NRG Energy (NRG) 10-Q 6 May 21 2021 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Mar. 31, 2021	May 06, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 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		244,753,963
Entity Central Index Key	0001013871
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Revenues
Total operating revenues	$ 8,091	$ 2,019
Operating Costs and Expenses
Cost of operations	6,864	1,457
Depreciation and amortization	317	109
Selling, general and administrative costs	330	190
Provision for credit losses	611	24
Acquisition-related transaction and integration costs	42	1
Total operating costs and expenses	8,164	1,781
Gain on sale of assets	17	6
Operating (Loss)/Income	(56)	244
Other (Expense)/Income
Equity in losses of unconsolidated affiliates	(6)	(11)
Impairment losses on investments	0	(18)
Other income, net	22	27
Interest expense	(127)	(98)
Total other expense	(111)	(100)
(Loss)/Income Before Income Taxes	(167)	144
Income tax (benefit)/expense	(85)	23
Net (Loss)/Income	$ (82)	$ 121
(Loss)/Income per Share
Weighted average number of common shares outstanding — basic (in shares)	245	248
(Loss)/Income per Weighted Average Common Share — Basic (in usd per share)	$ (0.33)	$ 0.49
Weighted average number of common shares outstanding — diluted (in shares)	245	249
(Loss)/income per weighted average common share — diluted (in usd per share)	$ (0.33)	$ 0.49

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS)/INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net (Loss)/Income	$ (82)	$ 121
Other Comprehensive Income/(Loss)
Foreign currency translation adjustments	3	(15)
Other comprehensive income/(loss)	3	(15)
Comprehensive (Loss)/Income	$ (79)	$ 106

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Current Assets
Cash and cash equivalents	$ 501	$ 3,905
Funds deposited by counterparties	55	19
Restricted cash	18	6
Accounts receivable, net	3,037	904
Inventory	316	327
Derivative instruments	1,816	560
Cash collateral paid in support of energy risk management activities	298	50
Prepayments and other current assets	511	257
Total current assets	6,552	6,028
Property, plant and equipment, net	2,328	2,547
Other Assets
Equity investments in affiliates	162	346
Operating lease right-of-use assets, net	312	301
Goodwill	1,572	579
Intangible assets, net	3,054	668
Nuclear decommissioning trust fund	909	890
Derivative instruments	1,008	261
Deferred income taxes	2,719	3,066
Other non-current assets	625	216
Total other assets	10,361	6,327
Total Assets	19,241	14,902
Current Liabilities
Current portion of long-term debt and finance leases	831	1
Current portion of operating lease liabilities	79	69
Accounts payable	2,216	649
Derivative instruments	1,606	499
Cash collateral received in support of energy risk management activities	55	19
Accrued expenses and other current liabilities	1,008	678
Total current liabilities	5,795	1,915
Other Liabilities
Long-term debt and finance lease	8,705	8,691
Non-current operating lease liabilities	280	278
Nuclear decommissioning reserve	308	303
Nuclear decommissioning trust liability	580	565
Derivative instruments	834	385
Deferred income taxes	30	19
Other non-current liabilities	1,192	1,066
Total other liabilities	11,929	11,307
Total Liabilities	17,724	13,222
Commitments and Contingencies
Stockholders' Equity
Common stock; $0.01 par value; 500,000,000 shares authorized; 423,519,121 and 423,057,848 shares issued and 244,693,206 and 244,231,933 shares outstanding at March 31, 2021 and December 31, 2020, respectively	4	4
Additional paid-in-capital	8,513	8,517
Accumulated deficit	(1,565)	(1,403)
Treasury stock, at cost - 178,825,915 shares at March 31, 2021 and December 31, 2020	(5,232)	(5,232)
Accumulated other comprehensive loss	(203)	(206)
Total Stockholders' Equity	1,517	1,680
Total Liabilities and Stockholders' Equity	$ 19,241	$ 14,902

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 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)	423,519,121	423,057,848
Common stock, shares outstanding (in shares)	244,693,206	244,231,933
Treasury stock, shares (in shares)	178,825,915	178,825,915

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash Flows from Operating Activities
Net (Loss)/Income	$ (82)	$ 121
Adjustments to reconcile net (loss)/income to cash (used)/provided by operating activities:
Distributions from and equity in losses of unconsolidated affiliates	17	16
Depreciation and amortization	317	109
Accretion of asset retirement obligations	3	11
Provision for credit losses	611	24
Amortization of nuclear fuel	13	13
Amortization of financing costs and debt discounts	11	6
Amortization of emissions allowances and energy credits	7	7
Amortization of unearned equity compensation	4	5
Gain on sale and disposal of assets	(18)	(14)
Impairment losses	0	18
Changes in derivative instruments	(902)	(46)
Changes in deferred income taxes and liability for uncertain tax benefits	(71)	19
Changes in collateral deposits in support of energy risk management activities	1	9
Changes in nuclear decommissioning trust liability	15	8
Changes in other working capital	(843)	(98)
Cash (used)/provided by operating activities	(917)	208
Cash Flows from Investing Activities
Payments for acquisitions of businesses, net of cash acquired	(3,482)	0
Capital expenditures	(63)	(66)
Net purchases of emission allowances	(5)	(8)
Investments in nuclear decommissioning trust fund securities	(129)	(121)
Proceeds from the sale of nuclear decommissioning trust fund securities	118	112
Proceeds from sale of assets, net of cash disposed	197	15
Cash used by investing activities	(3,364)	(68)
Cash Flows from Financing Activities
Payments of dividends to common stockholders	(80)	(74)
Payments for share repurchase activity	(9)	(179)
Net payments from settlement of acquired derivatives that include financing elements	190	(3)
Net proceeds of Revolving Credit Facility and Receivables Securitization Facilities	825	552
Payments of debt issuance costs	(2)	0
Proceeds from issuance of common stock	1	0
Repayments of long-term debt and finance leases	(1)	(60)
Proceeds from issuance of long-term debt	0	59
Purchase of and distributions to noncontrolling interests from subsidiaries	0	(2)
Net Cash Provided by Financing Activities	924	293
Effect of exchange rate changes on cash and cash equivalents	1	0
Net (Decrease)/increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash	(3,356)	433
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	$ 574	$ 818

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions		Total	Common Stock	Additional Paid-In Capital	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)
Equity-based awards activity, net	[1]	(21)		(21)
Repurchase of partners' equity interest in VIE		18		18
Share repurchases		(150)				(150)
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, 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)
[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 and $0.30 for the quarters ended March 31, 2021 and 2020, respectively

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares shares in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Dividends per common share (in usd per share)	$ 0.325	$ 0.30
Shares purchased for tax withholding obligation (in shares)	(9,000)	(27,000)

Nature of Business and Basis of

Nature of Business and Basis of Presentation	3 Months Ended
	Mar. 31, 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 an integrated power 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, in major competitive power markets in the U.S. and Canada in a manner that delivers value to all of NRG's stakeholders. NRG is a customer-centric business focused on perfecting the integrated model by balancing retail load with generation supply within its deregulated markets. The Company sells energy, services, and innovative, sustainable products and services directly to retail customers under the names NRG, Reliant, Green Mountain Energy, Stream, and XOOM Energy, as well as other brand names owned by NRG, supported by approximately 23,000 MW of generation as of March 31, 2021. NRG also conducts business under the brand name of Direct Energy as a result of the Company's acquisition of Direct Energy, a North American subsidiary of Centrica, on January 5, 2021. 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. In addition, Direct Energy is a participant in the wholesale gas and power markets in the United States 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 will be combined into the corresponding geographical segments of Texas, East and West/Services/Other. The East segment will also include the deregulated customer and market operations of Canada. The West/Services/Other segment will also include activity related to the regulated operations in Alberta, Canada and 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 March 31, 2021, and the results of operations, comprehensive income, cash flows and statements of stockholders' equity for the three months ended March 31, 2021 and 2020. Use of Estimates

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 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) March 31, 2021 December 31, 2020 Property, plant and equipment accumulated depreciation $ 1,566 $ 1,936 Intangible assets accumulated amortization 1,424 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 months ended March 31, 2021: (In millions) Three months ended March 31, 2021 Three months ended March 31, 2020 Beginning balance $ 67 $ 43 Acquired balance from Direct Energy 112 — Provision for credit losses 611 24 Write-offs (48) (32) Recoveries collected 7 4 Ending balance $ 749 $ 39 The increase in the provision for credit losses during the three months ended March 31, 2021, compared to the same period in 2020 was primarily due to the impacts of Winter Storm Uri on bilateral finance hedging risk of $393 million, counterparty credit risk of $109 million and ERCOT default shortfall payments of $83 million, as well as the acquisition of Direct Energy. 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) March 31, 2021 December 31, 2020 Cash and cash equivalents $ 501 $ 3,905 Funds deposited by counterparties 55 19 Restricted cash 18 6 Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows $ 574 $ 3,930 Funds deposited by counterparties consist of cash held by the Company as a result of collateral posting obligations from its counterparties. Some amounts are segregated into separate accounts that are not contractually restricted but, based on the Company's intention, are not available for the payment of general corporate obligations. 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 No. 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 No. 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. Early adoption is permitted in fiscal years beginning after December 15, 2020, including 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 related to earnings per share.

Revenue Recognition

Revenue Recognition	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition Performance Obligations As of March 31, 2021, estimated future fixed fee performance obligations are $544 million for the remaining nine months of fiscal year 2021, and $299 million, $51 million, $37 million and $20 million for the fiscal years 2022, 2023, 2024 and 2025, respectively. 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 months ended March 31, 2021 and 2020: Three months ended March 31, 2021 (In millions) Texas East West/Services/Other Corporate/Eliminations Total Retail revenue: Home (a) $ 1,542 $ 702 $ 474 $ — $ 2,718 Business 572 2,841 31 — 3,444 Total retail revenue 2,114 3,543 505 — 6,162 Energy revenue (c) 285 126 70 1 482 Capacity revenue (c) — 141 14 — 155 Mark-to-market for economic hedging activities (d) (1) (4) (28) 1 (32) Other revenue (b)(c) 1,304 19 4 (3) 1,324 Total operating revenue 3,702 3,825 565 (1) 8,091 Less: Lease revenue — — 2 — 2 Less: Realized and unrealized ASC 815 revenue 93 99 (34) 2 160 Total revenue from contracts with customers $ 3,609 $ 3,726 $ 597 $ (3) $ 7,929 (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 $ — $ 60 $ (4) $ 2 $ 58 Capacity revenue — 37 — — 37 Other revenue 94 6 (2) (1) 97 (d) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 Three months ended March 31, 2020 (In millions) Texas East West/Services/Other Corporate/Eliminations Total Retail revenue: Home (a) $ 1,032 $ 329 $ 18 $ (1) $ 1,378 Business 260 23 — — 283 Total retail revenue 1,292 352 18 (1) 1,661 Energy revenue (b) 5 45 75 (1) 124 Capacity revenue (b) — 134 15 — 149 Mark-to-market for economic hedging activities (c) — (20) 15 1 (4) Other revenue (b) 61 10 20 (2) 89 Total operating revenue 1,358 521 143 (3) 2,019 Less: Lease revenue — — 5 — 5 Less: Realized and unrealized ASC 815 revenue 7 39 44 (1) 89 Total revenue from contracts with customers $ 1,351 $ 482 $ 94 $ (2) $ 1,925 (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 $ — $ 35 $ 19 $ (1) $ 53 Capacity revenue — 24 — — 24 Other revenue 7 — 10 (1) 16 (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 March 31, 2021 and December 31, 2020: (In millions) March 31, 2021 December 31, 2020 Deferred customer acquisition costs $ 116 $ 113 Accounts receivable, net - Contracts with customers 2,920 866 Accounts receivable, net - Derivative instruments 113 33 Accounts receivable, net - Affiliate 4 5 Total accounts receivable, net $ 3,037 $ 904 Unbilled revenues (included within Accounts receivable, net - Contracts with customers) $ 1,234 $ 393 Deferred revenues (a) 258 60 (a) Deferred revenues from contracts with customers for the three months ended March 31, 2021 and the year ended December 31, 2020 were approximately $232 million and $31 million, respectively The revenue recognized from contracts with customers during the three months ended March 31, 2021 and 2020 relating to the deferred revenue balance at the beginning of each period was $23 million and $13 million, respectively. The change in deferred revenue balances during the three months ended March 31, 2021 and 2020 was primarily due to the timing difference of when consideration was received and when the performance obligation was transferred.

Acquisitions and Dispositions

Acquisitions and Dispositions	3 Months Ended
	Mar. 31, 2021
Business Combinations [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 final purchase price adjustment resulted in a reduction of $38 million. The Company expects to receive this payment from Centrica during the second quarter of 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 $22 million for the three months ended March 31, 2021 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 are 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 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 181 Total current assets 3,518 Property, plant and equipment, net 178 Other Assets Goodwill (a)(b) 990 Intangibles assets, net (b) 2,559 Derivative instruments 531 Other non-current assets 31 Total other assets 4,111 Total Assets $ 7,807 Current Liabilities Accounts payable $ 1,390 Derivative instruments 1,266 Cash collateral received in support of energy risk management activities 21 Accrued expenses and other current liabilities 440 Total current liabilities 3,117 Other Liabilities Derivative instruments 562 Deferred income taxes 433 Other non-current liabilities 31 Total other liabilities 1,026 Total Liabilities $ 4,143 Direct Energy Purchase Price $ 3,664 (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 expected to be deductible for tax purposes is $337 million. (b) The allocation of goodwill and intangible assets to the Company's reportable segments is anticipated to be completed in the second quarter of 2021 The Company recorded revenue from Direct Energy of $4,161 million and income before income tax of $134 million during the three months ended March 31, 2021. Pro forma comparative financial information for the Direct Energy acquisition has not been included for the three months ended March 31, 2021 and 2020, as the computation of such information is impracticable due to pre-acquisition financial statements for the reporting periods not being prepared in accordance with GAAP. 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. 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 in the fourth quarter of 2021 and is subject to various closing conditions, approvals and consents, including FERC, NYSPSC, and antitrust review under the Hart-Scott-Rodino Act. As of March 31, 2021, the following is classified as held for sale in the Consolidated Balance Sheet: (In millions) (a) Current assets (b) $ 55 Property, plant and equipment, net 385 Other non-current assets 3 Total non-current assets (c) 388 Total assets held for sale $ 443 Current liabilities (d) 27 Non-current liabilities (e) 60 Total liabilities held for sale $ 87 (a) Property, plant and equipment, net for the East and West/Services/Other segments was $237 million and $148 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 $2 million and $15 million during the three months ended March 31, 2021 and 2020, respectively.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 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: March 31, 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) 9,609 10,007 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 estimated fair value of the borrowing under the Revolving Credit Facility and Receivable Securitization Facilities approximates the carrying value because the interest rates vary with market interest rates, and is classified as Level 3 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. The following table presents the level within the fair value hierarchy for long-term debt, including current portion, as of March 31, 2021 and December 31, 2020: March 31, 2021 December 31, 2020 (In millions) Level 2 Level 3 Level 2 Level 3 Long-term debt, including current portion $ 9,182 $ 825 $ 9,446 $ — 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: March 31, 2021 (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and non-current assets) $ 24 $ 10 $ 14 $ — Nuclear trust fund investments: Cash and cash equivalents 20 20 — — U.S. government and federal agency obligations 73 72 1 — Federal agency mortgage-backed securities 78 — 78 — Commercial mortgage-backed securities 40 — 40 — Corporate debt securities 136 — 136 — Equity securities 466 466 — — Foreign government fixed income securities 7 1 6 — Other trust fund investments: U.S. government and federal agency obligations 1 1 — — Derivative assets: Commodity contracts 2,824 195 2,365 264 Measured using net asset value practical expedient: Equity securities — nuclear trust fund investments 89 Equity securities 8 Total assets $ 3,766 $ 765 $ 2,640 $ 264 Derivative liabilities: Foreign exchange contracts $ 2 $ — $ 2 $ — Commodity contracts 2,438 205 2,128 105 Total liabilities $ 2,440 $ 205 $ 2,130 $ 105 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: 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 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 months ended March 31, 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 March 31, 2021 Three months ended March 31, 2020 (In millions) Derivatives (a) Derivatives (a) Beginning balance $ (16) $ 38 Contracts added from Direct Energy acquisition (15) — Total gains realized/unrealized— included in earnings 180 22 Purchases 20 8 Transfers into Level 3 (b) 4 8 Transfers out of Level 3 (b) (14) (3) Ending balance $ 159 $ 73 Gains/(losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of period end $ 146 $ (9) (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 March 31, 2021, contracts valued with prices provided by models and other valuation techniques make up 9% of derivative assets and 4% 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 March 31, 2021 and December 31, 2020: March 31, 2021 Fair Value Input/Range (In millions) Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average Natural Gas Contracts $ 3 $ — Discounted Cash Flow Forward Market Price (per MMBtu) $ 1 $ 16 $ 14 Power Contracts 234 91 Discounted Cash Flow Forward Market Price (per MWh) 1 237 29 FTRs 27 14 Discounted Cash Flow Auction Prices (per MWh) (33) 320 0 $ 264 $ 105 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 March 31, 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 March 31, 2021, the credit reserve resulted in a $14 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 March 31, 2021, counterparty credit exposure, excluding credit exposure from RTOs, ISOs, registered commodity exchanges and certain long-term agreements, was $811 million and NRG held collateral (cash and letters of credit) against those positions of $140 million, resulting in a net exposure of $752 million. 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 43% 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 79 % Financial institutions 21 Total as of March 31, 2021 100 % Net Exposure (a)(b) Category by Counterparty Credit Quality (% of Total) Investment grade 61 % Non-investment grade/non-rated 39 Total as of March 31, 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 March 31, 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 $393 million. The Company is pursuing all means available to enforce its obligations 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 as of March 31, 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 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 March 31, 2021, aggregate credit risk exposure managed by NRG to these counterparties was approximately $925 million 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. As of March 31, 2021, the Company's retail customer credit exposure to Home and Business customers was diversified across many customers and various industries, as well as government entities. As a result of Winter Storm Uri, the Company incurred additional credit losses from Business customers primarily due to a segment of customers whose contracts included a pass through of wholesale power prices which were significantly escalated during the storm and from customers who failed to meet their obligations in ERCOT load curtailment programs.

Nuclear Decommissioning Trust F

Nuclear Decommissioning Trust Fund	3 Months Ended
	Mar. 31, 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 March 31, 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 $ 20 $ — $ — — $ 23 $ — $ — — U.S. government and federal agency obligations 73 4 2 12 70 6 — 10 Federal agency mortgage-backed securities 78 3 — 23 89 4 — 24 Commercial mortgage-backed securities 40 1 — 28 36 2 — 27 Corporate debt securities 136 7 1 12 144 13 — 12 Equity securities 555 403 — — 521 372 — — Foreign government fixed income securities 7 — — 9 7 1 — 10 Total $ 909 $ 418 $ 3 $ 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. Three months ended March 31, (In millions) 2021 2020 Realized gains $ 3 $ 2 Realized losses (2) (5) Proceeds from sale of securities 118 112

Accounting for Derivative Instr

Accounting for Derivative Instruments and Hedging Activities	3 Months Ended
	Mar. 31, 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 March 31, 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 2037 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 March 31, 2021, NRG had foreign exchange contracts extending through 2023. 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 March 31, 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 March 31, 2021 December 31, 2020 Emissions Short Ton — 1 Renewable Energy Certificates Certificates 13 5 Coal Short Ton 2 2 Natural Gas MMBtu 605 (286) Power MWh 201 57 Capacity MW/Day — (1) Foreign Exchange Dollars $ 158 $ — 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) March 31, 2021 December 31, 2020 March 31, 2021 December 31, 2020 Derivatives Not Designated as Cash Flow or Fair Value Hedges: Foreign exchange contracts - current $ — $ — $ 1 $ — Foreign exchange contracts -long-term — — 1 — Commodity contracts - current 1,816 560 1,605 499 Commodity contracts - long-term 1,008 261 833 385 Total Derivatives Not Designated as Cash Flow or Fair Value Hedges $ 2,824 $ 821 $ 2,440 $ 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 March 31, 2021 Foreign exchange contracts: Derivative liabilities $ (2) $ — $ — $ (2) Total foreign exchange contracts $ (2) $ — $ — $ (2) Commodity contracts: Derivative assets $ 2,824 $ (2,253) $ (10) $ 561 Derivative liabilities (2,438) 2,253 — (185) Total commodity contracts $ 386 $ — $ (10) $ 376 Total derivative instruments $ 384 $ — $ (10) $ 374 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 March 31, Unrealized mark-to-market results 2021 2020 Reversal of previously recognized unrealized losses on settled positions related to economic hedges $ 17 $ 9 Reversal of acquired loss positions related to economic hedges 145 1 Net unrealized gains on open positions related to economic hedges 559 34 Total unrealized mark-to-market gains for economic hedging activities 721 44 Reversal of previously recognized unrealized (gains) on settled positions related to trading activity (7) (2) Net unrealized gains on open positions related to trading activity 11 13 Total unrealized mark-to-market gains for trading activity 4 11 Total unrealized gains $ 725 $ 55 Three months ended March 31, (In millions) 2021 2020 Unrealized (losses)/gains included in operating revenues - commodities $ (28) $ 7 Unrealized gains included in cost of operations - commodities 755 48 Unrealized (losses) included in cost of operations - foreign exchange (2) — Total impact to statement of operations $ 725 $ 55 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 three months ended March 31, 2021, the $559 unrealized gain from open economic hedge positions was primarily the result of an increase in value of forward positions due to increases in ERCOT power prices and ERCOT heat rate expansion. For the three months ended March 31, 2020, the $34 million unrealized gain from open economic hedge positions was primarily the result of an increase in value of forward power positions due to decrease in West/Other power prices, as well as an increase in value of ERCOT heat rate positions due to ERCOT hear rate expansion. Credit Risk Related Contingent Features Certain of the Company's hedging agreements contain provisions that require the Company to post additional collateral if the counterparty determines that there has been deterioration in 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 March 31, 2021, were still supported by credit support posted by Centrica, and as a result, could require the Company to post additional collateral upon a deterioration or downgrade of Centrica. The collateral required for contracts with adequate assurance clauses that are in a net liability position as of March 31, 2021 was $642 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 $91 million as of March 31, 2021. If called for by the counterparty, $57 million of additional collateral would be required for all contracts with credit rating contingent features as of March 31, 2021. See Note 5, Fair Value of Financial Instruments , for discussion regarding concentration of credit risk.

Impairments

Impairments	3 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Impairments	Impairments 2020 Impairment Losses 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 is 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	3 Months Ended
	Mar. 31, 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) March 31, 2021 December 31, 2020 Interest rate % Recourse debt: Senior Notes, due 2026 $ 1,000 $ 1,000 7.250 Senior Notes, due 2027 1,230 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 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 Revolving Credit Facility 750 — L + 1.720 Tax-exempt bonds 466 466 1.250 - 4.750 Repurchase Facility 75 — L + 1.250 Subtotal recourse debt 9,680 8,855 Finance leases 16 4 various Subtotal long-term debt and finance leases (including current maturities) 9,696 8,859 Less current maturities (831) (1) Less debt issuance costs (89) (93) Discounts (71) (74) Total long-term debt $ 8,705 $ 8,691 (a) As of the ex-dividend date of January 29, 2021, the Convertible Senior Notes were convertible at a price of $45.91, which is equivalent to a conversion rate of approximately 21.79 shares of common stock per $1,000 principal amount. As of the ex-dividend date of April 30, 2021, the Convertible Senior Notes were convertible at a price of $45.54, which is equivalent to a conversion rate of approximately 21.96 shares of common stock per $1,000 principal amount Recourse Debt 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 that is 30 months after the date of closing of the Direct Energy acquisition. 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 by 12 months, but not beyond 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 upon January 5, 2021. As of March 31, 2021, total revolving commitments available, subject to usage, under the amended credit agreement was $3.7 billion. As of March 31, 2021, $750 million of borrowings were outstanding. As of May 6, 2021, there were $70 million of borrowings outstanding. 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 (a “Collateral Enforcement Event”). The LC Agreement and the Pledge Agreement were available on January 5, 2021. As of March 31, 2021, $689 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	3 Months Ended
	Mar. 31, 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) March 31, 2021 December 31, 2020 Accounts receivable $ 728 $ 647 Other current assets 1 2 Total assets 729 649 Current liabilities 76 78 Net assets $ 653 $ 571

Changes in Capital Structure

Changes in Capital Structure	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Changes in Capital Structure	Changes in Capital Structure As of March 31, 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 461,273 — 461,273 Balance as of March 31, 2021 423,519,121 (178,825,915) 244,693,206 Shares issued under LTIPs 790 — 790 Shares issued under ESPP — 59,967 59,967 Balance as of May 6, 2021 423,519,911 (178,765,948) 244,753,963 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 March 31, 2021. On April 19, 2021, NRG declared a quarterly dividend on the Company's common stock of $0.325 per share, payable on May 17, 2021 to stockholders of record as of May 3, 2021.

(Loss)_Income Per Share

(Loss)/Income Per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
(Loss)/Income Per Share	(Loss)/Income Per Share Basic (loss)/income per common share is computed by dividing net (loss)/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 (loss)/income per share is computed in a manner consistent with that of basic (loss)/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 (loss)/income per share. However, these instruments are included in the denominator for purposes of computing diluted (loss)/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 (loss)/income per share is shown in the following table: Three months ended March 31, (In millions, except per share data) 2021 2020 Basic (loss)/income per share: Net (loss)/income $ (82) $ 121 Weighted average number of common shares outstanding - basic 245 248 (Loss)/income per weighted average common share — basic $ (0.33) $ 0.49 Diluted (loss)/income per share: Net (loss)/income $ (82) $ 121 Weighted average number of common shares outstanding - basic 245 248 Incremental shares attributable to the issuance of equity compensation (treasury stock method) — 1 Weighted average number of common shares outstanding - dilutive 245 249 (Loss)/income per weighted average common share — diluted $ (0.33) $ 0.49

Segment Reporting

Segment Reporting	3 Months Ended
	Mar. 31, 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 East segment includes the deregulated customer and market operations of Canada. The West/Services/Other segment includes activity related to the regulated operations in Alberta, Canada and the services businesses. Three months ended March 31, 2021 (In millions) Texas East West/Services/Other Corporate Eliminations Total Operating revenues $ 3,702 $ 3,825 $ 565 $ — $ (1) $ 8,091 Depreciation and amortization 77 209 24 7 — 317 Gain on sale of assets — — 17 — — 17 Equity in losses of unconsolidated affiliates (1) — (5) — — (6) (Loss)/income before income taxes (425) 357 70 (169) — (167) Net (loss)/income $ (425) $ 353 $ 69 $ (79) $ — $ (82) Three months ended March 31, 2020 (In millions) Texas East West/Services/Other Corporate Eliminations Total Operating revenues $ 1,358 $ 521 $ 143 $ — $ (3) $ 2,019 Depreciation and amortization 59 32 9 9 — 109 Gain on sale of assets — — 1 5 — 6 Equity in losses of unconsolidated affiliates — — (11) — — (11) Income/(loss) before income taxes 162 20 45 (82) (1) 144 Net income/(loss) $ 162 $ 20 $ 45 $ (105) $ (1) $ 121

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Effective Income Tax Rate The income tax provision consisted of the following: Three months ended March 31, (In millions, except rates) 2021 2020 (Loss)/Income before income taxes $ (167) $ 144 Income tax (benefit)/expense (85) 23 Effective income tax rate 50.9 % 16.0 % For the three months ended March 31, 2021, the effective tax rate was higher than the statutory rate of 21% primarily due to state tax benefits and 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 period in 2020, the effective tax rate was lower than the statutory rate of 21% primarily due to an excess tax benefit related to share-based compensation, partially offset by state tax expense. Uncertain Tax Benefits As of March 31, 2021, NRG had a non-current tax liability of $23 million for uncertain tax benefits from positions taken on various federal and state income tax returns and accrued interest. For the three months ended March 31, 2021, NRG accrued an immaterial amount of interest relating to the uncertain tax benefits. As of March 31, 2021, NRG had cumulative interest and penalties related to these uncertain tax benefits of $2 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	3 Months Ended
	Mar. 31, 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 March 31, (In millions) 2021 2020 Revenues from Related Parties Included in Operating Revenues Gladstone $ 1 $ 1 Ivanpah (a) 12 13 Midway-Sunset 2 1 Total $ 15 $ 15 (a) Also includes fees under project management agreements with each project company

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 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 commitments as of the acquisition date 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 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 March 31, 2021, all hedges under the first lien program were in-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. 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 recently agreed to mediate this matter. In the interim, all written discovery is stayed. Direct Energy plans to depose the plaintiff in the next 60 days prior to mediation; (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; and (4) Julie and Richard Lane v. Direct Energy (S.D.Ill. Jun. 2019) - Plaintiff has amended her Complaint in response to the Court dismissing all claims except a claim under the Illinois Consumer Protection Act. Direct Energy’s Motion to Dismiss is pending the Court’s ruling. 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 continues to deny the allegations asserted by plaintiffs and intends to vigorously defend these matters. There are two putative class actions pending against Direct Energy: (1) Brittany Burk v. Direct Energy (S.D. Tex. Feb. 2019) - Written discovery is complete, and fact and expert discovery is ongoing. The briefing on Direct Energy’s Motion to Dismiss and Plaintiff’s Class Certification is complete; 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. This case is stayed pending the outcome of a Second Circuit appeal of the AAPC issue. In each case, Direct Energy has filed a Motion to Dismiss for lack of subject matter jurisdiction based on the Supreme Court’s 2020 AAPC decision invalidating the TCPA provision asserted in each case. 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	3 Months Ended
	Mar. 31, 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. FERC has the authority to require disgorgement of profits and to impose penalties and NRG retains any liability following the sale of the South Central Portfolio.

Environmental Matters

Environmental Matters	3 Months Ended
	Mar. 31, 2021
Environmental Matters 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 requires 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). Accordingly, we expect the EPA to promulgate a new rule to regulate GHG emissions from power plants. 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. The Company is in the process of estimating the environmental capital expenditures that will be required to comply. The capital expenditures required to comply will depend on elections regarding future operations of each coal-fired unit. NRG expects to make these elections for each unit in the fourth quarter of 2021, at which time the EPA will be notified as required. Accordingly, we do not expect to provide estimates of ELG compliance costs until early 2022. 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 amends the existing 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)	3 Months Ended
	Mar. 31, 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 year 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. Some amounts are segregated into separate accounts that are not contractually restricted but, based on the Company's intention, are not available for the payment of general corporate obligations. 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 No. 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 No. 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. Early adoption is permitted in fiscal years beginning after December 15, 2020, including 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 related to earnings per share.
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)	3 Months Ended
	Mar. 31, 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) March 31, 2021 December 31, 2020 Property, plant and equipment accumulated depreciation $ 1,566 $ 1,936 Intangible assets accumulated amortization 1,424 1,357
Activity in Allowance for Credit Losses	The following table represents the activity in the allowance for credit losses for the three months ended March 31, 2021: (In millions) Three months ended March 31, 2021 Three months ended March 31, 2020 Beginning balance $ 67 $ 43 Acquired balance from Direct Energy 112 — Provision for credit losses 611 24 Write-offs (48) (32) Recoveries collected 7 4 Ending balance $ 749 $ 39
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) March 31, 2021 December 31, 2020 Cash and cash equivalents $ 501 $ 3,905 Funds deposited by counterparties 55 19 Restricted cash 18 6 Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows $ 574 $ 3,930

Revenue Recognition (Tables)

Revenue Recognition (Tables)	3 Months Ended
	Mar. 31, 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 months ended March 31, 2021 and 2020: Three months ended March 31, 2021 (In millions) Texas East West/Services/Other Corporate/Eliminations Total Retail revenue: Home (a) $ 1,542 $ 702 $ 474 $ — $ 2,718 Business 572 2,841 31 — 3,444 Total retail revenue 2,114 3,543 505 — 6,162 Energy revenue (c) 285 126 70 1 482 Capacity revenue (c) — 141 14 — 155 Mark-to-market for economic hedging activities (d) (1) (4) (28) 1 (32) Other revenue (b)(c) 1,304 19 4 (3) 1,324 Total operating revenue 3,702 3,825 565 (1) 8,091 Less: Lease revenue — — 2 — 2 Less: Realized and unrealized ASC 815 revenue 93 99 (34) 2 160 Total revenue from contracts with customers $ 3,609 $ 3,726 $ 597 $ (3) $ 7,929 (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 $ — $ 60 $ (4) $ 2 $ 58 Capacity revenue — 37 — — 37 Other revenue 94 6 (2) (1) 97 (d) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 Three months ended March 31, 2020 (In millions) Texas East West/Services/Other Corporate/Eliminations Total Retail revenue: Home (a) $ 1,032 $ 329 $ 18 $ (1) $ 1,378 Business 260 23 — — 283 Total retail revenue 1,292 352 18 (1) 1,661 Energy revenue (b) 5 45 75 (1) 124 Capacity revenue (b) — 134 15 — 149 Mark-to-market for economic hedging activities (c) — (20) 15 1 (4) Other revenue (b) 61 10 20 (2) 89 Total operating revenue 1,358 521 143 (3) 2,019 Less: Lease revenue — — 5 — 5 Less: Realized and unrealized ASC 815 revenue 7 39 44 (1) 89 Total revenue from contracts with customers $ 1,351 $ 482 $ 94 $ (2) $ 1,925 (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 $ — $ 35 $ 19 $ (1) $ 53 Capacity revenue — 24 — — 24 Other revenue 7 — 10 (1) 16 (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 March 31, 2021 and December 31, 2020: (In millions) March 31, 2021 December 31, 2020 Deferred customer acquisition costs $ 116 $ 113 Accounts receivable, net - Contracts with customers 2,920 866 Accounts receivable, net - Derivative instruments 113 33 Accounts receivable, net - Affiliate 4 5 Total accounts receivable, net $ 3,037 $ 904 Unbilled revenues (included within Accounts receivable, net - Contracts with customers) $ 1,234 $ 393 Deferred revenues (a) 258 60 (a) Deferred revenues from contracts with customers for the three months ended March 31, 2021 and the year ended December 31, 2020 were approximately $232 million and $31 million, respectively

Acquisitions and Dispositions (

Acquisitions and Dispositions (Tables)	3 Months Ended
	Mar. 31, 2021
Business Combinations [Abstract]
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 181 Total current assets 3,518 Property, plant and equipment, net 178 Other Assets Goodwill (a)(b) 990 Intangibles assets, net (b) 2,559 Derivative instruments 531 Other non-current assets 31 Total other assets 4,111 Total Assets $ 7,807 Current Liabilities Accounts payable $ 1,390 Derivative instruments 1,266 Cash collateral received in support of energy risk management activities 21 Accrued expenses and other current liabilities 440 Total current liabilities 3,117 Other Liabilities Derivative instruments 562 Deferred income taxes 433 Other non-current liabilities 31 Total other liabilities 1,026 Total Liabilities $ 4,143 Direct Energy Purchase Price $ 3,664 (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 expected to be deductible for tax purposes is $337 million. (b) The allocation of goodwill and intangible assets to the Company's reportable segments is anticipated to be completed in the second quarter of 2021
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 Classified Held for Sale	As of March 31, 2021, the following is classified as held for sale in the Consolidated Balance Sheet: (In millions) (a) Current assets (b) $ 55 Property, plant and equipment, net 385 Other non-current assets 3 Total non-current assets (c) 388 Total assets held for sale $ 443 Current liabilities (d) 27 Non-current liabilities (e) 60 Total liabilities held for sale $ 87 (a) Property, plant and equipment, net for the East and West/Services/Other segments was $237 million and $148 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)	3 Months Ended
	Mar. 31, 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: March 31, 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) 9,609 10,007 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
Fair value hierarchy for long-term debt	The following table presents the level within the fair value hierarchy for long-term debt, including current portion, as of March 31, 2021 and December 31, 2020: March 31, 2021 December 31, 2020 (In millions) Level 2 Level 3 Level 2 Level 3 Long-term debt, including current portion $ 9,182 $ 825 $ 9,446 $ —
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: March 31, 2021 (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and non-current assets) $ 24 $ 10 $ 14 $ — Nuclear trust fund investments: Cash and cash equivalents 20 20 — — U.S. government and federal agency obligations 73 72 1 — Federal agency mortgage-backed securities 78 — 78 — Commercial mortgage-backed securities 40 — 40 — Corporate debt securities 136 — 136 — Equity securities 466 466 — — Foreign government fixed income securities 7 1 6 — Other trust fund investments: U.S. government and federal agency obligations 1 1 — — Derivative assets: Commodity contracts 2,824 195 2,365 264 Measured using net asset value practical expedient: Equity securities — nuclear trust fund investments 89 Equity securities 8 Total assets $ 3,766 $ 765 $ 2,640 $ 264 Derivative liabilities: Foreign exchange contracts $ 2 $ — $ 2 $ — Commodity contracts 2,438 205 2,128 105 Total liabilities $ 2,440 $ 205 $ 2,130 $ 105 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: 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 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 months ended March 31, 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 March 31, 2021 Three months ended March 31, 2020 (In millions) Derivatives (a) Derivatives (a) Beginning balance $ (16) $ 38 Contracts added from Direct Energy acquisition (15) — Total gains realized/unrealized— included in earnings 180 22 Purchases 20 8 Transfers into Level 3 (b) 4 8 Transfers out of Level 3 (b) (14) (3) Ending balance $ 159 $ 73 Gains/(losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of period end $ 146 $ (9) (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 March 31, 2021 and December 31, 2020: March 31, 2021 Fair Value Input/Range (In millions) Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average Natural Gas Contracts $ 3 $ — Discounted Cash Flow Forward Market Price (per MMBtu) $ 1 $ 16 $ 14 Power Contracts 234 91 Discounted Cash Flow Forward Market Price (per MWh) 1 237 29 FTRs 27 14 Discounted Cash Flow Auction Prices (per MWh) (33) 320 0 $ 264 $ 105 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 March 31, 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 79 % Financial institutions 21 Total as of March 31, 2021 100 % Net Exposure (a)(b) Category by Counterparty Credit Quality (% of Total) Investment grade 61 % Non-investment grade/non-rated 39 Total as of March 31, 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)	3 Months Ended
	Mar. 31, 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 March 31, 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 $ 20 $ — $ — — $ 23 $ — $ — — U.S. government and federal agency obligations 73 4 2 12 70 6 — 10 Federal agency mortgage-backed securities 78 3 — 23 89 4 — 24 Commercial mortgage-backed securities 40 1 — 28 36 2 — 27 Corporate debt securities 136 7 1 12 144 13 — 12 Equity securities 555 403 — — 521 372 — — Foreign government fixed income securities 7 — — 9 7 1 — 10 Total $ 909 $ 418 $ 3 $ 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. Three months ended March 31, (In millions) 2021 2020 Realized gains $ 3 $ 2 Realized losses (2) (5) Proceeds from sale of securities 118 112

Accounting for Derivative Ins_2

Accounting for Derivative Instruments and Hedging Activities (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 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 March 31, 2021 December 31, 2020 Emissions Short Ton — 1 Renewable Energy Certificates Certificates 13 5 Coal Short Ton 2 2 Natural Gas MMBtu 605 (286) Power MWh 201 57 Capacity MW/Day — (1) Foreign Exchange Dollars $ 158 $ —
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) March 31, 2021 December 31, 2020 March 31, 2021 December 31, 2020 Derivatives Not Designated as Cash Flow or Fair Value Hedges: Foreign exchange contracts - current $ — $ — $ 1 $ — Foreign exchange contracts -long-term — — 1 — Commodity contracts - current 1,816 560 1,605 499 Commodity contracts - long-term 1,008 261 833 385 Total Derivatives Not Designated as Cash Flow or Fair Value Hedges $ 2,824 $ 821 $ 2,440 $ 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 March 31, 2021 Foreign exchange contracts: Derivative liabilities $ (2) $ — $ — $ (2) Total foreign exchange contracts $ (2) $ — $ — $ (2) Commodity contracts: Derivative assets $ 2,824 $ (2,253) $ (10) $ 561 Derivative liabilities (2,438) 2,253 — (185) Total commodity contracts $ 386 $ — $ (10) $ 376 Total derivative instruments $ 384 $ — $ (10) $ 374 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 March 31, 2021 Foreign exchange contracts: Derivative liabilities $ (2) $ — $ — $ (2) Total foreign exchange contracts $ (2) $ — $ — $ (2) Commodity contracts: Derivative assets $ 2,824 $ (2,253) $ (10) $ 561 Derivative liabilities (2,438) 2,253 — (185) Total commodity contracts $ 386 $ — $ (10) $ 376 Total derivative instruments $ 384 $ — $ (10) $ 374 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 March 31, Unrealized mark-to-market results 2021 2020 Reversal of previously recognized unrealized losses on settled positions related to economic hedges $ 17 $ 9 Reversal of acquired loss positions related to economic hedges 145 1 Net unrealized gains on open positions related to economic hedges 559 34 Total unrealized mark-to-market gains for economic hedging activities 721 44 Reversal of previously recognized unrealized (gains) on settled positions related to trading activity (7) (2) Net unrealized gains on open positions related to trading activity 11 13 Total unrealized mark-to-market gains for trading activity 4 11 Total unrealized gains $ 725 $ 55 Three months ended March 31, (In millions) 2021 2020 Unrealized (losses)/gains included in operating revenues - commodities $ (28) $ 7 Unrealized gains included in cost of operations - commodities 755 48 Unrealized (losses) included in cost of operations - foreign exchange (2) — Total impact to statement of operations $ 725 $ 55

Long-term Debt and Finance Le_2

Long-term Debt and Finance Leases (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Long-term Debt and Finance Leases	Long-term debt and finance leases consisted of the following: (In millions, except rates) March 31, 2021 December 31, 2020 Interest rate % Recourse debt: Senior Notes, due 2026 $ 1,000 $ 1,000 7.250 Senior Notes, due 2027 1,230 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 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 Revolving Credit Facility 750 — L + 1.720 Tax-exempt bonds 466 466 1.250 - 4.750 Repurchase Facility 75 — L + 1.250 Subtotal recourse debt 9,680 8,855 Finance leases 16 4 various Subtotal long-term debt and finance leases (including current maturities) 9,696 8,859 Less current maturities (831) (1) Less debt issuance costs (89) (93) Discounts (71) (74) Total long-term debt $ 8,705 $ 8,691 (a) As of the ex-dividend date of January 29, 2021, the Convertible Senior Notes were convertible at a price of $45.91, which is equivalent to a conversion rate of approximately 21.79 shares of common stock per $1,000 principal amount. As of the ex-dividend date of April 30, 2021, the Convertible Senior Notes were convertible at a price of $45.54, which is equivalent to a conversion rate of approximately 21.96 shares of common stock per $1,000 principal amount

Investments Accounted for Usi_2

Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs (Tables)	3 Months Ended
	Mar. 31, 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) March 31, 2021 December 31, 2020 Accounts receivable $ 728 $ 647 Other current assets 1 2 Total assets 729 649 Current liabilities 76 78 Net assets $ 653 $ 571

Changes in Capital Structure (T

Changes in Capital Structure (Tables)	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Changes in NRG's common shares issued and outstanding	As of March 31, 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 461,273 — 461,273 Balance as of March 31, 2021 423,519,121 (178,825,915) 244,693,206 Shares issued under LTIPs 790 — 790 Shares issued under ESPP — 59,967 59,967 Balance as of May 6, 2021 423,519,911 (178,765,948) 244,753,963

(Loss)_Income Per Share (Tables

(Loss)/Income Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Reconciliation of NRG's basic and diluted (loss)/income per share	The reconciliation of NRG's basic and diluted (loss)/income per share is shown in the following table: Three months ended March 31, (In millions, except per share data) 2021 2020 Basic (loss)/income per share: Net (loss)/income $ (82) $ 121 Weighted average number of common shares outstanding - basic 245 248 (Loss)/income per weighted average common share — basic $ (0.33) $ 0.49 Diluted (loss)/income per share: Net (loss)/income $ (82) $ 121 Weighted average number of common shares outstanding - basic 245 248 Incremental shares attributable to the issuance of equity compensation (treasury stock method) — 1 Weighted average number of common shares outstanding - dilutive 245 249 (Loss)/income per weighted average common share — diluted $ (0.33) $ 0.49

Segment Reporting (Tables)

Segment Reporting (Tables)	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Three months ended March 31, 2021 (In millions) Texas East West/Services/Other Corporate Eliminations Total Operating revenues $ 3,702 $ 3,825 $ 565 $ — $ (1) $ 8,091 Depreciation and amortization 77 209 24 7 — 317 Gain on sale of assets — — 17 — — 17 Equity in losses of unconsolidated affiliates (1) — (5) — — (6) (Loss)/income before income taxes (425) 357 70 (169) — (167) Net (loss)/income $ (425) $ 353 $ 69 $ (79) $ — $ (82) Three months ended March 31, 2020 (In millions) Texas East West/Services/Other Corporate Eliminations Total Operating revenues $ 1,358 $ 521 $ 143 $ — $ (3) $ 2,019 Depreciation and amortization 59 32 9 9 — 109 Gain on sale of assets — — 1 5 — 6 Equity in losses of unconsolidated affiliates — — (11) — — (11) Income/(loss) before income taxes 162 20 45 (82) (1) 144 Net income/(loss) $ 162 $ 20 $ 45 $ (105) $ (1) $ 121

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Provision	The income tax provision consisted of the following: Three months ended March 31, (In millions, except rates) 2021 2020 (Loss)/Income before income taxes $ (167) $ 144 Income tax (benefit)/expense (85) 23 Effective income tax rate 50.9 % 16.0 %

Related Party Transactions (Tab

Related Party Transactions (Tables)	3 Months Ended
	Mar. 31, 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 March 31, (In millions) 2021 2020 Revenues from Related Parties Included in Operating Revenues Gladstone $ 1 $ 1 Ivanpah (a) 12 13 Midway-Sunset 2 1 Total $ 15 $ 15 (a) Also includes fees under project management agreements with each project company

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 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 commitments as of the acquisition date 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 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) MW in Thousands, customer in Millions	Jan. 05, 2021customerstatecounterparty	Mar. 31, 2021MW	Jan. 05, 2021province
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Generation capacity (in MW) | MW		23
Business Acquisition [Line Items]
Customers added (over) | counterparty	3,000,000
Direct Energy
Business Acquisition [Line Items]
Customers added (over) | customer	3
U.S. | Direct Energy
Business Acquisition [Line Items]
States in which entity operates | state	50
Canada | Direct Energy
Business Acquisition [Line Items]
Provinces in which entity operates	8		8

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Other Balance Sheet Information (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Property, plant and equipment accumulated depreciation	$ 1,566	$ 1,936
Intangible assets accumulated amortization	$ 1,424	$ 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
	Mar. 31, 2021	Mar. 31, 2020
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 67	$ 43
Acquired balance from Direct Energy	112	0
Provision for credit losses	611	24
Write-offs	(48)	(32)
Recoveries collected	7	4
Ending balance	749	$ 39
Increase in provision for credit losses due finance hedge risk	393
Increase in provision due to counterparty credit Risk	109
Increase in provision for credit Loss due to shortfall payments	$ 83

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Restricted Cash (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Cash and cash equivalents	$ 501	$ 3,905
Funds deposited by counterparties	55	19
Restricted cash	18	6
Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows	$ 574	$ 3,930	$ 818	$ 385

Revenue Recognition - Performan

Revenue Recognition - Performance Obligations Expected Timing of Satisfaction (Details) $ in Millions	Mar. 31, 2021USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated future fixed fee performance obligations	$ 544
Revenue remaining performance obligation period	9 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	$ 299
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	$ 51
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
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 7,929	$ 1,925
Mark-to-market for economic hedging activities	721	44
Operating revenues	8,091	2,019
Lease revenue	2	5
Derivative revenue	725	55
Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(3)	(2)
Operating revenues	(1)	(3)
Lease revenue	0	0
Retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6,162	1,661
Retail revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	(1)
Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	482	124
Derivative revenue	58	53
Energy revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	(1)
Derivative revenue	2	(1)
Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	155	149
Derivative revenue	37	24
Capacity revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Derivative revenue	0	0
Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(32)	(4)
Derivative revenue	160	89
Derivative revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	1	1
Derivative revenue	2	(1)
Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,324	89
Other revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(3)	(2)
Total operating revenue
Disaggregation of Revenue [Line Items]
Operating revenues	8,091	2,019
Total operating revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Operating revenues	(1)	(3)
Other revenue, derivative
Disaggregation of Revenue [Line Items]
Derivative revenue	97	16
Other revenue, derivative | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Derivative revenue	(1)	(1)
Home | Retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,718	1,378
Home | Retail revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	(1)
Business | Retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,444	283
Business | Retail revenue | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Texas | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,609	1,351
Operating revenues	3,702	1,358
Lease revenue	0	0
Texas | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,114	1,292
Texas | Energy revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	285	5
Derivative revenue	0	0
Texas | Capacity revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Derivative revenue	0	0
Texas | Derivative revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(1)	0
Derivative revenue	93	7
Texas | Other revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,304	61
Texas | Total operating revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Operating revenues	3,702	1,358
Texas | Other revenue, derivative | Operating Segments
Disaggregation of Revenue [Line Items]
Derivative revenue	94	7
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	1,542	1,032
Texas | Business | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	572	260
East | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,726	482
Operating revenues	3,825	521
Lease revenue	0	0
East | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,543	352
East | Energy revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	126	45
Derivative revenue	60	35
East | Capacity revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	141	134
Derivative revenue	37	24
East | Derivative revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(4)	(20)
Derivative revenue	99	39
East | Other revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	19	10
East | Total operating revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Operating revenues	3,825	521
East | Other revenue, derivative | Operating Segments
Disaggregation of Revenue [Line Items]
Derivative revenue	6	0
East | Home | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	702	329
East | Business | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,841	23
West/Services/Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	597	94
Operating revenues	565	143
Lease revenue	2	5
West/Services/Other | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	505	18
West/Services/Other | Energy revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	70	75
Derivative revenue	(4)	19
West/Services/Other | Capacity revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	14	15
Derivative revenue	0	0
West/Services/Other | Derivative revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(28)	15
Derivative revenue	(34)	44
West/Services/Other | Other revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4	20
West/Services/Other | Total operating revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Operating revenues	565	143
West/Services/Other | Other revenue, derivative | Operating Segments
Disaggregation of Revenue [Line Items]
Derivative revenue	(2)	10
West/Services/Other | Home | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	474	18
West/Services/Other | Business | Retail revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 31	$ 0

Revenue Recognition - Contract

Revenue Recognition - Contract Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Jun. 30, 2020	Dec. 31, 2020
Schedule Of Contract Assets And Liabilities [Line Items]
Deferred customer acquisition costs	$ 116			$ 113
Total accounts receivable, net	3,037			904
Unbilled revenues (included within Accounts receivable, net - Contracts with customers)	1,234			393
Deferred revenues	258			60
Deferred revenue from contract with customers	232		$ 31
Revenue recognized	23	$ 13
Accounts receivable, net - Contracts with customers
Schedule Of Contract Assets And Liabilities [Line Items]
Total accounts receivable, net	2,920			866
Accounts receivable, net - Derivative instruments
Schedule Of Contract Assets And Liabilities [Line Items]
Total accounts receivable, net	113			33
Accounts receivable, net - Affiliate
Schedule Of Contract Assets And Liabilities [Line Items]
Total accounts receivable, net	$ 4			$ 5

Acquisitions and Dispositions -

Acquisitions and Dispositions - Acquisitions (Details) customer in Millions, $ in Millions	Jan. 05, 2021USD ($)customerstatecounterparty	Dec. 31, 2020USD ($)	Mar. 31, 2021USD ($)	Jan. 05, 2021province
Business Acquisition [Line Items]
Customers added (over) | counterparty	3,000,000
Acquisition costs			$ 22
Direct Energy
Business Acquisition [Line Items]
Customers added (over) | customer	3
Purchase price	$ 3,625
Purchase price adjustment	77		$ (38)
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
Business acquisition, revenue	4,161
Business acquisition, net income	$ 134
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	8			8

Acquisitions and Dispositions_2

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

Acquisitions and Dispositions_3

Acquisitions and Dispositions - Purchase Price Allocation (Details) - USD ($) $ in Millions	Mar. 31, 2021	Jan. 05, 2021	Dec. 31, 2020
Other Assets
Goodwill	$ 1,572		$ 579
Other Liabilities
Goodwill, expected to be tax deductible		$ 337
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		181
Total current assets		3,518
Property, plant and equipment, net		178
Other Assets
Goodwill		990
Intangible assets		2,559
Derivative instruments		531
Other non-current assets		31
Total other assets		4,111
Total Assets		7,807
Current Liabilities
Accounts payable		1,390
Derivative instruments		1,266
Cash collateral received in support of energy risk management activities		21
Accrued expenses and other current liabilities		440
Total current liabilities		3,117
Other Liabilities
Derivative instruments		562
Deferred income taxes		433
Other non-current liabilities		31
Total other liabilities		1,026
Total Liabilities		4,143
Direct Energy Purchase Price		$ 3,664

Acquisitions and Dispositions_4

Acquisitions and Dispositions - Dispositions (Details) $ in Millions	Feb. 03, 2021USD ($)	Dec. 31, 2021USD ($)MW	Mar. 31, 2021USD ($)MW	Mar. 31, 2020USD ($)
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
Agua Caliente Solar Project | 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]
Percentage of ownership sold	35.00%
Cash consideration	$ 202
Gain on sale	17
Cash disposed	$ 7
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]
Proceeds from sale			$ 2	$ 15
East and West | Forecast | Subsequent Event | 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]
Generation capacity (in MW) | MW		4,850
Proceeds from sale		$ 760
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

Acquisitions and Dispositions_5

Acquisitions and Dispositions - Held For Sale (Details) - Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations $ in Millions	Mar. 31, 2021USD ($)
East and West
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current assets - discontinued operations	$ 55
Property, plant and equipment, net	385
Other non-current assets	3
Noncurrent assets	388
Total assets held for sale	443
Current liabilities	27
Non-current liabilities	60
Total liabilities held for sale	87
East
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property, plant and equipment, net	237
West/Services/Other
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property, plant and equipment, net	$ 148

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	Mar. 31, 2021	Dec. 31, 2020
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Notes receivable	$ 2	$ 2
Long-term debt, including current portion	9,609	8,781
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Notes receivable	2	2
Long-term debt, including current portion	10,007	9,446
Fair Value | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt, including current portion	9,182	9,446
Fair Value | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt, including current portion	$ 825	$ 0

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Assets and Liabilities Measured and Recorded at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 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)	$ 24	$ 25
Other trust fund investments:
U.S. government and federal agency obligations	1	1
Measured using net asset value practical expedient:
Total assets	3,766	1,745
Derivative liabilities:
Commodity contracts	2,440	884
Commodity contracts
Derivative assets:
Commodity contracts	2,824	821
Derivative liabilities:
Commodity contracts	2,438	884
Foreign exchange contract
Derivative liabilities:
Commodity contracts	2
Cash and cash equivalents
Nuclear trust fund investments:
Nuclear trust fund investments	20	23
U.S. government and federal agency obligations
Nuclear trust fund investments:
Nuclear trust fund investments	73	70
Federal agency mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	78	89
Commercial mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	40	36
Corporate debt securities
Nuclear trust fund investments:
Nuclear trust fund investments	136	144
Equity securities
Nuclear trust fund investments:
Nuclear trust fund investments	466	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	7	7
Equity securities — nuclear trust fund investments
Measured using net asset value practical expedient:
Equity securities	89	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)	10	10
Other trust fund investments:
U.S. government and federal agency obligations	1	1
Measured using net asset value practical expedient:
Total assets	765	597
Derivative liabilities:
Commodity contracts	205	86
Level 1 | Commodity contracts
Derivative assets:
Commodity contracts	195	59
Derivative liabilities:
Commodity contracts	205	86
Level 1 | Foreign exchange contract
Derivative liabilities:
Commodity contracts	0
Level 1 | Cash and cash equivalents
Nuclear trust fund investments:
Nuclear trust fund investments	20	23
Level 1 | U.S. government and federal agency obligations
Nuclear trust fund investments:
Nuclear trust fund investments	72	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	466	434
Level 1 | Foreign government fixed income securities
Nuclear trust fund investments:
Nuclear trust fund investments	1	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)	14	15
Other trust fund investments:
U.S. government and federal agency obligations	0	0
Measured using net asset value practical expedient:
Total assets	2,640	914
Derivative liabilities:
Commodity contracts	2,130	643
Level 2 | Commodity contracts
Derivative assets:
Commodity contracts	2,365	623
Derivative liabilities:
Commodity contracts	2,128	643
Level 2 | Foreign exchange contract
Derivative liabilities:
Commodity contracts	2
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	78	89
Level 2 | Commercial mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	40	36
Level 2 | Corporate debt securities
Nuclear trust fund investments:
Nuclear trust fund investments	136	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	6	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:
U.S. government and federal agency obligations	0	0
Measured using net asset value practical expedient:
Total assets	264	139
Derivative liabilities:
Commodity contracts	105	155
Level 3 | Commodity contracts
Derivative assets:
Commodity contracts	264	139
Derivative liabilities:
Commodity contracts	105	155
Level 3 | Foreign exchange contract
Derivative liabilities:
Commodity contracts	0
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
	Mar. 31, 2021	Mar. 31, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ (16)	$ 38
Contracts added from Direct Energy acquisition	(15)	0
Total (losses) — realized/unrealized included in earnings	180	22
Purchases	20	8
Transfers into Level 3	4	8
Transfers out of Level 3	(14)	(3)
Ending balance	159	73
Gains/(losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of period end	$ 146	$ (9)

Fair Value of Financial Instr_6

Fair Value of Financial Instruments - Derivative Fair Value Measurements, Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Total derivative assets valued with prices provided by models and other valuation techniques (as a percent)	9.00%
Total derivative liabilities valued with prices provided by models and other valuation techniques (as a percent)	4.00%
Increase in operating revenue	$ 14
Increase within cost of operations		$ 2

Fair Value of Financial Instr_7

Fair Value of Financial Instruments - Derivative Fair Value Measurements (Details) $ in Millions	Mar. 31, 2021USD ($)$ / MWh	Dec. 31, 2020USD ($)$ / MWh
Liabilities
Commodity contracts	$ 2,440	$ 884
Level 3
Liabilities
Commodity contracts	105	155
Commodity contracts
Assets
Derivative assets	2,824	821
Liabilities
Commodity contracts	2,438	884
Commodity contracts | Level 3
Assets
Derivative assets	264	139
Liabilities
Commodity contracts	105	155
Commodity contracts | Level 3 | Natural Gas Contracts
Assets
Derivative assets	3
Liabilities
Commodity contracts	$ 0
Commodity contracts | Level 3 | Natural Gas Contracts | Low
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	1
Commodity contracts | Level 3 | Natural Gas Contracts | High
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	16
Commodity contracts | Level 3 | Natural Gas Contracts | Weighted Average
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	14
Commodity contracts | Level 3 | Power Contracts
Assets
Derivative assets	$ 234	111
Liabilities
Commodity contracts	$ 91	$ 143
Commodity contracts | Level 3 | Power Contracts | Low
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	1	10
Commodity contracts | Level 3 | Power Contracts | High
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	237	105
Commodity contracts | Level 3 | Power Contracts | Weighted Average
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	29	21
Commodity contracts | Level 3 | FTRs
Assets
Derivative assets	$ 27	$ 28
Liabilities
Commodity contracts	$ 14	$ 12
Commodity contracts | Level 3 | FTRs | Low
Fair Value Inputs / Range
Auction Prices (per MWh) | $ / MWh	(33)	(28)
Commodity contracts | Level 3 | FTRs | High
Fair Value Inputs / Range
Auction Prices (per MWh) | $ / MWh	320	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
	Mar. 31, 2021USD ($)
Concentration of Credit Risk
Counterparty credit exposure to a portion of the Company's counterparties	$ 811
Collateral held (cash and letters of credit) against counterparty credit exposure to a portion of the Company's counterparties	140
Net counterparty credit exposure to a portion of the Company's counterparties	$ 752
Company's exposure before collateral expected to roll off (as a percent)	43.00%
Net exposure (as a percent)	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	$ 925
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	$ 393
Investment grade
Concentration of Credit Risk
Net exposure (as a percent)	61.00%
Non-Investment grade/Non-Rated
Concentration of Credit Risk
Net exposure (as a percent)	39.00%
Utilities, energy merchants, marketers and other
Concentration of Credit Risk
Net exposure (as a percent)	79.00%
Financial Institutions
Concentration of Credit Risk
Net exposure (as a percent)	21.00%

Nuclear Decommissioning Trust_3

Nuclear Decommissioning Trust Fund - Narrative (Details)	Mar. 31, 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	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Nuclear decommissioning trust fund
Fair Value	$ 909	$ 890
Unrealized Gains	418	398
Unrealized Losses	3	0
Cash and cash equivalents
Nuclear decommissioning trust fund
Fair Value	20	23
Unrealized Gains	0	0
Unrealized Losses	0	0
U.S. government and federal agency obligations
Nuclear decommissioning trust fund
Fair Value	73	70
Unrealized Gains	4	6
Unrealized Losses	$ 2	$ 0
Weighted-average Maturities (In years)	12 years	10 years
Federal agency mortgage-backed securities
Nuclear decommissioning trust fund
Fair Value	$ 78	$ 89
Unrealized Gains	3	4
Unrealized Losses	$ 0	$ 0
Weighted-average Maturities (In years)	23 years	24 years
Commercial mortgage-backed securities
Nuclear decommissioning trust fund
Fair Value	$ 40	$ 36
Unrealized Gains	1	2
Unrealized Losses	$ 0	$ 0
Weighted-average Maturities (In years)	28 years	27 years
Corporate debt securities
Nuclear decommissioning trust fund
Fair Value	$ 136	$ 144
Unrealized Gains	7	13
Unrealized Losses	$ 1	$ 0
Weighted-average Maturities (In years)	12 years	12 years
Equity securities
Nuclear decommissioning trust fund
Fair Value	$ 555	$ 521
Unrealized Gains	403	372
Unrealized Losses	0	0
Foreign government fixed income securities
Nuclear decommissioning trust fund
Fair Value	7	7
Unrealized Gains	0	1
Unrealized Losses	$ 0	$ 0
Weighted-average Maturities (In years)	9 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	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Regulated Operations [Abstract]
Realized gains	$ 3	$ 2
Realized losses	(2)	(5)
Proceeds from sale of securities	$ 118	$ 112

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, T in Millions, MWh in Millions, MMBTU in Millions, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021USD ($)MMBTUMWhcertificateT	Dec. 31, 2020USD ($)MMBTUMWhcertificateT
Long | Emissions
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, mass (ton) | T	0	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	2	2
Long | Power
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, energy measure (MMBtu/MW/Day) | MWh	201	57
Long | Foreign Exchange
Volumetric Underlying Derivative Transactions
Derivative, notional amount | $	$ 158	$ 0
Short | Natural Gas
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, energy measure (MMBtu/MW/Day) | MMBTU	605	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	Mar. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative Liabilities	$ 2,440	$ 884
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Assets	2,824	821
Derivative Liabilities	2,440	884
Not Designated as Hedging Instrument | Foreign exchange contracts - current
Derivative [Line Items]
Derivative Assets	0	0
Derivative Liabilities	1	0
Not Designated as Hedging Instrument | Foreign exchange contracts -long-term
Derivative [Line Items]
Derivative Assets	0	0
Derivative Liabilities	1	0
Not Designated as Hedging Instrument | Commodity contracts - current
Derivative [Line Items]
Derivative Assets	1,816	560
Derivative Liabilities	1,605	499
Not Designated as Hedging Instrument | Commodity contracts - long-term
Derivative [Line Items]
Derivative Assets	1,008	261
Derivative Liabilities	$ 833	$ 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	Mar. 31, 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	$ (55)	$ (19)
Derivative liabilities	(2,440)	(884)
Cash Collateral Posted	298	50
Gross Amounts of Recognized Assets / Liabilities	384
Derivative Instruments	0
Cash Collateral (Held) / Posted	(10)
Net Amount	374
Foreign exchange contract
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Derivative liabilities	(2)
Derivative Instruments	0
Cash Collateral Posted	0
Net Amount	(2)
Gross Amounts of Recognized Assets / Liabilities	(2)
Derivative Instruments	0
Cash Collateral (Held) / Posted	0
Net Amount	(2)
Commodity contracts
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Derivative assets	2,824	821
Derivative Instruments	(2,253)	(658)
Cash collateral received in support of energy risk management activities	(10)	(5)
Net Amount	561	158
Derivative liabilities	(2,438)	(884)
Derivative Instruments	2,253	658
Cash Collateral Posted	0	0
Net Amount	(185)	(226)
Gross Amounts of Recognized Assets / Liabilities	386	(63)
Derivative Instruments	0	0
Cash Collateral (Held) / Posted	(10)	(5)
Net Amount	$ 376	$ (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
	Mar. 31, 2021	Mar. 31, 2020
Unrealized mark-to-market results
Reversal of previously recognized unrealized losses on settled positions related to economic hedges	$ 17	$ 9
Reversal of acquired loss positions related to economic hedges	145	1
Net unrealized gains on open positions related to economic hedges	559	34
Total unrealized mark-to-market gains for economic hedging activities	721	44
Reversal of previously recognized unrealized (gains) on settled positions related to trading activity	(7)	(2)
Net unrealized gains on open positions related to trading activity	11	13
Total unrealized mark-to-market gains for trading activity	4	11
Total unrealized gains	725	55
Credit Risk Related Contingent Features
Unrealized gains from open economic hedge positions	559	34
Collateral due on net liability position that has not been called by a certain marginable agreement counterparty	91
Additional collateral required	57
Adequate Assurance Clauses
Credit Risk Related Contingent Features
Derivative net liability position, collateral required for contracts with credit rating contingent feature	642
Commodity contracts
Unrealized mark-to-market results
Total unrealized gains	725	55
Commodity contracts | Operating revenues
Unrealized mark-to-market results
Total unrealized gains	(28)	7
Commodity contracts | Cost of operations
Unrealized mark-to-market results
Total unrealized gains	755	48
Foreign exchange contract | Cost of operations
Unrealized mark-to-market results
Total unrealized gains	$ (2)	$ 0

Impairments (Details)

Impairments (Details) - Petra Nova $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Schedule of Equity Method Investments [Line Items]
Impairment losses	$ 18
Letters of credit issued	$ 12

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	Jan. 29, 2021$ / shares	Apr. 30, 2021$ / shares	Mar. 31, 2021USD ($)	May 06, 2021USD ($)	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Finance leases			$ 16		$ 4
Subtotal long-term debt and finance leases (including current maturities)			9,696		8,859
Less current maturities			(831)		(1)
Less debt issuance costs			(89)		(93)
Discounts			(71)		(74)
Total long-term debt			8,705		8,691
Recourse Debt
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			9,680		8,855
Recourse Debt | Senior Notes, due 2026
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 1,000		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)			$ 1,230		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 | Convertible Senior Notes Due 2048
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 575		575
Interest rate, stated percentage			2.75%
Convertible Notes, conversion price (in usd per share) | $ / shares	$ 45.91
Conversion rate	0.02179
Recourse Debt | Convertible Senior Notes Due 2048 | Subsequent Event
Debt Instrument [Line Items]
Convertible Notes, conversion price (in usd per share) | $ / shares		$ 45.54
Conversion rate		0.02196
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%
Line of Credit | Revolving Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 750		0
Line of Credit | Revolving Credit Facility | Revolving Credit Facility | Subsequent Event
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)				$ 70
Line of Credit | Revolving Credit Facility | Revolving Credit Facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate			1.72%
Non Recourse Debt | Repurchase Facility
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)			$ 75		$ 0
Basis spread on variable rate			1.25%

Long-term Debt and Finance Le_4

Long-term Debt and Finance Leases - Recourse Debt (Details) - Revolving Credit Facility - Line of Credit - Credit agreement - USD ($)	3 Months Ended
	Sep. 30, 2020	May 06, 2021	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Increase revolving commitments	$ 802,000,000
Revolving credit commitments	$ 273,000,000
Debt term	30 months
Debt extension, term	12 months
Total revolving commitments available			$ 3,700,000,000
Subtotal long-term debt (including current maturities)			$ 750,000,000	$ 0
Subsequent Event
Debt Instrument [Line Items]
Subtotal long-term debt (including current maturities)		$ 70,000,000

Long-term Debt and Finance Le_5

Long-term Debt and Finance Leases - Non-Recourse Debt (Details) - Letter Of Credit Agreement - USD ($) $ in Millions	Mar. 31, 2021	Dec. 02, 2020
Line of Credit Facility [Line Items]
Revolving credit commitments		$ 874
Letters of credit issued	$ 689

Investments Accounted for Usi_3

Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs (Details) - USD ($) $ in Millions	Mar. 31, 2021	Feb. 03, 2021	Dec. 31, 2020
Investments Accounted for by the Equity Method
Other current assets	$ 6,552		$ 6,028
Total Assets	19,241		14,902
Current liabilities	5,795		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	728		647
Other current assets	1		2
Total Assets	729		649
Current liabilities	76		78
Net assets	$ 653		$ 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	3 Months Ended
	May 06, 2021	Mar. 31, 2021
Schedule of Stock by Class, Equity [Roll Forward]
Balance as of beginning of period (in shares)	423,519,121	423,057,848
Treasury shares, balance as of beginning of period (in shares)	(178,825,915)	(178,825,915)
Outstanding, as of beginning of period (in shares)	244,693,206	244,231,933
Balance as of end of period (in shares)		423,519,121
Treasury shares, balance as of end of the period (in shares)		(178,825,915)
Outstanding, as of end of period (in shares)		244,693,206
Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		461,273
Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Outstanding, as of end of period (in shares)	244,753,963
Subsequent Event | Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	790
Subsequent Event | Shares issued under ESPP
Schedule of Stock by Class, Equity [Roll Forward]
Stock issued under ESPP (in shares)	59,967
Common Stock
Schedule of Stock by Class, Equity [Roll Forward]
Balance as of beginning of period (in shares)	423,519,121	423,057,848
Balance as of end of period (in shares)		423,519,121
Common Stock | Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		461,273
Common Stock | Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Balance as of end of period (in shares)	423,519,911
Common Stock | Subsequent Event | Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	790
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)	(178,825,915)	(178,825,915)
Treasury shares, balance as of end of the period (in shares)		(178,825,915)
Treasury | Shares issued under LTIPs
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		0
Treasury | Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Treasury shares, balance as of end of the period (in shares)	(178,765,948)
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)	59,967

Changes in Capital Structure _2

Changes in Capital Structure - Narrative (Details) - shares	1 Months Ended
	Mar. 31, 2019	Mar. 31, 2021	Dec. 31, 2020
Equity [Abstract]
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%

Changes in Capital Structure _3

Changes in Capital Structure - NRG Common Stock Dividends (Details) - $ / shares	Apr. 15, 2021	Mar. 31, 2021	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	$ 0.30
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%

(Loss)_Income Per Share - Recon

(Loss)/Income Per Share - Reconciliation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Basic (loss)/income per share:
Net (loss)/income	$ (82)	$ 121
Weighted average number of common shares outstanding — basic (in shares)	245,000	248,000
(Loss)/income per weighted average common share — basic (in usd per share)	$ (0.33)	$ 0.49
Diluted (loss)/income per share:
Net (loss)/income	$ (82)	$ 121
Weighted average number of common shares outstanding — basic (in shares)	245,000	248,000
Incremental shares attributable to the issuance of equity compensation (treasury stock method) (in shares)	0	1,000
Weighted average number of common shares outstanding- dilutive (in shares)	245,000	249,000
(Loss)/income per weighted average common share — diluted (in usd per share)	$ (0.33)	$ 0.49
Antidilutive securities (in shares)	1,000

Segment Reporting (Details)

Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information
Operating revenues	$ 8,091	$ 2,019
Depreciation and amortization	317	109
Gain on sale of assets	17	6
Equity in losses of unconsolidated affiliates	(6)	(11)
(Loss)/income from continuing operations before income taxes	(167)	144
Net (loss)/income	(82)	121
Corporate
Segment Reporting Information
Operating revenues	0	0
Depreciation and amortization	7	9
Gain on sale of assets	0	5
Equity in losses of unconsolidated affiliates	0	0
(Loss)/income from continuing operations before income taxes	(169)	(82)
Net (loss)/income	(79)	(105)
Eliminations
Segment Reporting Information
Operating revenues	(1)	(3)
Depreciation and amortization	0	0
Gain on sale of assets	0	0
Equity in losses of unconsolidated affiliates	0	0
(Loss)/income from continuing operations before income taxes	0	(1)
Net (loss)/income	0	(1)
Texas | Operating Segments
Segment Reporting Information
Operating revenues	3,702	1,358
Depreciation and amortization	77	59
Gain on sale of assets	0	0
Equity in losses of unconsolidated affiliates	(1)	0
(Loss)/income from continuing operations before income taxes	(425)	162
Net (loss)/income	(425)	162
East | Operating Segments
Segment Reporting Information
Operating revenues	3,825	521
Depreciation and amortization	209	32
Gain on sale of assets	0	0
Equity in losses of unconsolidated affiliates	0	0
(Loss)/income from continuing operations before income taxes	357	20
Net (loss)/income	353	20
West/Services/Other | Operating Segments
Segment Reporting Information
Operating revenues	565	143
Depreciation and amortization	24	9
Gain on sale of assets	17	1
Equity in losses of unconsolidated affiliates	(5)	(11)
(Loss)/income from continuing operations before income taxes	70	45
Net (loss)/income	$ 69	$ 45

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Effective Tax Rate
(Loss)/Income before income taxes	$ (167)	$ 144
Income tax (benefit)/expense	$ (85)	$ 23
Effective income tax rate	50.90%	16.00%
Uncertain Tax Benefits
Non-current tax liability for uncertain tax benefits	$ 23
Uncertain tax benefits, penalties and interest accrued	$ 2

Related Party Transactions - Sc

Related Party Transactions - Schedule of NRG's Material Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Related Party Transaction [Line Items]
Revenue from related parties	$ 15	$ 15
Gladstone
Related Party Transaction [Line Items]
Revenue from related parties	1	1
Ivanpah
Related Party Transaction [Line Items]
Revenue from related parties	12	13
Midway-Sunset
Related Party Transaction [Line Items]
Revenue from related parties	$ 2	$ 1

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