6 Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows $ 2,021 $ 3,930 Funds deposited by counterparties consist of cash held by the Company as a result of collateral posting obligations from its counterparties. Though some amounts are segregated into separate accounts, not all funds are contractually restricted. Based on the Company's intention, these funds are not available for the payment of general corporate obligations; however, they are available for liquidity management. Depending on market fluctuations and the settlement of the underlying contracts, the Company will refund this collateral to the hedge counterparties pursuant to the terms and conditions of the underlying trades. Since collateral requirements fluctuate daily and the Company cannot predict if any collateral will be held for more than twelve months, the funds deposited by counterparties are classified as a current asset on the Company's balance sheet, with an offsetting liability for this cash collateral received within current liabilities. Restricted cash consists primarily of funds held within the Company's projects that are restricted for specific uses. Recent Accounting Developments - Guidance Adopted in 2021 ASU 2019-12 — In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, or ASU 2019-12, to simplify various aspects related to accounting for income taxes. The guidance in ASU 2019-12 amends the general principles in Topic 740 to eliminate certain exceptions for recognizing deferred taxes for investment, performing intraperiod allocation and calculating income taxes in interim periods. This ASU also includes guidance to reduce complexity in certain areas, including recognizing deferred taxes for tax goodwill and allocating taxes to members of a consolidated group. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. The Company adopted the amendments effective January 1, 2021 using the prospective approach. The adoption did not have a material impact on the Company's results of operations, cash flows, or statement of financial position. Recent Accounting Developments - Guidance Not Yet Adopted ASU 2020-06 — In August 2020, the FASB issued ASU No. 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity’s Own Equity (Subtopic 815-40) , or ASU 2020-06. The guidance in ASU 2020-06 reduces the number of accounting models for convertible debt instruments and convertible preferred stock. In addition, ASU 2020-06 improves and amends the related earnings per share guidance. This standard is effective for fiscal years beginning after December 15, 2021 and interim periods within those fiscal years. The Company is currently in the process of assessing the impact of this guidance on the consolidated financial statements and disclosures. ASU 2021-08 — In October 2021, the FASB issued ASU No. 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers , or ASU 2021-08. Under current GAAP, an acquirer generally recognizes assets acquired and liabilities assumed in a business combination, including contract assets and contract liabilities arising from revenue contracts with customers and other similar contracts that are accounted for in accordance with ASC 606, Revenue from Contracts with Customers

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition Performance Obligations As of September 30, 2021, estimated future fixed fee performance obligations are $158 million for the remaining three months of fiscal year 2021, and $345 million, $89 million, $37 million and $20 million for the fiscal years 2022, 2023, 2024 and 2025, respectively. Certain performance obligations relate to the fossil generating assets that are planned for sale to Generation Bridge, as further described in Note 4, Acquisitions and Dispositions. These performance obligations are for cleared auction MWs in the PJM, ISO-NE, NYISO and MISO capacity auctions and are subject to penalties for non-performance. Disaggregated Revenues The following tables represent the Company’s disaggregation of revenue from contracts with customers for the three and nine months ended September 30, 2021 and 2020: Three months ended September 30, 2021 (In millions) Texas East West/Services/Other Corporate/Eliminations Total Retail revenue: Home (a) $ 1,776 $ 470 $ 400 $ — $ 2,646 Business 727 2,228 350 — 3,305 Total retail revenue 2,503 2,698 750 — 5,951 Energy revenue (b) 18 201 113 4 336 Capacity revenue (b) — 172 17 — 189 Mark-to-market for economic hedging activities (c) (1) (3) (6) 13 3 Contract amortization — (7) 4 — (3) Other revenue (b) 115 16 6 (4) 133 Total operating revenue 2,635 3,077 884 13 6,609 Less: Lease revenue — — 2 — 2 Less: Realized and unrealized ASC 815 revenue 38 76 (8) 14 120 Less: Contract amortization — (7) 4 — (3) Total revenue from contracts with customers $ 2,597 $ 3,008 $ 886 $ (1) $ 6,490 (a) Home includes Services (b) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: (In millions) Texas East West/Services/Other Corporate/Eliminations Total Energy revenue $ — $ 38 $ 2 $ 1 $ 41 Capacity revenue — 42 — — 42 Other revenue 39 (1) (4) — 34 (c) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 Three months ended September 30, 2020 (In millions) Texas East West/Services/Other Corporate/Eliminations Total Retail revenue: Home (a) $ 1,633 $ 327 $ 27 $ — $ 1,987 Business 288 27 — — 315 Total retail revenue 1,921 354 27 — 2,302 Energy revenue (b) 11 93 117 1 222 Capacity revenue (b) — 158 16 — 174 Mark-to-market for economic hedging activities (c) 1 43 (10) 5 39 Other revenue (b) 59 18 (1) (4) 72 Total operating revenue 1,992 666 149 2 2,809 Less: Lease revenue — — 5 — 5 Less: Realized and unrealized ASC 815 revenue 10 115 (10) 5 120 Total revenue from contracts with customers $ 1,982 $ 551 $ 154 $ (3) $ 2,684 (a) Home includes Services (b) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: (In millions) Texas East West/Services/Other Corporate/Eliminations Total Energy revenue $ — $ 23 $ 13 $ (1) $ 35 Capacity revenue — 49 — — 49 Other revenue 9 — (13) 1 (3) (c) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 Nine months ended September 30, 2021 (In millions) Texas East West/Services/Other Corporate/Eliminations Total Retail revenue: Home (a) $ 4,484 $ 1,469 $ 1,439 $ (1) $ 7,391 Business 2,091 6,560 887 — 9,538 Total retail revenue 6,575 8,029 2,326 (1) 16,929 Energy revenue (c) 317 428 238 6 989 Capacity revenue (c) — 568 47 — 615 Mark-to-market for economic hedging activities (d) (5) (53) (60) 19 (99) Contract amortization — (15) (4) — (19) Other revenue (b)(c) 1,475 45 17 (9) 1,528 Total operating revenue 8,362 9,002 2,564 15 19,943 Less: Lease revenue — 1 5 — 6 Less: Realized and unrealized ASC 815 revenue 129 193 (73) 20 269 Less: Contract amortization — (15) (4) — (19) Total revenue from contracts with customers $ 8,233 $ 8,823 $ 2,636 $ (5) $ 19,687 (a) Home includes Services (b) Other Revenue in Texas includes ancillary revenues of $1.2 billion driven by high pricing during Winter Storm Uri (c) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: (In millions) Texas East West/Services/Other Corporate/Eliminations Total Energy revenue $ — $ 122 $ (4) $ 2 $ 120 Capacity revenue — 119 — — 119 Other revenue 134 5 (9) (1) 129 (d) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 Nine months ended September 30, 2020 (In millions) Texas East West/Services/Other Corporate/Eliminations Total Retail revenue: Home (a) $ 3,938 $ 926 $ 66 $ (1) $ 4,929 Business 796 70 — — 866 Total retail revenue 4,734 996 66 (1) 5,795 Energy revenue (b) 21 157 252 (1) 429 Capacity revenue (b) — 471 47 — 518 Mark-to-market for economic hedging activities (c) 1 63 6 8 78 Other revenue (b) 172 45 36 (7) 246 Total operating revenue 4,928 1,732 407 (1) 7,066 Less: Lease revenue — 1 14 — 15 Less: Realized and unrealized ASC 815 revenue 24 239 50 5 318 Total revenue from contracts with customers $ 4,904 $ 1,492 $ 343 $ (6) $ 6,733 (a) Home includes Services (b) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: (In millions) Texas East West/Services/Other Corporate/Eliminations Total Energy revenue $ — $ 60 $ 42 $ (3) $ 99 Capacity revenue — 114 — — 114 Other revenue 23 2 2 — 27 (c) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 Contract Balances The following table reflects the contract assets and liabilities included in the Company’s balance sheet as of September 30, 2021 and December 31, 2020: (In millions) September 30, 2021 December 31, 2020 Deferred customer acquisition costs $ 124 $ 113 Accounts receivable, net - Contracts with customers 2,955 866 Accounts receivable, net - Derivative instruments 136 33 Accounts receivable, net - Affiliate 5 5 Total accounts receivable, net $ 3,096 $ 904 Unbilled revenues (included within Accounts receivable, net - Contracts with customers) $ 1,268 $ 393 Deferred revenues (a) 312 60 (a) Deferred revenues from contracts with customers for the nine months ended September 30, 2021 and the year ended December 31, 2020 were approximately $303 million and $31 million, respectively The revenue recognized from contracts with customers during the nine months ended September 30, 2021 and 2020 relating to the deferred revenue balance at the beginning of each period was $23 million and $13 million, respectively. The revenue recognized from contracts with customers during the three months ended September 30, 2021 and 2020 relating to the deferred revenue balance at the beginning of each period was $162 million and $31 million, respectively. The change in deferred revenue balances during the three and nine months ended September 30, 2021 and 2020 was primarily due to bill credits owed to certain C&I customers, a portion of which is long-term, as a result of power pricing during Winter Storm Uri and the timing difference of when consideration was received and when the performance obligation was transferred.

Acquisitions and Dispositions

Acquisitions and Dispositions	9 Months Ended
	Sep. 30, 2021
Business Combination and Asset Acquisition [Abstract]
Acquisitions and Dispositions	Acquisitions and Dispositions Acquisitions Direct Energy Acquisition On January 5, 2021 (the "Acquisition Closing Date"), the Company acquired all of the issued and outstanding common shares of Direct Energy, a North American subsidiary of Centrica. Direct Energy is a leading retail provider of electricity, natural gas, and home and business energy related products and services in North America, with operations in all 50 U.S. states and 8 Canadian provinces. The acquisition increased NRG's retail portfolio by over 3 million customers and strengthens its integrated model. It also broadens the Company's presence in the Northeast and into states and locales where it did not previously operate, supporting NRG's objective to diversify its business. The Company paid an aggregate purchase price of $3.625 billion in cash and an initial purchase price adjustment of $77 million. The Company funded the purchase price using a combination of $715 million of cash on hand, $166 million from a draw on its Revolving Credit Facility (of which $107 million was used to fund acquisition costs and financing fees that are not included in the aggregate purchase price above), as well as approximately $2.9 billion in secured and unsecured corporate debt issued in December 2020. The purchase price adjustment resulted in a reduction of $3 million, which is in negotiation with Centrica. The Company expects to receive this payment from Centrica in 2021. The Company also increased its collective liquidity and collateral facilities by $3.4 billion as of the Acquisition Closing Date to meet the additional liquidity requirements related to the acquisition, as detailed in the following table: (In millions) Available on Acquisition Closing Date Revolving Credit Facility commitment increase $ 802 Revolving Credit Facility new tranche 273 Facility agreement in connection with the sale of pre-capitalized trust securities 874 Available as of December 31, 2020 Credit default swap facility 150 Revolving accounts receivable financing facility 750 Repurchase facility 75 Bilateral letter of credit facilities 475 Total Increases to Liquidity and Collateral Facilities $ 3,399 For further discussion see Note 9, Long-term Debt and Finance Leases, and also Note 13, Receivables Securitization and Repurchase Facility, to the Company's 2020 Form 10-K. Acquisition costs were $1 million and $24 million for the three and nine months ended September 30, 2021, respectively, and are included in acquisition-related transaction and integration costs in the Company's consolidated statement of operations. The acquisition has been recorded as a business combination under ASC 805 with identifiable assets acquired and liabilities assumed provisionally recorded at their estimated fair values on the acquisition date. The initial accounting for the business combination is not complete because the evaluation necessary to assess the fair value of certain net assets acquired and the amount of goodwill to be recognized is still in process. The provisional amounts are subject to revision until the evaluations are completed to the extent that additional information is obtained about the facts and circumstances that existed as of the Acquisition Closing Date. The purchase price is provisionally allocated as follows: (In millions) Current Assets Cash and cash equivalents $ 152 Funds deposited by counterparties 21 Restricted cash 9 Accounts receivable, net 1,802 Inventory 106 Derivative instruments 1,014 Cash collateral paid in support of energy risk management activities 233 Prepayments and other current assets 183 Total current assets 3,520 Property, plant and equipment, net 151 Other Assets Goodwill (a) 1,257 Intangible assets, net: Customer relationships (b) 1,277 Customer and supply contracts (b) 610 Trade names (b) 310 Renewable energy credits 124 Total intangible assets, net 2,321 Derivative instruments 531 Other non-current assets 31 Total other assets 4,140 Total Assets $ 7,811 Current Liabilities Accounts payable $ 1,120 Derivative instruments 1,266 Cash collateral received in support of energy risk management activities 21 Accrued expenses and other current liabilities 690 Total current liabilities 3,097 Other Liabilities Derivative instruments 562 Deferred income taxes 338 Other non-current liabilities 115 Total other liabilities 1,015 Total Liabilities $ 4,112 Direct Energy Purchase Price $ 3,699 (a) Goodwill arising from the acquisition is attributed to the value of the platform acquired and the synergies expected from combining the operations of Direct Energy with NRG's existing businesses. Goodwill was provisionally allocated to the Texas, East, and West/Services/Other segments of $424 million, $663 million and $170 million, respectively. Goodwill expected to be deductible for tax purposes is $337 million (b) The weighted average amortization period for total amortizable intangible assets is 12 years Measurement Period Adjustments The following measurement period adjustments were recognized during the quarter ended September 30, 2021: (In millions) Increase/(Decrease) Assets Goodwill $ 11 Intangible assets, net (32) Total decrease in assets $ (21) Liabilities Accounts payable $ (270) Accrued expenses and other current liabilities 248 Deferred income taxes (1) Other non-current liabilities 2 Total decrease in liabilities $ (21) The measurement period adjustments to the provisional amounts are attributable primarily to refinement of the underlying assumptions used to estimate the fair value of assets acquired and liabilities assumed as more information is obtained about facts and circumstances that existed as of the Acquisition Closing Date. Fair Value Measurement of Intangible Assets The provisional fair values of intangible assets as of the Acquisition Closing Date were measured primarily based on significant inputs that are observable and unobservable in the market and thus represent Level 2 and Level 3 measurements, respectively. Significant inputs were as follows: Customer relationships — Customer relationships, reflective of Direct Energy’s customer base, were valued using an excess earning method of the income approach. Under this approach, the Company estimated the present value of expected future cash flows resulting from existing customer relationships, considering attrition and charges for contributory assets (such as net working capital, fixed assets, workforce and trade names) utilized in the business, discounted at an independent power producer peer group’s weighted average cost of capital. The customer relationships are amortized to depreciation and amortization, ratably based on discounted future cash flows. The weighted average amortization period is 12 years. Customer and supply contracts — The fair value of in-market and out-of-market customer and supply contracts were estimated based on contractual terms compared to market prices as of the Acquisition Closing Date. The majority of the contracts were valued using prices provided by external sources, primarily price quotations available through broker or over-the-counter and online exchanges. For contracts for which external sources or observable market quotes were not available, these values were based on valuation techniques including, but not limited to, internal models based on fundamental analysis of the market and extrapolation of the observable market data with similar characteristics. In addition, the Company applied a credit reserve to reflect credit risk, which is calculated based on published default probabilities. The customer and supply contracts are amortized to revenue and cost of operations, respectively, based upon the fair market value, as of the acquisition date, for each delivery month. The weighted average amortization period is 14 years. Trade names — Trade names were valued using a "relief from royalty" method of the income approach. Under this approach, the fair value is estimated to be the present value of royalties saved because NRG owns the intangible asset and therefore does not have to pay a royalty for its use. The trade names are amortized to depreciation and amortization, on a straight line basis, over a weighted average amortization period of 15 years. Renewable energy credits — Renewable energy credits were valued based on the market prices as of the Acquisition Closing Date. Renewable energy credits are retired, as required, for the applicable compliance period. They are expensed to cost of operations based on customer usage. Fair Value Measurement of Derivative Assets and Liabilities The fair values of derivatives assets and liabilities as of the Acquisition Closing Date were as follows: Fair Value (In millions) Total Level 1 Level 2 Level 3 Derivatives assets $ 1,545 $ 155 $ 1,272 $ 118 Derivatives liabilities $ 1,828 $ 207 $ 1,489 $ 132 Refer to Note 5, Fair Value of Financial Instruments to this Form 10-Q and Note 5, Fair Value of Financial Instruments to the Company's 2020 Form 10-K for discussion on derivative fair value measurements. Supplemental Information For the three and nine months ended September 30, 2021 Direct Energy contributed revenue and income before income taxes as follows: (In millions) Three months ended September 30, 2021 Nine months ended September 30, 2021 Revenue $ 3,599 $ 10,718 Income before income taxes 2,010 3,457 Supplemental Pro Forma Financial Information for the nine months ended September 30, 2021 and 2020 (a) The following table provides pro forma combined financial information of NRG and Direct Energy, after giving effect to the Direct Energy acquisition and related financing transactions as if they had occurred on January 1, 2020. The pro forma financial information has been prepared for illustrative and informational purposes only, and is not intended to project future operating results or indicative of what our financial performance would have been had the transactions occurred on the date assumed. No effect has been given to operating synergies. (In millions) Nine months ended September 30, 2021 Nine months ended September 30, 2020 Total operating revenues $ 19,932 $ 16,039 Net Income 2,585 832 (a) Pro forma comparative financial information for the three months ended September 30, 2021 and 2020 has not been included as computation of such information is impracticable as Direct Energy's pre-acquisition financial statements for the three months ended September 30, 2020 were not prepared in accordance with GAAP Amounts above reflect certain pro forma adjustments that were directly attributable to the Direct Energy acquisition. These adjustments include the following: (i) Income statement effects of fair value adjustments based on the preliminary purchase price allocation including amortization of intangible assets, depreciation of property, plant and equipment and lease expense. (ii) Interest expense assumes the financing transactions directly attributable to the Direct Energy acquisition occurred on January 1, 2020. (iii) Removal of Direct Energy historical interest expense associated with related party notes receivable/payable between Direct Energy and Centrica and its subsidiaries, as those notes are assumed to be repaid as of January 1, 2020. (iv) Elimination of transactions between NRG and Direct Energy. (v) Adjustments to reflect all acquisition costs occurring during the nine months ended September 30, 2020. (vi) Tax effects of pro forma adjustments on both periods and shifting the recognition of one time tax benefits resulting from the acquisition from the nine months ended September 30, 2021 to the period ended September 30, 2020. Midwest Generation Lease Purchase On September 29, 2020, Midwest Generation acquired all of the ownership interests in the Powerton facility and Units 7 and 8 of the Joliet facility, which were being leased through 2034 and 2030, respectively, for approximately $260 million. The purchase was funded with cash-on-hand. Upon closing the operating lease liability of $148 million was eliminated. Dispositions On February 28, 2021, the Company entered into a definitive purchase agreement with Generation Bridge, an affiliate of ArcLight Capital Partners, to sell approximately 4,850 MW of fossil generating assets from its East and West regions of operations for total proceeds of $760 million, subject to standard purchase price adjustments and certain other indemnifications. The purchase price adjustments will include a working capital deduction for cash flows generated of approximately $11 million per month from the beginning of the year until the closing of the transaction, in lieu of cash flows generated during the year. As part of the transaction, NRG is entering into a tolling agreement for its 866 MW Arthur Kill plant in New York City through April 2025. The transaction is expected to close by the end of 2021 and is subject to various closing conditions, approvals and consents, including approval from the NYPSC. The transaction has received FERC approval and approval under the Hart-Scott-Rodino Act. As of September 30, 2021, the following is classified as held for sale in the Consolidated Balance Sheet: (In millions) (a) Current assets (b) $ 51 Property, plant and equipment, net 391 Other non-current assets 3 Total non-current assets (c) 394 Total assets held for sale $ 445 Current liabilities (d) 14 Non-current liabilities (e) 61 Total liabilities held for sale $ 75 (a) Property, plant and equipment, net for the East and West/Services/Other segments was $242 million and $149 million, respectively. The remaining assets and liabilities were primarily in the East segment (b) Included in prepayments and other current assets in the Consolidated Balance Sheet (c) Included in other non-current assets in the Consolidated Balance Sheet (d) Included in accrued expenses and other current liabilities in the Consolidated Balance Sheet (e) Included in other non-current liabilities in the Consolidated Balance Sheet On February 3, 2021, the Company closed on the sale of its 35% ownership in the Agua Caliente solar project to Clearway Energy, Inc. for $202 million. NRG recognized a gain on the sale of $17 million, including cash disposed of $7 million. The Company completed other asset sales for cash proceeds of $3 million and $15 million during the nine months ended September 30, 2021 and 2020, respectively.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments For cash and cash equivalents, funds deposited by counterparties, restricted cash, accounts and other receivables, accounts payable, and cash collateral paid and received in support of energy risk management activities, the carrying amounts approximate fair values because of the short-term maturity of those instruments and are classified as Level 1 within the fair value hierarchy. The estimated carrying amounts and fair values of NRG's recorded financial instruments not carried at fair market value are as follows: September 30, 2021 December 31, 2020 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Assets: Notes receivable $ 2 $ 2 $ 2 $ 2 Liabilities: Long-term debt, including current portion (a) 8,537 8,897 8,781 9,446 (a) Excludes deferred financing costs, which are recorded as a reduction to long-term debt in the Company's consolidated balance sheets The fair value of the Company's publicly-traded long-term debt is based on quoted market prices and is classified as Level 2 within the fair value hierarchy. The fair value of certain notes receivable of the Company is based on expected future cash flows discounted at market interest rate and is classified as Level 3 within the fair value hierarchy. Recurring Fair Value Measurements Debt securities, equity securities, and trust fund investments, which are comprised of various U.S. debt and equity securities, and derivative assets and liabilities, are carried at fair market value. The following tables present assets and liabilities measured and recorded at fair value on the Company's condensed consolidated balance sheets on a recurring basis and their level within the fair value hierarchy: September 30, 2021 (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and non-current assets) $ 23 $ 7 $ 16 $ — Nuclear trust fund investments: Cash and cash equivalents 29 29 — — U.S. government and federal agency obligations 76 75 1 — Federal agency mortgage-backed securities 93 — 93 — Commercial mortgage-backed securities 43 — 43 — Corporate debt securities 116 — 116 — Equity securities 503 503 — — Foreign government fixed income securities 4 — 4 — Other trust fund investments (classified within other non-current assets): U.S. government and federal agency obligations 1 1 — — Derivative assets: Foreign exchange contracts 1 — 1 — Commodity contracts 11,198 2,161 8,474 563 Measured using net asset value practical expedient: Equity securities — nuclear trust fund investments 93 Equity securities (classified within other non-current assets) 8 Total assets $ 12,188 $ 2,776 $ 8,748 $ 563 Derivative liabilities: Commodity contracts $ 7,521 $ 1,376 $ 5,893 $ 252 Total liabilities $ 7,521 $ 1,376 $ 5,893 $ 252 December 31, 2020 (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and non-current assets) $ 25 $ 10 $ 15 $ — Nuclear trust fund investments: Cash and cash equivalents 23 23 — — U.S. government and federal agency obligations 70 69 1 — Federal agency mortgage-backed securities 89 — 89 — Commercial mortgage-backed securities 36 — 36 — Corporate debt securities 144 — 144 — Equity securities 434 434 — — Foreign government fixed income securities 7 1 6 — Other trust fund investments (classified within other non-current assets): U.S. government and federal agency obligations 1 1 — — Derivative assets: Commodity contracts 821 59 623 139 Measured using net asset value practical expedient: Equity securities — nuclear trust fund investments 87 Equity securities (classified within other non-current assets) 8 Total assets $ 1,745 $ 597 $ 914 $ 139 Derivative liabilities: Commodity contracts $ 884 $ 86 $ 643 $ 155 Total liabilities $ 884 $ 86 $ 643 $ 155 The following table reconciles, for the three and nine months ended September 30, 2021 and 2020, the beginning and ending balances for financial instruments that are recognized at fair value in the condensed consolidated financial statements, using significant unobservable inputs: Fair Value Measurement Using Significant Unobservable Inputs (Level 3) Three months ended September 30, 2021 Nine months ended September 30, 2021 (In millions) Derivatives (a) Derivatives (a) Beginning balance $ 574 $ (16) Contracts added from Direct Energy acquisition — (15) Total (losses)/gains realized/unrealized— included in earnings (175) 187 Purchases — 78 Transfers into Level 3 (b) (108) 64 Transfers out of Level 3 (b) 20 13 Ending balance $ 311 $ 311 (Losses)/gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of period end $ (237) $ 184 (a) Consists of derivative assets and liabilities, net (b) Transfers into/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. All transfers in/out are with Level 2 Fair Value Measurement Using Significant Unobservable Inputs (Level 3) Three months ended September 30, 2020 Nine months ended September 30, 2020 (In millions) Derivatives (a) Derivatives (a) Beginning balance $ 152 $ 38 Total (losses) realized/unrealized — included in earnings (92) (18) Purchases (10) 6 Transfers into Level 3 (b) (11) 22 Transfers out of Level 3 (b) 13 4 Ending balance $ 52 $ 52 Gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of period end $ 23 $ 50 (a) Consists of derivative assets and liabilities, net (b) Transfers into/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. All transfers in/out are with Level 2 Derivative Fair Value Measurements A portion of NRG's contracts are exchange-traded contracts with readily available quoted market prices. A majority of NRG's contracts are non-exchange-traded contracts valued using prices provided by external sources, primarily price quotations available through brokers or over-the-counter and on-line exchanges. The remainder of the assets and liabilities represent contracts for which external sources or observable market quotes are not available. These contracts are valued based on various valuation techniques including, but not limited to, internal models based on a fundamental analysis of the market and extrapolation of the observable market data with similar characteristics. As of September 30, 2021, contracts valued with prices provided by models and other valuation techniques make up 5% of derivative assets and 3% of derivative liabilities. NRG's significant positions classified as Level 3 include physical and financial natural gas and power contracts executed in illiquid markets, as well as FTRs. The significant unobservable inputs used in developing fair value include illiquid natural gas and power location pricing, which is derived as a basis to liquid locations. The basis spread is based on observable market data when available or derived from historic prices and forward market prices from similar observable markets when not available. For FTRs, NRG uses the most recent auction prices to derive the fair value. The following tables quantify the significant unobservable inputs used in developing the fair value of the Company's Level 3 positions as of September 30, 2021 and December 31, 2020: September 30, 2021 Fair Value Input/Range (In millions) Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average Natural Gas Contracts $ 19 $ 3 Discounted Cash Flow Forward Market Price (per MMBtu) $ 3 $ 49 $ 19 Power Contracts 512 218 Discounted Cash Flow Forward Market Price (per MWh) 3 263 40 FTRs 32 31 Discounted Cash Flow Auction Prices (per MWh) (131) 755 — $ 563 $ 252 December 31, 2020 Fair Value Input/Range (In millions) Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average Power Contracts $ 111 $ 143 Discounted Cash Flow Forward Market Price (per MWh) $ 10 $ 105 $ 21 FTRs 28 12 Discounted Cash Flow Auction Prices (per MWh) (28) 43 0 $ 139 $ 155 The following table provides sensitivity of fair value measurements to increases/(decreases) in significant unobservable inputs as of September 30, 2021 and December 31, 2020: Significant Unobservable Input Position Change In Input Impact on Fair Value Measurement Forward Market Price Natural Gas/Power Buy Increase/(Decrease) Higher/(Lower) Forward Market Price Natural Gas/Power Sell Increase/(Decrease) Lower/(Higher) FTR Prices Buy Increase/(Decrease) Higher/(Lower) FTR Prices Sell Increase/(Decrease) Lower/(Higher) The fair value of each contract is discounted using a risk-free interest rate. In addition, the Company applies a credit reserve to reflect credit risk, which is calculated based on published default probabilities. As of September 30, 2021, the credit reserve resulted in a $7 million decrease primarily within cost of operations. As of December 31, 2020, the credit reserve resulted in a $2 million increase primarily within cost of operations. Concentration of Credit Risk In addition to the credit risk discussion as disclosed in Note 2, Summary of Significant Accounting Policies , to the Company's 2020 Form 10-K, the following is a discussion of the concentration of credit risk for the Company's contractual obligations. Credit risk relates to the risk of loss resulting from non-performance or non-payment by counterparties pursuant to the terms of their contractual obligations. NRG is exposed to counterparty credit risk through various activities including wholesale sales, fuel purchases and retail supply arrangements, as well as retail customer credit risk through its retail load activities. Counterparty Credit Risk The Company's counterparty credit risk policies are disclosed in its 2020 Form 10-K. As of September 30, 2021, counterparty credit exposure, excluding credit exposure from RTOs, ISOs, registered commodity exchanges and certain long-term agreements, was $2.9 billion and NRG held collateral (cash and letters of credit) against those positions of $1.1 billion, resulting in a net exposure of $1.9 billion. NRG periodically receives collateral from counterparties in excess of their exposure. Collateral amounts shown include such excess while net exposure shown excludes excess collateral received. Approximately 59% of the Company's exposure before collateral is expected to roll off by the end of 2022. Counterparty credit exposure is valued through observable market quotes and discounted at a risk free interest rate. The following tables highlight net counterparty credit exposure by industry sector and by counterparty credit quality. Net counterparty credit exposure is defined as the aggregate net asset position for NRG with counterparties where netting is permitted under the enabling agreement and includes all cash flow, mark-to-market and NPNS, and non-derivative transactions. The exposure is shown net of collateral held and includes amounts net of receivables or payables. Net Exposure (a)(b) Category by Industry Sector (% of Total) Utilities, energy merchants, marketers and other 49 % Financial institutions 51 Total as of September 30, 2021 100 % Net Exposure (a)(b) Category by Counterparty Credit Quality (% of Total) Investment grade 78 % Non-investment grade/non-rated 22 Total as of September 30, 2021 100 % (a) Counterparty credit exposure excludes uranium and coal transportation contracts because of the unavailability of market prices (b) The figures in the tables above exclude potential counterparty credit exposure related to RTOs, ISOs, registered commodity exchanges and certain long-term contracts The Company currently has no exposure to wholesale counterparties in excess of 10% of total net exposure discussed above as of September 30, 2021. Changes in hedge positions and market prices will affect credit exposure and counterparty concentration. During Winter Storm Uri, the Company experienced nonperformance by a counterparty in one of its bilateral financial hedging transactions, resulting in exposure of $403 million. The Company is pursuing all means available to enforce its rights under this transaction but, given the size of the exposure, cannot determine with certainty what the amount of its ultimate recovery will be. The full exposure was recorded as a provision for credit losses during the nine months ended September 30, 2021. RTOs and ISOs The Company participates in the organized markets of CAISO, ERCOT, AESO, IESO, ISO-NE, MISO, NYISO and PJM, known as RTOs or ISOs. Trading in the majority of these markets is approved by FERC, whereas in the case of ERCOT, it is approved by the PUCT, and whereas in the case of AESO and IESO, both exist provincially with AESO primarily subject to Alberta Utilities Commission and the IESO to the Ontario Energy Board. These ISOs may include credit policies that, under certain circumstances, require that losses arising from the default of one member on spot market transactions be shared by the remaining participants. As a result, the counterparty credit risk to these markets is limited to NRG’s share of the overall market and are excluded from the above exposures. Exchange Traded Transactions The Company enters into commodity transactions on registered exchanges, notably ICE, NYMEX and Nodal. These clearinghouses act as the counterparty and transactions are subject to extensive collateral and margining requirements. As a result, these commodity transactions have limited counterparty credit risk. Long-Term Contracts Counterparty credit exposure described above excludes credit risk exposure under certain long-term contracts, primarily solar PPAs. As external sources or observable market quotes are not always available to estimate such exposure, the Company values these contracts based on various techniques including, but not limited to, internal models based on a fundamental analysis of the market and extrapolation of observable market data with similar characteristics. Based on these valuation techniques, as of September 30, 2021, aggregate credit risk exposure managed by NRG to these counterparties was approximately $1.4 billion for the next five years. Retail Customer Credit Risk The Company is exposed to retail credit risk through the Company's retail electricity and gas providers, which serve Home and Business customers. Retail credit risk results in losses when a customer fails to pay for services rendered. The losses may result from both non-payment of customer accounts receivable and the loss of in-the-money forward value. The Company manages retail credit risk through the use of established credit policies that include monitoring of the portfolio and the use of credit mitigation measures such as deposits or prepayment arrangements.

Nuclear Decommissioning Trust F

Nuclear Decommissioning Trust Fund	9 Months Ended
	Sep. 30, 2021
Regulated Operations [Abstract]
Nuclear Decommissioning Trust Fund	Nuclear Decommissioning Trust Fund NRG's Nuclear Decommissioning Trust Fund assets, which are for the decommissioning of its 44% interest in STP, are comprised of securities classified as available-for-sale and recorded at fair value based on actively quoted market prices. NRG accounts for the Nuclear Decommissioning Trust Fund in accordance with ASC 980, Regulated Operations , because the Company's nuclear decommissioning activities are subject to approval by the PUCT with regulated rates that are designed to recover all decommissioning costs and that can be charged to and collected from the ratepayers per PUCT mandate. Since the Company is in compliance with PUCT rules and regulations regarding decommissioning trusts and the cost of decommissioning is the responsibility of the Texas ratepayers, not NRG, all realized and unrealized gains or losses (including other-than-temporary impairments) related to the Nuclear Decommissioning Trust Fund are recorded to the Nuclear Decommissioning Trust liability and are not included in net income or accumulated OCI, consistent with regulatory treatment. The following table summarizes the aggregate fair values and unrealized gains and losses for the securities held in the trust funds, as well as information about the contractual maturities of those securities. As of September 30, 2021 As of December 31, 2020 (In millions, except maturities) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Cash and cash equivalents $ 29 $ — $ — — $ 23 $ — $ — — U.S. government and federal agency obligations 76 4 — 12 70 6 — 10 Federal agency mortgage-backed securities 93 3 — 24 89 4 — 24 Commercial mortgage-backed securities 43 1 — 27 36 2 — 27 Corporate debt securities 116 8 1 14 144 13 — 12 Equity securities 596 439 — — 521 372 — — Foreign government fixed income securities 4 — — 12 7 1 — 10 Total $ 957 $ 455 $ 1 $ 890 $ 398 $ — The following table summarizes proceeds from sales of available-for-sale securities held in the trust funds and the related realized gains and losses from these sales. The cost of securities sold is determined on the specific identification method. Nine months ended September 30, (In millions) 2021 2020 Realized gains $ 10 $ 22 Realized losses (6) (11) Proceeds from sale of securities 424 318

Accounting for Derivative Instr

Accounting for Derivative Instruments and Hedging Activities	9 Months Ended
	Sep. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Accounting for Derivative Instruments and Hedging Activities	Accounting for Derivative Instruments and Hedging Activities Energy-Related Commodities As of September 30, 2021, NRG had energy-related derivative instruments extending through 2036. The Company marks these derivatives to market through the statement of operations. NRG has executed power purchase agreements extending through 2038 that qualified for the NPNS exception and were therefore exempt from fair value accounting treatment. Foreign Exchange Contracts NRG is exposed to changes in foreign currency associated with the purchase of USD denominated natural gas for its Canadian business. In order to manage the Company's foreign exchange risk, NRG entered into foreign exchange contracts. As of September 30, 2021, NRG had foreign exchange contracts extending through 2024. The Company marks these derivatives to market through the statement of operations. Volumetric Underlying Derivative Transactions The following table summarizes the net notional volume buy/(sell) of NRG's open derivative transactions broken out by category, excluding those derivatives that qualified for the NPNS exception, as of September 30, 2021 and December 31, 2020. Option contracts are reflected using delta volume. Delta volume equals the notional volume of an option adjusted for the probability that the option will be in-the-money at its expiration date. Total Volume (In millions) Category Units September 30, 2021 December 31, 2020 Emissions Short Ton 1 1 Renewable Energy Certificates Certificates 13 5 Coal Short Ton 3 2 Natural Gas MMBtu 663 (286) Oil Barrels 1 — Power MWh 185 57 Capacity MW/Day — (1) Foreign Exchange Dollars $ 218 $ — The increase in positions was primarily the result of the Direct Energy acquisition. Fair Value of Derivative Instruments The following table summarizes the fair value within the derivative instrument valuation on the balance sheets: Fair Value Derivative Assets Derivative Liabilities (In millions) September 30, 2021 December 31, 2020 September 30, 2021 December 31, 2020 Derivatives Not Designated as Cash Flow or Fair Value Hedges: Foreign exchange contracts - current $ 1 $ — $ — $ — Commodity contracts - current 8,527 560 6,032 499 Commodity contracts - long-term 2,671 261 1,489 385 Total Derivatives Not Designated as Cash Flow or Fair Value Hedges $ 11,199 $ 821 $ 7,521 $ 884 The Company has elected to present derivative assets and liabilities on the balance sheet on a trade-by-trade basis and does not offset amounts at the counterparty master agreement level. In addition, collateral received or paid on the Company's derivative assets or liabilities are recorded on a separate line item on the balance sheet. The following table summarizes the offsetting of derivatives by counterparty master agreement level and collateral received or paid: Gross Amounts Not Offset in the Statement of Financial Position (In millions) Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount As of September 30, 2021 Foreign exchange contracts: Derivative assets $ 1 $ — $ — $ 1 Total foreign exchange contracts $ 1 $ — $ — $ 1 Commodity contracts: Derivative assets $ 11,198 $ (6,946) $ (1,712) $ 2,540 Derivative liabilities (7,521) 6,946 — (575) Total commodity contracts $ 3,677 $ — $ (1,712) $ 1,965 Total derivative instruments $ 3,678 $ — $ (1,712) $ 1,966 Gross Amounts Not Offset in the Statement of Financial Position (In millions) Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount As of December 31, 2020 Commodity contracts: Derivative assets $ 821 $ (658) $ (5) $ 158 Derivative liabilities (884) 658 — (226) Total commodity contracts $ (63) $ — $ (5) $ (68) Impact of Derivative Instruments on the Statements of Operations Unrealized gains and losses associated with changes in the fair value of derivative instruments not accounted for as cash flow and fair value hedges are reflected in current period results of operations. The following table summarizes the pre-tax effects of economic hedges that have not been designated as cash flow hedges or fair value hedges and trading activity on the Company's statement of operations. The effect of foreign exchange and commodity hedges are included within operating revenues and cost of operations. (In millions) Three months ended September 30, Nine months ended September 30, Unrealized mark-to-market results 2021 2020 2021 2020 Reversal of previously recognized unrealized (gains) on settled positions related to economic hedges $ (97) $ (101) $ (58) $ (62) Reversal of acquired (gain)/loss positions related to economic hedges (42) (2) 206 2 Net unrealized gains/(losses) on open positions related to economic hedges 1,924 (15) 3,875 73 Total unrealized mark-to-market gains/(losses) for economic hedging activities 1,785 (118) 4,023 13 Reversal of previously recognized unrealized (gains) on settled positions related to trading activity (6) (7) (16) (14) Net unrealized gains on open positions related to trading activity 14 2 18 19 Total unrealized mark-to-market gains/(losses) for trading activity 8 (5) 2 5 Total unrealized gains/(losses) $ 1,793 $ (123) $ 4,025 $ 18 Three months ended September 30, Nine months ended September 30, (In millions) 2021 2020 2021 2020 Unrealized gains/(losses) included in operating revenues - commodities $ 11 $ 34 $ (97) $ 83 Unrealized gains/(losses) included in cost of operations - commodities 1,777 (157) 4,121 (65) Unrealized gains included in cost of operations - foreign exchange 5 — 1 — Total impact to statement of operations $ 1,793 $ (123) $ 4,025 $ 18 The reversals of acquired loss positions were valued based upon the forward prices on the acquisition date. The roll-off amounts were offset by realized gains or losses at the settled prices and are reflected in operating revenue or cost of operations during the same period. For the nine months ended September 30, 2021, the $3.9 billion unrealized gain from open economic hedge positions was primarily the result of an increase in value of forward positions as a result of increases in natural gas and power prices. For the nine months ended September 30, 2020, the $73 million unrealized gain from open economic hedge positions was primarily the result of an increase in value of forward positions as a result of decreases in New York capacity and power prices, as well as increases in ERCOT power prices. Credit Risk Related Contingent Features Certain of the Company's hedging and trading agreements contain provisions that entitle the counterparty to demand that the Company post additional collateral if the counterparty determines that there has been deterioration in the Company's credit quality, generally termed “adequate assurance” under the agreements, or require the Company to post additional collateral if there were a downgrade in the Company's credit rating. In addition, as a result of the acquisition of Direct Energy from Centrica, certain of the Company’s agreements as of September 30, 2021, were still supported by credit support posted by Centrica, and as a result could require the Company to post collateral upon a deterioration or downgrade of Centrica. The collateral potentially required for all contracts with adequate assurance clauses that are in a net liability position as of September 30, 2021 was $865 million. The Company is also party to certain marginable agreements under which it has net liability position, but the counterparty has not called for the collateral due, which was $92 million as of September 30, 2021. In the event of a downgrade in the Company's credit rating and if called for by the counterparty, $35 million of additional collateral would be required for all contracts with credit rating contingent features as of September 30, 2021. See Note 5, Fair Value of Financial Instruments , for discussion regarding concentration of credit risk.

Impairments

Impairments	9 Months Ended
	Sep. 30, 2021
Property, Plant and Equipment [Abstract]
Impairments	Impairments 2021 Impairment Losses PJM Asset Impairments — During the second quarter of 2021, the results of the PJM Base Residual Auction for the 2022/2023 delivery year were released leading the Company to announce the near-term retirement of a significant portion of its PJM coal generating assets in June 2022. The Company considered the decline in PJM capacity prices and the near-term retirement dates of certain assets to be a trigger for impairment and performed impairment tests on the PJM generating assets and the goodwill associated with Midwest Generation. The Company measured the impairment losses on the PJM generation assets and Midwest Generation goodwill as the difference between the carrying amount and the fair value of the PJM generating assets and Midwest Generation reporting unit, respectively. Fair values were determined using an income approach in which the Company applied a discounted cash flow methodology to the long-term budgets for the plants and reporting unit. Significant inputs impacting the income approach include the Company's long-term view of capacity and fuel prices, projected generation, the physical and economic characteristics of each plant, and the discount rate applied to the after-tax cash flow projections. Impairment losses of $271 million and $35 million were recorded in the East segment on the PJM generating assets and Midwest Generation goodwill, respectively. 2020 Impairment Losses Home Solar — During the third quarter of 2020, the Company concluded its Home Solar business was held for sale as a result of advanced negotiations to sell the business. NRG recorded impairment losses of $29 million in the West/Other segment to adjust the carrying amount of the assets and liabilities to fair market value based on indicative sale prices. Petra Nova Parish Holdings — During the first quarter of 2020, due to the decline in oil prices, NRG determined that the carrying amount of the Company’s equity method investment exceeded the fair value of the investment and that the decline was considered to be other-than-temporary. In determining the fair value, the Company utilized an income approach to estimate future project cash flows. The Company recorded an impairment loss of $18 million in the Texas segment, which included the anticipated drawdown of the $12 million letter of credit posted in September 2019 to cover certain project debt reserve requirements.

Long-term Debt and Finance Leas

Long-term Debt and Finance Leases	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Long-term Debt and Finance Leases	Long-term Debt and Finance Leases Long-term debt and finance leases consisted of the following: (In millions, except rates) September 30, 2021 December 31, 2020 Interest rate % Recourse debt: Senior Notes, due 2026 $ — $ 1,000 7.250 Senior Notes, due 2027 875 1,230 6.625 Senior Notes, due 2028 821 821 5.750 Senior Notes, due 2029 733 733 5.250 Senior Notes, due 2029 500 500 3.375 Senior Notes, due 2031 1,030 1,030 3.625 Senior Notes, due 2032 1,100 — 3.875 Convertible Senior Notes, due 2048 (a) 575 575 2.750 Senior Secured First Lien Notes, due 2024 600 600 3.750 Senior Secured First Lien Notes, due 2025 500 500 2.000 Senior Secured First Lien Notes, due 2027 900 900 2.450 Senior Secured First Lien Notes, due 2029 500 500 4.450 Tax-exempt bonds 466 466 1.250 - 4.750 Subtotal recourse debt 8,600 8,855 Finance leases 13 4 various Subtotal long-term debt and finance leases (including current maturities) 8,613 8,859 Less current maturities (504) (1) Less debt issuance costs (89) (93) Discounts (63) (74) Total long-term debt and finance leases $ 7,957 $ 8,691 (a) As of the ex-dividend date of October 29, 2021, the Convertible Senior Notes were convertible at a price of $44.89, which is equivalent to a conversion rate of approximately 22.2761 shares of common stock per $1,000 principal amount Recourse Debt Issuance of 2032 Senior Notes On August 23, 2021, the Company issued $1.1 billion of aggregate principal amount at par of 3.875% senior notes due 2032 (the "2032 Senior Notes"). The 2032 Senior Notes are senior unsecured obligations of NRG and are guaranteed by certain of its subsidiaries. Interest is paid semi-annually beginning on February 15, 2022 until the maturity date of February 15, 2032. The 2032 Senior Notes were issued under NRG's Sustainability-Linked Bond Framework, which sets out certain sustainability targets, including reducing greenhouse gas emissions. Failure to meet such sustainability targets will result in a 25 basis point increase to the interest rate payable on the 2032 Senior Notes from and including August 15, 2026. The proceeds of the 2032 Senior Notes, along with cash on hand, were used to fund the redemption of $1.0 billion 7.250% Senior Notes due 2026 and $355 million of 6.625% Senior Notes due 2027. 2021 Senior Note Redemptions On August 24, 2021, the Company redeemed $1.4 billion in aggregate principal of its Senior Notes for $1.4 billion using the proceeds of the 2032 Senior Notes and cash on hand. In connection with the redemptions, a $57 million loss on debt extinguishment was recorded, which included the write-off of previously deferred financing costs of $9 million, during the nine months ended September 30, 2021. The Company redeemed an additional $500 million of its 6.625% Senior Notes due 2027 in October 2021. (In millions, except percentages) Principal Repurchased Cash Paid (a) Average Early Redemption Percentage 7.250% Senior Notes, due 2026 $ 1,000 $ 1,056 103.625 % 6.625% Senior Notes, due 2027 355 369 103.313 % Total Redemptions during the nine months ended September 30, 2021 $ 1,355 $ 1,425 6.625% Senior Notes, due 2027 $ 500 $ 524 103.313 % Total Redemptions January 1, 2021 through November 4, 2021 $ 1,855 $ 1,949 (a) Includes accrued interest of $22 million and $29 million for redemptions through September 30, 2021 and November 4, 2021, respectively Receivables Securitization Facilities On July 26, 2021, NRG Receivables LLC, a wholly-owned indirect subsidiary of the Company, entered into the First Amendment to its accounts receivable securitized borrowing facility dated September 22, 2020 with a group of conduit lenders and banks and Royal Bank of Canada, as Administrative Agent (as amended, the “Receivables Facility”) to, among other things, (i) increase the existing revolving commitments by $50 million to an aggregate amount of $800 million, (ii) extend the maturity date until July 26, 2022, (iii) make certain adjustments to the pool of receivables through the Receivables Facility and certain related covenants and (iv) provide for revised language relating to interest determination based on SOFR in case of a LIBOR cessation or the occurrence of certain other trigger events. As of September 30, 2021, there were no outstanding borrowings and there were $400 million in letters of credit issued under the Receivables Facility. On July 26, 2021, the Company renewed its existing Repurchase Facility to, among other things, (i) extend the maturity date to July 26, 2022 and (ii) provide for revised language relating to interest determination based on SOFR in case of a LIBOR cessation or the occurrence of certain other trigger events. Revolving Credit Facility During the third quarter of 2020, the Company amended its existing credit agreement to, among other things, (i) increase the existing revolving commitments in an aggregate amount of $802 million, and (ii) provide for a new tranche of revolving commitments in an aggregate amount of $273 million with a maturity date of July 5, 2023. The maturity date of the new revolving tranche of commitments may, upon request by the Company, and at the option of each applicable lender under the new tranche be extended to May 28, 2024, which is the maturity date of the existing and increased commitments. Other than with respect to the maturity date, the terms of all revolving commitments and loans made pursuant thereto are identical. The increase in the existing commitments, and the commitments with respect to the new tranche were effective on August 20, 2020 and became available on January 5, 2021 upon the closing of the Direct Energy Acquisition. As of September 30, 2021, total revolving commitments available, subject to usage, under the amended credit agreement was $3.7 billion. Non-Recourse Debt Put Option Agreement for Senior Debt Issuance As further discussed in Part IV, Item 15, Note 14, Long-term Debt and Finance Leases of the Company's 2020 Form 10-K, the Company entered into a Put Option Agreement for Senior Debt Issuances (the “P-Caps”). In connection with the issuance of the P-Caps, on December 11, 2020, NRG entered into an amended and restated facility agreement for the issuance of letters of credit (the “LC Agreement”) with Deutsche Bank Trust Company Americas as collateral agent (the “Collateral Agent”) and administrative agent pursuant to which certain financial institutions (the “LC Issuers”) have agreed to provide letters of credit in an aggregate amount not to exceed $874 million to support the operations of NRG and its subsidiaries and minority investments, including to replace certain letters of credit and other credit support issued for the account of entities acquired pursuant to the Direct Energy Acquisition. In addition, on December 11, 2020, the Trust entered into an amended and restated pledge and control agreement (the “Pledge Agreement”), among NRG, the Trust and the Collateral Agent for the LC Issuers, under which the Trust agreed to grant a pledge over the Eligible Treasury Assets in favor of the Collateral Agent for the benefit of the LC Issuers. Pursuant to the LC Agreement and the Pledge Agreement, the Collateral Agent is entitled to withdraw Eligible Treasury Assets from the Trust’s pledged account, following notice to NRG, in the event NRG has failed to reimburse amounts drawn under any letter of credit issued pursuant to the LC Agreement, and the LC Issuers have the right to instruct the Collateral Agent to enforce the pledge over the Eligible Treasury Assets upon the occurrence of any event of default under the LC Agreement. The LC Agreement and the Pledge Agreement were available on January 5, 2021. As of September 30, 2021, $864 million of letters of credit were issued under the LC Agreement .

Investments Accounted for Using

Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs	9 Months Ended
	Sep. 30, 2021
Variable Interest Entities Disclosure [Abstract]
Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs	Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs Entities that are not Consolidated NRG accounts for the Company's significant investments using the equity method of accounting. NRG's carrying value of equity investments can be impacted by a number of elements including impairments, unrealized gains and losses on derivatives and movements in foreign currency exchange rates. On February 3, 2021, the Company sold its 35% ownership in Agua Caliente to Clearway Energy, Inc. for $202 million as further described in Note 4, Acquisitions and Dispositions. Variable Interest Entities that are Consolidated The Company has a controlling financial interest that has been identified as a VIE under ASC 810 in NRG Receivables LLC, which has entered into financing transactions related to the Receivables Facility as further described in Note 13, Receivables Securitization and Repurchase Facility, to the Company’s 2020 Form 10-K. The summarized financial information for the Company's consolidated VIE consisted of the following: (In millions) September 30, 2021 December 31, 2020 Accounts receivable $ 730 $ 647 Other current assets — 2 Total assets 730 649 Current liabilities 78 78 Net assets $ 652 $ 571

Changes in Capital Structure

Changes in Capital Structure	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Changes in Capital Structure	Changes in Capital Structure As of September 30, 2021 and December 31, 2020, the Company had 500,000,000 shares of common stock authorized. The following table reflects the changes in NRG's common stock issued and outstanding: Issued Treasury Outstanding Balance as of December 31, 2020 423,057,848 (178,825,915) 244,231,933 Shares issued under LTIPs 487,413 — 487,413 Shares issued under ESPP — 59,967 59,967 Balance as of September 30, 2021 423,545,261 (178,765,948) 244,779,313 Shares issued under LTIPs 1,913 — 1,913 Shares issued under ESPP — 57,425 57,425 Balance as of November 4, 2021 423,547,174 (178,708,523) 244,838,651 Employee Stock Purchase Plan In March 2019, the Company reopened participation in the ESPP, which allows eligible employees to elect to withhold between 1% and 10% of their eligible compensation to purchase shares of NRG common stock at the lesser of 95% of its market value on the offering date or 95% of the fair market value on the exercise date. An offering date occurs each April 1 and October 1. An exercise date occurs each September 30 and March 31. NRG Common Stock Dividends During the first quarter of 2021, NRG increased the annual dividend to $1.30 from $1.20 per share and expects to target an annual dividend growth rate of 7-9% per share in subsequent years. A quarterly dividend of $0.325 per share was paid on the Company's common stock during the three months ended September 30, 2021. On October 15, 2021, NRG declared a quarterly dividend on the Company's common stock of $0.325 per share, payable on November 15, 2021 to stockholders of record as of November 1, 2021. Beginning in the first quarter of 2022, NRG will increase the annual dividend by 8% to $1.40 per share.

Income Per Share

Income Per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Income Per Share	Income Per Share Basic income per common share is computed by dividing net income by the weighted average number of common shares outstanding. Shares issued and treasury shares repurchased during the year are weighted for the portion of the year that they were outstanding. Diluted income per share is computed in a manner consistent with that of basic income per share while giving effect to all potentially dilutive common shares that were outstanding during the period. The outstanding relative performance stock units, non-vested restricted stock units, market stock units, and non-qualified stock options are not considered outstanding for purposes of computing basic income per share. However, these instruments are included in the denominator for purposes of computing diluted income per share under the treasury stock method. The Convertible Senior Notes are convertible, under certain circumstances, into the Company’s common stock, cash or combination thereof (at NRG's option). There is no dilutive effect for the Convertible Senior Notes due to the Company’s expectation to settle the liability in cash. The reconciliation of NRG's basic and diluted income per share is shown in the following table: Three months ended September 30, Nine months ended September 30, (In millions, except per share data) 2021 2020 2021 2020 Basic income per share: Net income $ 1,618 $ 249 $ 2,614 $ 683 Weighted average number of common shares outstanding - basic 245 244 245 246 Income per weighted average common share — basic $ 6.60 $ 1.02 $ 10.67 $ 2.78 Diluted income per share: Net income $ 1,618 $ 249 $ 2,614 $ 683 Weighted average number of common shares outstanding - basic 245 244 245 246 Incremental shares attributable to the issuance of equity compensation (treasury stock method) — 1 — 1 Weighted average number of common shares outstanding - dilutive 245 245 245 247 Income per weighted average common share — diluted $ 6.60 $ 1.02 $ 10.67 $ 2.77

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2021
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company’s segment structure reflects how management currently makes financial decisions and allocates resources. The Company manages its operations based on the combined results of the retail and wholesale generation businesses with a geographical focus. NRG’s chief operating decision maker, its chief executive officer, evaluates the performance of its segments based on operational measures including adjusted earnings before interest, taxes, depreciation and amortization, or Adjusted EBITDA, free cash flow and allocation of capital, as well as net income/(loss). The acquired operations of Direct Energy are integrated into the existing NRG segment structure. Domestic customer and market operations are combined into the corresponding geographical segments of Texas, East and West/Services/Other. The West/Services/Other segment includes activity related to the Canadian operations as well as the services businesses. Three months ended September 30, 2021 (In millions) Texas East West/Services/Other Corporate Eliminations Total Operating revenues $ 2,635 $ 3,077 $ 884 $ — $ 13 $ 6,609 Depreciation and amortization 84 88 20 7 — 199 Equity in earnings of unconsolidated affiliates (2) — 17 — — 15 Income/(loss) before income taxes 251 1,989 131 (208) — 2,163 Net income/(loss) $ 251 $ 1,976 $ 130 $ (739) $ — $ 1,618 Total assets as of September 30, 2021 $ 9,929 $ 19,940 $ 4,655 $ 10,507 $ (17,066) $ 27,965 Three months ended September 30, 2020 (In millions) Texas East West/Services/Other Corporate Eliminations Total Operating revenues $ 1,992 $ 666 $ 149 $ — $ 2 $ 2,809 Depreciation and amortization 49 33 10 7 — 99 Impairment losses — — 29 — — 29 Equity in losses of unconsolidated affiliates — — 36 — — 36 Income/(loss) before income taxes 287 146 23 (115) — 341 Net income/(loss) $ 287 $ 145 $ 23 $ (206) $ — $ 249 Nine months ended September 30, 2021 (In millions) Texas East West/Services/Other Corporate Eliminations Total Operating revenues $ 8,362 $ 9,002 $ 2,564 $ — $ 15 $ 19,943 Depreciation and amortization 245 238 65 21 — 569 Impairment losses — 306 — — — 306 Gain on sale of assets — — 17 — — 17 Equity in (losses)/earnings of unconsolidated affiliates (3) — 26 — — 23 Income/(loss) before income taxes 600 3,136 254 (536) — 3,454 Net income/(loss) $ 600 $ 3,107 $ 251 $ (1,344) $ — $ 2,614 Nine months ended September 30, 2020 (In millions) Texas East West/Services/Other Corporate Eliminations Total Operating revenues $ 4,928 $ 1,732 $ 407 $ — $ (1) $ 7,066 Depreciation and amortization 167 97 28 26 — 318 Impairment losses — — 29 — — 29 Gain on sale of assets — — 1 5 — 6 Equity in (losses)/earnings of unconsolidated affiliates (3) — 40 — — 37 Income/(loss) before income taxes 799 308 98 (306) — 899 Net income/(loss) $ 799 $ 307 $ 97 $ (520) $ — $ 683

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Effective Income Tax Rate The income tax provision consisted of the following: Three months ended September 30, Nine months ended September 30, (In millions, except rates) 2021 2020 2021 2020 Income before income taxes $ 2,163 $ 341 $ 3,454 $ 899 Income tax expense 545 92 840 216 Effective income tax rate 25.2 % 27.0 % 24.3 % 24.0 % For the three months ended September 30, 2021, the effective tax rate was higher than the statutory rate of 21% primarily due to state tax expense. For the nine months ended September 30, 2021, the effective tax rate was higher than the statutory rate of 21% primarily due to state tax expense partially offset by one-time tax benefits, as a result of the acquisition of Direct Energy, on the revaluation of state deferred tax assets, NOLs and valuation allowance. For the same periods in 2020, the effective tax rates were higher than the statutory rate of 21% due to state tax expense partially offset by an excess tax benefit related to share-based compensation. Uncertain Tax Benefits As of September 30, 2021, NRG had a non-current tax liability of $25 million for uncertain tax benefits from positions taken on various federal and state income tax returns and accrued interest. For the nine months ended September 30, 2021, NRG accrued an immaterial amount of interest relating to the uncertain tax benefits. As of September 30, 2021, NRG had cumulative interest and penalties related to these uncertain tax benefits of $3 million. The Company recognizes interest and penalties related to uncertain tax benefits in income tax expense. NRG is subject to examination by taxing authorities for income tax returns filed in the U.S. federal jurisdiction and various state and foreign jurisdictions including operations located in Australia and Canada. The Company is no longer subject to U.S. federal income tax examinations for years prior to 2017. With few exceptions, state and local income tax examinations are no longer open for years prior to 2012.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions NRG provides services to some of its equity method investments under operations and maintenance agreements. Fees for the services under these agreements include recovery of NRG's costs of operating the plants. Certain agreements also include fees for administrative service, a base monthly fee, profit margin and/or annual incentive bonus. The following table summarizes NRG's material related party transactions with third party affiliates: Three months ended September 30, Nine months ended September 30, (In millions) 2021 2020 2021 2020 Revenues from Related Parties Included in Operating Revenues Gladstone $ 1 $ 1 $ 2 $ 2 Ivanpah (a) 9 11 30 34 Midway-Sunset 1 1 4 4 Total $ 11 $ 13 $ 36 $ 40 (a) Also includes fees under project management agreements with each project company

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments The Company disclosed its commitments in Note 24, Commitments and Contingencies , to the Company's 2020 Form 10-K. NRG completed the acquisition of Direct Energy on January 5, 2021 and assumed additional purchased energy commitments as detailed below. Purchased Energy Commitments NRG assumed additional long-term contractual commitments related to electricity and natural gas products, including power purchases, gas transportation and storage. The Company's minimum commitments under such outstanding agreements as of the Acquisition Closing Date are estimated as follows: Period (In millions) 2021 $ 246 2022 396 2023 272 2024 180 2025 134 Thereafter 450 Total $ 1,678 First Lien Structure NRG has granted first liens to certain counterparties on a substantial portion of property and assets owned by NRG and the guarantors of its senior debt. NRG uses the first lien structure to reduce the amount of cash collateral and letters of credit that it would otherwise be required to post from time to time to support its obligations under out-of-the-money hedges. To the extent that the underlying hedge positions for a counterparty are out-of-the-money to NRG, the counterparty may have a claim under the first lien program. As of September 30, 2021, all hedges under the first lien program were out-of-the-money for NRG on a counterparty aggregate basis. Contingencies The Company's material legal proceedings are described below. The Company believes that it has valid defenses to these legal proceedings and intends to defend them vigorously. NRG records accruals for estimated losses from contingencies when information available indicates that a loss is probable and the amount of the loss, or range of loss, can be reasonably estimated. As applicable, the Company has established an adequate accrual for the applicable legal matters, including regulatory and environmental matters as further discussed in Note 17, Regulatory Matters , and Note 18, Environmental Matters . In addition, legal costs are expensed as incurred. Management has assessed each of the following matters based on current information and made a judgment concerning its potential outcome, considering the nature of the claim, the amount and nature of damages sought, and the probability of success. Unless specified below, the Company is unable to predict the outcome of these legal proceedings or reasonably estimate the scope or amount of any associated costs and potential liabilities. As additional information becomes available, management adjusts its assessment and estimates of such contingencies accordingly. Because litigation is subject to inherent uncertainties and unfavorable rulings or developments, it is possible that the ultimate resolution of the Company's liabilities and contingencies could be at amounts that are different from their currently recorded accruals and that such differences could be material. In addition to the legal proceedings noted below, NRG and its subsidiaries are party to other litigation or legal proceedings arising in the ordinary course of business. In management's opinion, the disposition of these ordinary course matters will not materially adversely affect NRG's consolidated financial position, results of operations, or cash flows. Environmental Lawsuits Sierra club et al. v. Midwest Generation LLC — In 2012, several environmental groups filed a complaint against Midwest Generation with the Illinois Pollution Control Board ("IPCB") alleging violations of environmental law resulting in groundwater contamination. In June 2019, the IPCB found that Midwest Generation violated the law because it had improperly handled coal ash at four facilities in Illinois and caused or allowed coal ash constituents to impact groundwater. On September 9, 2019, Midwest Generation filed a Motion to Reconsider numerous issues, which the court granted in part and denied in part on February 6, 2020. The IPCB will hold hearings to determine the appropriate relief. Midwest Generation has been working with the Illinois EPA to address the groundwater issues since 2010. Consumer Lawsuits Similar to other energy service companies (“ESCOs”) operating in the industry, from time-to-time, the Company and/or its subsidiaries may be subject to consumer lawsuits in various jurisdictions where they sell natural gas and electricity. Variable Price Cases — In the cases set forth below, referred to as the Variable Price Cases, such actions involve consumers alleging that one of the Company’s ESCOs promised that consumers would pay the same or less than they would have paid if they stayed with their default utility or previous energy supplier. The underlying claims of each case are similar and the Company continues to deny the allegations and is vigorously defending these matters. These matters were known and accrued for at the time of each acquisition. XOOM Energy XOOM Energy is a defendant in a putative class action lawsuit pending in New York. This case is in the discovery phase. Direct Energy There are four putative class actions pending against Direct Energy: (1) Linda Stanley v. Direct Energy (S.D.N.Y Apr. 2019) - The parties mediated in June and agreed on a settlement. Once the settlement is drafted and signed, it will be submitted to the Court for approval; (2) Martin Forte v. Direct Energy (N.D.N.Y. Mar. 2017) - Direct Energy’s Motion for Summary Judgment and Plaintiff’s Class Certification are fully briefed and awaiting a ruling; (3) Richard Schafer v. Direct Energy (W.D.N.Y. Dec. 2019; on appeal 2nd Cir. N.Y.) - The trial court dismissed this action. Plaintiff appealed to the Second Circuit Court of Appeals. Oral arguments took place in April 2021. Subsequently, the Second Circuit issued a summary opinion vacating the district court's dismissal of the case. The matter was remanded back to the district court for further action; and (4) Julie and Richard Lane v. Direct Energy (S.D.Ill. Jun. 2019) - Plaintiffs have amended their Complaint in response to the Court dismissing all claims except a claim under the Illinois Consumer Protection Act. Direct Energy’s Motion to Dismiss was granted by the Court on April 26, 2021. The time to appeal this determination has passed. Telephone Consumer Protection Act ("TCPA") Cases — In the cases set forth below, referred to as the TCPA Cases, such actions involve consumers alleging violations of the Telephone Consumer Protection Act of 1991, as amended, by receiving calls, texts or voicemails without consent in violation of the federal Telemarketing Sales Rule, and/or state counterpart legislation. The underlying claims of each case are similar. The Company denies the allegations asserted by plaintiffs and intends to vigorously defend these matters. These matters were known and accrued for at the time of the acquisition. There are two putative class actions pending against Direct Energy: (1) Brittany Burk v. Direct Energy (S.D. Tex. Feb. 2019) - The briefing on Direct Energy’s Motion to Dismiss and Plaintiff’s Class Certification is complete. The Court denied Plaintiff's Motion for Class Certification and Motion for Substitution of a New Plaintiff on September 20, 2021. The parties have reached a settlement of the plaintiff's individual claims and expect the Court to dismiss the matter in the next 30 to 60 days; and (2) Matthew Dickson v. Direct Energy (N.D.Ohio Jan. 2018) - Direct Energy has filed a Third-Party Petition against its vendor, Total Marketing Concepts, LLC, who placed voicemails without consent from Direct Energy and in violation of the parties’ agreement. The case was stayed pending the outcome of an appeal to the Sixth Circuit based on the unconstitutionality of the TCPA during the period from 2015-2020. The Sixth Circuit found the TCPA was in effect during that period and remanded the case back to the trial court. The stay has been lifted and the Company plans to refile its previous motions and start discovery. Winter Storm Uri Lawsuits The Company has been named in certain property damage and wrongful death claims that have been filed in connection with Winter Storm Uri. At this time, the Company is unable to determine the extent or impact of these various litigation matters due to their preliminary nature. The Company intends to vigorously defend these matters. Indemnifications and Other Contractual Arrangements Washington-St. Tammany and Claiborne Electric Cooperative v. LaGen — On June 28, 2017, plaintiffs Washington-St. Tammany Electric Cooperative, Inc. and Claiborne Electric Cooperative, Inc. filed a lawsuit against LaGen in the United States District Court for the Middle District of Louisiana. The plaintiffs claimed breach of contract against LaGen for allegedly improperly charging the plaintiffs for costs related to the installation and maintenance of certain pollution control technology. Plaintiffs sought damages for the alleged improper charges and a declaration as to which charges were proper under the contract. In February 2020, the court dismissed this lawsuit without prejudice for lack of subject matter jurisdiction. On March 17, 2020, plaintiffs filed a lawsuit in the Nineteenth Judicial District Court for the Parish of East Baton Rouge in Louisiana alleging substantially the same matters. On February 4, 2019, NRG sold the South Central Portfolio, including the entities subject to this litigation. However, NRG has agreed to indemnify the purchaser for certain losses suffered in connection therewith.

Regulatory Matters

Regulatory Matters	9 Months Ended
	Sep. 30, 2021
Regulatory Matters Disclosure [Abstract]
Regulatory Matters	Regulatory Matters Environmental regulatory matters are discussed within Note 18, Environmental Matters. NRG operates in a highly regulated industry and is subject to regulation by various federal, state and provincial agencies. As such, NRG is affected by regulatory developments at the federal, state and provincial levels and in the regions in which NRG operates. In addition, NRG is subject to the market rules, procedures, and protocols of the various ISO and RTO markets in which NRG participates. These power markets are subject to ongoing legislative and regulatory changes that may impact NRG's wholesale and retail operations. In addition to the regulatory proceedings noted below, NRG and its subsidiaries are parties to other regulatory proceedings arising in the ordinary course of business or have other regulatory exposure. In management's opinion, the disposition of these ordinary course matters will not materially adversely affect NRG's consolidated financial position, results of operations, or cash flows. California Station Power — As the result of unfavorable final and non-appealable litigation, the Company accrued a liability associated with consumption of station power at the Company's Encina power plant facility in California after August 30, 2010. The Company has established an appropriate accrual pending potential regulatory action by San Diego Gas & Electric regarding the Company's Encina facility. South Central — On August 4, 2016, NRG received a document hold notice from FERC regarding conduct in the MISO and PJM markets. FERC Office of Enforcement Staff investigated potential violations of MISO rules involving bidding for the Big Cajun 2 facility, as well as other aspects of NRG’s operations in MISO. On August 18, 2020, FERC Office of Enforcement presented NRG with its preliminary findings. NRG responded to the preliminary findings on January 15, 2021. On September 16, 2021, FERC Office of Enforcement Staff informed NRG that the investigation is closed with no further action.

Environmental Matters

Environmental Matters	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Environmental Matters	Environmental Matters NRG is subject to a wide range of environmental laws in the development, construction, ownership and operation of power plants. These laws generally require that governmental permits and approvals be obtained before construction and maintained during operation of power plants. The electric generation industry has been facing increasingly stringent requirements regarding air quality, GHG emissions, combustion byproducts, water discharge and use, and threatened and endangered species. In general, future laws are expected to require the addition of emissions controls or other environmental controls or to impose additional restrictions on the operations of the Company's facilities, which could have a material effect on the Company's consolidated financial position, results of operations, or cash flows. The Company has elected to use a $1 million disclosure threshold, as permitted, for environmental proceedings to which the government is a party. Air On July 8, 2019, the EPA promulgated the ACE rule, which rescinded the CPP, which had sought to broadly regulate CO 2 emissions from the power sector. The ACE rule required states that have coal-fired EGUs to develop plans to seek heat rate improvements from coal-fired EGUs. On January 19, 2021, the D.C. Circuit vacated the ACE rule (but on February 22, 2021, at the EPA's request, stayed the issuance of the portion of the mandate that would vacate the repeal of the CPP). On October 29, 2021, the U.S. Supreme Court agreed to review the D.C. Circuit's decision, which should provide some clarity regarding the scope of the EPA's authority to regulate CO 2 under the Clean Air Act. The Company expects the EPA to promulgate a new rule to regulate GHG emissions from power plants after a decision from the U.S. Supreme Court. Water Effluent Limitations Guidelines — In November 2015, the EPA revised the Effluent Limitations Guidelines ("ELG") for Steam Electric Generating Facilities, which imposed more stringent requirements (as individual permits were renewed) for wastewater streams from FGD, fly ash, bottom ash, and flue gas mercury control. On September 18, 2017, the EPA promulgated a final rule that, among other things, postponed the compliance dates to preserve the status quo for FGD wastewater and bottom ash transport water by two years to November 2020 until the EPA amended the rule. On October 13, 2020, the EPA amended the 2015 ELG rule by: (i) altering the stringency of certain limits for FGD wastewater; (ii) relaxing the zero-discharge requirement for bottom ash transport water; and (iii) changing several deadlines. On July 26, 2021, the EPA announced that it is initiating a new rulemaking to evaluate revising the ELG rule. While the EPA is developing the new rule, the existing rule (as amended in 2020) will stay in place, and the EPA expects permitting authorities to continue to implement the current regulation. The EPA anticipates releasing a proposed rule in fall 2022. In October 2021, NRG informed its regulators that the Company intends to comply with the ELG by ceasing combustion of coal by the end of 2028 at its domestic coal units outside of Texas, and installing appropriate controls by the end of 2025 at its two plants in Texas. Byproducts, Wastes, Hazardous Materials and Contamination In April 2015, the EPA finalized the rule regulating byproducts of coal combustion (e.g., ash and gypsum) as solid wastes under the RCRA. In September 2017, the EPA agreed to reconsider the rule. On July 30, 2018, the EPA promulgated a rule that amended the 2015 ash rule by extending some of the deadlines and providing more flexibility for compliance. On August 21, 2018, the D.C. Circuit found, among other things, that the EPA had not adequately regulated unlined ponds and legacy ponds. In 2019 and 2020, the EPA proposed several changes to this rule. On August 28, 2020, the EPA finalized "A Holistic Approach to Close Part A: Deadline to Initiate Closure," which amended the April 2015 Rule to address the August 2018 D.C. Circuit decision and extend some of the deadlines. On November 12, 2020, the EPA finalized "A Holistic Approach to Closure Part B," which further amended the April 2015 Rule to, among other things, provide procedures for requesting approval to operate existing impoundments with an alternative liner. The Company has updated its estimates of required environmental capital expenditures.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Use of Estimates	Use of EstimatesThe preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates.
Reclassifications	ReclassificationsCertain prior period amounts have been reclassified for comparative purposes. The reclassifications did not affect consolidated results from operations, net assets or consolidated cash flows
Credit Losses	Credit Losses On January 1, 2020, the Company adopted ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , or ASU No. 2016-13, using the modified retrospective approach. Following the adoption of the new standard, the Company’s process of estimating expected credit losses remains materially consistent with its historical practice. Retail trade receivables are reported on the balance sheet net of the allowance for credit losses. The Company accrues a provision for current expected credit losses based on (i) estimates of uncollectible revenues by analyzing accounts receivable aging and current and reasonable forecasts of expected economic factors including, but not limited to, unemployment rates and weather-related events, (ii) historical collections and delinquencies, and (iii) counterparty credit ratings for commercial and industrial customers.
Restricted Cash	Funds deposited by counterparties consist of cash held by the Company as a result of collateral posting obligations from its counterparties. Though some amounts are segregated into separate accounts, not all funds are contractually restricted. Based on the Company's intention, these funds are not available for the payment of general corporate obligations; however, they are available for liquidity management. Depending on market fluctuations and the settlement of the underlying contracts, the Company will refund this collateral to the hedge counterparties pursuant to the terms and conditions of the underlying trades. Since collateral requirements fluctuate daily and the Company cannot predict if any collateral will be held for more than twelve months, the funds deposited by counterparties are classified as a current asset on the Company's balance sheet, with an offsetting liability for this cash collateral received within current liabilities.Restricted cash consists primarily of funds held within the Company's projects that are restricted for specific uses.
Recent Accounting Developments	Recent Accounting Developments - Guidance Adopted in 2021 ASU 2019-12 — In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, or ASU 2019-12, to simplify various aspects related to accounting for income taxes. The guidance in ASU 2019-12 amends the general principles in Topic 740 to eliminate certain exceptions for recognizing deferred taxes for investment, performing intraperiod allocation and calculating income taxes in interim periods. This ASU also includes guidance to reduce complexity in certain areas, including recognizing deferred taxes for tax goodwill and allocating taxes to members of a consolidated group. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. The Company adopted the amendments effective January 1, 2021 using the prospective approach. The adoption did not have a material impact on the Company's results of operations, cash flows, or statement of financial position. Recent Accounting Developments - Guidance Not Yet Adopted ASU 2020-06 — In August 2020, the FASB issued ASU No. 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity’s Own Equity (Subtopic 815-40) , or ASU 2020-06. The guidance in ASU 2020-06 reduces the number of accounting models for convertible debt instruments and convertible preferred stock. In addition, ASU 2020-06 improves and amends the related earnings per share guidance. This standard is effective for fiscal years beginning after December 15, 2021 and interim periods within those fiscal years. The Company is currently in the process of assessing the impact of this guidance on the consolidated financial statements and disclosures. ASU 2021-08 — In October 2021, the FASB issued ASU No. 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers , or ASU 2021-08. Under current GAAP, an acquirer generally recognizes assets acquired and liabilities assumed in a business combination, including contract assets and contract liabilities arising from revenue contracts with customers and other similar contracts that are accounted for in accordance with ASC 606, Revenue from Contracts with Customers
Nuclear Decommissioning	NRG's Nuclear Decommissioning Trust Fund assets, which are for the decommissioning of its 44% interest in STP, are comprised of securities classified as available-for-sale and recorded at fair value based on actively quoted market prices. NRG accounts for the Nuclear Decommissioning Trust Fund in accordance with ASC 980, Regulated Operations
Segment Reporting	NRG’s chief operating decision maker, its chief executive officer, evaluates the performance of its segments based on operational measures including adjusted earnings before interest, taxes, depreciation and amortization, or Adjusted EBITDA, free cash flow and allocation of capital, as well as net income/(loss).

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Other Balance Sheet Information	The following table presents the accumulated depreciation included in property, plant and equipment, net and accumulated amortization included in intangible assets, net: (In millions) September 30, 2021 December 31, 2020 Property, plant and equipment accumulated depreciation $ 1,543 $ 1,936 Intangible assets accumulated amortization 1,542 1,357
Activity in Allowance for Credit Losses	The following table represents the activity in the allowance for credit losses for the three and nine months ended September 30, 2021 and 2020: Three months ended September 30, Nine months ended September 30, (In millions) 2021 2020 2021 2020 Beginning balance $ 761 $ 47 $ 67 $ 43 Acquired balance from Direct Energy — — 112 — Provision for credit losses 64 26 715 74 Write-offs (41) (19) (124) (71) Recoveries collected 8 3 22 11 Ending balance $ 792 $ 57 $ 792 $ 57
Reconciliation of Cash and Cash Equivalents, Restricted Cash and Funds Deposited by Counterparties	The following table provides a reconciliation of cash and cash equivalents, restricted cash and funds deposited by counterparties reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the statements of cash flows: (In millions) September 30, 2021 December 31, 2020 Cash and cash equivalents $ 259 $ 3,905 Funds deposited by counterparties 1,748 19 Restricted cash 14 6 Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows $ 2,021 $ 3,930

Revenue Recognition (Tables)

Revenue Recognition (Tables)	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue from Contracts with Customer	Disaggregated Revenues The following tables represent the Company’s disaggregation of revenue from contracts with customers for the three and nine months ended September 30, 2021 and 2020: Three months ended September 30, 2021 (In millions) Texas East West/Services/Other Corporate/Eliminations Total Retail revenue: Home (a) $ 1,776 $ 470 $ 400 $ — $ 2,646 Business 727 2,228 350 — 3,305 Total retail revenue 2,503 2,698 750 — 5,951 Energy revenue (b) 18 201 113 4 336 Capacity revenue (b) — 172 17 — 189 Mark-to-market for economic hedging activities (c) (1) (3) (6) 13 3 Contract amortization — (7) 4 — (3) Other revenue (b) 115 16 6 (4) 133 Total operating revenue 2,635 3,077 884 13 6,609 Less: Lease revenue — — 2 — 2 Less: Realized and unrealized ASC 815 revenue 38 76 (8) 14 120 Less: Contract amortization — (7) 4 — (3) Total revenue from contracts with customers $ 2,597 $ 3,008 $ 886 $ (1) $ 6,490 (a) Home includes Services (b) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: (In millions) Texas East West/Services/Other Corporate/Eliminations Total Energy revenue $ — $ 38 $ 2 $ 1 $ 41 Capacity revenue — 42 — — 42 Other revenue 39 (1) (4) — 34 (c) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 Three months ended September 30, 2020 (In millions) Texas East West/Services/Other Corporate/Eliminations Total Retail revenue: Home (a) $ 1,633 $ 327 $ 27 $ — $ 1,987 Business 288 27 — — 315 Total retail revenue 1,921 354 27 — 2,302 Energy revenue (b) 11 93 117 1 222 Capacity revenue (b) — 158 16 — 174 Mark-to-market for economic hedging activities (c) 1 43 (10) 5 39 Other revenue (b) 59 18 (1) (4) 72 Total operating revenue 1,992 666 149 2 2,809 Less: Lease revenue — — 5 — 5 Less: Realized and unrealized ASC 815 revenue 10 115 (10) 5 120 Total revenue from contracts with customers $ 1,982 $ 551 $ 154 $ (3) $ 2,684 (a) Home includes Services (b) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: (In millions) Texas East West/Services/Other Corporate/Eliminations Total Energy revenue $ — $ 23 $ 13 $ (1) $ 35 Capacity revenue — 49 — — 49 Other revenue 9 — (13) 1 (3) (c) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 Nine months ended September 30, 2021 (In millions) Texas East West/Services/Other Corporate/Eliminations Total Retail revenue: Home (a) $ 4,484 $ 1,469 $ 1,439 $ (1) $ 7,391 Business 2,091 6,560 887 — 9,538 Total retail revenue 6,575 8,029 2,326 (1) 16,929 Energy revenue (c) 317 428 238 6 989 Capacity revenue (c) — 568 47 — 615 Mark-to-market for economic hedging activities (d) (5) (53) (60) 19 (99) Contract amortization — (15) (4) — (19) Other revenue (b)(c) 1,475 45 17 (9) 1,528 Total operating revenue 8,362 9,002 2,564 15 19,943 Less: Lease revenue — 1 5 — 6 Less: Realized and unrealized ASC 815 revenue 129 193 (73) 20 269 Less: Contract amortization — (15) (4) — (19) Total revenue from contracts with customers $ 8,233 $ 8,823 $ 2,636 $ (5) $ 19,687 (a) Home includes Services (b) Other Revenue in Texas includes ancillary revenues of $1.2 billion driven by high pricing during Winter Storm Uri (c) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: (In millions) Texas East West/Services/Other Corporate/Eliminations Total Energy revenue $ — $ 122 $ (4) $ 2 $ 120 Capacity revenue — 119 — — 119 Other revenue 134 5 (9) (1) 129 (d) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 Nine months ended September 30, 2020 (In millions) Texas East West/Services/Other Corporate/Eliminations Total Retail revenue: Home (a) $ 3,938 $ 926 $ 66 $ (1) $ 4,929 Business 796 70 — — 866 Total retail revenue 4,734 996 66 (1) 5,795 Energy revenue (b) 21 157 252 (1) 429 Capacity revenue (b) — 471 47 — 518 Mark-to-market for economic hedging activities (c) 1 63 6 8 78 Other revenue (b) 172 45 36 (7) 246 Total operating revenue 4,928 1,732 407 (1) 7,066 Less: Lease revenue — 1 14 — 15 Less: Realized and unrealized ASC 815 revenue 24 239 50 5 318 Total revenue from contracts with customers $ 4,904 $ 1,492 $ 343 $ (6) $ 6,733 (a) Home includes Services (b) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: (In millions) Texas East West/Services/Other Corporate/Eliminations Total Energy revenue $ — $ 60 $ 42 $ (3) $ 99 Capacity revenue — 114 — — 114 Other revenue 23 2 2 — 27 (c) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815
Contract Asset and Liabilities	The following table reflects the contract assets and liabilities included in the Company’s balance sheet as of September 30, 2021 and December 31, 2020: (In millions) September 30, 2021 December 31, 2020 Deferred customer acquisition costs $ 124 $ 113 Accounts receivable, net - Contracts with customers 2,955 866 Accounts receivable, net - Derivative instruments 136 33 Accounts receivable, net - Affiliate 5 5 Total accounts receivable, net $ 3,096 $ 904 Unbilled revenues (included within Accounts receivable, net - Contracts with customers) $ 1,268 $ 393 Deferred revenues (a) 312 60 (a) Deferred revenues from contracts with customers for the nine months ended September 30, 2021 and the year ended December 31, 2020 were approximately $303 million and $31 million, respectively

Acquisitions and Dispositions (

Acquisitions and Dispositions (Tables)	9 Months Ended
	Sep. 30, 2021
Business Combination and Asset Acquisition [Abstract]
Schedule of Line of Credit Facilities	The Company also increased its collective liquidity and collateral facilities by $3.4 billion as of the Acquisition Closing Date to meet the additional liquidity requirements related to the acquisition, as detailed in the following table: (In millions) Available on Acquisition Closing Date Revolving Credit Facility commitment increase $ 802 Revolving Credit Facility new tranche 273 Facility agreement in connection with the sale of pre-capitalized trust securities 874 Available as of December 31, 2020 Credit default swap facility 150 Revolving accounts receivable financing facility 750 Repurchase facility 75 Bilateral letter of credit facilities 475 Total Increases to Liquidity and Collateral Facilities $ 3,399
Schedule of Purchase Price Allocation	The purchase price is provisionally allocated as follows: (In millions) Current Assets Cash and cash equivalents $ 152 Funds deposited by counterparties 21 Restricted cash 9 Accounts receivable, net 1,802 Inventory 106 Derivative instruments 1,014 Cash collateral paid in support of energy risk management activities 233 Prepayments and other current assets 183 Total current assets 3,520 Property, plant and equipment, net 151 Other Assets Goodwill (a) 1,257 Intangible assets, net: Customer relationships (b) 1,277 Customer and supply contracts (b) 610 Trade names (b) 310 Renewable energy credits 124 Total intangible assets, net 2,321 Derivative instruments 531 Other non-current assets 31 Total other assets 4,140 Total Assets $ 7,811 Current Liabilities Accounts payable $ 1,120 Derivative instruments 1,266 Cash collateral received in support of energy risk management activities 21 Accrued expenses and other current liabilities 690 Total current liabilities 3,097 Other Liabilities Derivative instruments 562 Deferred income taxes 338 Other non-current liabilities 115 Total other liabilities 1,015 Total Liabilities $ 4,112 Direct Energy Purchase Price $ 3,699 (a) Goodwill arising from the acquisition is attributed to the value of the platform acquired and the synergies expected from combining the operations of Direct Energy with NRG's existing businesses. Goodwill was provisionally allocated to the Texas, East, and West/Services/Other segments of $424 million, $663 million and $170 million, respectively. Goodwill expected to be deductible for tax purposes is $337 million (b) The weighted average amortization period for total amortizable intangible assets is 12 years The following measurement period adjustments were recognized during the quarter ended September 30, 2021: (In millions) Increase/(Decrease) Assets Goodwill $ 11 Intangible assets, net (32) Total decrease in assets $ (21) Liabilities Accounts payable $ (270) Accrued expenses and other current liabilities 248 Deferred income taxes (1) Other non-current liabilities 2 Total decrease in liabilities $ (21)
Schedule of Derivative Liabilities at Fair Value	The fair values of derivatives assets and liabilities as of the Acquisition Closing Date were as follows: Fair Value (In millions) Total Level 1 Level 2 Level 3 Derivatives assets $ 1,545 $ 155 $ 1,272 $ 118 Derivatives liabilities $ 1,828 $ 207 $ 1,489 $ 132
Schedule of Supplemental Information	For the three and nine months ended September 30, 2021 Direct Energy contributed revenue and income before income taxes as follows: (In millions) Three months ended September 30, 2021 Nine months ended September 30, 2021 Revenue $ 3,599 $ 10,718 Income before income taxes 2,010 3,457
Schedule of Pro Forma Financial Information	Supplemental Pro Forma Financial Information for the nine months ended September 30, 2021 and 2020 (a) The following table provides pro forma combined financial information of NRG and Direct Energy, after giving effect to the Direct Energy acquisition and related financing transactions as if they had occurred on January 1, 2020. The pro forma financial information has been prepared for illustrative and informational purposes only, and is not intended to project future operating results or indicative of what our financial performance would have been had the transactions occurred on the date assumed. No effect has been given to operating synergies. (In millions) Nine months ended September 30, 2021 Nine months ended September 30, 2020 Total operating revenues $ 19,932 $ 16,039 Net Income 2,585 832 (a) Pro forma comparative financial information for the three months ended September 30, 2021 and 2020 has not been included as computation of such information is impracticable as Direct Energy's pre-acquisition financial statements for the three months ended September 30, 2020 were not prepared in accordance with GAAP
Schedule of Classified Held for Sale	As of September 30, 2021, the following is classified as held for sale in the Consolidated Balance Sheet: (In millions) (a) Current assets (b) $ 51 Property, plant and equipment, net 391 Other non-current assets 3 Total non-current assets (c) 394 Total assets held for sale $ 445 Current liabilities (d) 14 Non-current liabilities (e) 61 Total liabilities held for sale $ 75 (a) Property, plant and equipment, net for the East and West/Services/Other segments was $242 million and $149 million, respectively. The remaining assets and liabilities were primarily in the East segment (b) Included in prepayments and other current assets in the Consolidated Balance Sheet (c) Included in other non-current assets in the Consolidated Balance Sheet (d) Included in accrued expenses and other current liabilities in the Consolidated Balance Sheet (e) Included in other non-current liabilities in the Consolidated Balance Sheet

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Estimated carrying amounts and fair values of NRG's recorded financial instruments not carried at fair market value	The estimated carrying amounts and fair values of NRG's recorded financial instruments not carried at fair market value are as follows: September 30, 2021 December 31, 2020 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Assets: Notes receivable $ 2 $ 2 $ 2 $ 2 Liabilities: Long-term debt, including current portion (a) 8,537 8,897 8,781 9,446 (a) Excludes deferred financing costs, which are recorded as a reduction to long-term debt in the Company's consolidated balance sheets
Assets and liabilities measured and recorded at fair value on the consolidated balance sheets on a recurring basis	The following tables present assets and liabilities measured and recorded at fair value on the Company's condensed consolidated balance sheets on a recurring basis and their level within the fair value hierarchy: September 30, 2021 (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and non-current assets) $ 23 $ 7 $ 16 $ — Nuclear trust fund investments: Cash and cash equivalents 29 29 — — U.S. government and federal agency obligations 76 75 1 — Federal agency mortgage-backed securities 93 — 93 — Commercial mortgage-backed securities 43 — 43 — Corporate debt securities 116 — 116 — Equity securities 503 503 — — Foreign government fixed income securities 4 — 4 — Other trust fund investments (classified within other non-current assets): U.S. government and federal agency obligations 1 1 — — Derivative assets: Foreign exchange contracts 1 — 1 — Commodity contracts 11,198 2,161 8,474 563 Measured using net asset value practical expedient: Equity securities — nuclear trust fund investments 93 Equity securities (classified within other non-current assets) 8 Total assets $ 12,188 $ 2,776 $ 8,748 $ 563 Derivative liabilities: Commodity contracts $ 7,521 $ 1,376 $ 5,893 $ 252 Total liabilities $ 7,521 $ 1,376 $ 5,893 $ 252 December 31, 2020 (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and non-current assets) $ 25 $ 10 $ 15 $ — Nuclear trust fund investments: Cash and cash equivalents 23 23 — — U.S. government and federal agency obligations 70 69 1 — Federal agency mortgage-backed securities 89 — 89 — Commercial mortgage-backed securities 36 — 36 — Corporate debt securities 144 — 144 — Equity securities 434 434 — — Foreign government fixed income securities 7 1 6 — Other trust fund investments (classified within other non-current assets): U.S. government and federal agency obligations 1 1 — — Derivative assets: Commodity contracts 821 59 623 139 Measured using net asset value practical expedient: Equity securities — nuclear trust fund investments 87 Equity securities (classified within other non-current assets) 8 Total assets $ 1,745 $ 597 $ 914 $ 139 Derivative liabilities: Commodity contracts $ 884 $ 86 $ 643 $ 155 Total liabilities $ 884 $ 86 $ 643 $ 155
Reconciliation of beginning and ending balances for financial instruments that are recognized at fair value in the consolidated financial statements at least annually using significant unobservable inputs	The following table reconciles, for the three and nine months ended September 30, 2021 and 2020, the beginning and ending balances for financial instruments that are recognized at fair value in the condensed consolidated financial statements, using significant unobservable inputs: Fair Value Measurement Using Significant Unobservable Inputs (Level 3) Three months ended September 30, 2021 Nine months ended September 30, 2021 (In millions) Derivatives (a) Derivatives (a) Beginning balance $ 574 $ (16) Contracts added from Direct Energy acquisition — (15) Total (losses)/gains realized/unrealized— included in earnings (175) 187 Purchases — 78 Transfers into Level 3 (b) (108) 64 Transfers out of Level 3 (b) 20 13 Ending balance $ 311 $ 311 (Losses)/gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of period end $ (237) $ 184 (a) Consists of derivative assets and liabilities, net (b) Transfers into/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. All transfers in/out are with Level 2 Fair Value Measurement Using Significant Unobservable Inputs (Level 3) Three months ended September 30, 2020 Nine months ended September 30, 2020 (In millions) Derivatives (a) Derivatives (a) Beginning balance $ 152 $ 38 Total (losses) realized/unrealized — included in earnings (92) (18) Purchases (10) 6 Transfers into Level 3 (b) (11) 22 Transfers out of Level 3 (b) 13 4 Ending balance $ 52 $ 52 Gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of period end $ 23 $ 50 (a) Consists of derivative assets and liabilities, net (b) Transfers into/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. All transfers in/out are with Level 2
Significant unobservable inputs used developing fair values, Quantitative Information	The following tables quantify the significant unobservable inputs used in developing the fair value of the Company's Level 3 positions as of September 30, 2021 and December 31, 2020: September 30, 2021 Fair Value Input/Range (In millions) Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average Natural Gas Contracts $ 19 $ 3 Discounted Cash Flow Forward Market Price (per MMBtu) $ 3 $ 49 $ 19 Power Contracts 512 218 Discounted Cash Flow Forward Market Price (per MWh) 3 263 40 FTRs 32 31 Discounted Cash Flow Auction Prices (per MWh) (131) 755 — $ 563 $ 252 December 31, 2020 Fair Value Input/Range (In millions) Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average Power Contracts $ 111 $ 143 Discounted Cash Flow Forward Market Price (per MWh) $ 10 $ 105 $ 21 FTRs 28 12 Discounted Cash Flow Auction Prices (per MWh) (28) 43 0 $ 139 $ 155
Fair value inputs, sensitivity analysis	The following table provides sensitivity of fair value measurements to increases/(decreases) in significant unobservable inputs as of September 30, 2021 and December 31, 2020: Significant Unobservable Input Position Change In Input Impact on Fair Value Measurement Forward Market Price Natural Gas/Power Buy Increase/(Decrease) Higher/(Lower) Forward Market Price Natural Gas/Power Sell Increase/(Decrease) Lower/(Higher) FTR Prices Buy Increase/(Decrease) Higher/(Lower) FTR Prices Sell Increase/(Decrease) Lower/(Higher)
Net counterparty credit exposure by industry sector and by counterparty credit quality	The following tables highlight net counterparty credit exposure by industry sector and by counterparty credit quality. Net counterparty credit exposure is defined as the aggregate net asset position for NRG with counterparties where netting is permitted under the enabling agreement and includes all cash flow, mark-to-market and NPNS, and non-derivative transactions. The exposure is shown net of collateral held and includes amounts net of receivables or payables. Net Exposure (a)(b) Category by Industry Sector (% of Total) Utilities, energy merchants, marketers and other 49 % Financial institutions 51 Total as of September 30, 2021 100 % Net Exposure (a)(b) Category by Counterparty Credit Quality (% of Total) Investment grade 78 % Non-investment grade/non-rated 22 Total as of September 30, 2021 100 % (a) Counterparty credit exposure excludes uranium and coal transportation contracts because of the unavailability of market prices (b) The figures in the tables above exclude potential counterparty credit exposure related to RTOs, ISOs, registered commodity exchanges and certain long-term contracts

Nuclear Decommissioning Trust_2

Nuclear Decommissioning Trust Fund (Tables)	9 Months Ended
	Sep. 30, 2021
Regulated Operations [Abstract]
Summary of aggregate fair values and unrealized gains and losses for the securities held in the trust fund	The following table summarizes the aggregate fair values and unrealized gains and losses for the securities held in the trust funds, as well as information about the contractual maturities of those securities. As of September 30, 2021 As of December 31, 2020 (In millions, except maturities) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Cash and cash equivalents $ 29 $ — $ — — $ 23 $ — $ — — U.S. government and federal agency obligations 76 4 — 12 70 6 — 10 Federal agency mortgage-backed securities 93 3 — 24 89 4 — 24 Commercial mortgage-backed securities 43 1 — 27 36 2 — 27 Corporate debt securities 116 8 1 14 144 13 — 12 Equity securities 596 439 — — 521 372 — — Foreign government fixed income securities 4 — — 12 7 1 — 10 Total $ 957 $ 455 $ 1 $ 890 $ 398 $ —
Summary of proceeds from sales of available-for-sale securities and the related realized gains and losses	The following table summarizes proceeds from sales of available-for-sale securities held in the trust funds and the related realized gains and losses from these sales. The cost of securities sold is determined on the specific identification method. Nine months ended September 30, (In millions) 2021 2020 Realized gains $ 10 $ 22 Realized losses (6) (11) Proceeds from sale of securities 424 318

Accounting for Derivative Ins_2

Accounting for Derivative Instruments and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Net notional volume buy/(sell) of NRG's open derivative transactions broken out by commodity	The following table summarizes the net notional volume buy/(sell) of NRG's open derivative transactions broken out by category, excluding those derivatives that qualified for the NPNS exception, as of September 30, 2021 and December 31, 2020. Option contracts are reflected using delta volume. Delta volume equals the notional volume of an option adjusted for the probability that the option will be in-the-money at its expiration date. Total Volume (In millions) Category Units September 30, 2021 December 31, 2020 Emissions Short Ton 1 1 Renewable Energy Certificates Certificates 13 5 Coal Short Ton 3 2 Natural Gas MMBtu 663 (286) Oil Barrels 1 — Power MWh 185 57 Capacity MW/Day — (1) Foreign Exchange Dollars $ 218 $ —
Fair value within the derivative instrument valuation on the balance sheets	The following table summarizes the fair value within the derivative instrument valuation on the balance sheets: Fair Value Derivative Assets Derivative Liabilities (In millions) September 30, 2021 December 31, 2020 September 30, 2021 December 31, 2020 Derivatives Not Designated as Cash Flow or Fair Value Hedges: Foreign exchange contracts - current $ 1 $ — $ — $ — Commodity contracts - current 8,527 560 6,032 499 Commodity contracts - long-term 2,671 261 1,489 385 Total Derivatives Not Designated as Cash Flow or Fair Value Hedges $ 11,199 $ 821 $ 7,521 $ 884
Offsetting of derivatives by counterparty assets	The following table summarizes the offsetting of derivatives by counterparty master agreement level and collateral received or paid: Gross Amounts Not Offset in the Statement of Financial Position (In millions) Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount As of September 30, 2021 Foreign exchange contracts: Derivative assets $ 1 $ — $ — $ 1 Total foreign exchange contracts $ 1 $ — $ — $ 1 Commodity contracts: Derivative assets $ 11,198 $ (6,946) $ (1,712) $ 2,540 Derivative liabilities (7,521) 6,946 — (575) Total commodity contracts $ 3,677 $ — $ (1,712) $ 1,965 Total derivative instruments $ 3,678 $ — $ (1,712) $ 1,966 Gross Amounts Not Offset in the Statement of Financial Position (In millions) Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount As of December 31, 2020 Commodity contracts: Derivative assets $ 821 $ (658) $ (5) $ 158 Derivative liabilities (884) 658 — (226) Total commodity contracts $ (63) $ — $ (5) $ (68)
Offsetting of derivatives by counterparty, liabilities	The following table summarizes the offsetting of derivatives by counterparty master agreement level and collateral received or paid: Gross Amounts Not Offset in the Statement of Financial Position (In millions) Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount As of September 30, 2021 Foreign exchange contracts: Derivative assets $ 1 $ — $ — $ 1 Total foreign exchange contracts $ 1 $ — $ — $ 1 Commodity contracts: Derivative assets $ 11,198 $ (6,946) $ (1,712) $ 2,540 Derivative liabilities (7,521) 6,946 — (575) Total commodity contracts $ 3,677 $ — $ (1,712) $ 1,965 Total derivative instruments $ 3,678 $ — $ (1,712) $ 1,966 Gross Amounts Not Offset in the Statement of Financial Position (In millions) Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount As of December 31, 2020 Commodity contracts: Derivative assets $ 821 $ (658) $ (5) $ 158 Derivative liabilities (884) 658 — (226) Total commodity contracts $ (63) $ — $ (5) $ (68)
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	The following table summarizes the pre-tax effects of economic hedges that have not been designated as cash flow hedges or fair value hedges and trading activity on the Company's statement of operations. The effect of foreign exchange and commodity hedges are included within operating revenues and cost of operations. (In millions) Three months ended September 30, Nine months ended September 30, Unrealized mark-to-market results 2021 2020 2021 2020 Reversal of previously recognized unrealized (gains) on settled positions related to economic hedges $ (97) $ (101) $ (58) $ (62) Reversal of acquired (gain)/loss positions related to economic hedges (42) (2) 206 2 Net unrealized gains/(losses) on open positions related to economic hedges 1,924 (15) 3,875 73 Total unrealized mark-to-market gains/(losses) for economic hedging activities 1,785 (118) 4,023 13 Reversal of previously recognized unrealized (gains) on settled positions related to trading activity (6) (7) (16) (14) Net unrealized gains on open positions related to trading activity 14 2 18 19 Total unrealized mark-to-market gains/(losses) for trading activity 8 (5) 2 5 Total unrealized gains/(losses) $ 1,793 $ (123) $ 4,025 $ 18 Three months ended September 30, Nine months ended September 30, (In millions) 2021 2020 2021 2020 Unrealized gains/(losses) included in operating revenues - commodities $ 11 $ 34 $ (97) $ 83 Unrealized gains/(losses) included in cost of operations - commodities 1,777 (157) 4,121 (65) Unrealized gains included in cost of operations - foreign exchange 5 — 1 — Total impact to statement of operations $ 1,793 $ (123) $ 4,025 $ 18

Long-term Debt and Finance Le_2

Long-term Debt and Finance Leases (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Long-term Debt and Finance Leases	Long-term debt and finance leases consisted of the following: (In millions, except rates) September 30, 2021 December 31, 2020 Interest rate % Recourse debt: Senior Notes, due 2026 $ — $ 1,000 7.250 Senior Notes, due 2027 875 1,230 6.625 Senior Notes, due 2028 821 821 5.750 Senior Notes, due 2029 733 733 5.250 Senior Notes, due 2029 500 500 3.375 Senior Notes, due 2031 1,030 1,030 3.625 Senior Notes, due 2032 1,100 — 3.875 Convertible Senior Notes, due 2048 (a) 575 575 2.750 Senior Secured First Lien Notes, due 2024 600 600 3.750 Senior Secured First Lien Notes, due 2025 500 500 2.000 Senior Secured First Lien Notes, due 2027 900 900 2.450 Senior Secured First Lien Notes, due 2029 500 500 4.450 Tax-exempt bonds 466 466 1.250 - 4.750 Subtotal recourse debt 8,600 8,855 Finance leases 13 4 various Subtotal long-term debt and finance leases (including current maturities) 8,613 8,859 Less current maturities (504) (1) Less debt issuance costs (89) (93) Discounts (63) (74) Total long-term debt and finance leases $ 7,957 $ 8,691 (a) As of the ex-dividend date of October 29, 2021, the Convertible Senior Notes were convertible at a price of $44.89, which is equivalent to a conversion rate of approximately 22.2761 shares of common stock per $1,000 principal amount
Debt Instrument Redemption	(In millions, except percentages) Principal Repurchased Cash Paid (a) Average Early Redemption Percentage 7.250% Senior Notes, due 2026 $ 1,000 $ 1,056 103.625 % 6.625% Senior Notes, due 2027 355 369 103.313 % Total Redemptions during the nine months ended September 30, 2021 $ 1,355 $ 1,425 6.625% Senior Notes, due 2027 $ 500 $ 524 103.313 % Total Redemptions January 1, 2021 through November 4, 2021 $ 1,855 $ 1,949 (a) Includes accrued interest of $22 million and $29 million for redemptions through September 30, 2021 and November 4, 2021, respectively

Investments Accounted for Usi_2

Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs (Tables)	9 Months Ended
	Sep. 30, 2021
Variable Interest Entities Disclosure [Abstract]
Financial Information for Consolidated VIEs	The summarized financial information for the Company's consolidated VIE consisted of the following: (In millions) September 30, 2021 December 31, 2020 Accounts receivable $ 730 $ 647 Other current assets — 2 Total assets 730 649 Current liabilities 78 78 Net assets $ 652 $ 571

Changes in Capital Structure (T

Changes in Capital Structure (Tables)	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Changes in NRG's common shares issued and outstanding	As of September 30, 2021 and December 31, 2020, the Company had 500,000,000 shares of common stock authorized. The following table reflects the changes in NRG's common stock issued and outstanding: Issued Treasury Outstanding Balance as of December 31, 2020 423,057,848 (178,825,915) 244,231,933 Shares issued under LTIPs 487,413 — 487,413 Shares issued under ESPP — 59,967 59,967 Balance as of September 30, 2021 423,545,261 (178,765,948) 244,779,313 Shares issued under LTIPs 1,913 — 1,913 Shares issued under ESPP — 57,425 57,425 Balance as of November 4, 2021 423,547,174 (178,708,523) 244,838,651

Income Per Share (Tables)

Income Per Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Reconciliation of NRG's basic and diluted (loss)/income per share	The reconciliation of NRG's basic and diluted income per share is shown in the following table: Three months ended September 30, Nine months ended September 30, (In millions, except per share data) 2021 2020 2021 2020 Basic income per share: Net income $ 1,618 $ 249 $ 2,614 $ 683 Weighted average number of common shares outstanding - basic 245 244 245 246 Income per weighted average common share — basic $ 6.60 $ 1.02 $ 10.67 $ 2.78 Diluted income per share: Net income $ 1,618 $ 249 $ 2,614 $ 683 Weighted average number of common shares outstanding - basic 245 244 245 246 Incremental shares attributable to the issuance of equity compensation (treasury stock method) — 1 — 1 Weighted average number of common shares outstanding - dilutive 245 245 245 247 Income per weighted average common share — diluted $ 6.60 $ 1.02 $ 10.67 $ 2.77

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2021
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Three months ended September 30, 2021 (In millions) Texas East West/Services/Other Corporate Eliminations Total Operating revenues $ 2,635 $ 3,077 $ 884 $ — $ 13 $ 6,609 Depreciation and amortization 84 88 20 7 — 199 Equity in earnings of unconsolidated affiliates (2) — 17 — — 15 Income/(loss) before income taxes 251 1,989 131 (208) — 2,163 Net income/(loss) $ 251 $ 1,976 $ 130 $ (739) $ — $ 1,618 Total assets as of September 30, 2021 $ 9,929 $ 19,940 $ 4,655 $ 10,507 $ (17,066) $ 27,965 Three months ended September 30, 2020 (In millions) Texas East West/Services/Other Corporate Eliminations Total Operating revenues $ 1,992 $ 666 $ 149 $ — $ 2 $ 2,809 Depreciation and amortization 49 33 10 7 — 99 Impairment losses — — 29 — — 29 Equity in losses of unconsolidated affiliates — — 36 — — 36 Income/(loss) before income taxes 287 146 23 (115) — 341 Net income/(loss) $ 287 $ 145 $ 23 $ (206) $ — $ 249 Nine months ended September 30, 2021 (In millions) Texas East West/Services/Other Corporate Eliminations Total Operating revenues $ 8,362 $ 9,002 $ 2,564 $ — $ 15 $ 19,943 Depreciation and amortization 245 238 65 21 — 569 Impairment losses — 306 — — — 306 Gain on sale of assets — — 17 — — 17 Equity in (losses)/earnings of unconsolidated affiliates (3) — 26 — — 23 Income/(loss) before income taxes 600 3,136 254 (536) — 3,454 Net income/(loss) $ 600 $ 3,107 $ 251 $ (1,344) $ — $ 2,614 Nine months ended September 30, 2020 (In millions) Texas East West/Services/Other Corporate Eliminations Total Operating revenues $ 4,928 $ 1,732 $ 407 $ — $ (1) $ 7,066 Depreciation and amortization 167 97 28 26 — 318 Impairment losses — — 29 — — 29 Gain on sale of assets — — 1 5 — 6 Equity in (losses)/earnings of unconsolidated affiliates (3) — 40 — — 37 Income/(loss) before income taxes 799 308 98 (306) — 899 Net income/(loss) $ 799 $ 307 $ 97 $ (520) $ — $ 683

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Provision	The income tax provision consisted of the following: Three months ended September 30, Nine months ended September 30, (In millions, except rates) 2021 2020 2021 2020 Income before income taxes $ 2,163 $ 341 $ 3,454 $ 899 Income tax expense 545 92 840 216 Effective income tax rate 25.2 % 27.0 % 24.3 % 24.0 %

Related Party Transactions (Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
Summary of NRG's Material Related Party Transactions	The following table summarizes NRG's material related party transactions with third party affiliates: Three months ended September 30, Nine months ended September 30, (In millions) 2021 2020 2021 2020 Revenues from Related Parties Included in Operating Revenues Gladstone $ 1 $ 1 $ 2 $ 2 Ivanpah (a) 9 11 30 34 Midway-Sunset 1 1 4 4 Total $ 11 $ 13 $ 36 $ 40 (a) Also includes fees under project management agreements with each project company

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Schedule of Additional Minimum Purchase Power Commitments	NRG completed the acquisition of Direct Energy on January 5, 2021 and assumed additional purchased energy commitments as detailed below. Purchased Energy Commitments NRG assumed additional long-term contractual commitments related to electricity and natural gas products, including power purchases, gas transportation and storage. The Company's minimum commitments under such outstanding agreements as of the Acquisition Closing Date are estimated as follows: Period (In millions) 2021 $ 246 2022 396 2023 272 2024 180 2025 134 Thereafter 450 Total $ 1,678

Nature of Business and Basis _2

Nature of Business and Basis of Presentation - General (Details) counterparty in Millions	9 Months Ended
	Sep. 30, 2021counterpartyMW
Business Acquisition [Line Items]
Generation capacity (in MW)	23,000
East
Business Acquisition [Line Items]
Generation capacity (in MW)	1,600
Disposal Group, Held-for-sale, Not Discontinued Operations
Business Acquisition [Line Items]
Generation capacity (in MW)	4,850
Home
Business Acquisition [Line Items]
Customers | counterparty	6

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Other Balance Sheet Information (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Property, plant and equipment accumulated depreciation	$ 1,543	$ 1,936
Intangible assets accumulated amortization	$ 1,542	$ 1,357

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Activity in the Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 761	$ 47	$ 67	$ 43
Acquired balance from Direct Energy	0	0	112	0
Provision for credit losses	64	26	715	74
Write-offs	(41)	(19)	(124)	(71)
Recoveries collected	8	3	22	11
Ending balance	$ 792	$ 57	792	$ 57
Increase in provision for credit losses due finance hedge risk			403
Increase in provision due to counterparty credit Risk			152
Increase in provision for credit Loss due to shortfall payments			$ 83

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Cash and cash equivalents	$ 259	$ 3,905
Funds deposited by counterparties	1,748	19
Restricted cash	14	6
Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows	$ 2,021	$ 3,930	$ 718	$ 385

Revenue Recognition - Performan

Revenue Recognition - Performance Obligations Expected Timing of Satisfaction (Details) $ in Millions	Sep. 30, 2021USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated future fixed fee performance obligations	$ 158
Revenue remaining performance obligation period	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated future fixed fee performance obligations	$ 345
Revenue remaining performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated future fixed fee performance obligations	$ 89
Revenue remaining performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated future fixed fee performance obligations	$ 37
Revenue remaining performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated future fixed fee performance obligations	$ 20
Revenue remaining performance obligation period	1 year

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 6,490	$ 2,684	$ 19,687	$ 6,733
Mark-to-market for economic hedging activities	1,785	(118)	4,023	13
Operating revenues	6,609	2,809	19,943	7,066
Lease revenue	2	5	6	15
Derivative revenue	1,793	(123)	4,025	18
Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(1)	(3)	(5)	(6)
Operating revenues	13	2	15	(1)
Lease revenue	0	0	0	0
Retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5,951	2,302	16,929	5,795
Retail revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	(1)	(1)
Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	336	222	989	429
Derivative revenue	41	35	120	99
Energy revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4	1	6	(1)
Derivative revenue	1	(1)	2	(3)
Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	189	174	615	518
Derivative revenue	42	49	119	114
Capacity revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Derivative revenue	0	0	0	0
Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	3	39	(99)	78
Derivative revenue	120	120	269	318
Derivative revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	13	5	19	8
Derivative revenue	14	5	20	5
Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	133	72	1,528	246
Contract amortization	(3)		(19)
Other revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(4)	(4)	(9)	(7)
Contract amortization	0		0
Total operating revenue
Disaggregation of Revenue [Line Items]
Operating revenues	6,609	2,809	19,943	7,066
Total operating revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Operating revenues	13	2	15	(1)
Other revenue, derivative
Disaggregation of Revenue [Line Items]
Derivative revenue	34	(3)	129	27
Other revenue, derivative | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Derivative revenue	0	1	(1)	0
Home | Retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,646	1,987	7,391	4,929
Home | Retail revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	(1)	(1)
Business | Retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,305	315	9,538	866
Business | Retail revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Texas | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,597	1,982	8,233	4,904
Operating revenues	2,635	1,992	8,362	4,928
Lease revenue	0	0	0	0
Texas | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,503	1,921	6,575	4,734
Texas | Energy revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	18	11	317	21
Derivative revenue	0	0	0	0
Texas | Capacity revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Derivative revenue	0	0	0	0
Texas | Derivative revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(1)	1	(5)	1
Derivative revenue	38	10	129	24
Texas | Other revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	115	59	1,475	172
Contract amortization	0		0
Texas | Total operating revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Operating revenues	2,635	1,992	8,362	4,928
Texas | Other revenue, derivative | Operating Segments
Disaggregation of Revenue [Line Items]
Derivative revenue	39	9	134	23
Texas | Other Ancillary | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,200
Texas | Home | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,776	1,633	4,484	3,938
Texas | Business | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	727	288	2,091	796
East | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,008	551	8,823	1,492
Operating revenues	3,077	666	9,002	1,732
Lease revenue	0	0	1	1
East | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,698	354	8,029	996
East | Energy revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	201	93	428	157
Derivative revenue	38	23	122	60
East | Capacity revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	172	158	568	471
Derivative revenue	42	49	119	114
East | Derivative revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(3)	43	(53)	63
Derivative revenue	76	115	193	239
East | Other revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	16	18	45	45
Contract amortization	(7)		(15)
East | Total operating revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Operating revenues	3,077	666	9,002	1,732
East | Other revenue, derivative | Operating Segments
Disaggregation of Revenue [Line Items]
Derivative revenue	(1)	0	5	2
East | Home | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	470	327	1,469	926
East | Business | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,228	27	6,560	70
West/Services/Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	886	154	2,636	343
Operating revenues	884	149	2,564	407
Lease revenue	2	5	5	14
West/Services/Other | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	750	27	2,326	66
West/Services/Other | Energy revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	113	117	238	252
Derivative revenue	2	13	(4)	42
West/Services/Other | Capacity revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	17	16	47	47
Derivative revenue	0	0	0	0
West/Services/Other | Derivative revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(6)	(10)	(60)	6
Derivative revenue	(8)	(10)	(73)	50
West/Services/Other | Other revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6	(1)	17	36
Contract amortization	4		(4)
West/Services/Other | Total operating revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Operating revenues	884	149	2,564	407
West/Services/Other | Other revenue, derivative | Operating Segments
Disaggregation of Revenue [Line Items]
Derivative revenue	(4)	(13)	(9)	2
West/Services/Other | Home | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	400	27	1,439	66
West/Services/Other | Business | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 350	$ 0	$ 887	$ 0

Revenue Recognition - Contract

Revenue Recognition - Contract Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Schedule Of Contract Assets And Liabilities [Line Items]
Deferred customer acquisition costs	$ 124			$ 124		$ 113
Total accounts receivable, net	3,096			3,096		904
Unbilled revenues (included within Accounts receivable, net - Contracts with customers)	1,268			1,268		393
Deferred revenues	312			312		60
Deferred revenue from contract with customers		$ 31		303
Revenue recognized	162		$ 31	23	$ 13
Accounts receivable, net - Contracts with customers
Schedule Of Contract Assets And Liabilities [Line Items]
Total accounts receivable, net	2,955			2,955		866
Accounts receivable, net - Derivative instruments
Schedule Of Contract Assets And Liabilities [Line Items]
Total accounts receivable, net	136			136		33
Accounts receivable, net - Affiliate
Schedule Of Contract Assets And Liabilities [Line Items]
Total accounts receivable, net	$ 5			$ 5		$ 5

Acquisitions and Dispositions -

Acquisitions and Dispositions - Acquisitions Narrative (Details) customer in Millions, $ in Millions	Jan. 25, 2021	Jan. 05, 2021USD ($)statecustomer	Sep. 29, 2020USD ($)	Dec. 31, 2020USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2021USD ($)
Business Acquisition [Line Items]
Acquisition costs					$ 1	$ 24
Leased Assets, Powerton facility and Units 7 and 8 of the Joliet facility
Business Acquisition [Line Items]
Decrease in operating lease liability			$ 148
Powerton Facility And Units 7 And 8 Of The Joliet Facility
Business Acquisition [Line Items]
Payments to acquire assets			$ 260
Direct Energy
Business Acquisition [Line Items]
Customers added (over) | customer		3
Purchase price		$ 3,625
Purchase price adjustment		77			$ 3
Cash paid to acquire business		715
Borrowings on credit facility		166
Acquisition costs		107
Proceeds from issuance of secured and unsecured debt				$ 2,900
Increase in collective collateral facilities		$ 3,400
Direct Energy | Customer relationships
Business Acquisition [Line Items]
Intangible asset amortization period	12 years
Direct Energy | Customer and supply contracts
Business Acquisition [Line Items]
Intangible asset amortization period	14 years
Direct Energy | Trade names
Business Acquisition [Line Items]
Intangible asset amortization period	15 years
Direct Energy | U.S.
Business Acquisition [Line Items]
States in which entity operates | state		50
Direct Energy | Canada
Business Acquisition [Line Items]
Provinces in which entity operates | state		8

Acquisitions and Dispositions_2

Acquisitions and Dispositions - Collective Collateral Facilities (Details) - Revolving Credit Facility - USD ($)	Jan. 05, 2021	Jan. 05, 2021	Jul. 26, 2021	Dec. 31, 2020
Revolving Credit Facility commitment increase
Line of Credit Facility [Line Items]
Revolving Credit Facility increases	$ 802,000,000
Revolving Credit Facility new tranche
Line of Credit Facility [Line Items]
Credit facility borrowing available	273,000,000	$ 273,000,000
Facility agreement in connection with the sale of pre-capitalized trust securities
Line of Credit Facility [Line Items]
Credit facility borrowing available	$ 874,000,000	874,000,000
Credit default swap facility
Line of Credit Facility [Line Items]
Credit facility borrowing available				$ 150,000,000
Revolving accounts receivable financing facility
Line of Credit Facility [Line Items]
Credit facility borrowing available			$ 800,000,000	750,000,000
Repurchase facility
Line of Credit Facility [Line Items]
Credit facility borrowing available				75,000,000
Bilateral letter of credit facilities
Line of Credit Facility [Line Items]
Credit facility borrowing available				$ 475,000,000
Total Increases to Liquidity and Collateral Facilities
Line of Credit Facility [Line Items]
Revolving Credit Facility increases		$ 3,399,000,000

Acquisitions and Dispositions_3

Acquisitions and Dispositions - Purchase Price Allocation (Details) - USD ($) $ in Millions	Jan. 25, 2021	Sep. 30, 2021	Jan. 05, 2021	Dec. 31, 2020
Other Assets
Goodwill		$ 1,801		$ 579
Direct Energy
Current Assets
Cash and cash equivalents			$ 152
Funds deposited by counterparties			21
Restricted cash			9
Accounts receivable, net			1,802
Inventory			106
Derivative instruments			1,014
Cash collateral paid in support of energy risk management activities			233
Prepayments and other current assets			183
Total current assets			3,520
Property, plant and equipment, net			151
Other Assets
Goodwill			1,257
Intangible assets, net			2,321
Derivative instruments			531
Other non-current assets			31
Total other assets			4,140
Total Assets			7,811
Current Liabilities
Accounts payable			1,120
Derivative instruments			1,266
Cash collateral received in support of energy risk management activities			21
Accrued expenses and other current liabilities			690
Total current liabilities			3,097
Other Liabilities
Derivative instruments			562
Deferred income taxes			338
Other non-current liabilities			115
Total other liabilities			1,015
Total Liabilities			4,112
Direct Energy Purchase Price			3,699
Goodwill, expected to be tax deductible			337
Direct Energy | Texas
Other Assets
Goodwill			424
Direct Energy | East
Other Assets
Goodwill			663
Direct Energy | West/Services/Other
Other Assets
Goodwill			170
Direct Energy | Customer relationships
Other Assets
Intangible assets, net			1,277
Other Liabilities
Weighted average amortization period	12 years
Direct Energy | Customer and supply contracts
Other Assets
Intangible assets, net			610
Other Liabilities
Weighted average amortization period	12 years
Direct Energy | Trade names
Other Assets
Intangible assets, net			310
Other Liabilities
Weighted average amortization period	12 years
Direct Energy | Renewable energy credits
Other Assets
Intangible assets, net			$ 124

Acquisitions and Dispositions_4

Acquisitions and Dispositions - Measurement Period Adjustment (Details) - Direct Energy $ in Millions	3 Months Ended
	Sep. 30, 2021USD ($)
Assets
Goodwill	$ 11
Intangible assets, net	(32)
Total decrease in assets	(21)
Liabilities
Accounts payable	(270)
Accrued expenses and other current liabilities	248
Deferred income taxes	(1)
Other non-current liabilities	2
Total decrease in liabilities	$ (21)

Acquisitions and Dispositions_5

Acquisitions and Dispositions -Fair Values of Derivatives Assets and Liabilities as of the Acquisition Closing Date (Details) - Direct Energy $ in Millions	Jan. 05, 2021USD ($)
Derivative [Line Items]
Derivatives assets	$ 1,545
Derivatives liabilities	1,828
Level 1
Derivative [Line Items]
Derivatives assets	155
Derivatives liabilities	207
Level 2
Derivative [Line Items]
Derivatives assets	1,272
Derivatives liabilities	1,489
Level 3
Derivative [Line Items]
Derivatives assets	118
Derivatives liabilities	$ 132

Acquisitions and Dispositions_6

Acquisitions and Dispositions - Direct Energy Contributed Revenue and Income Before Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Business Acquisition [Line Items]
Revenues	$ 6,609	$ 2,809	$ 19,943	$ 7,066
Income before income taxes	2,163	$ 341	3,454	$ 899
Direct Energy
Business Acquisition [Line Items]
Revenues	3,599		10,718
Income before income taxes	$ 2,010		$ 3,457

Acquisitions and Dispositions_7

Acquisitions and Dispositions - Supplemental Pro Forma Financial Information (Details) - Direct Energy - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Business Acquisition [Line Items]
Total operating revenues	$ 19,932	$ 16,039
Net Income	$ 2,585	$ 832

Acquisitions and Dispositions_8

Acquisitions and Dispositions - Dispositions (Details) $ in Millions	Feb. 03, 2021USD ($)	Dec. 31, 2021USD ($)MW	Sep. 30, 2021USD ($)MW	Sep. 30, 2020USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generation capacity (in MW) | MW			23,000
Gain on sale			$ 17	$ 6
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Agua Caliente Solar Project
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of ownership sold	35.00%
Cash consideration	$ 202
Gain on sale	17
Cash disposed	$ 7
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Other
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale			$ 3	$ 15
East and West | Forecast | Subsequent Event | Arthur Kill Plant
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generation capacity (in MW) | MW		866
East and West | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Forecast | Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generation capacity (in MW) | MW		4,850
Proceeds from sale		$ 760
Working capital adjustments		$ 11

Acquisitions and Dispositions_9

Acquisitions and Dispositions - Held For Sale (Details) $ in Millions	Dec. 31, 2021MW	Sep. 30, 2021USD ($)MW	Feb. 03, 2021USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Power Generation Capacity, Megawatts | MW		23,000
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Agua Caliente Solar Project
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration			$ 202
East and West | Arthur Kill Plant | Forecast | Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Power Generation Capacity, Megawatts | MW	866
East and West | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current assets - discontinued operations		$ 51
Property, plant and equipment, net		391
Other non-current assets		3
Noncurrent assets		394
Total assets held for sale		445
Current liabilities		14
Non-current liabilities		61
Total liabilities held for sale		$ 75
East and West | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Forecast | Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Power Generation Capacity, Megawatts | MW	4,850
East
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Power Generation Capacity, Megawatts | MW		1,600
East | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property, plant and equipment, net		$ 242
West/Services/Other | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property, plant and equipment, net		$ 149

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Estimated Carrying Amounts and Fair Value of Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Notes receivable	$ 2	$ 2
Long-term debt, including current portion	8,537	8,781
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Notes receivable	2	2
Long-term debt, including current portion	$ 8,897	$ 9,446

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Assets and Liabilities Measured and Recorded at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in securities (classified within other current and non-current assets)	$ 23	$ 25
Other trust fund investments (classified within other non-current assets):
U.S. government and federal agency obligations	1	1
Measured using net asset value practical expedient:
Total assets	12,188	1,745
Derivative liabilities:
Commodity contracts	7,521	884
Foreign exchange contract
Derivative assets:
Derivative contracts	1
Commodity contracts
Derivative assets:
Derivative contracts	11,198	821
Derivative liabilities:
Commodity contracts	7,521	884
Cash and cash equivalents
Nuclear trust fund investments:
Nuclear trust fund investments	29	23
U.S. government and federal agency obligations
Nuclear trust fund investments:
Nuclear trust fund investments	76	70
Federal agency mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	93	89
Commercial mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	43	36
Corporate debt securities
Nuclear trust fund investments:
Nuclear trust fund investments	116	144
Equity securities
Nuclear trust fund investments:
Nuclear trust fund investments	503	434
Measured using net asset value practical expedient:
Equity securities	8	8
Foreign government fixed income securities
Nuclear trust fund investments:
Nuclear trust fund investments	4	7
Equity securities — nuclear trust fund investments
Measured using net asset value practical expedient:
Equity securities	93	87
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in securities (classified within other current and non-current assets)	7	10
Other trust fund investments (classified within other non-current assets):
U.S. government and federal agency obligations	1	1
Measured using net asset value practical expedient:
Total assets	2,776	597
Derivative liabilities:
Commodity contracts	1,376	86
Level 1 | Foreign exchange contract
Derivative assets:
Derivative contracts	0
Level 1 | Commodity contracts
Derivative assets:
Derivative contracts	2,161	59
Derivative liabilities:
Commodity contracts	1,376	86
Level 1 | Cash and cash equivalents
Nuclear trust fund investments:
Nuclear trust fund investments	29	23
Level 1 | U.S. government and federal agency obligations
Nuclear trust fund investments:
Nuclear trust fund investments	75	69
Level 1 | Federal agency mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	0	0
Level 1 | Commercial mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	0	0
Level 1 | Corporate debt securities
Nuclear trust fund investments:
Nuclear trust fund investments	0	0
Level 1 | Equity securities
Nuclear trust fund investments:
Nuclear trust fund investments	503	434
Level 1 | Foreign government fixed income securities
Nuclear trust fund investments:
Nuclear trust fund investments	0	1
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in securities (classified within other current and non-current assets)	16	15
Other trust fund investments (classified within other non-current assets):
U.S. government and federal agency obligations	0	0
Measured using net asset value practical expedient:
Total assets	8,748	914
Derivative liabilities:
Commodity contracts	5,893	643
Level 2 | Foreign exchange contract
Derivative assets:
Derivative contracts	1
Level 2 | Commodity contracts
Derivative assets:
Derivative contracts	8,474	623
Derivative liabilities:
Commodity contracts	5,893	643
Level 2 | Cash and cash equivalents
Nuclear trust fund investments:
Nuclear trust fund investments	0	0
Level 2 | U.S. government and federal agency obligations
Nuclear trust fund investments:
Nuclear trust fund investments	1	1
Level 2 | Federal agency mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	93	89
Level 2 | Commercial mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	43	36
Level 2 | Corporate debt securities
Nuclear trust fund investments:
Nuclear trust fund investments	116	144
Level 2 | Equity securities
Nuclear trust fund investments:
Nuclear trust fund investments	0	0
Level 2 | Foreign government fixed income securities
Nuclear trust fund investments:
Nuclear trust fund investments	4	6
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in securities (classified within other current and non-current assets)	0	0
Other trust fund investments (classified within other non-current assets):
U.S. government and federal agency obligations	0	0
Measured using net asset value practical expedient:
Total assets	563	139
Derivative liabilities:
Commodity contracts	252	155
Level 3 | Foreign exchange contract
Derivative assets:
Derivative contracts	0
Level 3 | Commodity contracts
Derivative assets:
Derivative contracts	563	139
Derivative liabilities:
Commodity contracts	252	155
Level 3 | Cash and cash equivalents
Nuclear trust fund investments:
Nuclear trust fund investments	0	0
Level 3 | U.S. government and federal agency obligations
Nuclear trust fund investments:
Nuclear trust fund investments	0	0
Level 3 | Federal agency mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	0	0
Level 3 | Commercial mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	0	0
Level 3 | Corporate debt securities
Nuclear trust fund investments:
Nuclear trust fund investments	0	0
Level 3 | Equity securities
Nuclear trust fund investments:
Nuclear trust fund investments	0	0
Level 3 | Foreign government fixed income securities
Nuclear trust fund investments:
Nuclear trust fund investments	$ 0	$ 0

Fair Value of Financial Instr_5

Fair Value of Financial Instruments - Reconciliation of Level 3 Financial Instruments (Details) - Level 3 - Derivatives - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 574	$ 152	$ (16)	$ 38
Contracts added from Direct Energy acquisition	0			(15)
Total losses) gains— realized/unrealized included in earnings	(175)	(92)	187	(18)
Purchases	0	(10)	78	6
Transfers into Level 3	(108)	(11)	64	22
Transfers out of Level 3	20	13	13	4
Ending balance	311	52	311	52
(Losses)/gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of period end	$ (237)	$ 23	$ 184	$ 50

Fair Value of Financial Instr_6

Fair Value of Financial Instruments - Derivative Fair Value Measurements, Narrative (Details) - USD ($) $ in Millions	6 Months Ended	9 Months Ended
	Jun. 30, 2021	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Total derivative assets valued with prices provided by models and other valuation techniques (as a percent)		5.00%
Total derivative liabilities valued with prices provided by models and other valuation techniques (as a percent)		3.00%
Increase in operating revenue		$ 7
Increase within cost of operations	$ 2

Fair Value of Financial Instr_7

Fair Value of Financial Instruments - Derivative Fair Value Measurements (Details) $ in Millions	Sep. 30, 2021USD ($)$ / MWh	Dec. 31, 2020USD ($)$ / MWh
Liabilities
Commodity contracts	$ 7,521	$ 884
Level 3
Liabilities
Commodity contracts	252	155
Commodity contracts
Assets
Derivative assets	11,198	821
Liabilities
Commodity contracts	7,521	884
Commodity contracts | Level 3
Assets
Derivative assets	563	139
Liabilities
Commodity contracts	252	155
Commodity contracts | Level 3 | Natural Gas Contracts
Assets
Derivative assets	19
Liabilities
Commodity contracts	$ 3
Commodity contracts | Level 3 | Natural Gas Contracts | Low
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	3
Commodity contracts | Level 3 | Natural Gas Contracts | High
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	49
Commodity contracts | Level 3 | Natural Gas Contracts | Weighted Average
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	19
Commodity contracts | Level 3 | Power Contracts
Assets
Derivative assets	$ 512	111
Liabilities
Commodity contracts	$ 218	$ 143
Commodity contracts | Level 3 | Power Contracts | Low
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	3	10
Commodity contracts | Level 3 | Power Contracts | High
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	263	105
Commodity contracts | Level 3 | Power Contracts | Weighted Average
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	40	21
Commodity contracts | Level 3 | FTRs
Assets
Derivative assets	$ 32	$ 28
Liabilities
Commodity contracts	$ 31	$ 12
Commodity contracts | Level 3 | FTRs | Low
Fair Value Inputs / Range
Auction Prices (per MWh) | $ / MWh	(131)	(28)
Commodity contracts | Level 3 | FTRs | High
Fair Value Inputs / Range
Auction Prices (per MWh) | $ / MWh	755	43
Commodity contracts | Level 3 | FTRs | Weighted Average
Fair Value Inputs / Range
Auction Prices (per MWh) | $ / MWh	0	0

Fair Value of Financial Instr_8

Fair Value of Financial Instruments - Counterparty Credit Risk (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2021USD ($)
Concentration of Credit Risk
Counterparty credit exposure to a portion of the Company's counterparties		$ 2,900
Collateral held (cash and letters of credit) against counterparty credit exposure to a portion of the Company's counterparties	$ 1,100	1,100
Net counterparty credit exposure to a portion of the Company's counterparties	$ 1,900	$ 1,900
Company's exposure before collateral expected to roll off (as a percent)		59.00%
Net exposure (as a percent)	100.00%	100.00%
Counterparty credit risk exposure to certain counterparties, threshold (as a percent)		10.00%
Estimated counterparty credit risk exposure under certain long term agreements for the next 5 years		$ 1,400
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)		5 years
Designated as Hedging Instrument
Concentration of Credit Risk
Counterparty credit exposure to a portion of the Company's counterparties	$ 403
Investment grade
Concentration of Credit Risk
Net exposure (as a percent)	78.00%	78.00%
Non-Investment grade/Non-Rated
Concentration of Credit Risk
Net exposure (as a percent)	22.00%	22.00%
Utilities, energy merchants, marketers and other
Concentration of Credit Risk
Net exposure (as a percent)	49.00%	49.00%
Financial Institutions
Concentration of Credit Risk
Net exposure (as a percent)	51.00%	51.00%

Nuclear Decommissioning Trust_3

Nuclear Decommissioning Trust Fund - Narrative (Details)	Sep. 30, 2021
STP
Nuclear decommissioning trust fund
Ownership interest as percentage	44.00%

Nuclear Decommissioning Trust_4

Nuclear Decommissioning Trust Fund - Summary of aggregate fair values and realized gains and losses (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Nuclear decommissioning trust fund
Fair Value	$ 957	$ 890
Unrealized Gains	455	398
Unrealized Losses	1	0
Cash and cash equivalents
Nuclear decommissioning trust fund
Fair Value	29	23
Unrealized Gains	0	0
Unrealized Losses	0	0
U.S. government and federal agency obligations
Nuclear decommissioning trust fund
Fair Value	76	70
Unrealized Gains	4	6
Unrealized Losses	$ 0	$ 0
Weighted-average Maturities (In years)	12 years	10 years
Federal agency mortgage-backed securities
Nuclear decommissioning trust fund
Fair Value	$ 93	$ 89
Unrealized Gains	3	4
Unrealized Losses	$ 0	$ 0
Weighted-average Maturities (In years)	24 years	24 years
Commercial mortgage-backed securities
Nuclear decommissioning trust fund
Fair Value	$ 43	$ 36
Unrealized Gains	1	2
Unrealized Losses	$ 0	$ 0
Weighted-average Maturities (In years)	27 years	27 years
Corporate debt securities
Nuclear decommissioning trust fund
Fair Value	$ 116	$ 144
Unrealized Gains	8	13
Unrealized Losses	$ 1	$ 0
Weighted-average Maturities (In years)	14 years	12 years
Equity securities
Nuclear decommissioning trust fund
Fair Value	$ 596	$ 521
Unrealized Gains	439	372
Unrealized Losses	0	0
Foreign government fixed income securities
Nuclear decommissioning trust fund
Fair Value	4	7
Unrealized Gains	0	1
Unrealized Losses	$ 0	$ 0
Weighted-average Maturities (In years)	12 years	10 years

Nuclear Decommissioning Trust_5

Nuclear Decommissioning Trust Fund - Summary of proceeds from sales of available-for-sale securities and related gains and losses (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Regulated Operations [Abstract]
Realized gains	$ 10	$ 22
Realized losses	(6)	(11)
Proceeds from sale of securities	$ 424	$ 318

Accounting for Derivative Ins_3

Accounting for Derivative Instruments and Hedging Activities - Net notional volume buy/sell of open derivative transactions (Details) certificate in Millions, bbl in Millions, T in Millions, MWh in Millions, MMBTU in Millions, $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021USD ($)MMBTUMWhcertificateTbbl	Dec. 31, 2020USD ($)MMBTUMWhcertificateTbbl
Long | Emissions
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, mass (ton) | T	1	1
Long | Renewable Energy Certificates
Volumetric Underlying Derivative Transactions
Derivative, non-monetary notional amount (in shares) | certificate	13	5
Long | Coal
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, mass (ton) | T	3	2
Long | Oil
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount (in barrels) | bbl	1	0
Long | Power
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, energy measure (MMBtu/MW/Day) | MWh	185	57
Long | Foreign Exchange
Volumetric Underlying Derivative Transactions
Derivative, notional amount | $	$ 218	$ 0
Short | Natural Gas
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, energy measure (MMBtu/MW/Day) | MMBTU	663	286
Short | Capacity
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, energy measure (MMBtu/MW/Day) | MMBTU	0	1

Accounting for Derivative Ins_4

Accounting for Derivative Instruments and Hedging Activities - Fair value within the derivative instrument valuation (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative Liabilities	$ 7,521	$ 884
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Assets	11,199	821
Derivative Liabilities	7,521	884
Not Designated as Hedging Instrument | Foreign exchange contracts - current
Derivative [Line Items]
Derivative Assets	1	0
Derivative Liabilities	0	0
Not Designated as Hedging Instrument | Commodity contracts - current
Derivative [Line Items]
Derivative Assets	8,527	560
Derivative Liabilities	6,032	499
Not Designated as Hedging Instrument | Commodity contracts - long-term
Derivative [Line Items]
Derivative Assets	2,671	261
Derivative Liabilities	$ 1,489	$ 385

Accounting for Derivative Ins_5

Accounting for Derivative Instruments and Hedging Activities - Offsetting of derivatives by counterparty master agreement level and collateral received (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Cash collateral received in support of energy risk management activities	$ (1,748)	$ (19)
Derivative liabilities	(7,521)	(884)
Cash Collateral Posted	21	50
Total Derivative Contracts
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amounts of Recognized Assets / Liabilities	3,678
Derivative Instruments	0
Cash Collateral (Held) / Posted	(1,712)
Net Amount	1,966
Foreign exchange contract
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Derivative assets	1
Derivative Instruments	0
Cash collateral received in support of energy risk management activities	0
Net Amount	1
Gross Amounts of Recognized Assets / Liabilities	1
Derivative Instruments	0
Cash Collateral (Held) / Posted	0
Net Amount	1
Commodity contracts
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Derivative assets	11,198	821
Derivative Instruments	(6,946)	(658)
Cash collateral received in support of energy risk management activities	(1,712)	(5)
Net Amount	2,540	158
Derivative liabilities	(7,521)	(884)
Derivative Instruments	6,946	658
Cash Collateral Posted	0	0
Net Amount	(575)	(226)
Gross Amounts of Recognized Assets / Liabilities	3,677	(63)
Derivative Instruments	0	0
Cash Collateral (Held) / Posted	(1,712)	(5)
Net Amount	$ 1,965	$ (68)

Accounting for Derivative Ins_6

Accounting for Derivative Instruments and Hedging Activities - Pre-tax effects of economic hedges not designated a cash flow hedges (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Unrealized mark-to-market results
Reversal of previously recognized unrealized (gains) on settled positions related to economic hedges	$ (97)	$ (101)	$ (58)	$ (62)
Reversal of acquired (gain)/loss positions related to economic hedges	(42)	(2)	206	2
Net unrealized gains/(losses) on open positions related to economic hedges	1,924	(15)	3,875	73
Total unrealized mark-to-market gains/(losses) for economic hedging activities	1,785	(118)	4,023	13
Reversal of previously recognized unrealized (gains) on settled positions related to trading activity	(6)	(7)	(16)	(14)
Net unrealized gains on open positions related to trading activity	14	2	18	19
Total unrealized mark-to-market gains/(losses) for trading activity	8	(5)	2	5
Total unrealized gains/(losses)	1,793	(123)	4,025	18
Credit Risk Related Contingent Features
Unrealized gains from open economic hedge positions			3,900	73
Collateral due on net liability position that has not been called by a certain marginable agreement counterparty	92		92
Additional collateral required	35		35
Adequate Assurance Clauses
Credit Risk Related Contingent Features
Derivative net liability position, collateral required for contracts with credit rating contingent feature	865		865
Commodity contracts
Unrealized mark-to-market results
Total unrealized gains/(losses)	1,793	(123)	4,025	18
Commodity contracts | Operating revenues
Unrealized mark-to-market results
Total unrealized gains/(losses)	11	34	(97)	83
Commodity contracts | Cost of operations
Unrealized mark-to-market results
Total unrealized gains/(losses)	1,777	(157)	4,121	(65)
Foreign exchange contract | Cost of operations
Unrealized mark-to-market results
Total unrealized gains/(losses)	$ 5	$ 0	$ 1	$ 0

Impairments (Details)

Impairments (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2021	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019
Petra Nova
Schedule of Equity Method Investments [Line Items]
Impairment losses			$ 18
Letters of credit issued				$ 12
East
Schedule of Equity Method Investments [Line Items]
Property plant and equipment impairment loss	$ 271
Goodwill impairment loss	$ 35
West/Services/Other | Disposal Group, Held-for-sale, Not Discontinued Operations | Home Solar
Schedule of Equity Method Investments [Line Items]
Adjustment to carrying amount of assets and liabilities		$ 29

Long-term Debt and Finance Le_3

Long-term Debt and Finance Leases - Schedule of Long-term Debt and Finance Leases (Details) $ / shares in Units, $ in Millions	Oct. 29, 2021$ / shares	Nov. 04, 2021	Sep. 30, 2021USD ($)	Aug. 24, 2021	Aug. 23, 2021	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Finance leases			$ 13			$ 4
Subtotal long-term debt and finance leases (including current maturities)			8,613			8,859
Less current maturities			(504)			(1)
Less debt issuance costs			(89)			(93)
Discounts			(63)			(74)
Total long-term debt and finance leases			7,957			8,691
Senior Notes, due 2026
Debt Instrument [Line Items]
Interest rate, stated percentage				7.25%
Senior Notes, due 2027
Debt Instrument [Line Items]
Interest rate, stated percentage				6.625%
Senior Notes, due 2027 | Subsequent Event
Debt Instrument [Line Items]
Interest rate, stated percentage		6.625%
Senior Notes, due 2032
Debt Instrument [Line Items]
Interest rate, stated percentage					3.875%
Recourse Debt
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			8,600			8,855
Recourse Debt | Senior Notes, due 2026
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 0			1,000
Interest rate, stated percentage			7.25%
Recourse Debt | Senior Notes, due 2027
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 875			1,230
Interest rate, stated percentage			6.625%
Recourse Debt | Senior Notes, due 2028
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 821			821
Interest rate, stated percentage			5.75%
Recourse Debt | Senior Notes, due 2029
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 733			733
Interest rate, stated percentage			5.25%
Recourse Debt | Senior Notes, due 2029
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 500			500
Interest rate, stated percentage			3.375%
Recourse Debt | Senior Notes, due 2031
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 1,030			1,030
Interest rate, stated percentage			3.625%
Recourse Debt | Senior Notes, due 2032
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 1,100			0
Interest rate, stated percentage			3.875%
Recourse Debt | Convertible Senior Notes Due 2048
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 575			575
Interest rate, stated percentage			2.75%
Recourse Debt | Convertible Senior Notes Due 2048 | Subsequent Event
Debt Instrument [Line Items]
Convertible Notes, conversion price (in usd per share) | $ / shares	$ 44.89
Conversion rate	0.0222761
Recourse Debt | Senior Secured First Lien Notes, due 2024
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 600			600
Interest rate, stated percentage			3.75%
Recourse Debt | Senior Secured First Lien Notes, due 2025
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 500			500
Interest rate, stated percentage			2.00%
Recourse Debt | Senior Secured First Lien Notes, due 2027
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 900			900
Interest rate, stated percentage			2.45%
Recourse Debt | Senior Secured First Lien Notes, due 2029
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 500			500
Interest rate, stated percentage			4.45%
Recourse Debt | Tax-exempt bonds
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 466			$ 466
Recourse Debt | Tax-exempt bonds | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage			1.25%
Recourse Debt | Tax-exempt bonds | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage			4.75%

Long-term Debt and Finance Le_4

Long-term Debt and Finance Leases - Recourse Debt (Details) - USD ($)	Aug. 24, 2021	Aug. 23, 2021	Jul. 26, 2021	Nov. 04, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Debt Instrument [Line Items]
Aggregate principal redeemed	$ 1,400,000,000
Cash paid	1,400,000,000
Loss on debt extinguishment, net	$ 57,000,000				$ (57,000,000)	$ 0	$ (57,000,000)	$ (1,000,000)
Write off of previously deferred debt issuance costs							9,000,000
Senior Notes, due 2032
Debt Instrument [Line Items]
Debt issuance amount		$ 1,100,000,000
Interest rate, stated percentage		3.875%
Increase basis point, interest rate payable if sustainability targets not met		0.25%
Senior Notes, due 2026
Debt Instrument [Line Items]
Interest rate, stated percentage	7.25%
Aggregate principal redeemed	$ 1,000,000,000
Cash paid	$ 1,056,000,000
Senior Notes, due 2027
Debt Instrument [Line Items]
Interest rate, stated percentage	6.625%
Aggregate principal redeemed	$ 355,000,000
Cash paid	$ 369,000,000
Senior Notes, due 2027 | Subsequent Event
Debt Instrument [Line Items]
Interest rate, stated percentage				6.625%
Aggregate principal redeemed				$ 500,000,000
Cash paid				$ 524,000,000
Receivables Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Increase to existing revolving commitments			$ 50,000,000
Revolving credit commitments			$ 800,000,000						$ 750,000,000
Borrowings outstanding					0		0
Letters of credit issued					400,000,000		400,000,000
Repurchase Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit commitments									75,000,000
Credit agreement | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Revolving credit commitments									$ 273,000,000
Increase revolving commitments						$ 802,000,000
Total revolving commitments available					$ 3,700,000,000		$ 3,700,000,000

Long-term Debt and Finance Le_5

Long-term Debt and Finance Leases - Redemptions (Details) - USD ($)	Aug. 24, 2021	Nov. 04, 2021
Debt Instrument, Redemption [Line Items]
Principal Repurchased	$ 1,400,000,000
Cash paid	$ 1,400,000,000
Senior Notes, due 2026
Debt Instrument, Redemption [Line Items]
Interest rate, stated percentage	7.25%
Principal Repurchased	$ 1,000,000,000
Cash paid	$ 1,056,000,000
Average Early Redemption Percentage	103.625%
Senior Notes, due 2027
Debt Instrument, Redemption [Line Items]
Interest rate, stated percentage	6.625%
Principal Repurchased	$ 355,000,000
Cash paid	$ 369,000,000
Average Early Redemption Percentage	103.313%
Senior Notes, due 2027 | Subsequent Event
Debt Instrument, Redemption [Line Items]
Interest rate, stated percentage		6.625%
Principal Repurchased		$ 500,000,000
Cash paid		$ 524,000,000
Average Early Redemption Percentage		103.313%
Senior Notes
Debt Instrument, Redemption [Line Items]
Principal Repurchased	$ 1,355,000,000
Cash paid	1,425,000,000
Accrued interest	$ 22,000,000
Senior Notes | Subsequent Event
Debt Instrument, Redemption [Line Items]
Principal Repurchased		$ 1,855,000,000
Cash paid		1,949,000,000
Accrued interest		$ 29,000,000

Long-term Debt and Finance Le_6

Long-term Debt and Finance Leases - Non-Recourse Debt (Details) - Letter Of Credit Agreement - USD ($) $ in Millions	Sep. 30, 2021	Dec. 11, 2020
Line of Credit Facility [Line Items]
Credit facility borrowing available		$ 874
Letters of credit issued	$ 864

Investments Accounted for Usi_3

Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs (Details) - USD ($) $ in Millions	Sep. 30, 2021	Feb. 03, 2021	Dec. 31, 2020
Investments Accounted for by the Equity Method
Other current assets	$ 14,572		$ 6,028
Total Assets	27,965		14,902
Current liabilities	12,009		1,915
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Agua Caliente Solar Project
Investments Accounted for by the Equity Method
Cash consideration		$ 202
Variable Interest Entity, Primary Beneficiary
Investments Accounted for by the Equity Method
Accounts receivable	730		647
Other current assets	0		2
Total Assets	730		649
Current liabilities	78		78
Net assets	$ 652		$ 571
Agua Caliente
Investments Accounted for by the Equity Method
Ownership interest		35.00%

Changes in Capital Structure -

Changes in Capital Structure - Changes in NRG's common stock issued and outstanding (Details) - shares	1 Months Ended	9 Months Ended
	Nov. 04, 2021	Sep. 30, 2021
Schedule of Stock by Class, Equity [Roll Forward]
Balance as of beginning of period (in shares)	423,545,261	423,057,848
Treasury shares, balance as of beginning of period (in shares)	(178,765,948)	(178,825,915)
Outstanding, as of beginning of period (in shares)	244,779,313	244,231,933
Balance as of end of period (in shares)		423,545,261
Treasury shares, balance as of end of the period (in shares)		(178,765,948)
Outstanding, as of end of period (in shares)		244,779,313
Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		487,413
Shares issued under ESPP
Schedule of Stock by Class, Equity [Roll Forward]
Stock issued under ESPP (in shares)		59,967
Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Outstanding, as of end of period (in shares)	244,838,651
Subsequent Event | Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	1,913
Subsequent Event | Shares issued under ESPP
Schedule of Stock by Class, Equity [Roll Forward]
Stock issued under ESPP (in shares)	57,425
Common Stock
Schedule of Stock by Class, Equity [Roll Forward]
Balance as of beginning of period (in shares)	423,545,261	423,057,848
Balance as of end of period (in shares)		423,545,261
Common Stock | Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		487,413
Common Stock | Shares issued under ESPP
Schedule of Stock by Class, Equity [Roll Forward]
Stock issued under ESPP (in shares)		0
Common Stock | Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Balance as of end of period (in shares)	423,547,174
Common Stock | Subsequent Event | Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	1,913
Common Stock | Subsequent Event | Shares issued under ESPP
Schedule of Stock by Class, Equity [Roll Forward]
Stock issued under ESPP (in shares)	0
Treasury
Schedule of Stock by Class, Equity [Roll Forward]
Treasury shares, balance as of beginning of period (in shares)	(178,765,948)	(178,825,915)
Treasury shares, balance as of end of the period (in shares)		(178,765,948)
Treasury | Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		0
Treasury | Shares issued under ESPP
Schedule of Stock by Class, Equity [Roll Forward]
Stock issued under ESPP (in shares)		59,967
Treasury | Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Treasury shares, balance as of end of the period (in shares)	(178,708,523)
Treasury | Subsequent Event | Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	0
Treasury | Subsequent Event | Shares issued under ESPP
Schedule of Stock by Class, Equity [Roll Forward]
Stock issued under ESPP (in shares)	57,425

Changes in Capital Structure _2

Changes in Capital Structure - Narrative (Details) - $ / shares	1 Months Ended	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Class of Stock [Line Items]
Common stock, shares authorized (in shares)				500,000,000	500,000,000
Employee Stock Purchase Plan, minimum percentage of eligible compensation to purchase shares	1.00%
Employee Stock Purchase Plan, maximum percentage of eligible compensation	10.00%
Employee Stock Purchase Plan, exercise price as percentage of fair value	95.00%
Common stock dividends proposed annual amount (in usd per share)			$ 1.20	$ 1.30
Forecast
Class of Stock [Line Items]
Common stock dividends proposed annual amount (in usd per share)		$ 1.40
Annual dividend rate increase		8.00%

Changes in Capital Structure _3

Changes in Capital Structure - NRG Common Stock Dividends (Details) - $ / shares	Oct. 15, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2020
Subsequent Event [Line Items]
Common stock dividends proposed annual amount (in usd per share)				$ 1.20				$ 1.30
Dividends per common share (in usd per share)		$ 0.325	$ 0.325	$ 0.325	$ 0.30	$ 0.30	$ 0.30
Subsequent Event
Subsequent Event [Line Items]
Common stock dividends declared (in usd per share)	$ 0.325
Minimum
Subsequent Event [Line Items]
Common stock, annual dividend growth rate, percentage				700.00%
Maximum
Subsequent Event [Line Items]
Common stock, annual dividend growth rate, percentage				9.00%

Income Per Share - Reconciliati

Income Per Share - Reconciliation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Basic income per share:
Net income	$ 1,618	$ 249	$ 2,614	$ 683
Weighted average number of common shares outstanding — basic (in shares)	245	244	245	246
Income per weighted average common share — basic (in usd per share)	$ 6.60	$ 1.02	$ 10.67	$ 2.78
Diluted income per share:
Net income	$ 1,618	$ 249	$ 2,614	$ 683
Weighted average number of common shares outstanding — basic (in shares)	245	244	245	246
Incremental shares attributable to the issuance of equity compensation (treasury stock method) (in shares)	0	1	0	1
Weighted average number of common shares outstanding- dilutive (in shares)	245	245	245	247
Income per weighted average common share — diluted (in usd per share)	$ 6.60	$ 1.02	$ 10.67	$ 2.77

Segment Reporting (Details)

Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Segment Reporting Information
Operating revenues	$ 6,609	$ 2,809	$ 19,943	$ 7,066
Depreciation and amortization	199	99	569	318
Impairment losses	0	29	306	29
Gain on sale of assets			17	6
Equity in earnings of unconsolidated affiliates	15	36	23	37
Income/(loss) before income taxes	2,163	341	3,454	899
Net income/(loss)	1,618	249	2,614	683
Total assets	27,965		27,965		$ 14,902
Corporate
Segment Reporting Information
Operating revenues	0	0	0	0
Depreciation and amortization	7	7	21	26
Impairment losses		0	0	0
Gain on sale of assets			0	5
Equity in earnings of unconsolidated affiliates	0	0	0	0
Income/(loss) before income taxes	(208)	(115)	(536)	(306)
Net income/(loss)	(739)	(206)	(1,344)	(520)
Total assets	10,507		10,507
Eliminations
Segment Reporting Information
Operating revenues	13	2	15	(1)
Depreciation and amortization	0	0	0	0
Impairment losses		0	0	0
Gain on sale of assets			0	0
Equity in earnings of unconsolidated affiliates	0	0	0	0
Income/(loss) before income taxes	0	0	0	0
Net income/(loss)	0	0	0	0
Total assets	(17,066)		(17,066)
Texas | Operating Segments
Segment Reporting Information
Operating revenues	2,635	1,992	8,362	4,928
Depreciation and amortization	84	49	245	167
Impairment losses		0	0	0
Gain on sale of assets			0	0
Equity in earnings of unconsolidated affiliates	(2)	0	(3)	(3)
Income/(loss) before income taxes	251	287	600	799
Net income/(loss)	251	287	600	799
Total assets	9,929		9,929
East | Operating Segments
Segment Reporting Information
Operating revenues	3,077	666	9,002	1,732
Depreciation and amortization	88	33	238	97
Impairment losses		0	306	0
Gain on sale of assets			0	0
Equity in earnings of unconsolidated affiliates	0	0	0	0
Income/(loss) before income taxes	1,989	146	3,136	308
Net income/(loss)	1,976	145	3,107	307
Total assets	19,940		19,940
West/Services/Other | Operating Segments
Segment Reporting Information
Operating revenues	884	149	2,564	407
Depreciation and amortization	20	10	65	28
Impairment losses		29	0	29
Gain on sale of assets			17	1
Equity in earnings of unconsolidated affiliates	17	36	26	40
Income/(loss) before income taxes	131	23	254	98
Net income/(loss)	130	$ 23	251	$ 97
Total assets	$ 4,655		$ 4,655

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Effective Tax Rate
Income before income taxes	$ 2,163	$ 341	$ 3,454	$ 899
Income tax expense	$ 545	$ 92	$ 840	$ 216
Effective income tax rate	25.20%	27.00%	24.30%	24.00%
Uncertain Tax Benefits
Non-current tax liability for uncertain tax benefits	$ 25		$ 25
Uncertain tax benefits, penalties and interest accrued	$ 3		$ 3

Related Party Transactions - Sc

Related Party Transactions - Schedule of NRG's Material Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Related Party Transaction [Line Items]
Revenue from related parties	$ 11	$ 13	$ 36	$ 40
Gladstone
Related Party Transaction [Line Items]
Revenue from related parties	1	1	2	2
Ivanpah
Related Party Transaction [Line Items]
Revenue from related parties	9	11	30	34
Midway-Sunset
Related Party Transaction [Line Items]
Revenue from related parties	$ 1	$ 1	$ 4	$ 4

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Minimum Purchased Energy Commitments (Details) - Direct Energy - Purchased Energy Agreements $ in Millions	Jan. 05, 2021USD ($)
Minimum purchase commitment
2021	$ 246
2022	396
2023	272
2024	180
2025	134
Thereafter	450
Total	$ 1,678

Commitments and Contingencies_2

Commitments and Contingencies - Additional (Details)	Dec. 31, 2019case	Jun. 30, 2019facility
Sierra Club Et Al V. Midwest Generation LLC
Loss Contingencies
Number of facilities | facility		4
Direct Energy vs. Stanley, Forte, Schafer and Lane
Loss Contingencies
Pending lawsuits	4
Direct Energy vs. Burk and Dickson
Loss Contingencies
Pending lawsuits	2

Environmental Matters (Details)

Environmental Matters (Details)	Oct. 31, 2021facility
Subsequent Event
Subsequent Event [Line Items]
Number of plants	2