NRG Energy (NRG) 8-K 7 May 20 Other Events Financial data

Cover

Cover	May 07, 2020
Cover [Abstract]
Document Type	8-K
Document Period End Date	May 7, 2020
Entity Registrant Name	NRG ENERGY, INC.
Entity Incorporation, State or Country Code	DE
Entity File Number	001-15891
Entity Tax Identification Number	41-1724239
Entity Address, Address Line One	804 Carnegie Center
Entity Address, City or Town	Princeton
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	08540
City Area Code	609
Local Phone Number	524-4500
Written Communications	false
Soliciting Material	false
Pre-commencement Tender Offer	false
Pre-commencement Issuer Tender Offer	false
Title of 12(b) Security	Common Stock, par value $0.01
Trading Symbol	NRG
Security Exchange Name	NYSE
Entity Emerging Growth Company	false
Entity Central Index Key	0001013871
Amendment Flag	true

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Revenues
Total operating revenues		$ 2,195	$ 2,996	$ 2,465	$ 2,165	$ 1,992	$ 2,960	$ 2,461	$ 2,065	$ 9,821	$ 9,478	$ 9,074
Operating Costs and Expenses
Cost of operations										7,303	7,108	6,886
Depreciation and amortization										373	421	596
Impairment losses										5	99	1,534
Selling, general and administrative										827	799	836
Reorganization costs										23	90	44
Development costs										7	11	22
Total operating costs and expenses										8,538	8,528	9,918
Other income - affiliate	$ 84									0	0	87
Gain on sale of assets										7	32	16
Operating Income/(Loss)		209	540	320	221	49	398	174	361	1,290	982	(741)
Other Income/(Expense)
Equity in earnings/(losses) of unconsolidated affiliates										2	9	(14)
Impairment losses on investments										(108)	(15)	(79)
Other income, net										66	18	51
Loss on debt extinguishment, net										(51)	(44)	(49)
Interest expense										(413)	(483)	(557)
Total other expense										(504)	(515)	(648)
Income/(Loss) from Continuing Operations Before Income Taxes										786	467	(1,389)
Income tax (benefit)/expense										(3,334)	7	(44)
Income/(Loss) from Continuing Operations		3,463	374	189	94	(93)	287	27	238	4,120	460	(1,345)
Income/(loss) from discontinued operations, net of income tax		(78)	(2)	13	388	80	(336)	69	(5)	321	(192)	(992)
Net Income/(Loss)		3,385	372	202	482	(13)	(49)	96	233	4,441	268	(2,337)
Less: Net income/(loss) attributable to noncontrolling interest and redeemable interests		$ 2	$ 0	$ 1	$ 0	$ (2)	$ 23	$ 24	$ (46)	3	0	(184)
Net Income/(Loss) Attributable to NRG Energy, Inc.										$ 4,438	$ 268	$ (2,153)
Earnings/(Loss) Per Share Attributable to NRG Energy, Inc. Common Stockholders
Weighted average number of common shares outstanding — basic (in shares)		251,000,000	254,000,000	265,000,000	278,000,000	289,000,000	299,000,000	310,000,000	318,000,000	262,000,000	304,000,000	317,000,000
Income/(loss) from continuing operations per weighted average common share —basic (in usd per share)										$ 15.71	$ 1.51	$ (3.66)
Income/(loss) from discontinued operations per weighted average common share — basic (in usd per share)		$ (0.31)	$ (0.01)	$ 0.05	$ 1.39	$ 0.28	$ (1.12)	$ 0.22	$ (0.02)	1.23	(0.63)	(3.13)
Net Income/(Loss) per Weighted Average Common Share - Basic (in usd per share)		$ 13.48	$ 1.46	$ 0.76	$ 1.73	$ (0.04)	$ (0.24)	$ 0.23	$ 0.88	$ 16.94	$ 0.88	$ (6.79)
Weighted average number of common shares outstanding — diluted (in shares)		253,000,000	256,000,000	267,000,000	280,000,000	289,000,000	299,000,000	314,000,000	322,000,000	264,000,000	308,000,000	317,000,000
Income/(loss) from continuing operations per weighted average common share — diluted (in usd per share)										$ 15.59	$ 1.49	$ (3.66)
Income/(loss) from discontinued operations per weighted average common share — diluted (in usd per share)		$ (0.31)	$ (0.01)	$ 0.05	$ 1.38	$ 0.28	$ (1.12)	$ 0.22	$ (0.02)	1.22	(0.62)	(3.13)
Net Income/(Loss) per Weighted Average Common Share - Diluted (in usd per share)		$ 13.37	$ 1.45	$ 0.75	$ 1.72	$ (0.04)	$ (0.24)	$ 0.23	$ 0.87	$ 16.81	$ 0.87	$ (6.79)

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 3,385	$ 372	$ 202	$ 482	$ (13)	$ (49)	$ 96	$ 233	$ 4,441	$ 268	$ (2,337)
Other Comprehensive (Loss)/Income, net of tax
Unrealized gain on derivatives, net of income tax									0	23	13
Foreign currency translation adjustments, net of income tax									(1)	(11)	12
Available-for-sale securities, net of income tax									(19)	1	(8)
Defined benefit plans, net of income tax									(78)	(35)	46
Other comprehensive (loss)/income									(98)	(22)	63
Comprehensive Income/(Loss)									4,343	246	(2,274)
Less: Comprehensive income/(loss) attributable to noncontrolling interests and redeemable noncontrolling interests									3	14	(179)
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.									$ 4,340	$ 232	$ (2,095)

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Current Assets
Cash and cash equivalents	$ 345	$ 563
Funds deposited by counterparties	32	33
Restricted cash	8	17
Accounts receivable, net	1,025	1,024
Inventory	383	412
Derivative instruments	860	764
Cash collateral posted in support of energy risk management activities	190	287
Prepayments and other current assets	245	302
Current assets - held-for-sale	0	1
Current assets - discontinued operations	0	197
Total current assets	3,088	3,600
Property, plant and equipment, net	2,593	3,048
Other Assets
Equity investments in affiliates	388	412
Operating lease right-of-use assets, net	464
Goodwill	579	573
Intangible assets, net	789	591
Nuclear decommissioning trust fund	794	663
Derivative instruments	310	317
Deferred income taxes	3,286	46
Other non-current assets	240	289
Non-current assets - held-for-sale	0	77
Non-current assets - discontinued operations	0	1,012
Total other assets	6,850	3,980
Total Assets	12,531	10,628
Current Liabilities
Current portion of long-term debt and finance leases	88	72
Current portion of operating lease liabilities	73
Accounts payable	722	863
Derivative instruments	781	673
Cash collateral received in support of energy risk management activities	32	33
Accrued expenses and other current liabilities	663	680
Current liabilities - held for sale	0	5
Current liabilities - discontinued operations	0	72
Total current liabilities	2,359	2,398
Other Liabilities
Long-term debt and finance leases	5,803	6,449
Non-current operating lease liabilities	483
Nuclear decommissioning reserve	298	282
Nuclear decommissioning trust liability	487	371
Derivative instruments	322	304
Deferred income taxes	17	65
Other non-current liabilities	1,084	1,274
Non-current liabilities - held-for-sale		65
Non-current liabilities - held-for-sale	0	65
Non-current liabilities - discontinued operations	0	635
Total other liabilities	8,494	9,445
Total Liabilities	10,853	11,843
Redeemable noncontrolling interest in subsidiaries	20	19
Commitments and Contingencies
Stockholders' Equity
Common stock; $0.01 par value; 500,000,000 shares authorized; 421,890,790 and 420,288,886 shares issued; and 248,996,189 and 283,650,039 shares outstanding at December 31, 2019 and 2018	4	4
Additional paid-in capital	8,501	8,510
Accumulated deficit	(1,616)	(6,022)
Treasury stock, at cost; 172,894,601 and 136,638,847 shares at December 31, 2019 and 2018	(5,039)	(3,632)
Accumulated other comprehensive loss	(192)	(94)
Total Stockholders' Equity	1,658	(1,234)
Total Liabilities and Stockholders' Equity	$ 12,531	$ 10,628

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par 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)	421,890,790	420,288,886
Common stock, shares outstanding (in shares)	248,996,189	283,650,039
Treasury stock, shares (in shares)	172,894,601	136,638,847

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flows from Operating Activities
Net Income/(Loss)	$ 4,441	$ 268	$ (2,337)
Income/(loss) from discontinued operations, net of income tax	321	(192)	(992)
Income/(loss) from continuing operations	4,120	460	(1,345)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions and equity in earnings of unconsolidated affiliates	14	46	102
Depreciation and amortization	373	421	596
Accretion of asset retirement obligations	51	38	44
Provision for bad debts	95	85	68
Amortization of nuclear fuel	52	48	51
Amortization of financing costs and debt discount/premiums	26	29	29
Loss on debt extinguishment, net	51	44	49
Amortization of emission allowances and out-of-market contracts	38	45	54
Amortization of unearned equity compensation	20	25	35
Net gain on sale of assets and disposal of assets	(23)	(49)	(9)
Impairment losses	113	114	1,614
Changes in derivative instruments	34	37	(170)
Changes in deferred income taxes and liability for uncertain tax benefits	(3,353)	5	13
Changes in collateral deposits in support of risk management activities	105	(105)	(80)
Changes in nuclear decommissioning trust liability	37	60	11
GenOn settlement, net of insurance proceeds	0	(63)	0
Net loss on deconsolidation of Agua Caliente and Ivanpah projects	0	13	0
Cash provided/(used) by changes in other working capital, net of acquisition and disposition effects:
Accounts receivable - trade	5	(83)	(83)
Inventory	22	31	143
Prepayments and other current assets	29	(41)	(187)
Accounts payable	(177)	113	44
Accrued expenses and other current liabilities	(41)	(166)	(88)
Other assets and liabilities	(186)	(104)	(35)
Cash provided by continuing operations	1,405	1,003	856
Cash provided by discontinued operations	8	374	754
Net Cash Provided by Operating Activities	1,413	1,377	1,610
Cash Flows from Investing Activities
Payments for acquisitions of businesses	(355)	(243)	(14)
Capital expenditures	(228)	(388)	(254)
Net proceeds from sale of emission allowances	11	19	66
Investments in nuclear decommissioning trust fund securities	(416)	(572)	(512)
Proceeds from sales of nuclear decommissioning trust fund securities	381	513	501
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees	1,294	1,564	430
Deconsolidations of Agua Caliente and Ivanpah projects	0	(268)	0
Net contributions to investments in unconsolidated affiliates	(91)	(39)	(57)
Net (contributions to)/distributions from discontinued operations	(44)	(60)	150
Other	6	(6)	30
Cash provided by continuing operations	558	520	340
Cash used by discontinued operations	(2)	(725)	(979)
Net Cash Provided/(Used) by Investing Activities	556	(205)	(639)
Cash Flows from Financing Activities
Payments of dividends to common stockholders	(32)	(37)	(38)
Payments for share repurchase activity	(1,440)	(1,250)	0
Payments for debt extinguishment costs	(26)	(32)	(42)
Net distributions to noncontrolling interest from subsidiaries	(2)	(16)	(30)
Proceeds/(payments) from issuance of common stock	3	21	(2)
Proceeds from issuance of short and long-term debt	1,916	1,100	1,178
Payments of debt issuance costs	(35)	(19)	(18)
Payments for short and long-term debt	(2,571)	(1,734)	(1,884)
Receivable from affiliate	0	(26)	(125)
Other	(4)	(4)	(8)
Cash used by continuing operations	(2,191)	(1,997)	(969)
Cash provided/(used) by discontinued operations	43	471	(169)
Net Cash (Used)/Provided by Financing Activities	(2,148)	(1,526)	(1,138)
Effect of exchange rate changes on cash and cash equivalents	0	1	(1)
Change in Cash from discontinued operations	49	120	(394)
Net (Decrease)/Increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash	(228)	(473)	226
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period	613	1,086	860
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	$ 385	$ 613	$ 1,086

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	NRG Yield, Inc.	Common Stock	Additional Paid-In Capital	Additional Paid-In CapitalNRG Yield, Inc.	Accumulated Deficit	Treasury Stock	Accumulated Other Comprehensive Loss	Noncon- trolling Interest	Noncon- trolling InterestNRG Yield, Inc.
Beginning balance at Dec. 31, 2016	$ 4,446		$ 4	$ 8,358		$ (3,787)	$ (2,399)	$ (135)	$ 2,405
Increase (Decrease) in Stockholders' Equity
Net loss (income)	(2,251)					(2,153)			(98)
Other comprehensive income	51							51
Other comprehensive income (loss)	63
Sale of assets to NRG Yield, Inc		$ (5)			$ (25)					$ 20
ESPP share purchases	6			(3)		(4)	13
Equity-based compensation	25			25
Issuance of common stock	4			4
Common stock dividends	(38)					(38)
Distributions to noncontrolling interest and dividends paid	(65)	(108)							(65)	(108)
Contributions from noncontrolling interests	160								160
Early adoption of new accounting standards	(257)			17		(286)		12
Ending balance at Dec. 31, 2017	1,968		4	8,376		(6,268)	(2,386)	(72)	2,314
Increase (Decrease) in Stockholders' Equity
Adoption of new accounting standards	15					15
Net loss (income)	294					268			26
Other comprehensive income (loss)	(22)							(22)
Sale of assets to NRG Yield, Inc		16			$ 8					8
ESPP share purchases	2			(2)			4
Share repurchases	(1,250)						(1,250)
Equity-based compensation	6			6
Issuance of common stock	21			21
Common stock dividends	(37)					(37)
Distributions to noncontrolling interest and dividends paid	(43)	$ (61)							(43)	$ (61)
Contributions from noncontrolling interests	304								304
Early adoption of new accounting standards
Sale of NRG Yield and other business	(2,548)								(2,548)
Equity component of convertible senior notes	101			101
Ending balance at Dec. 31, 2018	(1,234)		4	8,510		(6,022)	(3,632)	(94)	0
Increase (Decrease) in Stockholders' Equity
Net loss (income)	4,438					4,438
Other comprehensive income (loss)	(98)							(98)
ESPP share purchases	3			1			2
Share repurchases	(1,409)						(1,409)
Equity-based compensation	(16)			(16)
Issuance of common stock	6			6
Common stock dividends	(32)					(32)
Ending balance at Dec. 31, 2019	$ 1,658		$ 4	$ 8,501		$ (1,616)	$ (5,039)	$ (192)	$ 0

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Dividends paid per share (in usd per share)	$ 0.12	$ 0.12	$ 0.12

Nature of Business

Nature of Business	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Nature of Business 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 electricity 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-driven 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 December 31, 2019. The Company began managing its integrated model based on the combined results of the retail and wholesale generation businesses with a geographical focus in 2020. As a result, the Company changed its business segments from Retail and Generation to Texas, East and West/Other beginning in the first quarter of 2020. The Company's updated segment structure reflects how management currently makes financial decisions and allocates resources. The Company's businesses are segregated as follows: • Texas, which includes all activity related to customer, plant and market operations in Texas; • East, which includes the remaining activity related to customer operations and all activity related to plant and market operations in the East; • West/Other, which includes the following assets and activities: (i) all activity related to plant and market operations in the West, (ii) activity related to the Cottonwood power plant that was sold to Cleco on February 4, 2019 and is being leased back until 2025, (iii) the remaining renewables activity, including the Company’s equity method investments in Ivanpah Master Holdings, LLC and Agua Caliente, the remaining Home Solar assets and the NFL stadium solar generating assets, and (iv) activity related to the Company’s equity method investment for the Gladstone power plant in Australia; and • Corporate activities. All affected disclosures presented herein have been recast to reflect these changes for all periods presented. For further discussion of segment reporting, refer to Note 19, Segment Reporting . Discontinued Operations On December 31, 2018, as described in Note 4, Acquisitions, Discontinued Operations and Dispositions , the Company concluded that the sale of its South Central Portfolio to Cleco, excluding the Cottonwood facility, met held-for-sale criteria and should be presented as a discontinued operation, as the sale represented a strategic shift in the business in which NRG operates. The financial information for all historical periods was recast in 2018 to reflect the presentation of these entities as discontinued operations. On August 31, 2018, as described in Note 4, Acquisitions, Discontinued Operations and Dispositions , the Company deconsolidated NRG Yield, Inc. and its Renewables Platform for financial reporting purposes. The financial information for all historical periods was recast in 2018 to reflect the presentation of these entities, as well as the Carlsbad project, as discontinued operations. As a result of the sale of NRG Yield, the Company no longer controls the Agua Caliente project. Due to this change in control, the Company deconsolidated the Agua Caliente project from its financial results and began accounting for the project as an equity method investment. On June 14, 2017, or the Petition Date, GenOn, along with GenOn Americas Generation and certain of their directly and indirectly-owned subsidiaries, or collectively the GenOn Entities, filed voluntary petitions for relief under the Chapter 11 Cases, of the U.S. Bankruptcy Code. As a result of the bankruptcy filings and beginning on June 14, 2017, GenOn and its subsidiaries were deconsolidated from NRG's consolidated financial statements. NRG determined that this disposal of GenOn and its subsidiaries was a discontinued operation and, accordingly, the financial information for all historical periods was recast to reflect GenOn as a discontinued operation. GenOn's plan of reorganization was confirmed on December 14, 2018.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation and Principles of Consolidation The Company's consolidated financial statements have been prepared in accordance with U.S. GAAP. The ASC, established by the FASB, is the source of authoritative U.S. GAAP to be applied by nongovernmental entities. In addition, the rules and interpretative releases of the SEC under authority of federal securities laws are also sources of authoritative U.S. GAAP for SEC registrants. The consolidated financial statements include NRG's accounts and operations and those of its subsidiaries in which the Company has a controlling interest. All significant intercompany transactions and balances have been eliminated in consolidation. The usual condition for a controlling financial interest is ownership of a majority of the voting interests of an entity. However, a controlling financial interest may also exist through arrangements that do not involve controlling voting interests. As such, NRG applies the guidance of ASC 810, Consolidations, or ASC 810, to determine when an entity that is insufficiently capitalized or not controlled through its voting interests, referred to as a VIE, should be consolidated. Net Income/(Loss) attributable to NRG Energy, Inc. The following table reflects the net income/(loss) attributable to NRG Energy, Inc. after removing the net loss attributable to the noncontrolling interest and redeemable noncontrolling interest: Year Ended December 31, (In millions) 2019 2018 2017 Income/(loss) from continuing operations, net of income tax $ 4,117 $ 465 $ (977) Income/(loss) from discontinued operations, net of income tax 321 (197) (1,176) Net income/(loss) attributable to NRG Energy, Inc. stockholders $ 4,438 $ 268 $ (2,153) Discontinued Operations As described in Note 4, Acquisitions, Discontinued Operations and Dispositions , the Company has determined that the South Central Portfolio, NRG Yield Inc. and its Renewables Platform, Carlsbad, and GenOn all qualified for treatment as discontinued operations. The financial information for all historical periods was recast in prior years to reflect the presentation of discontinued operations within the corporate segment. Cash and Cash Equivalents Cash and cash equivalents include highly liquid investments with an original maturity of three months or less at the time of purchase. Funds Deposited by Counterparties 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 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. Year Ended December 31, (In millions) 2019 2018 2017 Cash and cash equivalents $ 345 $ 563 $ 770 Funds deposited by counterparties 32 33 37 Restricted cash 8 17 279 Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statements of cash flows $ 385 $ 613 $ 1,086 Restricted cash consists primarily of funds held to satisfy the requirements of certain debt agreements and funds held within the Company's projects that are restricted in their use. Trade Receivables and Allowance for Doubtful Accounts Trade receivables are reported in the balance sheet at outstanding principal adjusted for any write-offs and the allowance for doubtful accounts. For its retail receivables, the Company accrues an allowance for doubtful accounts based on estimates of uncollectible revenues by analyzing counterparty credit ratings (for commercial and industrial customers), historical collections, accounts receivable aging and other factors. Accounts receivable balances are written-off against the allowance for doubtful accounts when a receivable is determined to be uncollectible. In addition, the Company considers a reserve for doubtful accounts based on the credit worthiness of the customers and continually reviews and adjusts for current economic trends that might impact the level of future credit losses. The reserve represents management's best estimate of uncollectible amounts. As of December 31, 2019 and 2018, the allowance for doubtful accounts was $43 million and $32 million, respectively. Inventory Inventory is valued at the lower of weighted average cost or market, and consists principally of fuel oil, coal and raw materials used to generate electricity or steam. The Company removes these inventories as they are used in the production of electricity or steam. Spare parts inventory is valued at weighted average cost. The Company removes these inventories when they are used for repairs, maintenance or capital projects. The Company expects to recover the fuel oil, coal, raw materials, and spare parts costs in the ordinary course of business. Finished goods inventory is valued at the lower of cost or net realizable value with cost being determined on a first-in first-out basis. The Company removes these inventories as they are sold to customers. Sales of inventory are classified as an operating activity in the consolidated statements of cash flows. Property, Plant and Equipment Property, plant and equipment are stated at cost or, in the case of business acquisitions, fair value; however, impairment adjustments are recorded whenever events or changes in circumstances indicate that their carrying values may not be recoverable. NRG also classifies nuclear fuel related to the Company's 44% ownership interest in STP as part of the Company's property, plant, and equipment. Significant additions or improvements extending asset lives are capitalized as incurred, while repairs and maintenance that do not improve or extend the life of the respective asset are charged to expense as incurred. Depreciation, other than nuclear fuel, is computed using the straight-line method, while nuclear fuel is amortized based on units of production over the estimated useful lives. Certain assets and their related accumulated depreciation amounts are adjusted for asset retirements and disposals with the resulting gain or loss included in cost of operations in the consolidated statements of operations. Asset Impairments Long-lived assets that are held and used are reviewed for impairment whenever events or changes in circumstances indicate carrying values may not be recoverable. Such reviews are performed in accordance with ASC 360. An impairment loss is indicated if the total future estimated undiscounted cash flows expected from an asset are less than its carrying value. An impairment charge is measured by the difference between an asset's carrying amount and fair value with the difference recorded in operating costs and expenses in the consolidated statements of operations. Fair values are determined by a variety of valuation methods, including third-party appraisals, sales prices of similar assets, and present value techniques. Investments accounted for by the equity method are reviewed for impairment in accordance with ASC 323, Investments-Equity Method and Joint Ventures , or ASC 323, which requires that a loss in value of an investment that is an other-than-temporary decline should be recognized. The Company identifies and measures losses in the value of equity method investments based upon a comparison of fair value to carrying value. For further discussion of these matters, refer to Note 11, Asset Impairments . Development Costs and Capitalized Interest Development costs include project development costs, which are expensed in the preliminary stages of a project and capitalized when the project is deemed to be commercially viable. Commercial viability is determined by one or a series of actions including, among others, Board of Director approval pursuant to a formal project plan that subjects the Company to significant future obligations that can only be discharged by the use of a Company asset. When a project is available for operations, capitalized interest and capitalized project development costs are reclassified to property, plant and equipment and depreciated on a straight-line basis over the estimated useful life of the project's related assets. Capitalized costs are charged to expense if a project is abandoned or management otherwise determines the costs to be unrecoverable. Interest incurred on funds borrowed to finance capital projects is capitalized until the project under construction is ready for its intended use. The amount of interest capitalized for the years ended December 31, 2019, 2018, and 2017, was $3 million, $7 million, and $20 million, respectively. Debt Issuance Costs Debt issuance costs are capitalized and amortized as interest expense on a basis which approximates the effective interest method over the term of the related debt. Debt issuance costs are presented as a direct deduction from the carrying amount of the related debt. Intangible Assets Intangible assets represent contractual rights held by the Company. The Company recognizes specifically identifiable intangible assets including customer contracts, customer relationships, energy supply contracts, marketing partnerships, power purchase agreements, trade names, emission allowances, and fuel contracts when specific rights and contracts are acquired. These intangible assets are amortized based on expected volumes, expected delivery, expected discounted future net cash flows, straight line or units of production basis. As of December 31, 2019 and 2018, the Company had accumulated amortization related to its intangible assets of $1.3 billion and $1.2 billion, respectively. Emission allowances held-for-sale, which are included in other non-current assets on the Company's consolidated balance sheet, are not amortized; they are carried at the lower of cost or fair value and reviewed for impairment in accordance with ASC 360. Goodwill In accordance with ASC 350, Intangibles-Goodwill and Other , or ASC 350, the Company recognizes goodwill for the excess cost of an acquired entity over the net value assigned to assets acquired and liabilities assumed. NRG performs goodwill impairment tests annually, during the fourth quarter, and when events or changes in circumstances indicate that the carrying value may not be recoverable. The Company first assesses qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. The more-likely-than-not threshold is defined as having a likelihood of more than 50 percent. If it is not more-likely-than-not that the fair value of a reporting unit is less than its carrying amount, there is no goodwill impairment. In the absence of sufficient qualitative factors indicating that it is more-likely-than-not that no impairment occurred, the Company performs a quantitative assessment by determining the fair value of the reporting unit and comparing the fair value to its book value. If the fair value of the reporting unit exceeds its book value, goodwill of the reporting unit is not considered impaired. If the book value exceeds fair value, the Company recognizes an impairment loss equal to the difference between book value and fair value. For further discussion of goodwill and goodwill impairment losses recognized refer to Note 12, Goodwill and Other Intangibles. Income Taxes The Company accounts for income taxes using the liability method in accordance with ASC 740, Income Taxes, or ASC 740, which requires that the Company use the asset and liability method of accounting for deferred income taxes and provide deferred income taxes for all significant temporary differences. The Company has two categories of income tax expense or benefit — current and deferred, as follows: • Current income tax expense or benefit consists solely of current taxes payable less applicable tax credits, and • Deferred income tax expense or benefit is the change in the net deferred income tax asset or liability, excluding amounts charged or credited to accumulated other comprehensive income The Company reports some of its revenues and expenses differently for financial statement purposes than for income tax return purposes, resulting in temporary and permanent differences between the Company's financial statements and income tax returns. The tax effects of such temporary differences are recorded as either deferred income tax assets or deferred income tax liabilities in the Company's consolidated balance sheets. The Company measures its deferred income tax assets and deferred income tax liabilities using income tax rates that are expected to be in effect when the deferred tax is realized. The Company accounts for uncertain tax positions in accordance with ASC 740, which applies to all tax positions related to income taxes. Under ASC 740, tax benefits are recognized when it is more-likely-than-not that a tax position will be sustained upon examination by the authorities. The benefit recognized from a position is the amount of benefit that has surpassed the more-likely-than-not threshold, as it is more than 50% likely to be realized upon settlement. The Company recognizes interest and penalties accrued related to uncertain tax benefits as a component of income tax expense. In accordance with ASC 805 and as discussed further in Note 20, Income Taxes , changes to existing net deferred tax assets or valuation allowances or changes to uncertain tax benefits, are recorded to income tax (benefit)/expense. Contract Amortization Assets and liabilities recognized through acquisitions related to the sale of electric capacity and energy in future periods for which the fair value has been determined to be significantly less or more than market are amortized to revenue over the term of each underlying contract based on actual generation and/or contracted volumes. Lease Revenue Certain of the Company’s revenues are obtained through leases of rooftop residential solar systems, which are accounted for as operating leases in accordance with ASC 842, Leases. Pursuant to the lease agreements, the customers’ monthly payments are pre-determined fixed monthly amounts and may include an annual fixed percentage escalation to reflect the impact of utility rate increases over the lease term, which is 20 years. The Company records operating lease revenue on a straight-line basis over the life of the lease term. Certain customers made initial down payments that are being amortized over the life of the lease. The difference between the payments received and the revenue recognized is recorded as deferred revenue. Lessor Accounting Certain of the Company's revenues are obtained through PPAs or other contractual agreements. Many of these agreements are accounted for as operating leases under ASC 842 . Certain of these leases have no minimum lease payments and all of the rent is recorded as contingent rent on an actual basis when the electricity is delivered. Judgment is required by management in determining the economic life of each generating facility, in evaluating whether certain lease provisions constitute minimum payments or represent contingent rent and other factors in determining whether a contract contains a lease and whether the lease is an operating lease or finance lease. Contingent rental income recognized in the years ended December 31, 2019, 2018, and 2017 was $5 million, $104 million, and $253 million, respectively. Gross Receipts and Sales Taxes In connection with its retail sales, the Company records gross receipts taxes on a gross basis in revenues and cost of operations in its consolidated statements of operations. During the years ended December 31, 2019, 2018, and 2017, the Company's revenues and cost of operations included gross receipts taxes of $109 million, $99 million, and $92 million, respectively. Additionally, the Company records sales taxes collected from its taxable retail customers and remitted to the various governmental entities on a net basis; thus, there is no impact on the Company's consolidated statement of operations. Cost of Energy for Retail Operations The cost of energy for electricity sales and services to retail customers is included in cost of operations and is based on estimated supply volumes for the applicable reporting period. A portion of the cost of energy, $103 million, $105 million, and $107 million as of December 31, 2019, 2018, and 2017, respectively, was accrued and consisted of estimated transmission and distribution charges not yet billed by the transmission and distribution utilities. In estimating supply volumes, the Company considers the effects of historical customer volumes, weather factors and usage by customer class. Transmission and distribution delivery fees are estimated using the same method used for electricity sales and services to retail customers. In addition, ISO fees are estimated based on historical trends, estimated supply volumes and initial ERCOT ISO settlements. Volume estimates are then multiplied by the supply rate and recorded as cost of operations in the applicable reporting period. Derivative Financial Instruments The Company accounts for derivative financial instruments under ASC 815, which requires the Company to record all derivatives on the balance sheet at fair value unless they qualify for a NPNS exception. Changes in the fair value of non-hedge derivatives are immediately recognized in earnings. Changes in the fair value of derivatives accounted for as cash flow hedges, if elected for hedge accounting, are deferred and recorded as a component of accumulated OCI until the hedged transactions occur and are recognized in earnings. The Company's primary derivative instruments are power purchase or sales contracts, fuels purchase contracts, and other energy related commodities used to mitigate variability in earnings due to fluctuations in market prices and interest rates. On an ongoing basis, the Company assesses the effectiveness of all derivatives that are designated as hedges for accounting purposes in order to determine that each derivative continues to be highly effective in offsetting changes in fair values or cash flows of hedged items. Internal analyses that measure the statistical correlation between the derivative and the associated hedged item determine the effectiveness of such a contract designated as a hedge. If it is determined that the derivative instrument is not highly effective as a hedge, hedge accounting will be discontinued prospectively. In this case, the gain or loss previously deferred in accumulated OCI would be frozen until the underlying hedged instrument is delivered unless the transactions being hedged are no longer probable of occurring in which case the amount in OCI would be immediately reclassified into earnings. If the derivative instrument is terminated, the effective portion of this derivative deferred in accumulated OCI will be frozen until the underlying hedged item is delivered. The Company had no cash flow hedges as of December 31, 2019. Revenues and expenses on contracts that qualify for the NPNS exception are recognized when the underlying physical transaction is delivered. While these contracts are considered derivative financial instruments under ASC 815, they are not recorded at fair value, but on an accrual basis of accounting. If it is determined that a transaction designated as NPNS no longer meets the scope exception, the fair value of the related contract is recorded on the balance sheet and immediately recognized through earnings. NRG's trading activities are subject to limits in accordance with the Company's Risk Management Policy. These contracts are recognized on the balance sheet at fair value and changes in the fair value of these derivative financial instruments are recognized in earnings. Foreign Currency Translation and Transaction Gains and Losses The local currencies are generally the functional currency of NRG's foreign operations. Foreign currency denominated assets and liabilities are translated at end-of-period rates of exchange. Revenues, expenses, and cash flows are translated at the weighted-average rates of exchange for the period. The resulting currency translation adjustments are not included in the Company's consolidated statements of operations for the period, but are accumulated and reported as a separate component of stockholders' equity until sale or complete or substantially complete liquidation of the net investment in the foreign entity takes place. Foreign currency transaction gains or losses are reported within other income/(expense) in the Company's consolidated statements of operations. For the years ended December 31, 2019, 2018, and 2017, amounts recognized as foreign currency transaction gains/(losses) were immaterial. The Company's cumulative translation adjustment balances as of December 31, 2019, 2018, and 2017 were $(13) million, $(13) million and $(2) million, respectively. Concentrations of Credit Risk Financial instruments which potentially subject the Company to concentrations of credit risk consist primarily of trust funds, accounts receivable, notes receivable, derivatives, and investments in debt securities. Trust funds are held in accounts managed by experienced investment advisors. Certain accounts receivable, notes receivable, and derivative instruments are concentrated within entities engaged in the energy industry. These industry concentrations may impact the Company's overall exposure to credit risk, either positively or negatively, in that the customers may be similarly affected by changes in economic, industry or other conditions. Receivables and other contractual arrangements are subject to collateral requirements under the terms of enabling agreements. However, the Company believes that the credit risk posed by industry concentration is offset by the diversification and creditworthiness of its customer base. See Note 5, Fair Value of Financial Instruments, for a further discussion of derivative concentrations. Fair Value of Financial Instruments The carrying amount of cash and cash equivalents, funds deposited by counterparties, receivables, accounts payable, and accrued liabilities approximate fair value because of the short-term maturity of these instruments. See Note 5, Fair Value of Financial Instruments, for a further discussion of fair value of financial instruments. Asset Retirement Obligations The Company accounts for AROs in accordance with ASC 410-20, Asset Retirement Obligations, or ASC 410-20. Retirement obligations associated with long-lived assets included within the scope of ASC 410-20 are those for which a legal obligation exists under enacted laws, statutes, and written or oral contracts, including obligations arising under the doctrine of promissory estoppel, and for which the timing and/or method of settlement may be conditional on a future event. ASC 410-20 requires an entity to recognize the fair value of a liability for an ARO in the period in which it is incurred and a reasonable estimate of fair value can be made. Upon initial recognition of a liability for an ARO, the Company capitalizes the asset retirement cost by increasing the carrying amount of the related long-lived asset by the same amount. Over time, the liability is accreted to its future value, while the capitalized cost is depreciated over the useful life of the related asset. See Note 14, Asset Retirement Obligations, for a further discussion of AROs. Pensions and Other Postretirement Benefits The Company offers pension benefits through a defined benefit pension plan. In addition, the Company provides postretirement health and welfare benefits for certain groups of employees. The Company accounts for pension and other postretirement benefits in accordance with ASC 715, Compensation — Retirement Benefits , or ASC 715 . The Company recognizes the funded status of the Company's defined benefit plans in the statement of financial position and records an offset for gains and losses as well as all prior service costs that have not been included as part of the Company's net periodic benefit cost to other comprehensive income. The determination of the Company's obligation and expenses for pension benefits is dependent on the selection of certain assumptions. These assumptions determined by management include the discount rate, the expected rate of return on plan assets and the rate of future compensation increases. The Company's actuarial consultants assist in determining assumptions for such items as retirement age. The assumptions used may differ materially from actual results, which may result in a significant impact to the amount of pension obligation or expense recorded by the Company. The Company measures the fair value of its pension assets in accordance with ASC 820, Fair Value Measurements and Disclosures, or ASC 820. Stock-Based Compensation The Company accounts for its stock-based compensation in accordance with ASC 718, Compensation — Stock Compensation, or ASC 718 . The fair value of the Company's non-qualified stock options and market stock units are estimated on the date of grant using the Black-Scholes option-pricing model and the Monte Carlo valuation model, respectively. NRG uses the Company's common stock price on the date of grant as the fair value of the Company's restricted stock units and deferred stock units. Forfeiture rates are estimated based on an analysis of the Company's historical forfeitures, employment turnover, and expected future behavior. The Company recognizes compensation expense for both graded and cliff vesting awards on a straight-line basis over the requisite service period for the entire award. Investments Accounted for by the Equity Method The Company has investments in various domestic energy projects, as well as one Australian project. The equity method of accounting is applied to such investments in affiliates, which include joint ventures and partnerships, because the ownership structure prevents the Company from exercising a controlling influence over the operating and financial policies of the projects. Under this method, equity in pre-tax income or losses of domestic partnerships and, generally, in the net income or losses of its Australian project, are reflected as equity in earnings of unconsolidated affiliates. Distributions from equity method investments that represent earnings on the Company's investment are included within cash flows from operating activities and distributions from equity method investments that represent a return of the Company's investment are included within cash flows from investing activities. Tax Equity Arrangements The Company’s redeemable noncontrolling interest in subsidiaries represents third-party interests in the net assets under certain tax equity arrangements, which are consolidated by the Company, that have been entered into to finance the cost of solar energy systems under operating leases. The Company has determined that the provisions in the contractual agreements of these structures represent substantive profit sharing arrangements. Further, the Company has determined that the appropriate methodology for calculating the redeemable noncontrolling interest that reflects the substantive profit sharing arrangements is a balance sheet approach utilizing the HLBV method. Under the HLBV method, the amounts reported as redeemable noncontrolling interests represent the amounts the investors that are party to the tax equity arrangements would hypothetically receive at each balance sheet date under the liquidation provisions of the contractual agreements, assuming the net assets of the funding structures were liquidated at their recorded amounts. The investors’ interests in the results of operations of the funding structures are determined as redeemable noncontrolling interests at the start and end of each reporting period, after taking into account any capital transactions between the structures and the funds’ investors. The calculations utilized to apply the HLBV method include estimated calculations of taxable income or losses for each reporting period. Redeemable Noncontrolling Interest To the extent that the third-party has the right to redeem their interests for cash or other assets, the Company has included the noncontrolling interest attributable to the third party as a component of temporary equity in the mezzanine section of the consolidated balance sheet. The following table reflects the changes in the Company's redeemable noncontrolling interest balance for the years ended December 31, 2019, 2018, and 2017. (In millions) Balance as of December 31, 2016 $ 46 Distributions to redeemable noncontrolling interest (2) Contributions from redeemable noncontrolling interest 99 Non-cash adjustments to redeemable noncontrolling interest 7 Comprehensive loss attributable to redeemable noncontrolling interest (72) Balance as of December 31, 2017 78 Distributions to redeemable noncontrolling interest (3) Contributions from redeemable noncontrolling interest 26 Non-cash adjustments to redeemable noncontrolling interest (8) Net income attributable to redeemable noncontrolling interest - continuing operations 1 Net loss attributable to redeemable noncontrolling interest - discontinued operations (27) Sale of NRG Yield and the Renewables Platform (a) (48) Balance as of December 31, 2018 19 Distributions to redeemable noncontrolling interest (2) Net income attributable to redeemable noncontrolling interest - continuing operations 3 Balance as of December 31, 2019 $ 20 (a) See Note 4, Acquisitions, Discontinued Operations and Dispositions , for further information regarding the sale of NRG Yield and its Renewables Platform Sale-Leaseback Arrangements NRG is party to sale-leaseback arrangements that provide for the sale of certain assets to a third party and simultaneously leases back the same asset to the Company. If the seller-lessee transfers control of the underlying assets to the buyer-lessor, the arrangement is accounted for under ASC 842-40, Sale-Leaseback Transactions. These arrangements are classified as operating leases on the Company's consolidated balance sheets. See Note 10, Leases, for further discussion. Marketing and Advertising Costs The Company expenses its marketing and advertising costs as incurred and includes them within selling, general and administrative expenses. The costs of tangible assets used in advertising campaigns are recorded as fixed assets or deferred advertising costs and amortized as advertising costs over the shorter of the useful life of the asset or the advertising campaign. The Company has several long-term sponsorship arrangements. Payments related to these arrangements are deferred and expensed over the term of the arrangement. Advertising expenses for the years ended December 31, 2019, 2018, and 2017 were $66 million, $73 million, and $66 million, respectively. Reorganization Costs Reorganization costs include costs incurred by the Company related to the Transformation Plan implementation and primarily reflect severance and contract modifications. Reorganization costs for the years ended December 31, 2019, 2018 and 2017 were $23 million, $90 million and $44 million, respectively. Business Combinations The Company accounts for its business combinations in accordance with ASC 805, Business Combinations, or ASC 805, which requires an acquirer to recognize and measure in its financial statements the identifiable assets acquired, the liabilities assumed, and any noncontrolling interest in the acquiree at fair value at the acquisition date. The Company also recognizes and measures the goodwill acquired or a gain from a bargain purchase in the business combination. In addition, transaction costs are expensed as incurred. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States 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 asset

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition Revenue from Contracts with Customers On January 1, 2018, the Company adopted the guidance in ASC 606, Revenue from Contracts , or ASC 606, with customers using the modified retrospective method applied to contracts that were not completed as of the adoption date. The Company recognized the cumulative effect of initially applying the new standard as a credit to the opening balance of accumulated deficit, resulting in a decrease of $15 million. The adjustment primarily related to costs incurred to obtain a contract with customers and customer incentives. Following the adoption of the new standard, the Company’s revenue recognition of its contracts with customers remains materially consistent with its historical practice. The 2017 comparative information was not restated and continues to be reported under the accounting standards in effect for that period. The Company's policies with respect to its various revenue streams are detailed below. The Company generally applies the invoicing practical expedient to recognize revenue for the revenue streams detailed below, except in circumstances where the invoiced amount does not represent the value transferred to the customer. Retail Revenue Gross revenues for energy sales and services to retail customers are recognized as the Company transfers the promised goods and services to the customer. For the majority of its electricity contracts, the Company’s performance obligation with the customer is satisfied over time and performance obligations for its electricity products are recognized as the customer takes possession of the product. The Company also allocates the contract consideration to distinct performance obligations in a contract for which the timing of the revenue recognized is different. Additionally, customer discounts and incentives reduce the contract consideration and are recognized over the term of the contract. Energy sales and services that have been delivered but not billed by period end are estimated. Accrued unbilled revenues are based on estimates of customer usage since the date of the last meter reading provided by the independent system operators or electric distribution companies. Volume estimates are based on daily forecasted volumes and estimated customer usage by class. Unbilled revenues are calculated by multiplying these volume estimates by the applicable rate by customer class. Estimated amounts are adjusted when actual usage is known and billed. As contracts for retail electricity can be for multi-year periods, the Company has performance obligations under these contracts that have not yet been satisfied. These performance obligations have transaction prices that are both fixed and variable, and that vary based on the contract duration, customer type, inception date and other contract-specific factors. For the fixed price contracts, the amount of any unsatisfied performance obligations will vary based on customer usage, which will depend on factors such as weather and customer activity and therefore it is not practicable to estimate such amounts. Energy Revenue Both physical and financial transactions consist of revenues billed to a third party at either market or negotiated contract terms to optimize the financial performance of the Company's generating facilities. Electric energy revenue is recognized upon transmission to the customer over time, using the output method for measuring progress of satisfaction of performance obligations. Physical transactions, or the sale of generated electricity to meet supply and demand, are recorded on a gross basis in the Company's consolidated statements of operations. The Company applies the invoicing practical expedient in recognizing energy revenue. Under the practical expedient, revenue is recognized based on the invoiced amount which is equal to the value to the customer of NRG’s performance obligation completed to date. Financial transactions used to hedge the sale of electricity are recorded net within operating revenues in the consolidated statements of operations in accordance with ASC 815. Capacity Revenue Capacity revenues consist of revenues billed to a third party at either market or negotiated contract terms for making installed generation and demand response capacity available in order to satisfy system integrity and reliability requirements. Capacity revenues are recognized over time, using the output method for measuring progress of satisfaction of performance obligations. The Company applies the invoicing practical expedient in recognizing capacity revenue. Under the practical expedient, revenue is recognized based on the invoiced amount which is equal to the value to the customer of NRG’s performance obligation completed to date. Performance Obligations As of December 31, 2019, estimated future fixed fee performance obligations are $564 million, $604 million, $303 million, $42 million, and $8 million for fiscal years 2020, 2021, 2022, 2023, and 2024, 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. Renewable Energy Credits Renewable energy credits are usually sold through long-term contracts. Revenue from the sale of self-generated RECs is recognized when related energy is generated and simultaneously delivered even in cases where there is a certification lag as it has been deemed to be perfunctory. In a bundled contract to sell energy, capacity and/or self-generated RECs, all performance obligations are deemed to be delivered at the same time and hence, timing of recognition of revenue for all performance obligations is the same and occurs over time. In such cases, it is often unnecessary to allocate transaction price to multiple performance obligations. Sale of Emission Allowances The Company records its inventory of emission allowances as part of intangible assets. From time to time, management may authorize the transfer of emission allowances in excess of expected usage from the Company's emission bank to intangible assets held-for-sale for trading purposes. The Company records the sale of emission allowances on a net basis within operating revenue in the Company's consolidated statements of operations. Disaggregated Revenue The following tables represent the Company’s disaggregation of revenue from contracts with customers for the years ended December 31, 2019 and 2018: For the Year Ended December 31, 2019 (In millions) Texas East West/Other Corporate/Eliminations Total Retail revenue Mass Market $ 5,027 $ 1,230 $ — $ (3) $ 6,254 Business Solutions 1,205 74 — — 1,279 Total retail revenue 6,232 1,304 — (3) 7,533 Energy revenue (a) 529 322 318 — 1,169 Capacity revenue (a) — 664 36 — 700 Mark-to-market for economic hedging activities (b) 47 (29) 16 (1) 33 Other revenue (a) 261 58 70 (3) 386 Total operating revenue 7,069 2,319 440 (7) 9,821 Less: Lease revenue — 1 19 — 20 Less: Realized and unrealized ASC 815 revenue 1,562 183 67 (2) 1,810 Total revenue from contracts with customers $ 5,507 $ 2,135 $ 354 $ (5) $ 7,991 (a) The following amounts of energy, capacity and other revenue relate to derivative instruments and are accounted for under ASC 815: (In millions) Texas East West/Other Corporate/Eliminations Total Energy revenue $ 1,459 $ 98 $ 39 $ (1) $ 1,595 Capacity revenue — 109 — — 109 Other revenue 56 5 12 — 73 (b) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 For the Year Ended December 31, 2018 (In millions) Texas East West/Other Corporate/Eliminations Total Retail revenue Mass Market $ 4,618 $ 974 $ — $ (1) $ 5,591 Business Solutions 1,238 65 — — 1,303 Total retail revenue 5,856 1,039 — (1) 6,894 Energy revenue (a) 371 546 566 13 1,496 Capacity revenue (a) — 746 79 — 825 Mark-to-market for economic hedging activities (b) (77) (35) (5) (13) (130) Other revenue (a)(c) 251 75 84 (17) 393 Total operating revenue 6,401 2,371 724 (18) 9,478 Less: Lease revenue 1 1 19 — 21 Less: Realized and unrealized ASC 815 revenue 1,096 210 2 1 1,309 Total revenue from contracts with customers $ 5,304 $ 2,160 $ 703 $ (19) 8,148 (a) The following amounts of energy, capacity and other revenue relate to derivative instruments and are accounted for under ASC 815: (In millions) Texas East West/Other Corporate/Eliminations Total Energy revenue $ 1,131 $ 90 $ (2) $ 14 $ 1,233 Capacity revenue — 137 — — 137 Other revenue 42 17 9 1 69 (b) 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 December 31, 2019 and 2018: (In millions) December 31, 2019 December 31, 2018 Deferred customer acquisition costs $ 133 $ 111 Accounts receivable, net - Contracts with customers 1,002 999 Accounts receivable, net - Derivative instruments 18 20 Accounts receivable, net - Affiliate 5 5 Total accounts receivable, net $ 1,025 $ 1,024 Unbilled revenues (included within Accounts receivable, net - Contracts with customers) $ 402 $ 392 Deferred revenues (a) $ 82 $ 67 (a) Deferred revenues from contracts with customers for the years ended December 31, 2019 and 2018 were approximately $24 million and $19 million, respectively. The revenue recognized from contracts with customers during years ended December 31, 2019 and 2018 relating to the deferred revenue balance at the beginning of each period was $13 million and $16 million, respectively. The change in deferred revenue balances during the years ended December 31, 2019 and 2018 was primarily due to the timing difference of when consideration was received and when the performance obligation was transferred. The Company's customer acquisition costs consist of broker fees, commission payments and other costs that represent incremental costs of obtaining the contract with customers for which the Company expects to recover. The Company amortizes these amounts over the estimated life of the customer contract. As a practical expedient, the Company expenses the incremental costs of obtaining a contract if the amortization period of the asset would have been one year or less. When the Company receives consideration from the customer that is in excess of the amount due, such consideration is reclassified to deferred revenue, which represents a contract liability. Generally, the Company will recognize revenue from contract liabilities in the next period as the Company satisfies its performance obligations.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments For cash and cash equivalents, funds deposited by counterparties, accounts and other receivables, accounts payable, restricted cash, and cash collateral posted and received in support of energy risk management activities, the carrying amount approximates fair value because of the short-term maturity of those instruments and are classified as Level 1 within the fair value hierarchy. The estimated carrying values and fair values of the Company's recorded financial instruments not carried at fair market value are as follows: As of December 31, 2019 2018 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Assets Notes receivable $ 11 $ 8 $ 17 $ 14 Liabilities Long-term debt, including current portion (a) $ 5,956 $ 6,504 $ 6,591 $ 6,697 (a) Excludes deferred financing costs, which are recorded as a reduction to long-term debt on the Company's consolidated balance sheets The fair value of the Company's publicly-traded long-term debt is based on quoted market prices and is classified as Level 2 within the fair value hierarchy. The fair value of debt securities, non-publicly traded long-term debt, and certain notes receivable of the Company are based on expected future cash flows discounted at market interest rates or current interest rates for similar instruments with equivalent credit quality and are 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 December 31, 2019 and 2018: As of December 31, 2019 As of December 31, 2018 (In millions) Level 2 Level 3 Level 2 Level 3 Long-term debt, including current portion $ 6,388 $ 116 $ 6,528 $ 169 Fair Value Accounting under ASC 820 ASC 820 establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three levels as follows: • Level 1 — quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access as of the measurement date. NRG's financial assets and liabilities utilizing Level 1 inputs include active exchange-traded securities, energy derivatives, and trust fund investments. • Level 2 — inputs other than quoted prices included within Level 1 that are directly observable for the asset or liability or indirectly observable through corroboration with observable market data. NRG's financial assets and liabilities utilizing Level 2 inputs include fixed income securities, exchange-based derivatives, and over the counter derivatives such as swaps, options and forward contracts. • Level 3 — unobservable inputs for the asset or liability only used when there is little, if any, market activity for the asset or liability at the measurement date. NRG's financial assets and liabilities utilizing Level 3 inputs include infrequently-traded, non-exchange-based derivatives and commingled investment funds, and are measured using present value pricing models. In accordance with ASC 820, the Company determines the level in the fair value hierarchy within which each fair value measurement in its entirety falls, based on the lowest level input that is significant to the fair value measurement in its entirety. 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 consolidated balance sheets on a recurring basis and their level within the fair value hierarchy: As of December 31, 2019 Fair Value (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and non-current assets) $ 20 $ — $ 20 $ — Nuclear trust fund investments: Cash and cash equivalents 17 17 — — U.S. government and federal agency obligations 68 68 — — Federal agency mortgage-backed securities 100 — 100 — Commercial mortgage-backed securities 29 — 29 — Corporate debt securities 109 — 109 — Equity securities 388 388 — — Foreign government fixed income securities 5 — 5 — Other trust fund investments: U.S. government and federal agency obligations 1 1 — — Derivative assets: Commodity contracts 1,170 84 893 193 Measured using net asset value practical expedient: Equity securities-nuclear trust fund investments 78 — — — Equity securities 8 — — — Total assets $ 1,993 $ 558 $ 1,156 $ 193 Derivative liabilities: Commodity contracts $ 1,103 $ 143 $ 805 $ 155 Total liabilities $ 1,103 $ 143 $ 805 $ 155 As of December 31, 2018 Fair Value (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current or non-current assets) $ 39 $ 2 $ 18 $ 19 Nuclear trust fund investments: Cash and cash equivalents 19 19 — — U.S. government and federal agency obligations 46 46 — — Federal agency mortgage-backed securities 100 — 100 — Commercial mortgage-backed securities 22 — 22 — Corporate debt securities 96 — 96 — Equity securities 312 312 — — Foreign government fixed income securities 4 — 4 — Other trust fund investments: U.S. government and federal agency obligations 1 1 — — Derivative assets: Commodity contracts 1,042 137 796 109 Interest rate contracts 39 — 39 — Measured using net asset value practical expedient: Equity securities-nuclear trust fund investments 64 — — — Equity securities 8 — — — Total assets $ 1,792 $ 517 $ 1,075 $ 128 Derivative liabilities: Commodity contracts $ 977 $ 224 $ 664 $ 89 Total liabilities $ 977 $ 224 $ 664 $ 89 The following tables reconcile, for the years ended December 31, 2019 and 2018, the 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: For the Year Ended December 31, 2019 Fair Value Measurement Using Significant Unobservable Inputs (Level 3) (In millions) Debt Securities Derivatives (a) Total Beginning balance as of January 1, 2019 $ 19 $ 20 $ 39 Contracts added from acquisitions — (3) (3) Total gains/(losses) — realized/unrealized: Included in earnings — (26) (26) Included in OCI — — — Purchases — 40 40 Sale (19) — (19) Transfers into Level 3 (b) — 2 2 Transfers out of Level 3 (b) — 5 5 Ending balance as of December 31, 2019 $ — $ 38 $ 38 Gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of December 31, 2019 $ — $ 17 $ 17 (a) Consists of derivatives 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 into/out of Level 3 are from/to Level 2 For the Year Ended December 31, 2018 Fair Value Measurement Using Significant Unobservable Inputs (Level 3) (In millions) Debt Securities Derivatives (a) Total Beginning balance as of January 1, 2018 $ 19 $ (15) $ 4 Contracts acquired in XOOM acquisition — 12 $ 12 Total gains realized/unrealized included in earnings — (21) (21) Purchases — 41 41 Transfers into Level 3 (b) — 5 5 Transfer out of Level 3 (b) — (2) (2) Ending balance as of December 31, 2018 $ 19 $ 20 $ 39 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 December 31, 2018 $ — $ (17) $ (17) (a) Consists of derivatives 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 into/out of Level 3 are from/to Level 2 Realized and unrealized gains and losses included in earnings that are related to the energy derivatives are recorded in operating revenues and cost of operations. Non-derivative fair value measurements NRG's investments in debt securities are classified as Level 3 and consist of non-traded debt instruments that are valued based on third-party market value assessments. The trust fund investments are held primarily to satisfy NRG's nuclear decommissioning obligations. These trust fund investments hold debt and equity securities directly and equity securities indirectly through commingled funds. The fair values of equity securities held directly by the trust funds are based on quoted prices in active markets and are categorized in Level 1. In addition, U.S. government and federal agency obligations are categorized as Level 1 because they trade in a highly liquid and transparent market. The fair values of corporate debt securities are based on evaluated prices that reflect observable market information, such as actual trade information of similar securities, adjusted for observable differences and are categorized in Level 2. Certain equity securities, classified as commingled funds, are analogous to mutual funds, are maintained by investment companies, and hold certain investments in accordance with a stated set of fund objectives. The fair value of the equity securities classified as commingled funds are based on net asset values per fund share (the unit of account), derived from the quoted prices in active markets of the underlying equity securities. However, because the shares in the commingled funds are not publicly quoted, not traded in an active market and are subject to certain restrictions regarding their purchase and sale, the commingled funds are measured using net asset value practical expedient. See also Note 7, Nuclear Decommissioning Trust Fund. Derivative fair value measurements A portion of the Company'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. For the majority of NRG markets, the Company receives quotes from multiple sources. To the extent that NRG receives multiple quotes, the Company's prices reflect the average of the bid-ask mid-point prices obtained from all sources that NRG believes provide the most liquid market for the commodity. If the Company receives one quote, then the mid-point of the bid-ask spread for that quote is used. The terms for which such price information is available vary by commodity, region and product. A significant portion of the fair value of the Company's derivative portfolio is based on price quotes from brokers in active markets who regularly facilitate those transactions and the Company believes such price quotes are executable. The Company does not use third party sources that derive price based on proprietary models or market surveys. The remainder of the assets and liabilities represents 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 observable market data with similar characteristics. Contracts valued with prices provided by models and other valuation techniques make up 16% of derivative assets and 14% of derivative liabilities. 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 for interest rate swaps is calculated utilizing the bilateral method based on published default probabilities. For commodities, to the extent that NRG's net exposure under a specific master agreement is an asset, the Company uses the counterparty's default swap rate. If the exposure under a specific master agreement is a liability, the Company uses NRG's default swap rate. For interest rate swaps and commodities, the credit reserve is added to the discounted fair value to reflect the exit price that a market participant would be willing to receive to assume NRG's liabilities or that a market participant would be willing to pay for NRG's assets. As of December 31, 2019 and December 31, 2018 the credit reserve did not result in a significant change in fair value. The fair values in each category reflect the level of forward prices and volatility factors as of December 31, 2019, and may change as a result of changes in these factors. Management uses its best estimates to determine the fair value of commodity and derivative contracts NRG holds and sells. These estimates consider various factors including closing exchange and over-the-counter price quotations, time value, volatility factors and credit exposure. It is possible, however, that future market prices could vary from those used in recording assets and liabilities from energy marketing and trading activities and such variations could be material. NRG's significant positions classified as Level 3 include physical and financial power executed in illiquid markets as well as financial transmission rights, or FTRs. The significant unobservable inputs used in developing fair value include illiquid 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 December 31, 2019 and 2018: Significant Unobservable Inputs December 31, 2019 Fair Value Input/Range (In millions) Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average Power Contracts $ 151 $ 139 Discounted Cash Flow Forward Market Price (per MWh) $ 8 $ 218 $ 24 FTRs 42 16 Discounted Cash Flow Auction Prices (per MWh) (105) 213 0 $ 193 $ 155 Significant Unobservable Inputs December 31, 2018 Fair Value Input/Range (In millions) Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average Power Contracts $ 89 $ 75 Discounted Cash Flow Forward Market Price (per MWh) $ 1 $ 214 $ 31 FTRs 20 14 Discounted Cash Flow Auction Prices (per MWh) (90) 34 0 $ 109 $ 89 The following table provides sensitivity of fair value measurements to increases/(decreases) in significant unobservable inputs as of December 31, 2019 and 2018: Significant Unobservable Input Position Change In Input Impact on Fair Value Measurement Forward Market Price Power Buy Increase/(Decrease) Higher/(Lower) Forward Market Price Power Sell Increase/(Decrease) Lower/(Higher) FTR Prices Buy Increase/(Decrease) Higher/(Lower) FTR Prices Sell Increase/(Decrease) Lower/(Higher) Under the guidance of ASC 815, entities may choose to offset cash collateral posted or received against the fair value of derivative positions executed with the same counterparties under the same master netting agreements. The Company has chosen not to offset positions as defined in ASC 815. As of December 31, 2019, the Company recorded $190 million of cash collateral posted and $32 million of cash collateral received on its balance sheet. Concentration of Credit Risk In addition to the credit risk discussion as disclosed in Note 2, Summary of Significant Accounting Policies , the following item is a discussion of the concentration of credit risk for the Company's financial instruments. 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. The Company monitors and manages credit risk through credit policies that include: (i) an established credit approval process; (ii) a daily monitoring of counterparties' credit limits; (iii) the use of credit mitigation measures such as margin, collateral, prepayment arrangements, or volumetric limits; (iv) the use of payment netting agreements; and (v) the use of master netting agreements that allow for the netting of positive and negative exposures of various contracts associated with a single counterparty. Risks surrounding counterparty performance and credit could ultimately impact the amount and timing of expected cash flows. The Company seeks to mitigate counterparty risk by having a diversified portfolio of counterparties. The Company also has credit protection within various agreements to call on additional collateral support if and when necessary. Cash margin is collected and held at the Company to cover the credit risk of the counterparty until positions settle. Counterparty Credit Risk As of December 31, 2019, counterparty credit exposure, excluding credit exposure from RTOs, ISOs, and registered commodity exchanges and certain long-term agreements, was $239 million and NRG held collateral (cash and letters of credit) against those positions of $51 million, resulting in a net exposure of $233 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 67% of the Company's exposure before collateral is expected to roll off by the end of 2021. 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. Category Net Exposure (a) (b) (% of Total) Utilities, energy merchants, marketers and other 84 % Financial institutions 16 Total 100 % Category Net Exposure (a) (b) (% of Total) Investment grade 56 % Non-Investment grade/Non-Rated 44 Total 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 $33 million exposure to one wholesale counterparty in excess of 10% of the total net exposure discussed above as of December 31, 2019. Changes in hedge positions and market prices will affect credit exposure and counterparty concentration. Given the credit quality, diversification and term of the exposure in the portfolio, NRG does not anticipate a material impact on the Company's financial position or results of operations from nonperformance by any of NRG's counterparties. RTOs and ISOs The Company participates in the organized markets of CAISO, ERCOT, ISO-NE, MISO, NYISO and PJM, known as RTOs or ISOs. Trading in these markets is approved by FERC, or in the case of ERCOT, approved by the PUCT and includes 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 overall market and are excluded from the above exposures. Exchange Traded Transactions The Company enters into commodity transactions on registered exchanges, notably ICE and NYMEX. 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 December 31, 2019, aggregate credit risk exposure managed by NRG to these counterparties was approximately $548 million for the next five Retail Customer Credit Risk The Company is exposed to retail credit risk through the Company's retail electricity providers, which serve C&I customers and the Mass market. Retail credit risk results in losses when a customer fails to pay for services rendered. The losses may result from both nonpayment 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 December 31, 2019, the Company's retail customer credit exposure to C&I and Mass customers was diversified across many customers and various industries, as well as government entities. The Company is also subject to risk with respect to its residential solar customers. The Company's bad debt expense was $95 million, $85 million, and $68 million for the years ending December 31, 2019, 2018, and 2017, respectively. Current economic conditions may affect the Company's customers' ability to pay bills in a timely manner, which could increase customer delinquencies and may lead to an increase in bad debt expense.

Accounting for Derivative Instr

Accounting for Derivative Instruments and Hedging Activities	12 Months Ended
	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Accounting for Derivative Instruments and Hedging Activities	Accounting for Derivative Instruments and Hedging Activities ASC 815 requires the Company to recognize all derivative instruments on the balance sheet as either assets or liabilities and to measure them at fair value each reporting period unless they qualify for a NPNS exception. The Company may elect to designate certain derivatives as cash flow hedges, if certain conditions are met, and defer the change in fair value of the derivatives to accumulated OCI, until the hedged transactions occur and are recognized in earnings. For derivatives that are not designated as cash flow hedges or do not qualify for hedge accounting treatment, the changes in the fair value will be immediately recognized in earnings. Certain derivative instruments may qualify for the NPNS exception and are therefore exempt from fair value accounting treatment. ASC 815 applies to NRG's energy related commodity contracts, interest rate swaps, and equity contracts. As the Company engages principally in the trading and marketing of its generation assets and retail businesses, some of NRG's commercial activities qualify for NPNS accounting. Most of the retail load contracts either qualify for the NPNS exception or fail to meet the criteria for a derivative and the majority of the retail supply and fuels supply contracts are recorded under mark-to-market accounting. All of NRG's hedging and trading activities are subject to limits within the Company's Risk Management Policy. Energy-Related Commodities To manage the commodity price risk associated with the Company's competitive supply activities and the price risk associated with wholesale power sales from the Company's electric generation facilities and retail power sales from NRG's retail businesses, NRG enters into a variety of derivative and non-derivative hedging instruments, utilizing the following: • Forward contracts, which commit NRG to purchase or sell energy commodities or purchase fuels in the future; • Futures contracts, which are exchange-traded standardized commitments to purchase or sell a commodity or financial instrument; • Swap agreements, which require payments to or from counterparties based upon the differential between two prices for a predetermined contractual, or notional, quantity; • Option contracts, which convey to the option holder the right but not the obligation to purchase or sell a commodity; • Extendable swaps, which include a combination of swaps and options executed simultaneously for different periods. This combination of instruments allows NRG to sell out-year volatility through call options in exchange for natural gas swaps with fixed prices in excess of the market price for natural gas at that time. The above-market swap combined with its later-year call option are priced in aggregate at market at the trade's inception; and • Weather derivative products used to mitigate a portion of lost revenue due to weather. The objectives for entering into derivative contracts designated as hedges include: • Fixing the price of a portion of anticipated power purchases for the Company's retail sales; • Fixing the price for a portion of anticipated future electricity sales that provides an acceptable return on the Company's electric generation operations; and • Fixing the price of a portion of anticipated fuel purchases for the operation of the Company's power plants. NRG's trading and hedging activities are subject to limits within the Company's Risk Management Policy. These contracts are recognized on the balance sheet at fair value and changes in the fair value of these derivative financial instruments are recognized in earnings. As of December 31, 2019, NRG's derivative assets and liabilities consisted primarily of the following: • Forward and financial contracts for the purchase/sale of electricity and related products economically hedging NRG's generation assets' forecasted output or NRG's retail load obligations through 2034; • Forward and financial contracts for the purchase of fuel commodities relating to the forecasted usage of NRG's generation assets through 2020; and • Other energy derivatives instruments extending through 2029. Also, as of December 31, 2019, NRG had other energy-related contracts that did not meet the definition of a derivative instrument or qualified for the NPNS exception and were therefore exempt from fair value accounting treatment as follows: • Load-following forward electric sale contracts extending through 2034; • Power tolling contracts through 2036; • Coal purchase contracts through 2021; • Power transmission contracts through 2025; • Natural gas transportation contracts and storage agreements through 2030; and • Coal transportation contracts through 2029. Interest Rate Swaps NRG was exposed to changes in interest rates through the Company's issuance of variable rate debt. In order to manage the Company's interest rate risk, NRG entered into interest rate swap agreements. As of December 31, 2019, NRG had no interest rate derivative instruments as a result of the early termination of such contracts in connection with the repayment of the 2023 Term Loan Facility during the second quarter of 2019. See Note 13, Debt and Finance Leases , for further discussion. Volumetric Underlying Derivative Transactions The following table summarizes the net notional volume buy/(sell) of NRG's open derivative transactions broken out by commodity, excluding those derivatives that qualified for the NPNS exception as of December 31, 2019 and 2018. 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. (In millions) Total Volume Commodity Units December 31, 2019 December 31, 2018 Emissions Short Ton 3 (2) Renewables Energy Certificates Certificates 1 1 Coal Short Ton 10 13 Natural Gas MMBtu (181) (330) Oil Barrels — 1 Power MWh 38 1 Capacity MW/Day (1) (1) Interest Dollars $ — $ 1,000 The decrease in the natural gas position was primarily the result of additional retail hedge positions and settlement of generation hedges. The increase in the power position was primarily the result of additional retail hedge positions and the settlement of generation hedges. The decrease in the interest position was the result of the early settlement of the interest rate swaps. Fair Value of Derivative Instruments The following table summarizes the fair value within the derivative instrument valuation on the balance sheet: Fair Value Derivative Assets Derivative Liabilities (In millions) December 31, 2019 December 31, 2018 December 31, 2019 December 31, 2018 Derivatives Not Designated as Cash Flow or Fair Value Hedges : Interest rate contracts current $ — $ 17 $ — $ — Interest rate contracts long-term — 22 — — Commodity contracts current 860 747 781 673 Commodity contracts long-term 310 295 322 304 Total Derivatives Not Designated as Cash Flow or Fair Value Hedges $ 1,170 $ 1,081 $ 1,103 $ 977 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 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 December 31, 2019 Commodity contracts: Derivative assets $ 1,170 $ (909) $ (7) $ 254 Derivative liabilities (1,103) 909 73 (121) Total commodity contracts $ 67 $ — $ 66 $ 133 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, 2018 Commodity contracts: Derivative assets $ 1,042 $ (778) $ (31) $ 233 Derivative liabilities (977) 778 114 (85) Total commodity contracts 65 — 83 148 Interest rate contracts: Derivative assets 39 — — 39 Total interest rate contracts 39 — — 39 Total derivative instruments $ 104 $ — $ 83 $ 187 Accumulated Other Comprehensive Income The following table summarizes the effects on NRG's accumulated OCI balance attributable to cash flow hedge derivatives, net of tax, for the years 2018 and 2017. As of December 31, 2019, NRG had no interest rate derivative instruments as a result of the early termination of such contracts in connection with the repayment of the 2023 Term Loan Facility, as further discussed in Note 13, Debt and Finance Leases. Interest Rate Contracts (In millions) 2018 2017 Accumulated OCI beginning balance $ (54) $ (66) Reclassified from accumulated OCI to income: Due to realization of previously deferred amounts 8 12 Mark-to-market of cash flow hedge accounting contracts 21 — Sale of NRG Yield and Renewables $ 25 $ — Accumulated OCI ending balance $ — $ (54) Amounts reclassified from accumulated OCI into income were recorded in discontinued operations. Impact of Derivative Instruments on the Statement of Operations Unrealized gains and losses associated with changes in the fair value of derivative instruments not accounted for as cash flow hedges are reflected in current period earnings. The following table summarizes the pre-tax effects of economic hedges that have not been designated as cash flow hedges, and trading activity on the Company's statement of operations. The effect of commodity hedges is included within operating revenues and cost of operations and the effect of interest rate hedges is included in interest expense. Year Ended December 31, (In millions) 2019 2018 2017 Unrealized mark-to-market results Reversal of previously recognized unrealized (gains)/losses on settled positions related to economic hedges $ (68) $ (73) $ 47 Reversal of acquired loss/(gain) positions related to economic hedges 6 (10) — Net unrealized gains on open positions related to economic hedges 42 97 159 Total unrealized mark-to-market (losses)/gains for economic hedging activities (20) 14 206 Reversal of previously recognized unrealized (gains) on settled positions related to trading activity (11) (12) (25) Net unrealized gains on open positions related to trading activity 31 29 14 Total unrealized mark-to-market gains/(losses) for trading activity 20 17 (11) Total unrealized gains $ — $ 31 $ 195 Year Ended December 31, (In millions) 2019 2018 2017 Unrealized gains/(losses) included in operating revenues $ 53 $ (113) $ 241 Unrealized (losses)/gains included in cost of operations (53) 144 (46) Total impact to statement of operations — energy commodities $ — $ 31 $ 195 Total impact to statement of operations — interest rate contracts $ (38) $ — $ 4 The reversal of gain or loss positions acquired as part of acquisitions were valued based upon the forward prices on the acquisition dates. The roll-off amounts were offset by realized gains or losses at the settled prices and are reflected in revenue or cost of operations during the same period. For the year ended December 31, 2019, 2018 and 2017 the $42 million, $97 million, and $159 million gains from economic hedge positions were primarily the result of an increase in the value of forward purchases of ERCOT heat rate contracts due to ERCOT heat 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 one notch downgrade in the Company's credit rating. The collateral required for contracts that have adequate assurance clauses that are in net liability positions as of December 31, 2019 was $14 million. The collateral required for contracts with credit rating contingent features that are in a net liability position as of December 31, 2019 was $24 million. The Company is also a party to certain marginable agreements under which it has a net liability position, but the counterparty has not called for the collateral due, which was approximately $3 million as of December 31, 2019. See Note 5, Fair Value of Financial Instruments, for discussion regarding concentration of credit risk.

Nuclear Decommissioning Trust F

Nuclear Decommissioning Trust Fund	12 Months Ended
	Dec. 31, 2019
Regulated Operations [Abstract]
Nuclear Decommissioning Trust Fund	Nuclear Decommissioning Trust Fund NRG's Nuclear Decommissioning Trust Fund assets, which are for the decommissioning of STP, are comprised of securities classified as available-for-sale and recorded at fair value based on actively quoted market prices. Although NRG is responsible for managing the decommissioning of its 44% interest in STP, the predecessor utilities that owned STP are authorized by the PUCT to collect decommissioning funds from their ratepayers to cover decommissioning costs on behalf of NRG. NRC requirements determine the decommissioning cost estimate which is the minimum required level of funding. In the event that funds from the ratepayers that accumulate in the nuclear decommissioning trust are ultimately determined to be inadequate to decommission the STP facilities, the utilities will be required to collect through rates charged to rate payers all additional amounts, with no obligation from NRG, provided that NRG has complied with PUCT rules and regulations regarding decommissioning trusts. Following completion of the decommissioning, if surplus funds remain in the decommissioning trusts, any excess will be refunded to the respective ratepayers of the utilities. NRG accounts for the Nuclear Decommissioning Trust Fund in accordance with ASC 980, Regulated Operations , or ASC 980, 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 other comprehensive income, 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 December 31, 2019 As of December 31, 2018 (In millions, except otherwise noted) 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 $ 17 $ — $ — — $ 19 $ — $ — — U.S. government and federal agency obligations 68 4 — 11 46 1 — 12 Federal agency mortgage-backed securities 100 3 — 24 100 1 2 23 Commercial mortgage-backed securities 29 1 1 24 22 — 1 22 Corporate debt securities 109 6 — 11 96 1 2 11 Equity securities 466 324 — — 376 231 1 — Foreign government fixed income securities 5 — — 10 4 — — 9 Total $ 794 $ 338 $ 1 $ 663 $ 234 $ 6 The following table summarizes proceeds from sales of available-for-sale securities and the related realized gains and losses from these sales. The cost of securities sold is determined using the specific identification method. Year Ended December 31, (In millions) 2019 2018 2017 Realized gains $ 18 $ 17 $ 22 Realized (losses) (9) (13) (8) Proceeds from sale of securities 381 513 501

Inventory

Inventory	12 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
Inventory	Inventory Inventory consisted of: As of December 31, (In millions) 2019 2018 Fuel oil $ 73 $ 74 Coal 93 97 Natural gas 21 28 Spare parts 196 213 Total Inventory $ 383 $ 412

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment The Company's major classes of property, plant, and equipment were as follows: As of December 31, Depreciable (In millions) 2019 2018 Lives Facilities and equipment $ 3,262 $ 3,763 1-40 years Land and improvements 324 347 Nuclear fuel 235 212 5 years Hardware and office equipment and furnishings 422 431 2-10 years Construction in progress 102 106 Total property, plant, and equipment 4,345 4,859 Accumulated depreciation (1,752) (1,811) Net property, plant, and equipment $ 2,593 $ 3,048

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases	Leases 2019 Leases The Company leases generating facilities, land, office and equipment, railcars, and storefront space at retail stores. Operating leases with an initial term greater than twelve months are recognized as right-of-use assets and lease liabilities in the consolidated balance sheets. The Company recognizes lease expense for all operating leases on a straight-line basis over the lease term. In the future, should another systematic basis become more representative of the pattern in which the lessee expects to consume the remaining economic benefit of the right-of-use asset, the Company will use that basis for lease expense. The Company considers a contract to be or to contain a lease when both of the following conditions apply: 1) an asset is either explicitly or implicitly identified in the contract and 2) the contract conveys to the Company the right to control the use of the identified asset for a period of time. The Company has the right to control the use of the identified asset when the Company has both the right to obtain substantially all the economic benefits from the use of the identified asset and the right to direct how and for what purpose the identified asset is used throughout the period of use. Lease payments are typically fixed and payable on a monthly, quarterly, semi-annual or annual basis. Lease payments under certain agreements may escalate over the lease term either by a fixed percentage or a fixed dollar amount. Certain leases may provide for variable lease payments in the form of payments based on usage, a percentage of sales from the location under lease, or index-based (e.g., the U.S. Consumer Price Index) adjustments to lease payments. The Company has no leases which contain residual value guarantees provided by the Company as a lessee. The Company’s leases may grant the Company an option to renew a lease for an additional term(s) or to terminate the lease after a certain period. As part of its transition from the guidance contained in ASC 840 to the updated guidance in ASC 842, the Company elected not to use the practical expedient of using hindsight to determine the lease term and in assessing impairment of the right-of-use assets. As permitted by ASC 842, the Company made an accounting policy election for all asset classes not to recognize right-of-use assets and lease liabilities in the consolidated balance sheets for its short-term leases, which are leases that have a lease term of twelve months or less. For the initial measurement of lease liabilities, the Company uses as the discount rate either the rate implicit in the lease, if known, or its incremental borrowing rate, which is the rate of interest that the Company would have to pay to borrow, on a collateralized basis, over a similar term an amount equal to the payments for the lease. In transition to ASC 842, the Company elected to apply the effective date transition method as of the January 1, 2019 adoption date. In accordance with this method, the Company’s reporting for comparative periods prior to January 1, 2019 presented in the financial statements continues to be in conformity with the guidance in ASC 840. The Company elected the following practical expedients, which allow entities to: • Not reassess whether any contracts that existed prior to the January 1, 2019 implementation date are or contain leases; • Not reassess the lease classification for any leases that commenced prior to the January 1, 2019 implementation date, meaning that all commenced capital leases under ASC 840 will be classified as finance leases under ASC 842 and all commenced operating leases under ASC 840 will be classified as operating leases under ASC 842; • Not reassess initial direct costs for any leases; • Not reassess whether existing land easements, which were not previously accounted as leases under ASC 840, are or contain leases; and • Not separate lease and non-lease components for all asset classes, except office space leases and generation facilities leases. As described in Note 4, Acquisitions, Discontinued Operations and Dispositions , upon the close of the South Central Portfolio sale, the Company entered into an agreement to leaseback the Cottonwood facility through May 2025. The lease was accounted for in accordance with ASC 842-40, Sale and Leaseback Transactions , as an operating lease and accordingly, a right-of-use asset and lease liability were established on the lease commencement date and will be amortized through the end of the lease. Lease Cost: (In millions) For the Year Ended December 31, 2019 Finance lease cost: $ — Amortization of right-of-use assets — Shares issued under ESPP — Interest on lease liabilities — Operating lease cost $ 109 Short-term lease cost 3 Variable lease cost 6 Sublease income (17) Total lease cost $ 101 Other information: (In millions) For the Year Ended December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 104 Right-of-use assets obtained in exchange for new operating lease liabilities 215 Lease Term and Discount Rate for operating leases: December 31, 2019 Weighted average remaining lease term (in years) 7.8 Weighted average discount rate 5.72 % As of December 31, 2019, annual payments based on the maturities of NRG's leases are expected to be as follows: (In millions) 2020 $ 96 2021 87 2022 87 2023 85 2024 75 Thereafter 296 Total undiscounted lease payments $ 726 Less: present value adjustment (170) Total discounted lease payments $ 556 2018 Operating Lease Commitments The below describes the Company's operating lease commitments as reported in the Company's Annual Report on Form 10-K for the year ended December 31, 2018, under Note 21, Commitments and Contingencies , prior to the adoption of ASC 842. The Company leases 100% interests in the Powerton facility and Unit 7 and Unit 8 of the Joliet facility through 2034 and 2030, respectively, through its indirect subsidiary, Midwest Generation, LLC. The Company accounted for these leases as operating leases and recorded lease expense on a straight-line basis over the lease term. In connection with the acquisition of Midwest Generation, the Company recorded the out-of-market value as a liability of $159 million in 2014. The liability was being amortized through rent expense on a straight-line basis over the term of the lease. The Company recorded lease expense, net of amortization of the out-of-market liability, of approximately $14 million per year. The accounting for these out-of-market contracts changed effective January 1, 2019, upon the adoption of ASC 842. Future minimum lease commitments under the Powerton and Joliet operating leases as of December 31, 2018 were as follows: Period (In millions) 2019 $ 1 2020 1 2021 3 2022 6 2023 6 Thereafter 222 Total (a) $ 239 (a) Termination of leases could be at a significant premium to the remaining lease payments Other Operating Leases NRG leases certain Company facilities and equipment under operating leases, some of which include escalation clauses, expiring on various dates through 2036. Lease expense under operating leases, other than Powerton and Joliet, was $66 million and $69 million for the years ended December 31, 2018 and 2017, respectively. Future minimum lease commitments under operating leases, other than Powerton and Joliet, as of December 31, 2018 were as follows: Period (a) (In millions) 2019 $ 60 2020 55 2021 43 2022 40 2023 39 Thereafter 95 Total $ 332 (a) Amounts in the table exclude future sublease income of $29 million associated with long-term leases for office locations

Asset Impairments

Asset Impairments	12 Months Ended
	Dec. 31, 2019
Asset Impairment Charges [Abstract]
Asset Impairments	Asset Impairments 2019 Impairment Losses Petra Nova Parish Holdings — During the third quarter of 2019, NRG contributed $95 million in cash to Petra Nova and posted a $12 million letter of credit to cover certain project debt reserve requirements. The cash portion of the contribution was used by Petra Nova to prepay a significant portion of the project debt. As a result, the previously disclosed guarantee of up to $124 million related to the project level debt provided by NRG was canceled and the remaining project debt became non-recourse to NRG. In relation to this contribution, the Company evaluated the project for impairment and 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 and considered project specific assumptions for the estimated future project cash flows. The Company measured the impairment loss as the difference between the carrying amount and the fair value of the investment and recorded an impairment loss of $101 million. Other Impairments — For the year ended December 31, 2019, the Company recorded $12 million of impairment losses primarily related to investments and intangibles. 2018 Impairment Losses Guam — During the fourth quarter of 2018, the Company concluded its wholly-owned subsidiary, NRG Solar Guam, LLC, was held for sale after board approval and advanced negotiations to sell the business. Accordingly, the Company recorded the assets and liabilities at fair market value as of December 31, 2018 based on the contractual sale price, which resulted in an impairment loss of $12 million. On February 20, 2019, the Company completed the sale of Guam for cash consideration of approximately $8 million. Keystone and Conemaugh — On September 5, 2018, the Company sold its approximately 3.7% interests in the Keystone and Conemaugh generating stations. NRG recorded impairment losses of $14 million for Keystone and $14 million for Conemaugh to adjust the carrying amount of the assets to fair value based on the contractual sale price. Dunkirk — During the second quarter of 2018, NRG ceased its development of the project to add gas capability at the Dunkirk generating station. The project was put on hold in 2015 pending the resolution of a lawsuit filed by Entergy Corporation against the NYPSC, which challenged the legality of its contract with Dunkirk. The lawsuit was later dropped and development continued, but the delay imposed a new requirement on Dunkirk to enter into the NYISO interconnection study process. The NYISO studies have concluded that extensive electric system upgrades would be necessary for the station to return to service. This would cause the Company to incur a material increase in cost and delay the project schedule that would render the project impractical. Consequently, the Company has recorded an impairment loss of $46 million, reducing the carrying amount of the related assets to $0. Other Impairments — As of December 31, 2018, the Company recorded additional asset impairment losses of $13 million and impairment losses on equity method investments of $15 million. 2017 Impairment Losses South Texas Project — The Company recognized an impairment loss of $1,248 million related to its interest in STP as a result of the decrease in the Company's view of long-term power prices in ERCOT. Indian River — The Company recognized an impairment loss of $36 million for Indian River as a result of the decrease in the Company's view of long-term power prices in PJM. Keystone and Conemaugh — The Company recognized impairment losses of $35 million for Keystone and $35 million for Conemaugh as a result of the decrease in the Company's view of long-term power prices in PJM. Bacliff Project — On June 16, 2017, NRG Texas Power LLC provided notice to BTEC New Albany, LLC that it was exercising its right to terminate the Amended and Restated Membership Interest Purchase Agreement, or MIPA, due to the Bacliff Project, a new peaking facility at the former P.H. Robinson Electric Generating Station, not achieving commercial completion by the contractual expiration date of May 31, 2017. As a result of the MIPA termination, the Company recorded an impairment loss of $41 million to reduce the carrying amount of the related construction in progress to $0 during the second quarter of 2017. Subsequent to the MIPA termination, BTEC filed claims against NRG Texas Power LLC with respect to the termination of the MIPA and NRG filed counterclaims against BTEC. On June 7, 2018, the parties resolved all claims and counterclaims in the lawsuit. Petra Nova Parish Holdings — In connection with the preparation of the annual budget during the fourth quarter of 2017, management revised its view of oil production expectations with respect to Petra Nova Parish Holdings. As a result, the Company reviewed its 50% interest in Petra Nova Parish Holdings for impairment utilizing the other-than-temporary impairment model. In determining fair value, the Company utilized an income approach and considered project specific assumptions for the future project cash flows. The carrying amount of the Company's equity method investment exceeded the fair value of the investment and the Company concluded that the decline is considered to be other-than-temporary. As a result, the Company measured the impairment loss as the difference between the carrying amount and the fair value of the investment and recorded an impairment loss of $69 million. Other Impairments — During the year ended 2017, the Company recorded impairment losses of $29 million in connection with renewable assets that were not divested as part of the sale of NRG Yield and the Renewables Platform. In addition, the Company recorded an impairment loss of $20 million related to excess SO 2 allowances and $10 million in impairment losses for other investments.

Goodwill and Other Intangibles

Goodwill and Other Intangibles	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangibles	Goodwill and Other Intangibles Goodwill NRG's goodwill balance was $579 million and $573 million as of December 31, 2019 and 2018, respectively. The increase in goodwill is due to the acquisition of Stream Energy. As of December 31, 2019, goodwill consisted of $165 million associated with the acquisition of Midwest Generation and $414 million for retail business acquisitions, including Texas non-commodity, XOOM and Stream Energy. 2017 Impairments of Goodwill BETM — During the fourth quarter of 2017, the Company concluded that BETM was held for sale following board approval and advanced negotiations to sell the business. Accordingly, the Company recorded the assets and liabilities at fair market value as of December 31, 2018, which resulted in an impairment loss of $90 million to record BETM's goodwill at fair market value. The remaining goodwill balance for BETM of $21 million was included within non-current assets held-for-sale as of December 31, 2018. Intangible Assets The Company's intangible assets as of December 31, 2019, primarily reflect intangible assets established with the acquisitions of various companies, including Stream Energy, XOOM, other retail acquisitions, and Texas Genco. Intangible assets are comprised of the following: • Emission Allowances — These intangibles primarily consist of SO 2 emission allowances established with the 2006 Texas Genco acquisition and also include RGGI emission credits which NRG began purchasing in 2009. These emission allowances are held-for-use and are amortized to cost of operations, with SO 2 allowances and RGGI credits amortized based on units of production. During the year ended December 31, 2018, the Company recorded an impairment loss of $5 million to reduce the value of excess SO 2 allowances to zero. During the year ended December 31, 2019, there were no impairment losses related to SO 2 emissions allowances. • In-market nuclear fuel contracts — These intangibles were established with the Texas Genco acquisition in 2006 and are amortized to cost of operations over expected volumes over the life of each contract. • Customer relationships — These intangibles represent the fair value at the acquisition date of acquired businesses' customer base. The customer relationships are amortized to depreciation and amortization expense based on the expected discounted future net cash flows by year. • Marketing partnerships — These intangibles represent the fair value at the acquisition date of existing agreements with marketing vendors and loyalty and affinity partners for customer acquisition. The marketing partnerships are amortized to depreciation and amortization expense based on the expected discounted future net cash flows by year. • Trade names — These intangibles are amortized to depreciation and amortization expense on a straight-line basis. • Other — Consists of renewable energy credits, costs to extend the operating license for STP Units 1 and 2, and energy supply contracts acquired with Stream Energy that represent the fair value at the acquisition date of in-market contracts for the purchase of energy to serve retail electric customers. Renewable energy credits are amortized to cost of operations as they are retired for usage. Energy supply contracts are amortized to depreciation and amortization based on the expected delivery under the respective contracts. The following tables summarize the components of NRG's intangible assets subject to amortization: (In millions) Year Ended December 31, 2019 Emission Allowances Fuel Contracts Customer Relationships Marketing Partnerships Trade Names Other Total January 1, 2019 $ 659 $ 49 $ 478 $ 131 $ 345 $ 80 $ 1,742 Purchases 13 — — — — 29 42 Acquisition of businesses (a) — — 110 154 28 26 318 Usage (4) — — — — (17) (21) Write-off of fully amortized balances (8) — (13) — — (9) (30) Impairment — — (2) — — — (2) Other 2 — — — — — 2 December 31, 2019 662 49 573 285 373 109 2,051 Less accumulated amortization (539) (45) (345) (75) (220) (38) (1,262) Net carrying amount $ 123 $ 4 $ 228 $ 210 $ 153 $ 71 $ 789 (a) The weighted average life of acquired intangibles was: customer relationships 7 years, marketing partnerships 9 years, trade names 12 years, and energy supply contracts 2 years (In millions) Year Ended December 31, 2018 Emission Allowances Fuel Contracts Customer Relationships Marketing Partnerships Trade Names Other Total January 1, 2018 $ 755 $ 49 $ 768 $ 88 $ 342 $ 78 $ 2,080 Purchases 33 — — — — 28 61 Acquisition of businesses (a) — — 122 43 13 — 178 Usage (1) — — — — (26) (27) Write-off of fully amortized balances (107) — (411) — (10) — (528) Impairment (5) — (1) — — — (6) Other (16) — — — — — (16) December 31, 2018 659 49 478 131 345 80 1,742 Less accumulated amortization (515) (45) (314) (61) (195) (21) (1,151) Net carrying amount $ 144 $ 4 $ 164 $ 70 $ 150 $ 59 $ 591 (a) The weighted average life of acquired intangibles was: customer relationships 6 years, trade names 7 years, and marketing partnerships 14 years The following table presents NRG's amortization of intangible assets for each of the past three years: Years Ended December 31, (In millions) 2019 2018 2017 Emission allowances $ 32 $ 39 $ 71 Customer relationships 44 32 34 Marketing partnerships 15 9 5 Trade names 25 23 23 Other 35 30 33 Total amortization $ 151 $ 133 $ 166 The following table presents estimated amortization of NRG's intangible assets as of December 31, 2019 for each of the next five years: (In millions) Year Ended December 31, Emission Allowances Fuel Contracts Customer Relationships Marketing Partnerships Trade Names Other Total 2020 $ 36 $ 1 $ 68 $ 24 $ 27 $ 33 $ 189 2021 35 — 52 24 27 3 141 2022 38 — 36 23 27 3 127 2023 40 1 35 23 26 3 128 2024 35 — 15 23 17 3 93 Intangible assets held-for-sale — From time to time, management may authorize the transfer from the Company's emission bank of emission allowances held-for-use to intangible assets held-for-sale. Emission allowances held-for-sale are included in other non-current assets on the Company's consolidated balance sheet and are not amortized, but rather expensed as sold. As of December 31, 2019 and 2018, the value of emission allowances held-for-sale was $6 million and $12 million, respectively, within the Corporate segment. Once transferred to held-for-sale, these emission allowances are prohibited from moving back to held-for-use. Out-of-market contracts — Due primarily to business acquisitions, NRG acquired certain out-of-market contracts, which were classified as non-current liabilities on NRG's consolidated balance sheet. These included out-of-market lease contracts acquired with Midwest Generation of $121 million as of December 31, 2018. As a result of the Company's adoption of ASC 842

Debt and Finance Leases

Debt and Finance Leases	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Debt and Finance Leases	LIBOR

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2019
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations The Company's AROs are primarily related to the environmental obligations for nuclear decommissioning, ash disposal, site closures, fuel storage facilities and future dismantlement of equipment on leased property. In addition, the Company has also identified conditional AROs for asbestos removal and disposal, which are specific to certain power generation operations. See Note 7, Nuclear Decommissioning Trust Fund, for a further discussion of the Company's nuclear decommissioning obligations. Accretion for the nuclear decommissioning ARO and amortization of the related ARO asset are recorded to the Nuclear Decommissioning Trust Liability to the ratepayers and are not included in net income, consistent with treatment per ASC 980, Regulated Operations . The following table represents the balance of ARO obligations as of December 31, 2019 and 2018, along with the additions, reductions and accretion related to the Company's ARO obligations for the year ended December 31, 2019: (In millions) Nuclear Decommission Other Total Balance as of December 31, 2018 $ 282 $ 397 $ 679 Revisions in estimates for current obligations (a) — 27 27 Additions — 9 9 Spending for current obligations — (33) (33) Accretion (a) 16 30 46 Balance as of December 31, 2019 $ 298 $ 430 $ 728 (a) Total ARO accretion expense includes non-Nuclear Decommissioning Trust accretion and revised asset retirement liabilities on non-operating plants

Benefit Plans and Other Postret

Benefit Plans and Other Postretirement Benefits	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
Benefit Plans and Other Postretirement Benefits	Benefit Plans and Other Postretirement Benefits NRG sponsors and operates defined benefit pension and other postretirement plans. NRG pension benefits are available to eligible non-union and union employees through various defined benefit pension plans. These benefits are based on pay, service history and age at retirement. Most pension benefits are provided through tax- qualified plans. NRG also provides postretirement health and welfare benefits for certain groups of employees. Cost sharing provisions vary by the terms of any applicable collective bargaining agreements. NRG maintains two separate qualified pension plans, the NRG Pension Plan for Bargained Employees and the NRG Pension Plan. Participation in the NRG Pension Plan for Bargained Employees depends upon whether an employee is covered by a bargaining agreement. NRG and GenOn entered into a Restructuring Support Agreement in which NRG agreed to retain GenOn's pension liability for service provided by GenOn employees prior to the completion of the GenOn reorganization. NRG determined that the retention of this liability was probable and recorded the estimated accumulated pension benefit obligation as of December 31, 2017 of $92 million, which reflects a $13 million contribution made by NRG to the plan in 2017, in other non-current liabilities with a corresponding loss from discontinued operations. NRG also agreed to retain the liability for GenOn's post-employment and retiree health and welfare benefits. NRG's obligation for both of these liabilities was revalued upon GenOn's emergence from bankruptcy resulting in an obligation of $23 million as of December 31, 2018. NRG expects to contribute $56 million to the Company's pension plans in 2020, of which $21 million relates to GenOn. NRG Defined Benefit Plans The annual net periodic benefit cost/(credit) related to NRG's pension and other postretirement benefit plans include the following components: Year Ended December 31, Pension Benefits (In millions) 2019 2018 2017 Service cost benefits earned $ 10 $ 23 $ 26 Interest cost on benefit obligation 46 44 43 Expected return on plan assets (59) (62) (58) Amortization of unrecognized net loss 3 — 4 Settlement/curtailment expense — 7 — Net periodic benefit cost $ — $ 12 $ 15 Year Ended December 31, Other Postretirement Benefits (In millions) 2019 2018 2017 Service cost benefits earned $ 1 $ 1 $ 1 Interest cost on benefit obligation 3 4 4 Amortization of unrecognized prior service credit (13) (10) (9) Amortization of unrecognized net (gain)/loss — — (1) Curtailment gain — (10) — Net periodic benefit (credit) $ (9) $ (15) $ (5) A comparison of the pension benefit obligation, other postretirement benefit obligations and related plan assets for NRG's plans on a combined basis is as follows: As of December 31, Pension Benefits Other Postretirement (In millions) 2019 2018 2019 2018 Benefit obligation at January 1 $ 1,222 $ 1,329 $ 83 $ 128 Service cost 10 23 1 1 Interest cost 46 44 3 4 Plan amendments — 17 (2) (28) Actuarial (gain)/loss 207 (95) 16 (6) Employee and retiree contributions — — 4 3 Curtailment gain — (20) — (7) Benefit payments (88) (76) (12) (12) Benefit obligation at December 31 1,397 1,222 93 83 Fair value of plan assets at January 1 981 1,104 — — Actual return on plan assets 216 (80) — — Employee and retiree contributions — — 4 3 Employer contributions 41 33 7 9 Benefit payments (88) (76) (11) (12) Fair value of plan assets at December 31 1,150 981 — — Funded status at December 31 — excess of obligation over assets $ (247) $ (241) $ (93) $ (83) Amounts recognized in NRG's balance sheets were as follows: As of December 31, Pension Benefits Other Postretirement Benefits (In millions) 2019 2018 2019 2018 Other current liabilities $ — $ — $ 7 $ 7 Other non-current liabilities 247 241 86 76 Amounts recognized in NRG's accumulated OCI that have not yet been recognized as components of net periodic benefit cost were as follows: As of December 31, Pension Benefits Other Postretirement Benefits (In millions) 2019 2018 2019 2018 Net loss/(gain) $ 138 $ 90 $ 7 $ (9) Prior service cost/(credit) 2 3 (43) (53) Total accumulated OCI $ 140 $ 93 $ (36) $ (62) Net accumulated OCI $ 140 $ 93 $ (36) $ (62) Other changes in plan assets and benefit obligations recognized in OCI were as follows: Year Ended December 31, Pension Benefits Other Postretirement Benefits (In millions) 2019 2018 2019 2018 Net actuarial loss/(gain) $ 50 $ 47 $ 16 $ (5) Amortization of net actuarial (gain)/loss (3) — — — Curtailment — (27) — 2 Prior service credit — 17 (2) (28) Amortization of prior service cost — — 12 10 Total recognized in OCI $ 47 $ 37 $ 26 $ (21) Net periodic benefit cost/(credit) — 12 (9) (15) Net recognized in net periodic pension cost/(credit) and OCI $ 47 $ 49 $ 17 $ (36) The Company's estimated unrecognized loss for NRG's pension plan as of December 31, 2019 that will be amortized from accumulated OCI to net periodic cost over the next fiscal year is $5 million. The Company's estimated unrecognized loss and unrecognized prior service credit for NRG's postretirement plan as of December 31, 2019 that will be amortized from accumulated OCI to net periodic cost over the next fiscal year is $1 million and $14 million, respectively. The following table presents the balances of significant components of NRG's pension plan: As of December 31, Pension Benefits (In millions) 2019 2018 Projected benefit obligation $ 1,397 $ 1,222 Accumulated benefit obligation 1,362 1,188 Fair value of plan assets 1,150 981 NRG's market-related value of its plan assets is the fair value of the assets. The fair values of the Company's pension plan assets by asset category and their level within the fair value hierarchy are as follows: Fair Value Measurements as of December 31, 2019 (In millions) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Total Common/collective trust investment — U.S. equity $ — $ 233 $ 233 Common/collective trust investment — non-U.S. equity — 73 73 Common/collective trust investment — non-core assets — 143 143 Common/collective trust investment — fixed income — 272 272 Short-term investment fund 12 — 12 Subtotal fair value $ 12 $ 721 $ 733 Measured at net asset value practical expedient: Common/collective trust investment — non-U.S. equity 84 Common/collective trust investment — fixed income 279 Common/collective trust investment — non-core assets 24 Partnerships/joint ventures 30 Total fair value $ 1,150 Fair Value Measurements as of December 31, 2018 (In millions) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Total Common/collective trust investment — U.S. equity $ — $ 183 $ 183 Common/collective trust investment — non-U.S. equity — 53 53 Common/collective trust investment — non-core assets — 117 117 Common/collective trust investment — fixed income — 256 256 Short-term investment fund 12 — 12 Subtotal fair value $ 12 $ 609 $ 621 Measured at net asset value practical expedient: Common/collective trust investment — non-U.S. equity 70 Common/collective trust investment — fixed income 249 Common/collective trust investment — non-core assets 16 Partnerships/joint ventures 25 Total fair value $ 981 In accordance with ASC 820, the Company determines the level in the fair value hierarchy within which each fair value measurement in its entirety falls, based on the lowest level input that is significant to the fair value measurement in its entirety. The fair value of the common/collective trust investments is valued at fair value which is equal to the sum of the market value of all of the fund's underlying investments. Certain common/collective trust investments have readily determinable fair value as they publish daily net asset value, or NAV, per share and are categorized as Level 2. Certain other common/collective trust investments and partnerships/joint ventures use NAV per share, or its equivalent, as a practical expedient for valuation, and thus have been removed from the fair value hierarchy table. The following table presents the significant assumptions used to calculate NRG's benefit obligations: As of December 31, Pension Benefits Other Postretirement Benefits Weighted-Average Assumptions 2019 2018 2019 2018 Discount rate 3.26 % 4.38 % 3.26 % 4.37 % Rate of compensation increase 3.00 % 3.00 % — % — % Health care trend rate — — 7.5% grading to 4.5% in 2028 7.8% grading to 4.5% in 2025 The following table presents the significant assumptions used to calculate NRG's benefit expense: As of December 31, Pension Benefits Other Postretirement Benefits Weighted-Average Assumptions 2019 2018 2017 2019 2018 2017 Discount rate 4.38%/4.2% 3.71%/4.04% 4.26 % 4.37% 3.71% /4.08% 4.29 % Expected return on plan assets 6.35 % 6.17 % 6.85 % — — — Rate of compensation increase 3.00 % 3.00 % 3.00 % — — — Health care trend rate — — — 7.8% grading to 4.5% in 2025 8.2% grading to 4.5% in 2025 7.0% grading to 5.0% in 2025 NRG uses December 31 of each respective year as the measurement date for the Company's pension and other postretirement benefit plans. The Company sets the discount rate assumptions on an annual basis for each of NRG's defined benefit retirement plans as of December 31. The discount rate assumptions represent the current rate at which the associated liabilities could be effectively settled at December 31. The Company utilizes the Aon AA Above Median, or AA-AM, yield curve to select the appropriate discount rate assumption for each retirement plan. The AA-AM yield curve is a hypothetical AA yield curve represented by a series of annualized individual spot discount rates from 6 months to 99 years. Each bond issue used to build this yield curve must be non-callable, and have an average rating of AA when averaging available Moody's Investor Services, Standard & Poor's and Fitch ratings. NRG employs a total return investment approach, whereby a mix of equities and fixed income investments are used to maximize the long-term return of plan assets for a prudent level of risk. Risk tolerance is established through careful consideration of plan liabilities, plan funded status, and corporate financial condition. The Investment Committee reviews the asset mix periodically and as the plan assets increase in future years, the Investment Committee may examine other asset classes such as real estate or private equity. NRG employs a building block approach to determining the long-term rate of return assumption for plan assets, with proper consideration given to diversification and rebalancing. Historical markets are studied and long-term historical relationships between equities and fixed income are preserved, consistent with the widely accepted capital market principle that assets with higher volatility generate a greater return over the long run. Current factors such as inflation and interest rates are evaluated before long-term capital market assumptions are determined. Peer data and historical returns are reviewed to check for reasonableness and appropriateness. The target allocations of NRG's pension plan assets were as follows for the year ended December 31, 2019: U.S. equity 20 % Non-U.S. equity 13 % Non-core assets 17 % U.S. fixed income 50 % Plan assets are currently invested in a diversified blend of equity and fixed-income investments. Furthermore, equity investments are diversified across U.S., non-U.S., global, and emerging market equities, as well as among growth, value, small and large capitalization stocks. Investment risk and performance are monitored on an ongoing basis through quarterly portfolio reviews of each asset fund class to a related performance benchmark, if applicable, and annual pension liability measurements. Performance benchmarks are composed of the following indices: Asset Class Index U.S. equities Dow Jones U.S. Total Stock Market Index Non-U.S. equities MSCI All Country World Ex-U.S. IMI Index Non-core assets (a) Various (per underlying asset class) Fixed income securities Barclays Capital Long Term Government/Credit Index & Barclays Strips 20+ Index (a) Non-Core Assets are defined as diversifying asset classes approved by the Investment Committee that are intended to enhance returns and/or reduce volatility of the U.S. and non-U.S. equities. Asset classes considered Non-Core include, but may not be limited to: Emerging Market Equity, Emerging Market Debt, Non-US Developed Market Small Cap, High Yield Fixed Income, Real Estate, Bank Loans, Global Infrastructure and other Alternatives. NRG's expected future benefit payments for each of the next five years, and in the aggregate for the five years thereafter, are as follows: Other Postretirement Benefit (In millions) Pension Benefit Payments Benefit Payments Medicare Prescription Drug Reimbursements 2020 $ 84 $ 7 $ — 2021 86 6 — 2022 86 6 — 2023 86 6 — 2024 86 6 — 2025-2029 402 19 2 Assumed health care cost trend rates have a significant effect on the amounts reported for the health care plans. The impact of a one-percentage-point change in assumed health care cost trend rates is immaterial on total service and interest costs components but would have the following effect: (In millions) 1-Percentage- Point Increase 1-Percentage- Point Decrease Effect on postretirement benefit obligation $ 7 $ (5) STP Defined Benefit Plans NRG has a 44% undivided ownership interest in STP, as discussed further in Note 28, Jointly Owned Plants . STPNOC, which operates and maintains STP, provides its employees a defined benefit pension plan, as well as postretirement health and welfare benefits. Although NRG does not sponsor the STP plan, it reimburses STPNOC for 44% of the contributions made towards its retirement plan obligations. During the third quarter of 2019, STPNOC announced that the defined benefit pension plan will be frozen for non-union employees on December 31, 2021, This resulted in the curtailment of benefits, thereby requiring a remeasurement, including an update to the discount rate used to determine benefit obligations. As a result, NRG recognized a gain of $8 million related to the curtailment of benefits and an increase of $32 million to the pension liability was recorded to other comprehensive income. The Company measures the fair value of its pension assets in accordance with ASC 820, Fair Value Measurements and Disclosures, or ASC 820. For the years ended December 31, 2019 and December 31, 2018, NRG reimbursed STPNOC $24 million and $13 million, respectively, for its contribution to the plans. In 2020, NRG expects to reimburse STPNOC $7 million for its contribution to the plan. The Company has recognized the following in its statement of financial position, statement of operations and accumulated OCI related to its 44% interest in STP: As of December 31, Pension Benefits Other Postretirement Benefits (In millions) 2019 2018 2019 2018 Funded status — STPNOC benefit plans $ (77) $ (78) $ (20) $ (19) Net periodic benefit cost/(credit) 9 8 (4) (7) Other changes in plan assets and benefit obligations recognized in other comprehensive (loss)/income (13) (7) 6 2 Defined Contribution Plans NRG's employees are also eligible to participate in defined contribution 401(k) plans. The Company's contributions to these plans were as follows: Year Ended December 31, (In millions) 2019 2018 2017 Company contributions to defined contribution plans $ 22 $ 28 $ 56

Capital Structure

Capital Structure	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Capital Structure	Capital Structure For the period from December 31, 2016 to December 31, 2019, the Company had 10,000,000 shares of preferred stock authorized and 500,000,000 shares of common stock authorized. The following table reflects the changes in NRG's common shares issued and outstanding for each period presented: Common Issued Treasury Outstanding Balance as of December 31, 2016 417,583,825 (102,140,814) 315,443,011 Shares issued under ESPP — 560,769 560,769 Shares issued under LTIPs 739,309 — 739,309 Balance as of December 31, 2017 418,323,134 (101,580,045) 316,743,089 Shares issued under ESPP — 175,862 175,862 Shares issued under LTIPs 1,965,752 — 1,965,752 Share repurchases — (35,234,664) (35,234,664) Balance as of December 31, 2018 420,288,886 (136,638,847) 283,650,039 Shares issued under ESPP — 46,128 46,128 Shares issued under LTIPs 1,601,904 — 1,601,904 Share repurchases — (36,301,882) (36,301,882) Balance as of December 31, 2019 421,890,790 (172,894,601) 248,996,189 Common Stock As of December 31, 2019, NRG had 16,029,127 shares of common stock reserved for the maximum number of shares potentially issuable based on the conversion and redemption features of the long-term incentive plans. Common stock dividends — The Company paid $0.03 quarterly dividend per common share, or $0.12 per share on an annualized basis, for years 2017, 2018 and 2019. The Company's common stock dividends are subject to available capital, market conditions, and compliance with associated laws, regulations and other contractual obligations. Beginning in the first quarter of 2020, NRG increased the annual dividend to $1.20 per share and expects to target an annual dividend growth rate of 7-9% per share in subsequent years. On January 21, 2020, NRG declared a quarterly dividend on the Company's common stock of $0.30 per share, or $1.20 per share on an annualized basis, payable on February 18, 2020, to stockholders of record as of February 3, 2020. Employee Stock Purchase Plan — In March 2019, the Company reopened participation in the ESPP under the Amended and Restated Employee Stock Purchase Plan, 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 will occur each April 1 and October 1. An exercise date will occur each September 30 and March 31. The ESPP plan, that was suspended in 2018, allowed eligible employees to elect to withhold up to 10% of their eligible compensation to purchase shares of NRG common stock at the lesser of 85% of its fair market value on the offering date or 85% of the fair market value on the exercise date. An offering date occurred each January 1 and July 1. An exercise date occurred each June 30 and December 31. As of December 31, 2019, there remained 2,885,060 shares of treasury stock reserved for issuance under the ESPP. Share Repurchases — In 2018, the Company's board of directors authorized the Company to repurchase $1.5 billion of its common stock. The Company executed $1.25 billion of these share repurchases in 2018, with the remaining $0.25 billion completed in the first quarter of 2019. In 2019, the Company's board of directors authorized the Company to repurchase an additional $1.25 billion of its common stock. The Company executed $1.194 billion of these share repurchases in 2019, with the remaining $56 million completed by February 27, 2020. In addition, the Company adopted in the fourth quarter of 2019 a long-term capital allocation policy that targets allocating 50% of cash available for allocation generated each year to growth investments and 50% to be returned to shareholders. The return of capital to shareholders is expected to be completed through the increased dividend discussed above, supplemented by share repurchases. The following table summarizes the shares repurchases made from 2018 through February 27, 2020: Total number of shares and share equivalents purchased Average price paid per share and share equivalent Amounts paid for shares and share equivalents purchased (in millions) 2018 repurchases: Shares repurchased under May 24, 2018 Accelerated Repurchase Agreement 10,829,903 354 Shares repurchased under September 5, 2018 Accelerated Repurchase Agreement 13,307,130 500 Other repurchases 11,097,631 396 Total Share Repurchases during 2018 35,234,664 $35.48 $ 1,250 2019 repurchases: Repurchases under February 28, 2019 Accelerated Share Repurchase Agreement 9,438,671 400 Other repurchases 26,863,211 1,008 Equivalent shares purchased in lieu of tax withholdings on equity compensation issuances (a) 936,928 36 Total Share Repurchases during 2019 37,238,810 $ 38.79 $ 1,444 2020 repurchases: Repurchases made subsequent to December 31, 2019 2,428,545 92 Equivalent shares purchased in lieu of tax withholdings on equity compensation issuances (a) 709,536 27 Total share repurchases January 1, 2020 through February 27, 2020 3,138,081 $ 37.87 $ 119 (a) NRG elected to pay cash for tax withholding on equity awards instead of issuing actual shares to management. The average price per equivalent shares withheld was $38.24 and $38.78 in 2020 and 2019, respectively. See Note 21, Stock-Based Compensation , for further discussion of the equity awards

Investments Accounted for by th

Investments Accounted for by the Equity Method and Variable Interest Entities	12 Months Ended
	Dec. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Investments Accounted for by the Equity Method and Variable Interest Entities	Investments Accounted for by the Equity Method and Variable Interest Entities 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. The following table summarizes NRG's equity method investments as of December 31, 2019: (In millions, except percentages) Name Economic Investment Balance Agua Caliente 35.0 % 213 Gladstone 37.5 % 124 Ivanpah Master Holdings, LLC 54.5 % 20 Watson Cogeneration Company 49.0 % 15 Midway-Sunset Cogeneration Company 50.0 % 9 Other (a) Various 7 Total equity investments in affiliates $ 388 (a) Refer to Note 11, Asset Impairments , for discussion of NRG's investment in Petra Nova Parish Holdings, LLC As of December 31, (In millions) 2019 2018 Undistributed earnings from equity investments $ 42 $ 34 PG&E Bankruptcy — The Agua Caliente project and two of the three Ivanpah units are party to PPAs with PG&E. Both projects have project financing with the U.S. DOE. On January 29, 2019, PG&E Corp. and subsidiary utility PG&E filed for Chapter 11 bankruptcy protection. As part of their filing, PG&E asked the Bankruptcy Court to confirm exclusive jurisdiction over their "rights to reject" PPAs or other contracts regulated by FERC . As a result of the bankruptcy filing, the Agua Caliente and Ivanpah projects have issued notices of events of default under their respective loan agreements. The Ivanpah project signed a forbearance agreement with the Department of Energy on October 25, 2019. The Company's subsidiaries are working with their partners on the projects and the loan counterparties. On September 9, 2019, PG&E filed a plan of reorganization that would assume all power purchase agreements, including those held by the Agua Caliente project and the two Ivanpah units. On January 22, 2020 the noteholders agreed to support the PG&E plan, which will continue to provide for assumption of all power purchase agreements. The plan was subsequently amended, and a hearing before the Bankruptcy Court to consider whether the PG&E plan will be approved and confirmed is currently expected to occur on May 27, 2020. NRG's maximum exposure to loss is limited to its equity investment, which was $213 million for Agua Caliente and $20 million for Ivanpah as of December 31, 2019. See Note 13, Debt and Finance Leases for further discussion on Agua Caliente. Variable Interest Entities NRG accounts for its interests in certain entities that are considered VIEs under ASC 810, Consolidation , for which NRG is not the primary beneficiary, under the equity method. Through its consolidated subsidiary, NRG Solar Ivanpah LLC, NRG owns a 54.5% interest in Ivanpah Master Holdings, LLC, or Ivanpah, the owner of three solar electric generating projects located in the Mojave Desert with a total capacity of 393 MW. NRG considers this investment a VIE under ASC 810 and NRG is not considered the primary beneficiary. The Company accounts for its interest under the equity method of accounting. The Ivanpah solar electric generating projects were funded in large part by loans guaranteed by the U.S. DOE and equity from the projects' partners. During the first quarter of 2018, all interested parties sought a restructuring of Ivanpah's debt in order to avoid a potential event of default with respect to the loans in connection with several recent events. Ensuing negotiations culminated in a settlement during the second quarter of 2018 between the parties which resulted in certain transactions, including the release of reserves totaling $95 million to fund equity distributions to the partners, which reduced the equity at risk, and the prepayment of certain of the debt balance outstanding, and the amendment of certain of Ivanpah's governing documents. The equity distributions and prepayment of debt were funded by the agreed upon release of reserve funds. These events were considered to be a reconsideration event in accordance with ASC 810. As a result, NRG determined that it is not the primary beneficiary and deconsolidated Ivanpah. NRG recognized a loss of $22 million on the deconsolidation and subsequent recognition of Ivanpah as an equity method investment. The deconsolidation of Ivanpah reduced the Company's assets by approximately $1.3 billion, which was primarily property, plant and equipment, and reduced the Company's liabilities by $1.2 billion, which was primarily long-term debt. Other Equity Investments Gladstone — Through a joint venture, NRG owns a 37.5% interest in Gladstone, a 1,613 MW coal-fueled power generation facility in Queensland, Australia. The power generation facility is managed by the joint venture participants and the facility is operated by NRG. Operating expenses incurred in connection with the operation of the facility are funded by each of the participants in proportion to their ownership interests. Coal is sourced from local mines in Queensland. NRG and the joint venture participants receive their respective share of revenues directly from the off takers in proportion to the ownership interests in the joint venture. Power generated by the facility is primarily sold to an adjacent aluminum smelter, with excess power sold to the Queensland Government-owned utility under long-term supply contracts. NRG's investment in Gladstone was $124 million as of December 31, 2019. Entities that are Consolidated The Company has a controlling financial interest in certain entities which have been identified as VIEs under ASC 810. These arrangements are related to tax equity arrangements entered into with third-parties in order to finance the cost of solar energy systems under operating leases eligible for certain tax credits as further described in Note 2, Summary of Significant Accounting Policies . The summarized financial information for the Company's consolidated VIEs consisted of the following: (In millions) December 31, 2019 December 31, 2018 Current assets $ 3 $ 3 Net property, plant and equipment 71 76 Other long-term assets 27 28 Total assets 101 107 Current liabilities 4 2 Long-term debt 24 29 Other long-term liabilities 8 7 Total liabilities 36 38 Redeemable noncontrolling interests 20 19 Net assets less noncontrolling interests $ 45 $ 50

Earnings_(Loss) Per Share

Earnings/(Loss) Per Share	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Earnings/(Loss) Per Share	Earnings/(Loss) Per Share Basic income/(loss) per common share is computed by dividing net income/(loss) by the weighted average number of common shares outstanding. Shares issued and treasury shares repurchased during the year are weighted for the portion of the year that they were outstanding. Diluted income/(loss) per share is computed in a manner consistent with that of basic income/(loss) per share, while giving effect to all potentially dilutive common shares that were outstanding during the period. Dilutive effect for equity compensation and other equity instruments — The outstanding non-qualified stock options, non-vested restricted stock units, and market stock units and relative performance stock units are not considered outstanding for purposes of computing basic income/(loss) per share. However, these instruments are included in the denominator for purposes of computing diluted income/(loss) per share under the treasury stock method. The 2048 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 2048 Convertible Senior Notes due to the Company’s expectation to settle the liability in cash. The reconciliation of NRG's basic income/(loss) per share to diluted income/(loss) per share is shown in the following table: Year Ended December 31, (In millions, except per share amounts) 2019 2018 2017 Basic income/(loss) per share attributable to NRG, Inc; Net income/(loss) attributable to NRG Energy, Inc. common stockholders $ 4,438 $ 268 $ (2,153) Weighted average number of common shares outstanding-basic 262 304 317 Income/(Loss) per weighted average common share — basic $ 16.94 $ 0.88 $ (6.79) Diluted income/(loss) per share attributable to NRG, Inc; Net income/(loss) attributable to NRG Energy, Inc. common stockholders $ 4,438 $ 268 $ (2,153) Weighted average number of common shares outstanding-basic 262 304 317 Incremental shares attributable to the issuance of equity compensation (treasury stock method) 2 4 — Weighted average number of common shares outstanding-diluted 264 308 317 Income/(Loss) per weighted average common share — diluted $ 16.81 $ 0.87 $ (6.79) The following table summarizes NRG's outstanding equity instruments that are anti-dilutive and were not included in the computation of the Company's diluted income/(loss) per share: Year Ended December 31, (In millions) 2019 2018 2017 Equity compensation plans — — 5

Segment Reporting

Segment Reporting	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting As of December 31, 2019, the Company's reportable segments were Generation, Retail and Corporate. Retail included Mass market and C&I customers, as well as other distributed and reliability products. Generation included all power plant activities, as well as renewables. The Company began managing its integrated model based on the combined results of the retail and wholesale generation businesses with a geographical focus in 2020. As a result, the Company changed its business segments to Texas, East and West/Other beginning in the first quarter of 2020. The Company's updated segment structure reflects how management currently makes financial decisions and allocates resources. All affected disclosures presented herein have been recast to reflect these changes for all periods presented. For further discussion, refer to Note 1, Nature of Busines s. 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 capital for allocation, as well as net income/(loss) and net income/(loss) attributable to NRG Energy, Inc. On February 4, 2019, the Company completed the sale and deconsolidation of South Central Portfolio. On August 31, 2018, NRG deconsolidated NRG Yield Inc., its Renewables Platform and Carlsbad for financial reporting purposes. In 2018, the financial information for historical periods was recast to reflect the presentation of discontinued operations within the corporate segment. Refer to Note 4, Acquisitions, Discontinued Operations and Dispositions , for further discussion. The Company had no customer that comprised more than 10% of the Company's consolidated revenues during the years ended December 31, 2019 and 2017. The company had one customer in the Texas segment that comprised 11% of the Company's consolidated revenues during the year ended December 31, 2018. Intersegment sales are accounted for at market. For the Year Ended December 31, 2019 (In millions) Texas East West/Other Corporate (a) Eliminations Total Operating revenues (a) $ 7,069 $ 2,319 $ 440 $ — $ (7) $ 9,821 Operating expenses 5,818 1,895 397 50 (7) 8,153 Depreciation and amortization 188 121 33 31 — 373 Impairment losses 1 — 4 — — 5 Development costs 3 3 1 — — 7 Total operating cost and expenses 6,010 2,019 435 81 (7) 8,538 Gain on sale of assets — 1 — 6 — 7 Operating income/(loss) 1,059 301 5 (75) — 1,290 Equity in (losses)/earnings of unconsolidated affiliates (4) — 6 — — 2 Impairment losses on investments (103) — — (5) — (108) Other income, net 20 6 10 30 — 66 Loss on debt extinguishment — — (3) (48) — (51) Interest expense — (18) (10) (385) — (413) Income/(loss) from continuing operations before income taxes 972 289 8 (483) — 786 Income tax expense/(benefit) — 2 1 (3,337) — (3,334) Net income from continuing operations 972 287 7 2,854 — 4,120 Gain from discontinued operations, net of income tax — — — 321 — 321 Net Income 972 287 7 3,175 — 4,441 Less: Net income attributable to noncontrolling interests and redeemable noncontrolling interests — — 3 — — 3 Net income attributable to NRG Energy, Inc. $ 972 $ 287 $ 4 $ 3,175 $ — $ 4,438 Balance sheet Equity investments in affiliates $ 6 $ — $ 382 $ — $ — $ 388 Capital expenditures 136 30 25 37 — 228 Goodwill (b) 325 254 — — — 579 Total assets $ 5,711 $ 2,160 $ 1,190 $ 8,342 $ (4,872) $ 12,531 (a) Inter-segment sales and inter-segment net derivative gains and losses included in operating revenues $ 1 $ 8 $ (2) $ — $ — $ 7 (b) Goodwill was allocated based on the regions in which the business operates and are expected to benefit using a relative fair value approach For the Year Ended December 31, 2018 (In millions) Texas East West/Other Corporate (a) Eliminations Total Operating revenues (a) $ 6,401 $ 2,371 $ 724 $ — $ (18) $ 9,478 Operating expenses 5,399 2,024 467 125 (18) 7,997 Depreciation and amortization 156 105 127 33 — 421 Impairment losses 5 82 12 — — 99 Development costs 3 3 3 2 — 11 Total operating cost and expenses 5,563 2,214 609 160 (18) 8,528 Gain on sale of assets 4 — (2) 30 — 32 Operating income/(loss) 842 157 113 (130) — 982 Equity in (losses)/earnings of unconsolidated affiliates (3) — 13 (1) — 9 Impairment losses on investments (15) — — — — (15) Other income/(loss), net 13 2 4 (1) — 18 Loss on debt extinguishment — — — (44) — (44) Interest expense — (22) (39) (422) — (483) Income/(loss) from continuing operations before income taxes 837 137 91 (598) — 467 Income tax expense — 1 — 6 — 7 Net income/(loss) from continuing operations 837 136 91 (604) — 460 Loss from discontinued operations, net of income tax — — — (192) — (192) Net Income/(loss) 837 136 91 (796) — 268 Less: Net income/(loss) attributable to noncontrolling interests and redeemable noncontrolling interests — — 5 (5) — — Net income/(loss) attributable to NRG Energy, Inc. $ 837 $ 136 $ 86 $ (791) $ — $ 268 Balance sheet Equity investments in affiliates $ 6 $ — 406 $ — $ — $ 412 Capital expenditures 143 171 29 45 — 388 Goodwill (b) 320 253 — — — 573 Total assets $ 5,357 $ 2,187 $ 1,548 $ 6,631 $ (5,095) $ 10,628 (a) Inter-segment sales and inter-segment net derivative gains and losses included in operating revenues $ 19 $ (5) 4 $ — $ — $ 18 (b) Goodwill was allocated based on the regions in which the business operates and are expected to benefit using a relative fair value approach For the Year Ended December 31, 2017 (In millions) Texas East West/Other Corporate (a) Eliminations Total Operating revenues (a) $ 6,318 $ 2,009 $ 788 $ 6 $ (47) $ 9,074 Operating expenses 5,393 1,684 498 239 (48) 7,766 Depreciation and amortization 258 112 194 35 (3) 596 Impairment losses 1,317 106 111 — — 1,534 Development costs 4 6 6 6 — 22 Total operating costs and expenses 6,972 1,908 809 280 (51) 9,918 Other income - affiliate — — — 87 — 87 Gain/(loss) on sale of assets 5 15 (5) 1 — 16 Operating (loss)/income (649) 116 (26) (186) 4 (741) Equity in (losses)/earnings of unconsolidated affiliates (22) — 10 (2) — (14) Impairment losses on investments (69) — (6) (4) — (79) Other (expense)/income, net (2) 4 22 27 — 51 Loss on debt extinguishment — — — (49) — (49) Interest expense — (29) (77) (451) — (557) (Loss)/income from continuing operations before income taxes (742) 91 (77) (665) 4 (1,389) Income tax benefit — — (6) (38) — (44) Net (loss)/income from continuing operations (742) 91 (71) (627) 4 (1,345) Loss from discontinued operations, net of income tax — — — (992) — (992) Net (loss)/income (742) 91 (71) (1,619) 4 (2,337) Less: Net income/(loss) attributable to noncontrolling interests and redeemable noncontrolling interests — — 1 (189) 4 (184) Net (loss)/income attributable to NRG Energy, Inc. $ (742) $ 91 $ (72) $ (1,430) $ — $ (2,153) (a) Inter-segment sales and inter-segment net derivative gains and losses included in operating revenues $ 41 $ 1 (4) $ 9 $ — $ 47

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The income tax provision from continuing operations consisted of the following amounts: Year Ended December 31, (In millions, except effective income tax rate) 2019 2018 2017 Current State $ 2 $ 6 $ 19 Foreign 4 — — Total — current 6 6 19 Deferred U.S. Federal (3,000) (16) (60) State (340) 16 (5) Foreign — 1 2 Total — deferred (3,340) 1 (63) Total income tax (benefit)/expense $ (3,334) $ 7 $ (44) Effective income tax rate (424.2) % 1.5 % 3.2 % During the year ended December 31, 2019, NRG released the majority of its valuation allowance against its U.S. federal and state deferred tax assets, resulting in a non-cash benefit to income tax expense of approximately $3.5 billion. In making the determination to release the majority of the valuation allowance as of December 31, 2019, the Company evaluated a number of factors, including its recent history of pre-tax earnings, utilization of $593 million of NOLs in 2019, as well as its forecasted future pre-tax earnings. Based on this evaluation, the Company determined that the majority of its future tax benefits are more-likely-than-not to be realized. Given the Company’s current level of pre-tax earnings and forecasted future pre-tax earnings, the Company expects to generate income before taxes in the U.S. in future periods at a level that would fully utilize its U.S. federal NOL carryforwards and the majority of its state NOL carryforwards prior to their expiration. The following represented the domestic and foreign components of income/(loss) from continuing operations before income taxes: Year Ended December 31, (In millions) 2019 2018 2017 U.S. $ 771 $ 468 $ (1,406) Foreign 15 (1) 17 Total $ 786 $ 467 $ (1,389) Reconciliations of the U.S. federal statutory tax rate to NRG's effective tax rate were as follows: Year Ended December 31, (In millions, except effective income tax rate) 2019 2018 2017 Income/(loss) from continuing operations before income taxes $ 786 $ 467 $ (1,389) Tax at federal statutory tax rate 165 98 (486) State taxes 13 18 19 Foreign operations — — 2 Permanent differences (9) 7 — Valuation allowance - current period activities (3,492) (106) 455 Book goodwill impairment — — 30 Deferred impact of state tax rate changes 12 — — Production tax credits ("PTC") — (7) (8) Recognition of uncertain tax benefits (10) 1 (5) Alternative minimum tax ("AMT") refundable credit — (4) (64) Tax Act - corporate income tax rate change — — 665 Valuation allowance due to corporate income tax rate change — — (660) Other (13) — 8 Income tax (benefit)/expense $ (3,334) $ 7 $ (44) Effective income tax rate (424.2) % 1.5 % 3.2 % For the year ended December 31, 2019, NRG's effective income tax rate was lower than the federal statutory tax rate of 21% primarily due to the tax benefit from the release of the valuation allowance. For the year ended December 31, 2018, NRG's effective income tax rate was lower than the federal statutory tax rate of 21% primarily due to a tax benefit for the change in valuation allowance, the generation of PTCs from various wind facilities and establishment of the previously sequestered AMT credit receivable, partially offset by current state tax expense. For the year ended December 31, 2017, NRG's effective income tax rate was lower than the federal statutory tax rate of 35% primarily due to tax expense recorded from the revaluation of the existing net deferred tax asset and state taxes, partially offset by the change in valuation allowance, establishing the AMT credit and the generation of PTCs from various wind facilities. The tax expense recorded for revaluation of the net deferred tax asset is required to reflect the reduction in the corporate income tax rate from 35% to 21% in accordance with the Tax Act. The temporary differences, which gave rise to the Company's deferred tax assets and liabilities consisted of the following: As of December 31, (In millions) 2019 2018 Deferred tax assets: Deferred compensation, accrued vacation and other reserves $ 81 $ 134 Difference between book and tax basis of property 548 554 Goodwill — 11 Differences between book and tax basis of contracts — 38 Pension and other postretirement benefits 86 87 Equity compensation 11 9 Bad debt reserve 13 14 U.S. Federal net operating loss carryforwards 2,116 2,241 Foreign net operating loss carryforwards 105 63 State net operating loss carryforwards 360 379 Federal and state tax credit carryforwards 384 381 Federal benefit on state uncertain tax positions 4 6 Intangibles amortization (excluding goodwill) — 21 Interest disallowance carryforward per §163(j) of the Tax Act 82 102 Inventory obsolescence 7 7 Other 3 — Discontinued operations — 17 Total deferred tax assets 3,800 4,064 Deferred tax liabilities: Emissions allowances 19 15 Derivatives, net 27 37 Goodwill 8 — Intangibles amortization (excluding goodwill) 15 — Equity method investments 201 180 Convertible Debt 19 21 Other — 1 Discontinued operations — 36 Total deferred tax liabilities 289 290 Total deferred tax assets less deferred tax liabilities 3,511 3,774 Valuation allowance (242) (3,812) Discontinued operations — 19 Total deferred tax assets/(liabilities), net of valuation allowance $ 3,269 $ (19) The following table summarizes NRG's net deferred tax position as presented in the consolidated balance sheets: As of December 31, (In millions) 2019 2018 Deferred tax asset $ 3,286 $ 46 Deferred tax liability (17) (65) Net deferred tax asset/(liability) $ 3,269 $ (19) The primary driver for the change from a $19 million net deferred tax liability as of December 31, 2018 to a net deferred tax asset of $3.3 billion as of December 31, 2019 is the release in the Company’s valuation allowance, partially offset by utilization of federal and state NOLs. Deferred tax assets and valuation allowance Net deferred tax balance — As of December 31, 2019 and 2018, NRG recorded a net deferred tax asset, excluding valuation allowance, of $3.5 billion and $3.8 billion, respectively. The Company believes certain state net operating losses may not be realizable under the more-likely-than-not measurement and as such, a valuation allowance was recorded as of December 31, 2019 as discussed below. NOL carryforwards — As of December 31, 2019, the Company had tax effected cumulative U.S. NOLs consisting of carryforwards for federal and state income tax purposes of $2.1 billion and $360 million, respectively. The Company estimates it will need to generate future taxable income to fully realize the net federal deferred tax asset before the expiration of certain carryforwards commences in 2031. In addition, NRG has cumulative foreign NOL carryforwards of $105 million with no expiration date. Valuation allowance — As of December 31, 2019, the Company's tax-effected valuation allowance was $242 million, consisting of state NOL carryforwards and foreign NOL carryforwards. The valuation allowance was recorded based on the assessment of cumulative and forecasted pre-tax book earnings and the future reversal of existing taxable temporary differences. Taxes Receivable and Payable As of December 31, 2019, NRG recorded a current tax payable of $13 million that represents a tax liability due for state income taxes that is primarily comprised of Texas margin tax. NRG has a tax receivable of $1 million, comprised of refunds due from state income tax estimated payments and return filings. Uncertain tax benefits NRG has identified uncertain tax benefits with after-tax value of $15 million and $26 million as of December 31, 2019 and 2018, for which NRG has recorded a non-current tax liability of $17 million and $30 million, respectively. The Company recognizes interest and penalties related to uncertain tax benefits in income tax expense. The Company recognized expense of $1 million related to interest in each of the years ended December 31, 2019, 2018 and 2017. As of December 31, 2019 and 2018, NRG had cumulative interest and penalties related to these uncertain tax benefits of $2 million and $4 million, respectively. Tax jurisdictions — 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. The Company is no longer subject to U.S. federal income tax examinations for years prior to 2016. With few exceptions, state and local income tax examinations are no longer open for years before 2011. The following table summarizes uncertain tax benefits activity: As of December 31, (In millions) 2019 2018 Balance as of January 1 $ 26 $ 30 Increase due to current year positions 2 4 Settlements, payments and statute closure (13) (8) Uncertain tax benefits as of December 31 $ 15 $ 26

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement, Noncash Expense [Abstract]
Stock-Based Compensation	Stock-Based Compensation NRG Energy, Inc. Long-Term Incentive Plan On April 27, 2017, the NRG LTIP was amended to increase the number of shares available for issuance by 3,000,000. As of December 31, 2019 and 2018, a total of 25,000,000 shares of NRG common stock were authorized for issuance under the NRG LTIP. There were 9,935,750 and 8,564,611 shares of common stock remaining available for grants under the NRG LTIP as of December 31, 2019 and 2018, respectively. The NRG LTIP is subject to adjustments in the event of reorganization, recapitalization, stock split, reverse stock split, stock dividend, and a combination of shares, merger or similar change in NRG's structure or outstanding shares of common stock. Upon adoption of the amended NRG LTIP effective April 27, 2017, no shares of NRG common stock remain available for future issuance under the NRG GenOn LTIP. As of December 31, 2019 and 2018, there were 319,264 and 520,182 shares of common stock remaining available for grants under the NRG GenOn LTIP, respectively. Restricted Stock Units As of December 31, 2019, RSUs granted under the Company's LTIPs typically have three Units Weighted Average Grant Date Fair Value per Unit Non-vested at December 31, 2018 1,458,082 $ 16.16 Granted 266,938 37.37 Forfeited (73,905) 24.73 Vested (933,876) 14.20 Non-vested at December 31, 2019 717,239 25.56 The total fair value of RSUs vested during the years ended December 31, 2019, 2018, and 2017 was $36 million, $42 million, and $19 million, respectively. The weighted average grant date fair value of RSUs granted during the years ended December 31, 2019, 2018, and 2017 was $37.37, $28.90, and $12.44, respectively. Deferred Stock Units DSUs represent the right of a participant to be paid one share of NRG common stock at the end of a deferral period established under the terms of the award. DSUs granted under the Company's LTIPs are fully vested at the date of issuance. Fair value of the DSUs, which is based on the closing price of NRG common stock on the date of grant, is recorded as compensation expense in the period of grant. The following table summarizes the Company's outstanding DSU awards and changes during the year: Units Weighted Average Grant Date Fair Value per Unit Outstanding at December 31, 2018 331,915 $ 22.94 Granted 57,630 34.84 Converted to Common Stock (58,322) 28.93 Outstanding at December 31, 2019 331,223 23.98 The aggregate intrinsic values for DSUs outstanding as of December 31, 2019, 2018, and 2017 were approximately $13 million, $13 million, and $12 million, respectively. The aggregate intrinsic values for DSUs converted to common stock for the years ended December 31, 2019, 2018, and 2017 were $2 million, $6 million, and $4 million, respectively. The weighted average grant date fair value of DSUs granted during the years ended December 31, 2019, 2018, and 2017 was $34.84, $33.43, and $16.76, respectively. Performance Stock Units PSUs entitle the recipient to stock upon vesting. The amount of the award is subject to the Company's achievement of certain performance measures over the vesting period. PSUs include RPSUs and MSUs. As of December 31, 2019, non-vested PSUs consist primarily of RPSUs. Relative Performance Stock Units — RPSUs are restricted grants where the quantity of shares increases and decreases alongside the Company's Total Shareholder Return, or TSR, relative to the TSR of the Company's current proxy peer group and the total returns of select indexes, or Peer Group. Each RPSU represents the potential to receive NRG common stock after the completion of the performance period, typically three Market Stock Units — MSUs are restricted grants where the quantity of shares increases and decreases alongside the Company's TSR. Each MSU represents the potential to receive NRG common stock after the completion of the performance period, typically three years of service from the date of grant. The number of shares of common stock to be paid as of the vesting date for each MSU is : (i) zero shares, if the TSR has decreased by more than 25% over the performance period, (ii) three-quarters of one share, if the TSR has decreased by 25% over the performance period; (iii) interpolated between three-quarters of one share and one share, if the TSR has decreased less than 25% over the performance period; (iv) one share, if there is no change in TSR over the performance period; (v) interpolated between one share and two shares, if TSR increases less than 100% during the performance period; and (vi) two shares, if the TSR increases 100% over the performance period. The value of the common stock on the date of grant was based on the closing price of NRG common stock on the date of grant. The Company last granted MSUs during the year ended December 31, 2016. The following table summarizes the Company's non-vested PSU awards and changes during the year: Units Weighted Average Grant-Date Fair Value per Unit Non-vested at December 31, 2018 1,710,634 $ 19.12 Granted (a) 936,889 22.50 Forfeited (37,526) 23.04 Vested (b) (1,409,456) 14.72 Non-vested at December 31, 2019 (c) 1,200,541 26.65 (a) The weighted average grant date fair value per unit includes RPSUs that were granted during 2019 with grant date fair value of $45.77 and MSUs with 2016 grant date fair value of $14.72, that due to vesting at 200%, were considered additional grants in 2019 (b) MSUs granted during 2016 vested during 2019 at 200% (c) Non-vested units includes 8,645 MSUs The weighted average grant date fair value of PSUs granted during the years ended December 31, 2019, 2018, and 2017, was $22.50, $35.36, and $15.91, respectively. The fair value of PSUs is estimated on the date of grant using a Monte Carlo simulation model and expensed over the service period, which equals the vesting period. Significant assumptions used in the fair value model with respect to the Company's PSUs are summarized below: 2019 2018 2017 2016 RPSUs RPSUs RPSUs MSUs Expected volatility 40.72 % 47.52 % 43.96 % 34.33 % Expected term (in years) 3 3 3 3 Risk free rate 2.45 % 2.01 % 1.5 % 1.31 % For the years ended December 31, 2019 and 2018, expected volatility is calculated based on NRG's historical stock price volatility data over the period commensurate with the expected term of the PSU, which equals the vesting period. Non-Qualified Stock Options All NQSOs granted under the Company's LTIP were fully vested as of December 31, 2019, 2018, and 2017. No NQSOs were granted in 2019, 2018 or 2017. NRG recognizes compensation costs for NQSOs over the requisite service period for the entire award. No compensation expense was recognized during 2019, 2018 and 2017 as it was fully recognized in prior years. The maximum contractual term is 10 years for NRG's outstanding NQSOs. The following table summarizes the Company's NQSO activity and changes during the year: Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in millions) Outstanding at December 31, 2018 279,934 $ 25.04 2 $ 4 Expired (8,254) 26.76 Exercised (137,282) 24.67 Outstanding at December 31, 2019 134,398 25.31 1 2 Exercisable at December 31, 2019 134,398 25.31 1 2 The following table summarizes the total intrinsic value of options exercised and the cash received from the exercises of options: Year Ended December 31, (In millions) 2019 2018 2017 Total intrinsic value of options exercised $ 2 $ 10 $ 1 Cash received from options exercised 3 24 4 Supplemental Information The following table summarizes NRG's total compensation expense recognized for the years presented, as well as total non-vested compensation costs not yet recognized and the period over which this expense is expected to be recognized as of December 31, 2019, for each of the types of awards issued under the LTIPs. Minimum tax withholdings of $36 million, $19 million, and $5 million for the years ended December 31, 2019, 2018, and 2017, respectively, are reflected as a reduction to additional paid-in capital on the Company's consolidated balance sheets. Non-vested Compensation Cost (In millions, except weighted average data) Compensation Expense Unrecognized Total Cost Weighted Average Recognition Period Remaining (In years) Year Ended December 31, As of December 31, Award 2019 2018 2017 2019 2019 RSUs 9 12 15 8 1.06 DSUs 2 2 2 — 0.00 MSUs — 4 5 — 0.50 RPSUs 10 7 3 9 0.71 PRSUs (a) 11 16 13 10 1.05 Total (b) $ 32 $ 41 $ 38 $ 27 Tax detriment recognized $ (12) $ (4) $ (5) (a) Phantom Restricted Stock Units, PRSUs, are liability-classified time-based awards that typically vest ratably over a three

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2019
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: Year Ended December 31, (In millions) 2019 2018 2017 Revenues from Related Parties Included in Operating Revenues Gladstone $ 4 $ 3 $ 3 GenConn (a) — 4 5 Ivanpah (b) 35 20 — Midway-Sunset 5 5 — Total $ 44 $ 32 $ 8 (a) As of August 31, 2018, NRG no longer had an ownership interest in GenConn as a result of the sale of its ownership interests in NRG Yield, Inc. and its Renewables Platform (b) Also includes fees under project management agreements with each project company. Ivanpah became a related party to NRG upon deconsolidation in the second quarter of 2018 Services Agreement and Transition Services Agreement with GenOn The Company provided GenOn with various management, personnel and other services, which included human resources, regulatory and public affairs, accounting, tax, legal, information systems, treasury, risk management, commercial operations, and asset management, as set forth in the services agreement with GenOn, or the Services Agreement. The annual fees under the Services Agreement was approximately $193 million and management had concluded that this method of charging overhead costs was reasonable. In connection with the Restructuring Support Agreement in 2017, NRG agreed to provide shared services to GenOn under the Services Agreement for an adjusted annualized fee of $84 million. In December 2017, in conjunction with the confirmation of the GenOn Entities' plan of reorganization, the Services Agreement was terminated and replaced by the transition services agreement. Under the transition services agreement, NRG provided the shared services and other separation services at an annualized rate of $84 million, subject to certain credits and adjustments. GenOn provided notice to NRG of its intent to terminate the transition services agreement effective August 15, 2018 and in connection with the settlement agreement described in Note 4, Acquisitions, Discontinued Operations and Dispositions , all amounts owed and payable to NRG were settled against the $28 million credit provided for in the Restructuring Support Agreement. For the year ended December 31, 2018 , NRG recorded approximately $53 million, under the transition services agreement against selling, general and administrative expenses post-Chapter 11 Filing. For the year ended December 31, 2017 , NRG recorded other income - affiliate related to these services of $87 million prior to the Chapter 11 Filing and $42 million against selling, general and administrative expenses post-Chapter 11 Filing. Credit Agreement with GenOn NRG and GenOn were party to a secured intercompany revolving credit agreement. The intercompany revolving credit agreement provided for a $500 million revolving credit facility, all of which was available for revolving loans and letters of credit. As a result of the GenOn bankruptcy, no additional revolving loans or letters of credit were available to GenOn. As of December 31, 2017, $92 million of letters of credit were issued and outstanding. As a result of the GenOn Settlement, as further described in Note 4 , Acquisitions, Discontinued Operations and Dispositions, outstanding borrowings were repaid to NRG, except for certain LCs issued which are further discussed below. The facility was terminated on December 14, 2018. On December 7, 2018, NRG, GenOn and REMA entered into an agreement to support the outstanding LCs from the intercompany revolving credit agreement previously issued. As of December 31, 2019, $14 million was outstanding. GenOn and REMA have provided support for these outstanding LCs through back-to-back letters of credit and cash collateral. The outstanding letters of credit will continue to accrue any contractual fees and expenses until they are terminated.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Coal, Gas and Transportation Commitments NRG has entered into long-term contractual arrangements to procure fuel and transportation services for the Company's generation assets. As of December 31, 2019, the Company's minimum commitments under such outstanding agreements are estimated as follows: Period (In millions) 2020 $ 124 2021 125 2022 73 2023 53 2024 62 Thereafter 139 Total (a) $ 576 (a) Actual coal, gas and transportation purchases are significantly higher than these estimated minimum unconditional long- term firm commitments For the years ended December 31, 2019, 2018, and 2017, the Company purchased $1.2 billion, $1.2 billion, and $1.1 billion, respectively under such arrangements. Purchased Power Commitments NRG has purchased power contracts of various quantities and durations, including renewable purchased power agreements under PPAs with third-party project developers, that are not classified as derivative assets and liabilities and do not qualify as operating leases. These contracts are not included in the consolidated balance sheet as of December 31, 2019. Minimum purchase commitment obligations are as follows as of December 31, 2019: Period (In millions) 2020 $ 35 2021 49 2022 68 2023 56 2024 56 Thereafter 349 Total $ 613 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 hedge agreements for forward sales of power or gas used as a proxy for power. To the extent that the underlying hedge positions for a counterparty are out-of-the-money to NRG, the counterparty would have a claim under the first lien program. As of December 31, 2019, hedges under the first lien were in-the-money for NRG on a counterparty aggregate basis. Jewett Mine Lignite Contract The Company's Limestone facility historically burned lignite obtained from the Jewett mine, which was operated by Texas Westmoreland Coal Co., or TWCC. On or about March 15, 2019, the Jewett mine and related lignite supply agreement with NRG were acquired by Westmoreland Mining LLC pursuant to a plan of reorganization confirmed by the U.S. Bankruptcy Court for the Southern District of Texas. Active mining under the lignite supply agreement ceased as of December 31, 2016; however, under the terms of the lignite supply agreement, the mine operator remains responsible for undertaking reclamation activities and NRG is responsible for reclamation costs. NRG has recorded an adequate ARO liability. The Railroad Commission of Texas has imposed a bond obligation of approximately $99 million for the reclamation of the Jewett mine, which NRG supports through surety bonds. The cost of the reclamation may exceed the value of the bonds. Additionally, the lignite supply agreement obligates NRG to provide additional performance assurance if required by the Railroad Commission of Texas. Nuclear Insurance STP maintains required insurance coverage for liability claims arising from nuclear incidents pursuant to the Price-Anderson Act. The current liability limit per incident is $13.9 billion, subject to change to account for the effects of inflation and the number of licensed reactors. An inflation adjustment must be made at least once every five years with the next due no later than September 10, 2023. Under the Price-Anderson Act, owners of nuclear power plants in the U.S. are required to purchase primary insurance limits of $450 million for each operating site. In addition, the Price-Anderson Act requires an additional layer of protection through mandatory participation in a retrospective rating plan for power reactors resulting in an additional $13.5 billion in funds available for public liability claims. The current maximum assessment per incident, per reactor, is approximately $138 million, taking into account a 5% adjustment for administrative fees, payable at approximately $21 million per year, per reactor. NRG would be responsible for 44% of the maximum assessment, or $9 million per year, per reactor, and a maximum of $61 million per incident. In addition, the U.S. Congress retains the ability to impose additional financial requirements on the nuclear industry to pay liability claims that exceed $14 billion for a single incident. The liabilities of the co-owners of STP with respect to the retrospective premium assessments for nuclear liability insurance are joint and several. STP purchases insurance for property damage and site decontamination cleanup costs from Nuclear Electric Insurance Limited, or NEIL, and European Mutual Association for Nuclear Insurance, or EMANI, both of which are industry mutual insurance companies, of which STP is a member. STP has purchased $2.75 billion in limits for nuclear events and $1.0 billion in limits for non-nuclear events. The nuclear event limit remains the maximum available from NEIL. The upper $1.25 billion in nuclear events limits (excess of the first $1.5 billion in nuclear events limits) is a single limit blanket policy shared with two Diablo Canyon nuclear reactors, which have no affiliation with the Company. This shared limit is not subject to automatic reinstatement in the event of a loss. The NEIL primary policy covers both nuclear and non-nuclear property damage events, and a NEIL companion policy provides Accidental Outage coverage for the co-owners of STP's lost revenue following a property damage event, at a weekly indemnity limit of $2.5 million per unit up to a maximum of $274 million nuclear per unit and $184 million non-nuclear per unit, and is subject to an eight-week waiting period. NRG also purchases an Accidental Outage policy from NEIL, which provides protection for lost revenue due to an insurable event. This coverage allows for reimbursement up to $1.98 million per week per unit up to a maximum of $216 million nuclear and $144 million non-nuclear, and is subject to an eight-week waiting period. Under the terms of the NEIL and EMANI policies, member companies may be assessed up to ten and six times their annual premiums respectively if the NEIL or EMANI Board of Directors determines their surplus has been depleted due to the payment of property losses at any of the licensed reactors in a single policy year. NEIL and EMANI require that their members maintain an investment grade credit rating or insure their annual retrospective obligation by providing a financial guarantee, letter of credit, deposit premium, or an insurance policy. NRG has purchased an insurance policy from NEIL and EMANI to guarantee the Company's obligation; however note the NEIL aspect of this insurance will only respond to retrospective premium adjustments assessed within twenty-four 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 24, Regulatory Matters , and Note 25, 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 its currently recorded accruals and that such difference 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. Midwest Generation Asbestos Liabilities — The Company, through its subsidiaries, settled the indemnification claims brought by Commonwealth Edison Company and Exelon Generation Company LLC (collectively, "ComEd") as a result of the Company's acquisition of EME. Pursuant to a settlement agreement dated as of May 29, 2019, the Company paid $26 million to ComEd during the second quarter of 2019, which was previously accrued. In addition, ComEd released all claims that were or could have been asserted in its claims in the EME bankruptcy case and certain of the Company's subsidiaries released all permissive and compulsory counter claims they could have asserted in response to the ComEd claims. 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 Louisiana Generating, L.L.C., or LaGen, in the United States District Court for the Middle District of Louisiana. The plaintiffs claim 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 seek damages for the alleged improper charges and a declaration as to which charges are proper under the contract. In February 2020, the court dismissed this lawsuit without prejudice for lack of subject matter jurisdiction. 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. 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. XOOM Energy Litigation — XOOM is a defendant in two purported class action lawsuits pending in Maryland and New York. The plaintiffs generally claim that they did not receive the savings they were promised in their natural gas and electricity bills. The parties in the Maryland lawsuit are briefing summary judgment and class certification. In the New York case, XOOM filed a motion to dismiss, which the court granted on September 21, 2018, later entering judgment in XOOM's favor on September 24, 2018. The plaintiffs in the New York case appealed to the U.S. Court of Appeals for the Second Circuit. On July 26, 2019, the Second Circuit reversed the judgment of the district court and remanded to the district court with instructions that plaintiffs be permitted to proceed on their proposed amended complaint. This matter was known and accrued for at the time of the acquisition.

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2019
Regulatory Matters Disclosure [Abstract]
Regulatory Matters	Regulatory Matters NRG operates in a highly regulated industry and is subject to regulation by various federal and state agencies. As such, NRG is affected by regulatory developments at both the federal and state 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 businesses. 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 SDG&E 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. It required NRG to retain communications related to multiple generating units in the South Central region. Since sending the notice, FERC has been investigating potential violations of MISO rules involving bidding for the Big Cajun 2 facility, as well as other aspects of NRG’s operations in MISO. 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. We expect a preliminary finding from FERC in 2020.

Environmental Matters

Environmental Matters	12 Months Ended
	Dec. 31, 2019
Environmental Matters Disclosure [Abstract]
Environmental Matters	Environmental Matters Air On July 8, 2019, the EPA promulgated the Affordable Clean Energy (ACE) rule, which rescinded the Clean Power Plan (CPP), which 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. Numerous parties have challenged the ACE rule in the D.C. Circuit and numerous parties have filed petitions for reconsideration with the EPA. Water Effluent Limitations Guidelines — In November 2015, the EPA revised the Effluent Limitations Guidelines for Steam Electric Generating Facilities, which would have imposed more stringent requirements (as individual permits were renewed) for wastewater streams from flue gas desulfurization (FGD), fly ash, bottom ash, and flue gas mercury control. On September 18, 2017, the EPA promulgated a final rule that, among other things, postpones 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 completes its next rulemaking. On April 12, 2019, the United States Court of Appeals for the Fifth Circuit addressed challenges to the rule brought by several environmental groups related to legacy wastewaters and coal ash leachate and remanded portions of the rule to the EPA. On November 22, 2019, the EPA proposed amending the 2015 ELG rule by: (x) decreasing the stringency of the selenuim limit (but increasing the stringency of the nitrate and mercury limits) for FGD wastewater; (y) relaxing the zero-discharge requirement for bottom ash transport water; and (z) changing several deadlines. The Company has eliminated its estimate of the environmental capital expenditures that would have been required to comply with permits incorporating the revised guidelines. The Company will revisit these estimates after the EPA finalizes revisions to the rule. 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 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. On August 14, 2019, the EPA proposed targeted changes to the April 2015 Rule including changes to address the August 2018 D.C. Circuit decision. On December 2, 2019, the EPA released for comment "Closure Part A Proposal" to revise the CCR Rule to address the D.C. Circuit's 2018 decision regarding the adequacy of clay-lined impoundments, obligations to close all unlined impoundments and related deadlines. On February 20, 2020, the EPA proposed the framework for developing and implementing a federal permit program for states that are not approved to administer the CCR rule. We anticipate that the EPA will promulgate new regulations to address these and other issues as it reconsiders other aspects of the existing rule. The Company will determine estimates of the cost of compliance after the rule is revised.

Cash Flow Information

Cash Flow Information	12 Months Ended
	Dec. 31, 2019
Supplemental Cash Flow Information [Abstract]
Cash Flow Information	Cash Flow Information Detail of supplemental disclosures of cash flow and non-cash investing and financing information was: Year Ended December 31, (In millions) 2019 2018 2017 Interest paid, net of amount capitalized $ 372 $ 436 $ 543 Income taxes paid, net of refunds 8 9 9 Non-cash investing activities: Additions to fixed assets for accrued capital expenditures 1 20 19

Guarantees

Guarantees	12 Months Ended
	Dec. 31, 2019
Guarantees [Abstract]
Guarantees	Guarantees The following table summarizes the maximum potential exposures that can be estimated for NRG's guarantees, indemnities, and other contingent liabilities by maturity: By Remaining Maturity at December 31, (In millions) 2019 Guarantees Under 1 Year 1-3 Years 3-5 Years Over 5 Years Total 2018 Total Letters of credit and surety bonds (a) $ 878 $ 115 $ 31 $ — $ 1,024 $ 1,253 Asset sales guarantee obligations 4 490 — 204 698 793 Other guarantees 77 5 — 206 288 721 Total guarantees $ 959 $ 610 $ 31 $ 410 $ 2,010 $ 2,767 (a) December 31, 2019 includes $14 million of letter of credit and surety bonds for the benefit of GenOn where NRG holds cash or letter of credit to back stop the liability Letters of credit and surety bonds — As of December 31, 2019, NRG and its consolidated subsidiaries were contingently obligated for a total of $1.0 billion under letters of credit and surety bonds. Most of these letters of credit and surety bonds are issued in support of the Company's obligations to perform under commodity agreements and obligations associated with future closure and maintenance of ash sites, as well as for financing or other arrangements. A majority of these letters of credit and surety bonds expire within one The material indemnities, within the scope of ASC 460, are as follows: Asset sales — The purchase and sale agreements which govern NRG's asset or share investments and divestitures customarily contain guarantees and indemnifications of the transaction to third parties. The contracts indemnify the parties for liabilities incurred as a result of a breach of a representation or warranty by the indemnifying party, or as a result of a change in tax laws. These obligations generally have a discrete term and are intended to protect the parties against risks that are difficult to predict or estimate at the time of the transaction. In several cases, the contract limits the liability of the indemnifier. NRG has no reason to believe that the Company currently has any material liability relating to such routine indemnification obligations, except as described in Note 4, Acquisitions, Discontinued Operations and Dispositions. Other guarantees — NRG has issued other guarantees of obligations including payments under certain agreements with respect to certain of its unconsolidated subsidiaries, payment or performance by fuel providers and payment or reimbursement of credit support and deposits. The Company does not believe that it will be required to perform under these guarantees. Other indemnities — Other indemnifications NRG has provided cover operational, tax, litigation and breaches of representations, warranties and covenants. NRG has also indemnified, on a routine basis in the ordinary course of business, consultants or other vendors who have provided services to the Company. NRG's maximum potential exposure under these indemnifications can range from a specified dollar amount to an indeterminate amount, depending on the nature of the transaction. Total maximum potential exposure under these indemnifications is not estimable due to uncertainty as to whether claims will be made or how they will be resolved. NRG does not have any reason to believe that the Company will be required to make any material payments under these indemnity provisions. Because many of the guarantees and indemnities NRG issues to third parties and affiliates do not limit the amount or duration of its obligations to perform under them, there exists a risk that the Company may have obligations in excess of the amounts described above. For those guarantees and indemnities that do not limit the Company's liability exposure, it may not be able to estimate what the Company's liability would be, until a claim is made for payment or performance, due to the contingent nature of these contracts.

Jointly Owned Plants

Jointly Owned Plants	12 Months Ended
	Dec. 31, 2019
Jointly Owned Plants Disclosure [Abstract]
Jointly Owned Plants	Jointly Owned Plants Certain NRG subsidiaries own undivided interests in jointly-owned plants, as described below. These plants are maintained and operated pursuant to their joint ownership participation and operating agreements. NRG is responsible for its subsidiaries' share of operating costs and direct expenses and includes its proportionate share of the facilities and related revenues and direct expenses in these jointly-owned plants in the corresponding balance sheet and income statement captions of the Company's consolidated financial statements. The following table summarizes NRG's proportionate ownership interest in the Company's jointly-owned facilities: (In millions unless otherwise stated) As of December 31, 2019 Ownership Interest Property, Plant & Equipment Accumulated Depreciation Construction in Progress South Texas Project Units 1 and 2, Bay City, TX 44.00 % $ 413 $ (206) $ 8 Cedar Bayou Unit 4, Baytown, TX 50.00 % 218 (93) 7

Unaudited Quarterly Financial D

Unaudited Quarterly Financial Data	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Unaudited Quarterly Financial Data	Unaudited Quarterly Financial Data Refer to Note 4, Acquisitions, Discontinued Operations and Dispositions , Note 11, Asset Impairments , and Note 20 , Income Taxes , for a description of the effect of unusual or infrequently occurring events during the quarterly periods. Summarized unaudited quarterly financial data is as follows: Quarter Ended 2019 (In millions, except per share data) December 31 September 30 June 30 March 31 Operating revenues $ 2,195 $ 2,996 $ 2,465 $ 2,165 Operating income 209 540 320 221 Net income from continuing operations 3,463 374 189 94 (Loss)/income from discontinued operations (78) (2) 13 388 Net income 3,385 372 202 482 Less: Net income attributable to noncontrolling interests and redeemable noncontrolling interests 2 — 1 — Income available to Common Stockholders $ 3,383 $ 372 $ 201 $ 482 Weighted average number of common shares outstanding — basic 251 254 265 278 (Loss)/income from discontinued operations per weighted average common share — basic $ (0.31) $ (0.01) $ 0.05 $ 1.39 Net Income per weighted average common share — basic $ 13.48 $ 1.46 $ 0.76 $ 1.73 Weighted average number of common shares outstanding — diluted 253 256 267 280 (Loss)/income from discontinued operations per weighted average common share — diluted $ (0.31) $ (0.01) $ 0.05 $ 1.38 Net income per weighted average common share — diluted $ 13.37 $ 1.45 $ 0.75 $ 1.72 Quarter Ended 2018 (In millions, except per share data) December 31 September 30 June 30 March 31 Operating revenues $ 1,992 $ 2,960 $ 2,461 $ 2,065 Operating income 49 398 174 361 Net (loss)/income from continuing operations (93) 287 27 238 Income/(loss) from discontinued operations 80 (336) 69 (5) Net (loss)/income (13) (49) 96 233 Less: Net (loss)/income attributable to noncontrolling interests and redeemable noncontrolling interests (2) 23 24 (46) (Loss)/income available to Common Stockholders $ (11) $ (72) $ 72 $ 279 Weighted average number of common shares outstanding — basic 289 299 310 318 Income/(loss) from discontinued operations per weighted average common share — basic $ 0.28 $ (1.12) $ 0.22 $ (0.02) Net (loss)/income per weighted average common share — basic $ (0.04) $ (0.24) $ 0.23 $ 0.88 Weighted average number of common shares outstanding — diluted 289 299 314 322 Income/(loss) from discontinued operations per weighted average common share — diluted $ 0.28 $ (1.12) $ 0.22 $ (0.02) Net (loss)/income per weighted average common share — diluted $ (0.04) $ (0.24) $ 0.23 $ 0.87

Condensed Consolidating Financi

Condensed Consolidating Financial Information	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Condensed Consolidating Financial Information	Condensed Consolidating Financial Information As of December 31, 2019, the Company had outstanding $4.4 billion of Senior Notes due 2026 to 2048 and outstanding $1.1 billion of Senior Secured First Lien Notes due from 2024 to 2029, as shown in Note 13, Debt and Finance Leases. These Senior Notes and Senior Secured First Lien Notes are guaranteed by certain of NRG's current and future 100% owned domestic subsidiaries, or guarantor subsidiaries. These guarantees are both joint and several. The non-guarantor subsidiaries include all of NRG's foreign subsidiaries and certain domestic subsidiaries. Unless otherwise noted below, each of the following guarantor subsidiaries fully and unconditionally guaranteed the Senior Notes and Senior Secured First Lien Notes as of December 31, 2019: Ace Energy, Inc. NRG Astoria Gas Turbine Operations Inc. NRG Oswego Harbor Power Operations Inc. Allied Home Warranty GP LLC NRG Business Services LLC NRG PacGen Inc. Allied Warranty LLC NRG Cabrillo Power Operations Inc. NRG Portable Power LLC Arthur Kill Power LLC NRG California Peaker Operations LLC NRG Power Marketing LLC Astoria Gas Turbine Power LLC NRG Cedar Bayou Development Company, LLC NRG Reliability Solutions LLC BidURenergy, Inc. NRG Connected Home LLC NRG Renter's Protection LLC Cabrillo Power I LLC NRG Connecticut Affiliate Services Inc. NRG Retail LLC Cabrillo Power II LLC NRG Construction LLC NRG Retail Northeast LLC Carbon Management Solutions LLC NRG Curtailment Solutions, Inc NRG Rockford Acquisition LLC Cirro Group, Inc. NRG Development Company Inc. NRG Saguaro Operations Inc. Cirro Energy Services, Inc. NRG Devon Operations Inc. NRG Security LLC Connecticut Jet Power LLC NRG Dispatch Services LLC NRG Services Corporation Devon Power LLC NRG Distributed Energy Resources Holdings LLC NRG SimplySmart Solutions LLC Dunkirk Power LLC NRG Distributed Generation PR LLC NRG South Central Affiliate Services Inc. Eastern Sierra Energy Company LLC NRG Dunkirk Operations Inc. NRG South Central Operations Inc. El Segundo Power, LLC NRG ECOKAP Holdings LLC NRG South Texas LP El Segundo Power II LLC NRG El Segundo Operations Inc. NRG Texas Gregory LLC Energy Alternatives Wholesale, LLC NRG Energy Labor Services LLC NRG Texas Holding Inc. Energy Choice Solutions LLC NRG Energy Services Group LLC NRG Texas LLC Energy Plus Holdings LLC NRG Energy Services International Inc. NRG Texas Power LLC Energy Plus Natural Gas LLC NRG Energy Services LLC NRG Warranty Services LLC Energy Protection Insurance Company NRG Generation Holdings, Inc. NRG West Coast LLC Everything Energy LLC NRG Greenco LLC NRG Western Affiliate Services Inc. Forward Home Security, LLC NRG Home & Business Solutions LLC O'Brien Cogeneration, Inc. II GCP Funding Company, LLC NRG Home Services LLC Oswego Harbor Power LLC Green Mountain Energy Company NRG Home Solutions LLC Reliant Energy Northeast LLC Gregory Partners, LLC NRG Home Solutions Product LLC Reliant Energy Power Supply, LLC Gregory Power Partners LLC NRG Homer City Services LLC Reliant Energy Retail Holdings, LLC Huntley Power LLC NRG HQ DG LLC Reliant Energy Retail Services, LLC Independence Energy Alliance LLC NRG Huntley Operations Inc. RERH Holdings, LLC Independence Energy Group LLC NRG Identity Protect LLC Saguaro Power LLC Independence Energy Natural Gas LLC NRG Ilion Limited Partnership Somerset Operations Inc. Indian River Operations Inc. NRG Ilion LP LLC Somerset Power LLC Indian River Power LLC NRG International LLC Texas Genco GP, LLC Meriden Gas Turbines LLC NRG Maintenance Services LLC Texas Genco Holdings, Inc. Middletown Power LLC NRG Mextrans Inc. Texas Genco LP, LLC Montville Power LLC NRG MidAtlantic Affiliate Services Inc. Texas Genco Services, LP NEO Corporation NRG Middletown Operations Inc. US Retailers LLC New Genco GP, LLC NRG Montville Operations Inc. Vienna Operations Inc. Norwalk Power LLC NRG North Central Operations Inc. Vienna Power LLC NRG Advisory Services LLC NRG Northeast Affiliate Services Inc. WCP (Generation) Holdings LLC NRG Affiliate Services Inc. NRG Norwalk Harbor Operations Inc. West Coast Power LLC NRG Arthur Kill Operations Inc. NRG Operating Services, Inc. NRG conducts much of its business through and derives much of its income from its subsidiaries. Therefore, the Company's ability to make required payments with respect to its indebtedness and other obligations depends on the financial results and condition of its subsidiaries and NRG's ability to receive funds from its subsidiaries. There are no restrictions on the ability of any of the guarantor subsidiaries to transfer funds to NRG. In addition, there may be restrictions for certain non-guarantor subsidiaries. The following condensed consolidating financial information presents the financial information of NRG Energy, Inc., the guarantor subsidiaries and the non-guarantor subsidiaries in accordance with Rule 3-10 under the SEC's Regulation S-X. The financial information may not necessarily be indicative of results of operations or financial position had the guarantor subsidiaries or non-guarantor subsidiaries operated as independent entities. In this presentation, NRG Energy, Inc. consists of parent company operations. Guarantor subsidiaries and non-guarantor subsidiaries of NRG are reported on an equity basis. For companies acquired, the fair values of the assets and liabilities acquired have been presented on a push-down accounting basis. In addition, the condensed parent company financial statements are provided in accordance with Rule 12-04, Schedule I of Regulation S-X, as the restricted net assets of NRG Energy, Inc.'s subsidiaries exceed 25 percent of the consolidated net assets of NRG Energy, Inc. These statements should be read in conjunction with the consolidated statements and notes thereto of NRG Energy, Inc. For a discussion of NRG Energy, Inc.'s long-term debt, see Note 13, Debt and Finance Leases , to the consolidated financial statements. For a discussion of NRG Energy, Inc.'s contingencies, see Note 23, Commitments and Contingencies , to the consolidated financial statements. For a discussion of NRG Energy, Inc.'s guarantees, see Note 27, Guarantees , NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the Year Ended December 31, 2019 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Operating Revenues Total operating revenues $ 8,041 $ 1,791 $ — $ (11) $ 9,821 Operating Costs and Expenses Cost of operations 5,936 1,351 27 (11) 7,303 Depreciation and amortization 212 130 31 — 373 Impairment losses 1 4 — — 5 Selling, general and administrative 466 83 278 — 827 Reorganization costs — — 23 — 23 Development costs — — 7 — 7 Total operating costs and expenses 6,615 1,568 366 (11) 8,538 Gain on sale of assets 1 — 6 — 7 Operating Income/(Loss) 1,427 223 (360) — 1,290 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 48 — 1,562 (1,610) — Equity in earnings of unconsolidated affiliates — 2 — — 2 Impairment losses on investments — (101) (7) — (108) Other income, net 23 12 31 — 66 Loss on debt extinguishment, net — (3) (48) — (51) Interest expense (14) (14) (385) — (413) Total other income/(expense) 57 (104) 1,153 (1,610) (504) Income from Continuing Operations Before Income Taxes 1,484 119 793 (1,610) 786 Income tax expense/(benefit) — 4 (3,338) — (3,334) Income from Continuing Operations 1,484 115 4,131 (1,610) 4,120 Income from discontinued operations, net of income tax 9 5 307 — 321 Net Income 1,493 120 4,438 (1,610) 4,441 Less: Net income attributable to redeemable noncontrolling interests — 3 — — 3 Net Income Attributable to NRG Energy, Inc. $ 1,493 $ 117 $ 4,438 $ (1,610) $ 4,438 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME For the Year Ended December 31, 2019 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Net Income $ 1,493 $ 120 $ 4,438 $ (1,610) $ 4,441 Other Comprehensive Loss, net of tax Foreign currency translation adjustments, net — (1) (1) 1 (1) Available-for-sale securities, net — — (19) — (19) Defined benefit plan, net (17) — (78) 17 (78) Other comprehensive loss (17) (1) (98) 18 (98) Comprehensive Income 1,476 119 4,340 (1,592) 4,343 Less: Comprehensive income attributable to redeemable noncontrolling interests — 3 — — 3 Comprehensive Income Attributable to NRG Energy, Inc. $ 1,476 $ 116 $ 4,340 $ (1,592) $ 4,340 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2019 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated Balance ASSETS Current Assets Cash and cash equivalents $ — $ 20 $ 325 $ — $ 345 Funds deposited by counterparties 32 — — — 32 Restricted cash 5 1 2 — 8 Accounts receivable, net 1,293 239 233 (740) 1,025 Inventory 272 111 — — 383 Derivative instruments 856 45 — (41) 860 Cash collateral posted in support of energy risk management activities 182 8 — — 190 Prepayments and other current assets 170 8 67 — 245 Total current assets 2,810 432 627 (781) 3,088 Property, plant and equipment, net 1,483 952 158 — 2,593 Other Assets Investment in subsidiaries 710 — 4,785 (5,495) — Equity investments in affiliates — 388 — — 388 Operating lease right-of-use assets, net 81 261 122 — 464 Goodwill 359 220 — — 579 Intangible assets, net 375 414 — — 789 Nuclear decommissioning trust fund 794 — — — 794 Derivative instruments 308 15 — (13) 310 Deferred income taxes 421 (19) 2,884 — 3,286 Other non-current assets 145 30 65 — 240 Total other assets 3,193 1,309 7,856 (5,508) 6,850 Total Assets $ 7,486 $ 2,693 $ 8,641 $ (6,289) $ 12,531 LIABILITIES AND STOCKHOLDERS' EQUITY Current Liabilities Current portion of long-term debt $ — $ 5 $ 83 $ — $ 88 Current portion of operating lease liabilities 20 32 21 — 73 Accounts payable 918 141 403 (740) 722 Derivative instruments 797 25 — (41) 781 Cash collateral received in support of energy risk management activities 32 — — — 32 Accrued expenses and other current liabilities 280 44 339 — 663 Total current liabilities 2,047 247 846 (781) 2,359 Other Liabilities Long-term debt 302 28 5,473 — 5,803 Non-current operating lease liabilities 64 301 118 — 483 Nuclear decommissioning reserve 298 — — — 298 Nuclear decommissioning trust liability 487 — — — 487 Derivative instruments 334 1 — (13) 322 Deferred income taxes — 17 — — 17 Other non-current liabilities 399 153 532 — 1,084 Total other liabilities 1,884 500 6,123 (13) 8,494 Total Liabilities 3,931 747 6,969 (794) 10,853 Redeemable noncontrolling interest in subsidiaries — 20 — — 20 Stockholders' Equity 3,555 1,926 1,672 (5,495) 1,658 Total Liabilities and Stockholders' Equity $ 7,486 $ 2,693 $ 8,641 $ (6,289) $ 12,531 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the Year Ended December 31, 2019 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Cash Flows from Operating Activities Net income $ 1,493 $ 120 $ 4,438 $ (1,610) $ 4,441 Income from discontinued operations 9 5 307 — 321 Net income from continuing operations 1,484 115 4,131 (1,610) 4,120 Adjustments to reconcile net income to net cash provided by operating activities: Distributions and equity in earnings of unconsolidated affiliates and consolidated subsidiaries (48) 14 (1,562) 1,610 14 Depreciation and amortization 212 130 31 — 373 Accretion of asset retirement obligations 43 8 — — 51 Provision for bad debts 78 17 — — 95 Amortization of nuclear fuel 52 — — — 52 Amortization of financing costs and debt discount/premiums — — 26 — 26 Adjustment for debt extinguishment — 3 48 — 51 Amortization of emission allowances 24 14 — — 38 Amortization of unearned equity compensation — — 20 — 20 Net gain on sale and disposal of assets (20) — (3) — (23) Impairment losses 1 105 7 — 113 Changes in derivative instruments 20 (24) 38 — 34 Changes in deferred income taxes and liability for uncertain tax benefits (525) (168) (2,660) — (3,353) Changes in collateral deposits in support of energy risk management activities 101 4 — — 105 Changes in nuclear decommissioning trust liability 37 — — — 37 Changes in other working capital (220) (118) (10) — (348) Cash provided by continuing operations 1,239 100 66 — 1,405 Cash provided/(used) by discontinued operations 17 (9) — — 8 Net Cash Provided by Operating Activities 1,256 91 66 — 1,413 Cash Flows from Investing Activities Intercompany dividends — — 2,513 (2,513) — Payments for acquisitions of businesses (355) — — — (355) Capital expenditures (164) (27) (37) — (228) Net proceeds from sale of emission allowances 11 — — — 11 Investments in nuclear decommissioning trust fund securities (416) — — — (416) Proceeds from sales of nuclear decommissioning trust fund securities 381 — — — 381 Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees 1 400 893 — 1,294 Changes in investments in unconsolidated affiliates — (91) — — (91) Net contributions to discontinued operations — (44) — — (44) Other — — 6 — 6 Cash (used)/provided by continuing operations (542) 238 3,375 (2,513) 558 Cash used by discontinued operations — (2) — — (2) Net Cash (Used)/Provided by Investing Activities (542) 236 3,375 (2,513) 556 Cash Flows from Financing Activities Intercompany dividends and transfers (751) (214) (1,548) 2,513 — Payments of dividends to common stockholders — — (32) — (32) Payments for share repurchase activity — — (1,440) — (1,440) Payments for debt extinguishment costs — — (26) — (26) Net distributions to redeemable noncontrolling interests from subsidiaries — (2) — — (2) Proceeds from issuance of common stock — — 3 — 3 Proceeds from issuance of long-term debt — — 1,916 — 1,916 Payments of debt issuance costs — — (35) — (35) Payments for short and long-term debt — (139) (2,432) — (2,571) Other (4) — — — (4) Cash used by continuing operations (755) (355) (3,594) 2,513 (2,191) Cash provided by discontinued operations — 43 — — 43 Net Cash Used by Financing Activities (755) (312) (3,594) 2,513 (2,148) Change in cash from discontinued operations 17 32 — — 49 Net Decrease in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties (58) (17) (153) — (228) Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at Beginning of Period 95 38 480 — 613 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at End of Period $ 37 $ 21 $ 327 $ — $ 385 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the Year Ended December 31, 2018 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Operating Revenues Total operating revenues $ 8,119 $ 1,385 $ — $ (26) $ 9,478 Operating Costs and Expenses Cost of operations 6,147 959 28 (26) 7,108 Depreciation and amortization 238 150 33 — 421 Impairment losses 6 93 — — 99 Selling, general and administrative 462 63 348 (74) 799 Reorganization costs 4 — 86 — 90 Development costs — 1 11 (1) 11 Total operating costs and expenses 6,857 1,266 506 (101) 8,528 Gain on sale of assets 4 28 — — 32 Operating Income/(Loss) 1,266 147 (506) 75 982 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 23 — 1,291 (1,314) — Equity in earnings/(losses) of unconsolidated affiliates — 10 (1) — 9 Impairment losses on investments — (15) — — (15) Other income/(expense), net 32 (13) (1) — 18 Loss on debt extinguishment, net — — (44) — (44) Interest expense (14) (49) (420) — (483) Total other income/(expense) 41 (67) 825 (1,314) (515) Income from Continuing Operations Before Income Taxes 1,307 80 319 (1,239) 467 Income tax expense/(benefit) 372 19 (384) — 7 Income from Continuing Operations 935 61 703 (1,239) 460 Income/(loss) from discontinued operations, net of income tax 62 75 (329) — (192) Net Income 997 136 374 (1,239) 268 Less: Net (loss)/income attributable to noncontrolling interests and redeemable noncontrolling interests — (181) 106 75 — Net Income Attributable to NRG Energy, Inc. $ 997 $ 317 $ 268 $ (1,314) $ 268 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME For the Year Ended December 31, 2018 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Net Income $ 997 $ 136 $ 374 $ (1,239) $ 268 Other Comprehensive Income/(Loss), net of tax Unrealized gain on derivatives, net — 29 9 (15) 23 Foreign currency translation adjustments, net (10) (10) (13) 22 (11) Available-for-sale securities, net — — 1 — 1 Defined benefit plan, net (9) — (35) 9 (35) Other comprehensive (loss)/income (19) 19 (38) 16 (22) Comprehensive Income 978 155 336 (1,223) 246 Less: Comprehensive (loss)/income attributable to noncontrolling interests and redeemable noncontrolling interests — (166) 104 76 14 Comprehensive Income Attributable to NRG Energy, Inc. $ 978 $ 321 $ 232 $ (1,299) $ 232 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2018 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated Balance ASSETS Current Assets Cash and cash equivalents $ 55 $ 28 $ 480 $ — $ 563 Funds deposited by counterparties 33 — — — 33 Restricted cash 7 10 — — 17 Accounts receivable. net 1,354 115 309 (754) 1,024 Inventory 278 134 — — 412 Derivative instruments 779 50 16 (81) 764 Cash collateral posted in support of energy risk management activities 275 12 — — 287 Prepayments and other current assets 180 32 90 — 302 Current assets - held-for-sale — 1 — — 1 Current assets - discontinued operations 177 20 — — 197 Total current assets 3,138 402 895 (835) 3,600 Property, plant and equipment, net 1,938 957 153 — 3,048 Other Assets Investment in subsidiaries 446 — 4,707 (5,153) — Equity investments in affiliates — 412 — — 412 Goodwill 359 214 — — 573 Intangible assets, net 422 169 — — 591 Nuclear decommissioning trust fund 663 — — — 663 Derivative instruments 296 4 22 (5) 317 Deferred income taxes 6 (143) 183 — 46 Other non-current assets 133 71 97 (12) 289 Non-current assets - held-for-sale — 77 — — 77 Non-current assets - discontinued operations 405 607 — — 1,012 Total other assets 2,730 1,411 5,009 (5,170) 3,980 Total Assets $ 7,806 $ 2,770 $ 6,057 $ (6,005) $ 10,628 LIABILITIES AND STOCKHOLDERS' EQUITY Current Liabilities Current portion of long-term debt and finance leases $ — $ 55 $ 17 $ — $ 72 Accounts payable 1,368 (185) 434 (754) 863 Derivative instruments 713 41 — (81) 673 Cash collateral received in support of energy risk management activities 33 — — — 33 Accrued expenses and other current liabilities 291 36 353 — 680 Current liabilities - held-for-sale — 5 — — 5 Current liabilities - discontinued operations 24 48 — — 72 Total current liabilities 2,429 — 804 (835) 2,398 Other Liabilities Long-term debt and finance leases 244 192 6,025 (12) 6,449 Nuclear decommissioning reserve 282 — — — 282 Nuclear decommissioning trust liability 371 — — — 371 Derivative instruments 306 3 — (5) 304 Deferred income taxes 112 61 (108) — 65 Other non-current liabilities 402 320 552 — 1,274 Non-current liabilities - held-for-sale — 65 — — 65 Non-current liabilities - discontinued operations 58 577 — — 635 Total other liabilities 1,775 1,218 6,469 (17) 9,445 Total Liabilities 4,204 1,218 7,273 (852) 11,843 Redeemable noncontrolling interest in subsidiaries — 19 — — 19 Stockholders' Equity 3,602 1,533 (1,216) (5,153) (1,234) Total Liabilities and Stockholders' Equity $ 7,806 $ 2,770 $ 6,057 $ (6,005) $ 10,628 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the Year Ended December 31, 2018 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Cash Flows from Operating Activities Net income $ 997 $ 136 $ 374 $ (1,239) $ 268 Income/(loss) from discontinued operations 62 75 (329) — (192) Net income from continuing operations 935 61 703 (1,239) 460 Adjustments to reconcile net income to net cash provided by operating activities: Distributions and equity in earnings of unconsolidated affiliates and consolidated subsidiaries (23) 47 (1,231) 1,253 46 Depreciation and amortization 238 150 33 — 421 Accretion of asset retirement obligations 28 10 — — 38 Provision for bad debts 79 6 — — 85 Amortization of nuclear fuel 48 — — — 48 Amortization of financing costs and debt discount/premiums — 6 23 — 29 Adjustment for debt extinguishment — — 44 — 44 Amortization of emission allowances and out-of-market contracts 36 9 — — 45 Amortization of unearned equity compensation — — 25 — 25 Net (gain)/loss on sale and disposal of assets (30) (20) 1 — (49) Impairment losses 5 109 — — 114 Changes in derivative instruments 25 15 11 (14) 37 Changes in deferred income taxes and liability for uncertain tax benefits 372 5 (372) — 5 Changes in collateral deposits in support of energy risk management activities (94) (11) — — (105) Changes in nuclear decommissioning trust liability 60 — — — 60 GenOn settlement, net of insurance proceeds — — (63) — (63) Net loss on deconsolidation of Agua Caliente and Ivanpah projects — 13 — — 13 Changes in other working capital (100) (166) 16 — (250) Cash provided/(used) by continuing operations 1,579 234 (810) — 1,003 Cash provided by discontinued operations 89 285 — — 374 Net Cash Provided/(Used) by Operating Activities 1,668 519 (810) — 1,377 Cash Flows from Investing Activities Intercompany dividends — — 2,006 (2,006) — Payments for acquisitions of businesses (40) (203) — — (243) Capital expenditures (192) (151) (45) — (388) Net proceeds from sale of emission allowances 19 — — — 19 Investments in nuclear decommissioning trust fund securities (572) — — — (572) Proceeds from sales of nuclear decommissioning trust fund securities 513 — — — 513 Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees 14 8 1,542 — 1,564 Deconsolidation of Agua Caliente and Ivanpah projects — (268) — — (268) Changes in investments in unconsolidated affiliates — (39) — — (39) Net contributions to discontinued operations — (60) — — (60) Other — — (6) — (6) Cash (used)/provided by continuing operations (258) (713) 3,497 (2,006) 520 Cash used by discontinued operations — (725) — — (725) Net Cash (Used)/Provided by Investing Activities (258) (1,438) 3,497 (2,006) (205) Cash Flows from Financing Activities Intercompany dividends and transfers (1,267) 86 (825) 2,006 — Payments of dividends to common stockholders — — (37) — (37) Payments for treasury stock — — (1,250) — (1,250) Payments for debt extinguishment costs — — (32) — (32) Net distributions to noncontrolling interests from subsidiaries — (16) — — (16) Proceeds from issuance of common stock — — 21 — 21 Proceeds from issuance of long-term debt — 163 937 — 1,100 Payments of debt issuance costs — — (19) — (19) Payments for short and long-term debt — (138) (1,596) — (1,734) Receivable from affiliate — — (26) — (26) Other — (4) — — (4) Cash (used)/provided by continuing operations (1,267) 91 (2,827) 2,006 (1,997) Cash provided by discontinued operations — 471 — — 471 Net Cash (Used)/Provided by Financing Activities (1,267) 562 (2,827) 2,006 (1,526) Effect of exchange rate changes on cash and cash equivalents — 1 — — 1 Change in cash from discontinued operations 89 31 — — 120 Net Increase/(Decrease) in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties 54 (387) (140) — (473) Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at Beginning of Period 41 425 620 — 1,086 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at End of Period $ 95 $ 38 $ 480 $ — $ 613 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the Year Ended December 31, 2017 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated Balance Operating Revenues Total operating revenues $ 7,818 $ 1,304 $ — $ (48) $ 9,074 Operating Costs and Expenses Cost of operations 5,998 862 72 (46) 6,886 Depreciation and amortization 343 221 32 — 596 Impairment losses 1,346 188 — — 1,534 Selling, general and administrative 410 64 364 (2) 836 Reorganization costs 6 — 38 — 44 Development costs — 4 18 — 22 Total operating costs and expenses 8,103 1,339 524 (48) 9,918 Other income - affiliate — — 87 — 87 Gain on sale of assets 4 12 — — 16 Operating Loss (281) (23) (437) — (741) Other Income/(Expense) Equity in earnings of consolidated subsidiaries 18 — 28 (46) — Equity in losses of unconsolidated affiliates — (10) (4) — (14) Impairment losses on investments — (75) (4) — (79) Other income, net 9 14 28 — 51 Loss on debt extinguishment, net — — (49) — (49) Interest expense (14) (91) (452) — (557) Total other income/(expense) 13 (162) (453) (46) (648) Loss from Continuing Operations Before Income Taxes (268) (185) (890) (46) (1,389) Income tax (benefit)/expense (598) (62) 616 — (44) Income/(Loss) from Continuing Operations 330 (123) (1,506) (46) (1,345) Income/(loss) from discontinued operations, net of income tax 91 (420) (663) — (992) Net Income/(Loss) 421 (543) (2,169) (46) (2,337) Less: Net loss attributable to noncontrolling interests and redeemable noncontrolling interests — (168) (16) — (184) Net Income/(Loss) Attributable to NRG Energy, Inc. $ 421 $ (375) $ (2,153) $ (46) $ (2,153) (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) For the Year Ended December 31, 2017 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Net Income/(Loss) $ 421 $ (543) $ (2,169) $ (46) $ (2,337) Other Comprehensive Income/(Loss), net of tax Unrealized gain on derivatives, net 1 13 25 (26) 13 Foreign currency translation adjustments, net 6 7 — (1) 12 Available-for-sale securities, net — — (8) — (8) Defined benefit plan, net (13) 30 46 (17) 46 Other comprehensive (loss)/income (6) 50 63 (44) 63 Comprehensive Income/(Loss) 415 (493) (2,106) (90) (2,274) Less: Comprehensive loss attributable to noncontrolling interest and redeemable noncontrolling interests — (103) (16) (60) (179) Comprehensive Income/(Loss) Attributable to NRG Energy, Inc. $ 415 $ (390) $ (2,090) $ (30) $ (2,095) (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the Year Ended December 31, 2017 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Cash Flows from Operating Activities Net income/(loss) $ 421 $ (543) $ (2,169) $ (46) $ (2,337) Income/(loss) from discontinued operations 91 (420) (663) — (992) Net income/(loss) from continuing operations 330 (123) (1,506) (46) (1,345) Adjustments to reconcile net income/(loss) to net cash provided by operating activities: Distributions and equity in earnings of unconsolidated affiliates and consolidated subsidiaries (18) 12 60 48 102 Depreciation and amortization 343 221 32 — 596 Accretion of asset retirement obligations 37 7 — — 44 Provision for bad debts 56 — 12 — 68 Amortization of nuclear fuel 51 — — — 51 Amortization of financing costs and debt discount/premiums — 13 16 — 29 Adjustment for debt extinguishment — — 49 — 49 Amortization of emission allowances and out-of-market contracts 42 12 — — 54 Amortization of unearned equity compensation — — 35 — 35 Net loss/(gain) on sale and disposal of assets 2 (11) — — (9) Impairment losses 1,346 264 4 — 1,614 Changes in derivative instruments (214) 50 (4) (2) (170) Changes in deferred income taxes and liability for uncertain tax benefits (300) (9) 322 — 13 Changes in collateral deposits in support of energy risk management activities (98) 18 — — (80) Changes in nuclear decommissioning trust liability 11 — — — 11 Changes in other working capital (15) (396) 205 — (206) Cash provided/(used) by continuing operations 1,573 58 (775) — 856 Cash provided by discontinued operations 116 638 — — 754 Net Cash Provided/(Used) by Operating Activities 1,689 696 (775) — 1,610 Cash Flows from Investing Activities Intercompany dividends — — 1,665 (1,665) — Payments for acquisitions of businesses (14) — — — (14) Capital expenditures (180) (43) (31) — (254) Net proceeds from sale of emission allowances 66 — — — 66 Investments in nuclear decommissioning trust fund securities (512) — — — (512) Proceeds from sales of nuclear decommissioning trust fund securities 501 — — — 501 Proceeds from sale of assets, net of cash disposed 33 54 343 — 430 Changes in investments in unconsolidated affiliates — (57) — — (57) Net distributions from discontinued operations — — 150 — 150 Other 18 12 — — 30 Cash (used)/provided by continuing operations (88) (34) 2,127 (1,665) 340 Cash used by discontinued operations (13) (966) — — (979) Net Cash (Used)/Provided by Investing Activities (101) (1,000) 2,127 (1,665) (639) Cash Flows from Financing Activities Intercompany dividends and transfers (1,447) (4) (214) 1,665 — Payment of dividends to common stockholders — — (38) — (38) Payments for debt extinguishment costs — — (42) — (42) Net distributions to noncontrolling interests from subsidiaries — (30) — — (30) Payments for issuance of common stock — — (2) — (2) Proceeds from issuance of long-term debt — 94 1,084 — 1,178 Payment of debt issuance costs — (2) (16) — (18) Payments for short and long-term debt — (183) (1,701) — (1,884) Receivable from affiliate — — (125) — (125) Other — (8) — — (8) Cash used by continuing operations (1,447) (133) (1,054) 1,665 (969) Cash used by discontinued operations (109) (60) — — (169) Net Cash Used by Financing Activities (1,556) (193) (1,054) 1,665 (1,138) Effect of exchange rate changes on cash and cash equivalents — (1) — — (1) Change in cash from discontinued operations (6) (388) — — (394) Net Increase/(Decrease) in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties 38 (110) 298 — 226 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at Beginning of Period 3 535 322 — 860 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at End of Period $ 41 $ 425 $ 620 $ — $ 1,086 (a) All significant intercompany transactions have been eliminated in consolidation

SCHEDULE II - VALUATION AND QUA

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS	12 Months Ended
	Dec. 31, 2019
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS	SCHEDULE II — VALUATION AND QUALIFYING ACCOUNTS For the Years Ended December 31, 2019, 2018, and 2017 (In millions) Balance at Beginning of Period Charged to Costs and Expenses Charged to Other Accounts Deductions Balance at End of Period Allowance for doubtful accounts, deducted from accounts receivable Year Ended December 31, 2019 $ 32 $ 95 $ — $ (84) (a) $ 43 Year Ended December 31, 2018 28 83 — (79) (a) 32 Year Ended December 31, 2017 28 57 — (57) (a) 28 Income tax valuation allowance, deducted from deferred tax assets Year Ended December 31, 2019 $ 3,794 $ (3,543) $ (9) $ — $ 242 Year Ended December 31, 2018 1,863 1,934 (128) 125 (b) 3,794 Year Ended December 31, 2017 4,116 (151) (15) (2,087) (c) 1,863 (a) Represents principally net amounts charged as uncollectible (b) Represents removal of NRG Yield, Inc. and its Renewables Platform due to their sale on August 31, 2018 (c) Represents deconsolidation of GenOn due to its petition for bankruptcy on June 14, 2017

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Discontinued Operations	Discontinued Operations On December 31, 2018, as described in Note 4, Acquisitions, Discontinued Operations and Dispositions , the Company concluded that the sale of its South Central Portfolio to Cleco, excluding the Cottonwood facility, met held-for-sale criteria and should be presented as a discontinued operation, as the sale represented a strategic shift in the business in which NRG operates. The financial information for all historical periods was recast in 2018 to reflect the presentation of these entities as discontinued operations. On August 31, 2018, as described in Note 4, Acquisitions, Discontinued Operations and Dispositions , the Company deconsolidated NRG Yield, Inc. and its Renewables Platform for financial reporting purposes. The financial information for all historical periods was recast in 2018 to reflect the presentation of these entities, as well as the Carlsbad project, as discontinued operations. As a result of the sale of NRG Yield, the Company no longer controls the Agua Caliente project. Due to this change in control, the Company deconsolidated the Agua Caliente project from its financial results and began accounting for the project as an equity method investment. On June 14, 2017, or the Petition Date, GenOn, along with GenOn Americas Generation and certain of their directly and indirectly-owned subsidiaries, or collectively the GenOn Entities, filed voluntary petitions for relief under the Chapter 11 Cases, of the U.S. Bankruptcy Code. As a result of the bankruptcy filings and beginning on June 14, 2017, GenOn and its subsidiaries were deconsolidated from NRG's consolidated financial statements. NRG determined that this disposal of GenOn and its subsidiaries was a discontinued operation and, accordingly, the financial information for all historical periods was recast to reflect GenOn as a discontinued operation. GenOn's plan of reorganization was confirmed on December 14, 2018.
Basis of Presentation	The Company's consolidated financial statements have been prepared in accordance with U.S. GAAP. The ASC, established by the FASB, is the source of authoritative U.S. GAAP to be applied by nongovernmental entities. In addition, the rules and interpretative releases of the SEC under authority of federal securities laws are also sources of authoritative U.S. GAAP for SEC registrants.
Principles of Consolidation	The consolidated financial statements include NRG's accounts and operations and those of its subsidiaries in which the Company has a controlling interest. All significant intercompany transactions and balances have been eliminated in consolidation. The usual condition for a controlling financial interest is ownership of a majority of the voting interests of an entity. However, a controlling financial interest may also exist through arrangements that do not involve controlling voting interests. As such, NRG applies the guidance of ASC 810, Consolidations, or ASC 810, to determine when an entity that is insufficiently capitalized or not controlled through its voting interests, referred to as a VIE, should be consolidated.
Segment Reporting	As described in Note 4, Acquisitions, Discontinued Operations and Dispositions
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents include highly liquid investments with an original maturity of three months or less at the time of purchase.
Funds Deposited by Counterparties	Funds Deposited by Counterparties 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
Restricted Cash	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. Year Ended December 31, (In millions) 2019 2018 2017 Cash and cash equivalents $ 345 $ 563 $ 770 Funds deposited by counterparties 32 33 37 Restricted cash 8 17 279 Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statements of cash flows $ 385 $ 613 $ 1,086
Trade Receivables and Allowance for Doubtful Accounts	Trade Receivables and Allowance for Doubtful AccountsTrade receivables are reported in the balance sheet at outstanding principal adjusted for any write-offs and the allowance for doubtful accounts. For its retail receivables, the Company accrues an allowance for doubtful accounts based on estimates of uncollectible revenues by analyzing counterparty credit ratings (for commercial and industrial customers), historical collections, accounts receivable aging and other factors. Accounts receivable balances are written-off against the allowance for doubtful accounts when a receivable is determined to be uncollectible. In addition, the Company considers a reserve for doubtful accounts based on the credit worthiness of the customers and continually reviews and adjusts for current economic trends that might impact the level of future credit losses. The reserve represents management's best estimate of uncollectible amounts.
Inventory	Inventory Inventory is valued at the lower of weighted average cost or market, and consists principally of fuel oil, coal and raw materials used to generate electricity or steam. The Company removes these inventories as they are used in the production of electricity or steam. Spare parts inventory is valued at weighted average cost. The Company removes these inventories when they are used for repairs, maintenance or capital projects. The Company expects to recover the fuel oil, coal, raw materials, and spare parts costs in the ordinary course of business. Finished goods inventory is valued at the lower of cost or net realizable value with cost being determined on a first-in first-out basis. The Company removes these inventories as they are sold to customers. Sales of inventory are classified as an operating activity in the consolidated statements of cash flows.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are stated at cost or, in the case of business acquisitions, fair value; however, impairment adjustments are recorded whenever events or changes in circumstances indicate that their carrying values may not be recoverable. NRG also classifies nuclear fuel related to the Company's 44% ownership interest in STP as part of the Company's property, plant, and equipment. Significant additions or improvements extending asset lives are capitalized as incurred, while repairs and maintenance that do not improve or extend the life of the respective asset are charged to expense as incurred. Depreciation, other than nuclear fuel, is computed using the straight-line method, while nuclear fuel is amortized based on units of production over the estimated useful lives. Certain assets and their related accumulated depreciation amounts are adjusted for asset retirements and disposals with the resulting gain or loss included in cost of operations in the consolidated statements of operations.
Asset Impairments	Asset Impairments Long-lived assets that are held and used are reviewed for impairment whenever events or changes in circumstances indicate carrying values may not be recoverable. Such reviews are performed in accordance with ASC 360. An impairment loss is indicated if the total future estimated undiscounted cash flows expected from an asset are less than its carrying value. An impairment charge is measured by the difference between an asset's carrying amount and fair value with the difference recorded in operating costs and expenses in the consolidated statements of operations. Fair values are determined by a variety of valuation methods, including third-party appraisals, sales prices of similar assets, and present value techniques. Investments accounted for by the equity method are reviewed for impairment in accordance with ASC 323, Investments-Equity Method and Joint Ventures , or ASC 323, which requires that a loss in value of an investment that is an other-than-temporary decline should be recognized. The Company identifies and measures losses in the value of equity method investments based upon a comparison of fair value to carrying value. For further discussion of these matters, refer to Note 11, Asset Impairments .
Development Costs and Capitalized Interest	Development Costs and Capitalized Interest Development costs include project development costs, which are expensed in the preliminary stages of a project and capitalized when the project is deemed to be commercially viable. Commercial viability is determined by one or a series of actions including, among others, Board of Director approval pursuant to a formal project plan that subjects the Company to significant future obligations that can only be discharged by the use of a Company asset. When a project is available for operations, capitalized interest and capitalized project development costs are reclassified to property, plant and equipment and depreciated on a straight-line basis over the estimated useful life of the project's related assets. Capitalized costs are charged to expense if a project is abandoned or management otherwise determines the costs to be unrecoverable.
Debt Issuance Costs	Debt Issuance CostsDebt issuance costs are capitalized and amortized as interest expense on a basis which approximates the effective interest method over the term of the related debt. Debt issuance costs are presented as a direct deduction from the carrying amount of the related debt.
Intangible Assets	Intangible Assets Intangible assets represent contractual rights held by the Company. The Company recognizes specifically identifiable intangible assets including customer contracts, customer relationships, energy supply contracts, marketing partnerships, power purchase agreements, trade names, emission allowances, and fuel contracts when specific rights and contracts are acquired. These intangible assets are amortized based on expected volumes, expected delivery, expected discounted future net cash flows, straight line or units of production basis. As of December 31, 2019 and 2018, the Company had accumulated amortization related to its intangible assets of $1.3 billion and $1.2 billion, respectively. Emission allowances held-for-sale, which are included in other non-current assets on the Company's consolidated balance sheet, are not amortized; they are carried at the lower of cost or fair value and reviewed for impairment in accordance with ASC 360.
Goodwill	Goodwill In accordance with ASC 350, Intangibles-Goodwill and Other , or ASC 350, the Company recognizes goodwill for the excess cost of an acquired entity over the net value assigned to assets acquired and liabilities assumed. NRG performs goodwill impairment tests annually, during the fourth quarter, and when events or changes in circumstances indicate that the carrying value may not be recoverable. The Company first assesses qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. The more-likely-than-not threshold is defined as having a likelihood of more than 50 percent. If it is not more-likely-than-not that the fair value of a reporting unit is less than its carrying amount, there is no goodwill impairment. In the absence of sufficient qualitative factors indicating that it is more-likely-than-not that no impairment occurred, the Company performs a quantitative assessment by determining the fair value of the reporting unit and comparing the fair value to its book value. If the fair value of the reporting unit exceeds its book value, goodwill of the reporting unit is not considered impaired. If the book value exceeds fair value, the Company recognizes an impairment loss equal to the difference between book value and fair value.
Income Taxes	Income Taxes The Company accounts for income taxes using the liability method in accordance with ASC 740, Income Taxes, or ASC 740, which requires that the Company use the asset and liability method of accounting for deferred income taxes and provide deferred income taxes for all significant temporary differences. The Company has two categories of income tax expense or benefit — current and deferred, as follows: • Current income tax expense or benefit consists solely of current taxes payable less applicable tax credits, and • Deferred income tax expense or benefit is the change in the net deferred income tax asset or liability, excluding amounts charged or credited to accumulated other comprehensive income The Company reports some of its revenues and expenses differently for financial statement purposes than for income tax return purposes, resulting in temporary and permanent differences between the Company's financial statements and income tax returns. The tax effects of such temporary differences are recorded as either deferred income tax assets or deferred income tax liabilities in the Company's consolidated balance sheets. The Company measures its deferred income tax assets and deferred income tax liabilities using income tax rates that are expected to be in effect when the deferred tax is realized. The Company accounts for uncertain tax positions in accordance with ASC 740, which applies to all tax positions related to income taxes. Under ASC 740, tax benefits are recognized when it is more-likely-than-not that a tax position will be sustained upon examination by the authorities. The benefit recognized from a position is the amount of benefit that has surpassed the more-likely-than-not threshold, as it is more than 50% likely to be realized upon settlement. The Company recognizes interest and penalties accrued related to uncertain tax benefits as a component of income tax expense. In accordance with ASC 805 and as discussed further in Note 20, Income Taxes , changes to existing net deferred tax assets or valuation allowances or changes to uncertain tax benefits, are recorded to income tax (benefit)/expense.
Revenue Recognition	Contract Amortization Assets and liabilities recognized through acquisitions related to the sale of electric capacity and energy in future periods for which the fair value has been determined to be significantly less or more than market are amortized to revenue over the term of each underlying contract based on actual generation and/or contracted volumes.
Lease Revenue and Lessor Accounting	Lease Revenue Certain of the Company’s revenues are obtained through leases of rooftop residential solar systems, which are accounted for as operating leases in accordance with ASC 842, Leases. Pursuant to the lease agreements, the customers’ monthly payments are pre-determined fixed monthly amounts and may include an annual fixed percentage escalation to reflect the impact of utility rate increases over the lease term, which is 20 years. The Company records operating lease revenue on a straight-line basis over the life of the lease term. Certain customers made initial down payments that are being amortized over the life of the lease. The difference between the payments received and the revenue recognized is recorded as deferred revenue. Lessor Accounting Certain of the Company's revenues are obtained through PPAs or other contractual agreements. Many of these agreements are accounted for as operating leases under ASC 842 . Sale-Leaseback Arrangements NRG is party to sale-leaseback arrangements that provide for the sale of certain assets to a third party and simultaneously leases back the same asset to the Company. If the seller-lessee transfers control of the underlying assets to the buyer-lessor, the arrangement is accounted for under ASC 842-40, Sale-Leaseback Transactions. These arrangements are classified as operating leases on the Company's consolidated balance sheets. See Note 10, Leases, for further discussion.
Gross Receipts and Sales Taxes	Gross Receipts and Sales Taxes In connection with its retail sales, the Company records gross receipts taxes on a gross basis in revenues and cost of operations in its consolidated statements of operations. During the years ended December 31, 2019, 2018, and 2017, the Company's revenues and cost of operations included gross receipts taxes of $109 million, $99 million, and $92 million, respectively. Additionally, the Company records sales taxes collected from its taxable retail customers and remitted to the various governmental entities on a net basis; thus, there is no impact on the Company's consolidated statement of operations.
Cost of Energy for Retail Operations	Cost of Energy for Retail Operations The cost of energy for electricity sales and services to retail customers is included in cost of operations and is based on estimated supply volumes for the applicable reporting period. A portion of the cost of energy, $103 million, $105 million, and $107 million as of December 31, 2019, 2018, and 2017, respectively, was accrued and consisted of estimated transmission and distribution charges not yet billed by the transmission and distribution utilities. In estimating supply volumes, the Company considers the effects of historical customer volumes, weather factors and usage by customer class. Transmission and distribution delivery fees are estimated using the same method used for electricity sales and services to retail customers. In addition, ISO fees are estimated based on historical trends, estimated supply volumes and initial ERCOT ISO settlements. Volume estimates are then multiplied by the supply rate and recorded as cost of operations in the applicable reporting period.
Derivative Financial Instruments	Derivative Financial Instruments The Company accounts for derivative financial instruments under ASC 815, which requires the Company to record all derivatives on the balance sheet at fair value unless they qualify for a NPNS exception. Changes in the fair value of non-hedge derivatives are immediately recognized in earnings. Changes in the fair value of derivatives accounted for as cash flow hedges, if elected for hedge accounting, are deferred and recorded as a component of accumulated OCI until the hedged transactions occur and are recognized in earnings. The Company's primary derivative instruments are power purchase or sales contracts, fuels purchase contracts, and other energy related commodities used to mitigate variability in earnings due to fluctuations in market prices and interest rates. On an ongoing basis, the Company assesses the effectiveness of all derivatives that are designated as hedges for accounting purposes in order to determine that each derivative continues to be highly effective in offsetting changes in fair values or cash flows of hedged items. Internal analyses that measure the statistical correlation between the derivative and the associated hedged item determine the effectiveness of such a contract designated as a hedge. If it is determined that the derivative instrument is not highly effective as a hedge, hedge accounting will be discontinued prospectively. In this case, the gain or loss previously deferred in accumulated OCI would be frozen until the underlying hedged instrument is delivered unless the transactions being hedged are no longer probable of occurring in which case the amount in OCI would be immediately reclassified into earnings. If the derivative instrument is terminated, the effective portion of this derivative deferred in accumulated OCI will be frozen until the underlying hedged item is delivered. The Company had no cash flow hedges as of December 31, 2019. Revenues and expenses on contracts that qualify for the NPNS exception are recognized when the underlying physical transaction is delivered. While these contracts are considered derivative financial instruments under ASC 815, they are not recorded at fair value, but on an accrual basis of accounting. If it is determined that a transaction designated as NPNS no longer meets the scope exception, the fair value of the related contract is recorded on the balance sheet and immediately recognized through earnings. NRG's trading activities are subject to limits in accordance with the Company's Risk Management Policy. These contracts are recognized on the balance sheet at fair value and changes in the fair value of these derivative financial instruments are recognized in earnings.
Foreign Currency Translation and Transaction Gains and Losses	Foreign Currency Translation and Transaction Gains and LossesThe local currencies are generally the functional currency of NRG's foreign operations. Foreign currency denominated assets and liabilities are translated at end-of-period rates of exchange. Revenues, expenses, and cash flows are translated at the weighted-average rates of exchange for the period. The resulting currency translation adjustments are not included in the Company's consolidated statements of operations for the period, but are accumulated and reported as a separate component of stockholders' equity until sale or complete or substantially complete liquidation of the net investment in the foreign entity takes place. Foreign currency transaction gains or losses are reported within other income/(expense) in the Company's consolidated statements of operations.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments which potentially subject the Company to concentrations of credit risk consist primarily of trust funds, accounts receivable, notes receivable, derivatives, and investments in debt securities. Trust funds are held in accounts managed by experienced investment advisors. Certain accounts receivable, notes receivable, and derivative instruments are concentrated within entities engaged in the energy industry. These industry concentrations may impact the Company's overall exposure to credit risk, either positively or negatively, in that the customers may be similarly affected by changes in economic, industry or other conditions. Receivables and other contractual arrangements are subject to collateral requirements under the terms of enabling agreements. However, the Company believes that the credit risk posed by industry concentration is offset by the diversification and creditworthiness of its customer base. See Note 5, Fair Value of Financial Instruments, for a further discussion of derivative concentrations.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amount of cash and cash equivalents, funds deposited by counterparties, receivables, accounts payable, and accrued liabilities approximate fair value because of the short-term maturity of these instruments. See Note 5, Fair Value of Financial Instruments, for a further discussion of fair value of financial instruments.
Asset Retirement Obligations	Asset Retirement Obligations The Company accounts for AROs in accordance with ASC 410-20, Asset Retirement Obligations, or ASC 410-20. Retirement obligations associated with long-lived assets included within the scope of ASC 410-20 are those for which a legal obligation exists under enacted laws, statutes, and written or oral contracts, including obligations arising under the doctrine of promissory estoppel, and for which the timing and/or method of settlement may be conditional on a future event. ASC 410-20 requires an entity to recognize the fair value of a liability for an ARO in the period in which it is incurred and a reasonable estimate of fair value can be made. Upon initial recognition of a liability for an ARO, the Company capitalizes the asset retirement cost by increasing the carrying amount of the related long-lived asset by the same amount. Over time, the liability is accreted to its future value, while the capitalized cost is depreciated over the useful life of the related asset. See Note 14, Asset Retirement Obligations, for a further discussion of AROs.
Pensions and Other Postretirement Benefits	Pensions and Other Postretirement Benefits The Company offers pension benefits through a defined benefit pension plan. In addition, the Company provides postretirement health and welfare benefits for certain groups of employees. The Company accounts for pension and other postretirement benefits in accordance with ASC 715, Compensation — Retirement Benefits , or ASC 715 . The Company recognizes the funded status of the Company's defined benefit plans in the statement of financial position and records an offset for gains and losses as well as all prior service costs that have not been included as part of the Company's net periodic benefit cost to other comprehensive income. The determination of the Company's obligation and expenses for pension benefits is dependent on the selection of certain assumptions. These assumptions determined by management include the discount rate, the expected rate of return on plan assets and the rate of future compensation increases. The Company's actuarial consultants assist in determining assumptions for such items as retirement age. The assumptions used may differ materially from actual results, which may result in a significant impact to the amount of pension obligation or expense recorded by the Company. The Company measures the fair value of its pension assets in accordance with ASC 820, Fair Value Measurements and Disclosures,
Stock-Based Compensation	Stock-Based Compensation The Company accounts for its stock-based compensation in accordance with ASC 718, Compensation — Stock Compensation, or ASC 718 . The fair value of the Company's non-qualified stock options and market stock units are estimated on the date of grant using the Black-Scholes option-pricing model and the Monte Carlo valuation model, respectively. NRG uses the Company's common stock price on the date of grant as the fair value of the Company's restricted stock units and deferred stock units. Forfeiture rates are estimated based on an analysis of the Company's historical forfeitures, employment turnover, and expected future behavior. The Company recognizes compensation expense for both graded and cliff vesting awards on a straight-line basis over the requisite service period for the entire award.
Investments Accounted for by the Equity Method	Investments Accounted for by the Equity MethodThe Company has investments in various domestic energy projects, as well as one Australian project. The equity method of accounting is applied to such investments in affiliates, which include joint ventures and partnerships, because the ownership structure prevents the Company from exercising a controlling influence over the operating and financial policies of the projects. Under this method, equity in pre-tax income or losses of domestic partnerships and, generally, in the net income or losses of its Australian project, are reflected as equity in earnings of unconsolidated affiliates. Distributions from equity method investments that represent earnings on the Company's investment are included within cash flows from operating activities and distributions from equity method investments that represent a return of the Company's investment are included within cash flows from investing activities.
Tax Equity Arrangements	Tax Equity Arrangements The Company’s redeemable noncontrolling interest in subsidiaries represents third-party interests in the net assets under certain tax equity arrangements, which are consolidated by the Company, that have been entered into to finance the cost of solar energy systems under operating leases. The Company has determined that the provisions in the contractual agreements of these structures represent substantive profit sharing arrangements. Further, the Company has determined that the appropriate methodology for calculating the redeemable noncontrolling interest that reflects the substantive profit sharing arrangements is a balance sheet approach utilizing the HLBV method. Under the HLBV method, the amounts reported as redeemable noncontrolling interests represent the amounts the investors that are party to the tax equity arrangements would hypothetically receive at each balance sheet date under the liquidation provisions of the contractual agreements, assuming the net assets of the funding structures were liquidated at their recorded amounts. The investors’ interests in the results of operations of the funding structures are determined as redeemable noncontrolling interests at the start and end of each reporting period, after taking into account any capital transactions between the structures and the funds’ investors. The calculations utilized to apply the HLBV method include estimated calculations of taxable income or losses for each reporting period.
Redeemable Noncontrolling Interest	Redeemable Noncontrolling InterestTo the extent that the third-party has the right to redeem their interests for cash or other assets, the Company has included the noncontrolling interest attributable to the third party as a component of temporary equity in the mezzanine section of the consolidated balance sheet.
Sale-Leaseback Arrangements	Lease Revenue Certain of the Company’s revenues are obtained through leases of rooftop residential solar systems, which are accounted for as operating leases in accordance with ASC 842, Leases. Pursuant to the lease agreements, the customers’ monthly payments are pre-determined fixed monthly amounts and may include an annual fixed percentage escalation to reflect the impact of utility rate increases over the lease term, which is 20 years. The Company records operating lease revenue on a straight-line basis over the life of the lease term. Certain customers made initial down payments that are being amortized over the life of the lease. The difference between the payments received and the revenue recognized is recorded as deferred revenue. Lessor Accounting Certain of the Company's revenues are obtained through PPAs or other contractual agreements. Many of these agreements are accounted for as operating leases under ASC 842 . Sale-Leaseback Arrangements NRG is party to sale-leaseback arrangements that provide for the sale of certain assets to a third party and simultaneously leases back the same asset to the Company. If the seller-lessee transfers control of the underlying assets to the buyer-lessor, the arrangement is accounted for under ASC 842-40, Sale-Leaseback Transactions. These arrangements are classified as operating leases on the Company's consolidated balance sheets. See Note 10, Leases, for further discussion.
Marketing and Advertising Costs	Marketing and Advertising Costs The Company expenses its marketing and advertising costs as incurred and includes them within selling, general and administrative expenses. The costs of tangible assets used in advertising campaigns are recorded as fixed assets or deferred advertising costs and amortized as advertising costs over the shorter of the useful life of the asset or the advertising campaign. The Company has several long-term sponsorship arrangements. Payments related to these arrangements are deferred and expensed over the term of the arrangement.
Reorganization Costs	Reorganization CostsReorganization costs include costs incurred by the Company related to the Transformation Plan implementation and primarily reflect severance and contract modifications. Reorganization costs for the years ended
Business Combinations	Business Combinations The Company accounts for its business combinations in accordance with ASC 805, Business Combinations, or ASC 805, which requires an acquirer to recognize and measure in its financial statements the identifiable assets acquired, the liabilities assumed, and any noncontrolling interest in the acquiree at fair value at the acquisition date. The Company also recognizes and measures the goodwill acquired or a gain from a bargain purchase in the business combination. In addition, transaction costs are expensed as incurred.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States 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. In recording transactions and balances resulting from business operations, the Company uses estimates based on the best information available. Estimates are used for such items as plant depreciable lives, tax provisions, uncollectible accounts, actuarially determined benefit costs, the valuation of energy commodity contracts, environmental liabilities, legal costs incurred in connection with recorded loss contingencies, and assets acquired and liabilities assumed in business combinations, among others. In addition, estimates are used to test long-lived assets and goodwill for impairment and to determine the fair value of impaired assets. As better information becomes available or actual amounts are determinable, the recorded estimates are revised. Consequently, operating results can be affected by revisions to prior accounting estimates.
Reclassifications	Reclassifications Certain prior year amounts have been reclassified for comparative purposes. The reclassifications did not affect results from operations, net assets or cash flows.
Recent Accounting Developments	Recent Accounting Developments - Guidance Adopted in 2019 ASU 2016-02 - In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) , or Topic 842, which was further amended through various updates issued by the FASB thereafter, with the objective to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and to improve financial reporting by expanding the related disclosures. The guidance in Topic 842 provides that a lessee that may have previously accounted for a lease as an operating lease under current GAAP should recognize the assets and liabilities that arise from a lease on the balance sheet. In addition, Topic 842 expands the required quantitative and qualitative disclosures with regards to lease arrangements. The Company adopted the standard and its subsequent corresponding updates effective January 1, 2019 using the modified retrospective approach, as further described in Note 10, Leases . The Company recognized operating lease liabilities of $404 million and right of use assets of $321 million upon adoption. Recent Accounting Developments - Guidance Not Yet Adopted ASU 2019-12 - In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, 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,. Early adoption is permitted, including adoption in an interim period. The Company is currently in the process of assessing the impact of this guidance on the consolidated financial statements. ASU 2018-17 - In October 2018, the FASB issued ASU No. 2018-17, Consolidations (Topic 810): Targeted Improvements to Related Party Guidance for Variable Interest Entities , or ASU No. 2018-17, in response to stakeholders’ observations that Topic 810, Consolidations , could be improved thereby improving general purpose financial reporting. Specifically, ASU No. 2018-17 requires application of the variable interest entity (VIE) guidance to private companies under common control and consideration of indirect interest held through related parties under common control for determining whether fees paid to decision makers and service providers are variable interests. The amendments are effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. All entities are required to apply the amendments retrospectively with a cumulative-effect adjustment to opening retained earnings of the earliest period presented. The Company will adopt the amendments during the first quarter of 2020 and does not expect the adoption to have a material impact on its results of operations, cash flows, or statement of financial position. ASU 2018-13 - In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirement for Fair value Measurement) , or ASU No. 2018-13. The amendments in ASU No. 2018-13 eliminate such disclosures as the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy and add new disclosure requirements for Level 3 measurements. ASU No. 2018-13 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Certain disclosures in ASU No. 2018-13 are required to be applied on a retrospective basis and others on a prospective basis. The Company will adopt the amendments during the first quarter of 2020. As the amendments contemplates changes in disclosures only, it will have no impact on the Company's results of operations, cash flows, or statement of financial position. ASU 2016-13 - In June 2016, the FASB issues ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , or ASU No. 2016-13, which was further amended through various updates issued by the FASB thereafter. The guidance in ASU No. 2016-13 provides a new model for recognizing credit losses on financial assets carried at amortized cost using an estimate of expected credit losses, instead of the "incurred loss" methodology previously required for recognizing credit losses that delayed recognition until it was probable that a loss was incurred. The estimate of expected credit losses is to be based on consideration of past events, current conditions and reasonable and supportable forecasts of future conditions. ASU No. 2016-13 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. The guidance is required to be adopted using a modified retrospective approach through a cumulative-effect adjustment to opening retained earnings as of the effective date and requires additional disclosures. The Company will adopt the guidance during the first quarter of 2020 and does not expect the adoption to have a material impact on its results of operations, cash flows, or statement of financial position.
Nuclear Decommissioning Policy	NRG accounts for the Nuclear Decommissioning Trust Fund in accordance with ASC 980, Regulated Operations , or ASC 980, 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 other comprehensive income, consistent with regulatory treatment.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Net income/(loss) attributable to continuing and discontinued operations	The following table reflects the net income/(loss) attributable to NRG Energy, Inc. after removing the net loss attributable to the noncontrolling interest and redeemable noncontrolling interest: Year Ended December 31, (In millions) 2019 2018 2017 Income/(loss) from continuing operations, net of income tax $ 4,117 $ 465 $ (977) Income/(loss) from discontinued operations, net of income tax 321 (197) (1,176) Net income/(loss) attributable to NRG Energy, Inc. stockholders $ 4,438 $ 268 $ (2,153)
Reconciliation of cash, cash equivalents, and restricted cash and cash equivalents	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. Year Ended December 31, (In millions) 2019 2018 2017 Cash and cash equivalents $ 345 $ 563 $ 770 Funds deposited by counterparties 32 33 37 Restricted cash 8 17 279 Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statements of cash flows $ 385 $ 613 $ 1,086 Detail of supplemental disclosures of cash flow and non-cash investing and financing information was: Year Ended December 31, (In millions) 2019 2018 2017 Interest paid, net of amount capitalized $ 372 $ 436 $ 543 Income taxes paid, net of refunds 8 9 9 Non-cash investing activities: Additions to fixed assets for accrued capital expenditures 1 20 19
Changes in redeemable noncontrolling interest	The following table reflects the changes in the Company's redeemable noncontrolling interest balance for the years ended December 31, 2019, 2018, and 2017. (In millions) Balance as of December 31, 2016 $ 46 Distributions to redeemable noncontrolling interest (2) Contributions from redeemable noncontrolling interest 99 Non-cash adjustments to redeemable noncontrolling interest 7 Comprehensive loss attributable to redeemable noncontrolling interest (72) Balance as of December 31, 2017 78 Distributions to redeemable noncontrolling interest (3) Contributions from redeemable noncontrolling interest 26 Non-cash adjustments to redeemable noncontrolling interest (8) Net income attributable to redeemable noncontrolling interest - continuing operations 1 Net loss attributable to redeemable noncontrolling interest - discontinued operations (27) Sale of NRG Yield and the Renewables Platform (a) (48) Balance as of December 31, 2018 19 Distributions to redeemable noncontrolling interest (2) Net income attributable to redeemable noncontrolling interest - continuing operations 3 Balance as of December 31, 2019 $ 20 (a) See Note 4, Acquisitions, Discontinued Operations and Dispositions , for further information regarding the sale of NRG Yield and its Renewables Platform

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Disaggregation of revenue	The following tables represent the Company’s disaggregation of revenue from contracts with customers for the years ended December 31, 2019 and 2018: For the Year Ended December 31, 2019 (In millions) Texas East West/Other Corporate/Eliminations Total Retail revenue Mass Market $ 5,027 $ 1,230 $ — $ (3) $ 6,254 Business Solutions 1,205 74 — — 1,279 Total retail revenue 6,232 1,304 — (3) 7,533 Energy revenue (a) 529 322 318 — 1,169 Capacity revenue (a) — 664 36 — 700 Mark-to-market for economic hedging activities (b) 47 (29) 16 (1) 33 Other revenue (a) 261 58 70 (3) 386 Total operating revenue 7,069 2,319 440 (7) 9,821 Less: Lease revenue — 1 19 — 20 Less: Realized and unrealized ASC 815 revenue 1,562 183 67 (2) 1,810 Total revenue from contracts with customers $ 5,507 $ 2,135 $ 354 $ (5) $ 7,991 (a) The following amounts of energy, capacity and other revenue relate to derivative instruments and are accounted for under ASC 815: (In millions) Texas East West/Other Corporate/Eliminations Total Energy revenue $ 1,459 $ 98 $ 39 $ (1) $ 1,595 Capacity revenue — 109 — — 109 Other revenue 56 5 12 — 73 (b) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 For the Year Ended December 31, 2018 (In millions) Texas East West/Other Corporate/Eliminations Total Retail revenue Mass Market $ 4,618 $ 974 $ — $ (1) $ 5,591 Business Solutions 1,238 65 — — 1,303 Total retail revenue 5,856 1,039 — (1) 6,894 Energy revenue (a) 371 546 566 13 1,496 Capacity revenue (a) — 746 79 — 825 Mark-to-market for economic hedging activities (b) (77) (35) (5) (13) (130) Other revenue (a)(c) 251 75 84 (17) 393 Total operating revenue 6,401 2,371 724 (18) 9,478 Less: Lease revenue 1 1 19 — 21 Less: Realized and unrealized ASC 815 revenue 1,096 210 2 1 1,309 Total revenue from contracts with customers $ 5,304 $ 2,160 $ 703 $ (19) 8,148 (a) The following amounts of energy, capacity and other revenue relate to derivative instruments and are accounted for under ASC 815: (In millions) Texas East West/Other Corporate/Eliminations Total Energy revenue $ 1,131 $ 90 $ (2) $ 14 $ 1,233 Capacity revenue — 137 — — 137 Other revenue 42 17 9 1 69 (b) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815
Contract assets and liabilities	The following table reflects the contract assets and liabilities included in the Company's balance sheet as of December 31, 2019 and 2018: (In millions) December 31, 2019 December 31, 2018 Deferred customer acquisition costs $ 133 $ 111 Accounts receivable, net - Contracts with customers 1,002 999 Accounts receivable, net - Derivative instruments 18 20 Accounts receivable, net - Affiliate 5 5 Total accounts receivable, net $ 1,025 $ 1,024 Unbilled revenues (included within Accounts receivable, net - Contracts with customers) $ 402 $ 392 Deferred revenues (a) $ 82 $ 67 (a) Deferred revenues from contracts with customers for the years ended December 31, 2019 and 2018 were approximately $24 million and $19 million, respectively.

Acquisitions, Discontinued Oper

Acquisitions, Discontinued Operations and Dispositions (Tables)	12 Months Ended
	Dec. 31, 2019
Discontinued Operations and Disposal Groups [Abstract]
Schedule of Purchase Price Allocation	The purchase price was allocated as follows: (In millions) Account receivable $ 98 Accounts payable (73) Other net current and non-current working capital 5 Marketing partnership 154 Customer relationships 85 Trade name 28 Other intangible assets 26 Goodwill (a) 6 Stream Purchase Price $ 329 (a) Goodwill arising from the acquisition is attributed to the value of the platform acquired and the synergies expected from combining the operations of Stream Energy with NRG's existing businesses. Goodwill of $5 million and $1 million was assigned to the Texas and East segments, respectively, and is not deductible for tax purposes
Schedule of Allocation of Purchase Price	The acquisition increased NRG's retail portfolio by approximately 395,000 RCEs or 300,000 customers. The purchase price was allocated as follows: (In millions) Net current and non-current working capital $ 46 Other intangible assets 133 Goodwill 34 XOOM Purchase Price $ 213
Summary of Results of Discontinued Operations	Summarized results of South Central discontinued operations were as follows: Year Ended December 31, (In millions) 2019 2018 2017 Operating revenues $ 31 $ 410 $ 422 Operating costs and expenses (23) (346) (335) Other income — 2 — Gain from operations of discontinued components 8 66 87 Gain on disposal of discontinued operations, net of tax 20 — — Gain from discontinued operations, including disposal, net of tax $ 28 $ 66 $ 87 The following table summarizes the major classes of assets and liabilities classified as discontinued operations of South Central: (In millions) December 31, 2018 Cash and cash equivalents $ 89 Accounts receivable, net 49 Inventory 35 Other current assets 5 Current assets - discontinued operations 178 Property, plant and equipment, net 408 Other non-current assets 1 Non-current assets - discontinued operations 409 Accounts payable 19 Other current liabilities 5 Current liabilities - discontinued operations 24 Out-of-market contracts, net 50 Other non-current liabilities 11 Non-current liabilities - discontinued operations $ 61 Summarized results of NRG Yield, Inc. and Renewables Platform and Carlsbad discontinued operations were as follows: Year Ended December 31, (In millions) 2019 2018 2017 Operating revenues $ 19 $ 909 $ 1,164 Operating costs and expenses (9) (661) (1,114) Other expenses (5) (174) (288) Gain/(loss) from operations of discontinued components, before tax 5 74 (238) Income tax expense — 4 52 Gain/(loss) from discontinued operations, net of tax 5 70 (290) Gain/(loss) on disposal of discontinued operations, net of tax 265 (134) — Income/(expense) from California property tax indemnification 22 (153) — Income/(expense) from other commitments, indemnification and fees 4 (75) — Income/(loss) on disposal of discontinued operations, net of tax 291 (362) — Income/(loss) from discontinued operations, net of tax $ 296 $ (292) $ (290) The following table summarizes the major classes of assets and liabilities classified as discontinued operations: (In millions) December 31, 2018 (a) Restricted Cash $ 4 Accounts receivable, net 10 Other current assets 5 Current assets - discontinued operations 19 Property, plant and equipment, net 590 Intangible assets, net 9 Other non-current assets 4 Non-current assets - discontinued operations 603 Current portion of long term debt and capital leases 20 Accounts payable 27 Other current liabilities 1 Current liabilities - discontinued operations 48 Long-term debt and capital leases 572 Other non-current liabilities 2 Non-current liabilities - discontinued operations $ 574 Summarized results of discontinued operations were as follows: Year Ended December 31, (In millions) 2019 2018 2017 Operating revenues $ — $ — $ 646 Operating costs and expenses — — (702) Other expenses — — (98) Loss from operations of discontinued components, before tax — — (154) Income tax expense — — 9 Loss from discontinued operations — — (163) Interest income - affiliate — 3 8 Income/(loss) from discontinued operations, net of tax — 3 (155) Pre-tax loss on deconsolidation — — (208) Settlement consideration, insurance and services credit — 63 (289) Pension and post-retirement liability assumption — 21 (131) Other (3) (53) (6) (Loss)/income on disposal of discontinued operations, net of tax (3) 31 (634) (Loss)/income from discontinued operations, net of tax $ (3) $ 34 $ (789)

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Estimated Carrying Amounts and Fair Values of Financial Instruments Not Carried at Fair Value	The estimated carrying values and fair values of the Company's recorded financial instruments not carried at fair market value are as follows: As of December 31, 2019 2018 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Assets Notes receivable $ 11 $ 8 $ 17 $ 14 Liabilities Long-term debt, including current portion (a) $ 5,956 $ 6,504 $ 6,591 $ 6,697 (a) Excludes deferred financing costs, which are recorded as a reduction to long-term debt on the Company's consolidated balance sheets The fair value of the Company's publicly-traded long-term debt is based on quoted market prices and is classified as Level 2 within the fair value hierarchy. The fair value of debt securities, non-publicly traded long-term debt, and certain notes receivable of the Company are based on expected future cash flows discounted at market interest rates or current interest rates for similar instruments with equivalent credit quality and are 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 December 31, 2019 and 2018: As of December 31, 2019 As of December 31, 2018 (In millions) Level 2 Level 3 Level 2 Level 3 Long-term debt, including current portion $ 6,388 $ 116 $ 6,528 $ 169
Assets and Liabilities Measured and Recorded at Fair Value Measured on a Recurring Basis	The following tables present assets and liabilities measured and recorded at fair value on the Company's consolidated balance sheets on a recurring basis and their level within the fair value hierarchy: As of December 31, 2019 Fair Value (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and non-current assets) $ 20 $ — $ 20 $ — Nuclear trust fund investments: Cash and cash equivalents 17 17 — — U.S. government and federal agency obligations 68 68 — — Federal agency mortgage-backed securities 100 — 100 — Commercial mortgage-backed securities 29 — 29 — Corporate debt securities 109 — 109 — Equity securities 388 388 — — Foreign government fixed income securities 5 — 5 — Other trust fund investments: U.S. government and federal agency obligations 1 1 — — Derivative assets: Commodity contracts 1,170 84 893 193 Measured using net asset value practical expedient: Equity securities-nuclear trust fund investments 78 — — — Equity securities 8 — — — Total assets $ 1,993 $ 558 $ 1,156 $ 193 Derivative liabilities: Commodity contracts $ 1,103 $ 143 $ 805 $ 155 Total liabilities $ 1,103 $ 143 $ 805 $ 155 As of December 31, 2018 Fair Value (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current or non-current assets) $ 39 $ 2 $ 18 $ 19 Nuclear trust fund investments: Cash and cash equivalents 19 19 — — U.S. government and federal agency obligations 46 46 — — Federal agency mortgage-backed securities 100 — 100 — Commercial mortgage-backed securities 22 — 22 — Corporate debt securities 96 — 96 — Equity securities 312 312 — — Foreign government fixed income securities 4 — 4 — Other trust fund investments: U.S. government and federal agency obligations 1 1 — — Derivative assets: Commodity contracts 1,042 137 796 109 Interest rate contracts 39 — 39 — Measured using net asset value practical expedient: Equity securities-nuclear trust fund investments 64 — — — Equity securities 8 — — — Total assets $ 1,792 $ 517 $ 1,075 $ 128 Derivative liabilities: Commodity contracts $ 977 $ 224 $ 664 $ 89 Total liabilities $ 977 $ 224 $ 664 $ 89
Reconciliation of Beginning and Ending Balances for Financial Instruments that are Recognized at Fair Value using Significant Unobservable Inputs	The following tables reconcile, for the years ended December 31, 2019 and 2018, the 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: For the Year Ended December 31, 2019 Fair Value Measurement Using Significant Unobservable Inputs (Level 3) (In millions) Debt Securities Derivatives (a) Total Beginning balance as of January 1, 2019 $ 19 $ 20 $ 39 Contracts added from acquisitions — (3) (3) Total gains/(losses) — realized/unrealized: Included in earnings — (26) (26) Included in OCI — — — Purchases — 40 40 Sale (19) — (19) Transfers into Level 3 (b) — 2 2 Transfers out of Level 3 (b) — 5 5 Ending balance as of December 31, 2019 $ — $ 38 $ 38 Gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of December 31, 2019 $ — $ 17 $ 17 (a) Consists of derivatives 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 into/out of Level 3 are from/to Level 2 For the Year Ended December 31, 2018 Fair Value Measurement Using Significant Unobservable Inputs (Level 3) (In millions) Debt Securities Derivatives (a) Total Beginning balance as of January 1, 2018 $ 19 $ (15) $ 4 Contracts acquired in XOOM acquisition — 12 $ 12 Total gains realized/unrealized included in earnings — (21) (21) Purchases — 41 41 Transfers into Level 3 (b) — 5 5 Transfer out of Level 3 (b) — (2) (2) Ending balance as of December 31, 2018 $ 19 $ 20 $ 39 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 December 31, 2018 $ — $ (17) $ (17) (a) Consists of derivatives 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 into/out of Level 3 are from/to Level 2
Schedule of Significant Unobservable Inputs used in Developing Fair Value of Level 3 Positions	The following tables quantify the significant unobservable inputs used in developing the fair value of the Company's Level 3 positions as of December 31, 2019 and 2018: Significant Unobservable Inputs December 31, 2019 Fair Value Input/Range (In millions) Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average Power Contracts $ 151 $ 139 Discounted Cash Flow Forward Market Price (per MWh) $ 8 $ 218 $ 24 FTRs 42 16 Discounted Cash Flow Auction Prices (per MWh) (105) 213 0 $ 193 $ 155 Significant Unobservable Inputs December 31, 2018 Fair Value Input/Range (In millions) Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average Power Contracts $ 89 $ 75 Discounted Cash Flow Forward Market Price (per MWh) $ 1 $ 214 $ 31 FTRs 20 14 Discounted Cash Flow Auction Prices (per MWh) (90) 34 0 $ 109 $ 89
Fair Value Inputs, Sensitivity Analysis	The following table provides sensitivity of fair value measurements to increases/(decreases) in significant unobservable inputs as of December 31, 2019 and 2018: Significant Unobservable Input Position Change In Input Impact on Fair Value Measurement Forward Market Price Power Buy Increase/(Decrease) Higher/(Lower) Forward Market Price 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. Category Net Exposure (a) (b) (% of Total) Utilities, energy merchants, marketers and other 84 % Financial institutions 16 Total 100 % Category Net Exposure (a) (b) (% of Total) Investment grade 56 % Non-Investment grade/Non-Rated 44 Total 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.

Accounting for Derivative Ins_2

Accounting for Derivative Instruments and Hedging Activities (Tables)	12 Months Ended
	Dec. 31, 2019
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 commodity, excluding those derivatives that qualified for the NPNS exception as of December 31, 2019 and 2018. 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. (In millions) Total Volume Commodity Units December 31, 2019 December 31, 2018 Emissions Short Ton 3 (2) Renewables Energy Certificates Certificates 1 1 Coal Short Ton 10 13 Natural Gas MMBtu (181) (330) Oil Barrels — 1 Power MWh 38 1 Capacity MW/Day (1) (1) Interest Dollars $ — $ 1,000
Fair Value Within the Derivative Instrument Valuation On the Balance Sheet	The following table summarizes the fair value within the derivative instrument valuation on the balance sheet: Fair Value Derivative Assets Derivative Liabilities (In millions) December 31, 2019 December 31, 2018 December 31, 2019 December 31, 2018 Derivatives Not Designated as Cash Flow or Fair Value Hedges : Interest rate contracts current $ — $ 17 $ — $ — Interest rate contracts long-term — 22 — — Commodity contracts current 860 747 781 673 Commodity contracts long-term 310 295 322 304 Total Derivatives Not Designated as Cash Flow or Fair Value Hedges $ 1,170 $ 1,081 $ 1,103 $ 977
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received Or Paid	The following table summarizes the offsetting 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 December 31, 2019 Commodity contracts: Derivative assets $ 1,170 $ (909) $ (7) $ 254 Derivative liabilities (1,103) 909 73 (121) Total commodity contracts $ 67 $ — $ 66 $ 133 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, 2018 Commodity contracts: Derivative assets $ 1,042 $ (778) $ (31) $ 233 Derivative liabilities (977) 778 114 (85) Total commodity contracts 65 — 83 148 Interest rate contracts: Derivative assets 39 — — 39 Total interest rate contracts 39 — — 39 Total derivative instruments $ 104 $ — $ 83 $ 187
Effects on the Company's Accumulated OCI Balance Attributable to Cash Flow Hedge Derivatives, Net of Tax	The following table summarizes the effects on NRG's accumulated OCI balance attributable to cash flow hedge derivatives, net of tax, for the years 2018 and 2017. As of December 31, 2019, NRG had no interest rate derivative instruments as a result of the early termination of such contracts in connection with the repayment of the 2023 Term Loan Facility, as further discussed in Note 13, Debt and Finance Leases. Interest Rate Contracts (In millions) 2018 2017 Accumulated OCI beginning balance $ (54) $ (66) Reclassified from accumulated OCI to income: Due to realization of previously deferred amounts 8 12 Mark-to-market of cash flow hedge accounting contracts 21 — Sale of NRG Yield and Renewables $ 25 $ — Accumulated OCI ending balance $ — $ (54)
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, and trading activity on the Company's statement of operations. The effect of commodity hedges is included within operating revenues and cost of operations and the effect of interest rate hedges is included in interest expense. Year Ended December 31, (In millions) 2019 2018 2017 Unrealized mark-to-market results Reversal of previously recognized unrealized (gains)/losses on settled positions related to economic hedges $ (68) $ (73) $ 47 Reversal of acquired loss/(gain) positions related to economic hedges 6 (10) — Net unrealized gains on open positions related to economic hedges 42 97 159 Total unrealized mark-to-market (losses)/gains for economic hedging activities (20) 14 206 Reversal of previously recognized unrealized (gains) on settled positions related to trading activity (11) (12) (25) Net unrealized gains on open positions related to trading activity 31 29 14 Total unrealized mark-to-market gains/(losses) for trading activity 20 17 (11) Total unrealized gains $ — $ 31 $ 195 Year Ended December 31, (In millions) 2019 2018 2017 Unrealized gains/(losses) included in operating revenues $ 53 $ (113) $ 241 Unrealized (losses)/gains included in cost of operations (53) 144 (46) Total impact to statement of operations — energy commodities $ — $ 31 $ 195 Total impact to statement of operations — interest rate contracts $ (38) $ — $ 4

Nuclear Decommissioning Trust_2

Nuclear Decommissioning Trust Fund (Tables)	12 Months Ended
	Dec. 31, 2019
Regulated Operations [Abstract]
Summary of Aggregate Fair Values and Unrealized Gains And Losses (Including Other-Than-Temporary Impairments) for the Securities Held in The Nuclear Decommissioning 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 December 31, 2019 As of December 31, 2018 (In millions, except otherwise noted) 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 $ 17 $ — $ — — $ 19 $ — $ — — U.S. government and federal agency obligations 68 4 — 11 46 1 — 12 Federal agency mortgage-backed securities 100 3 — 24 100 1 2 23 Commercial mortgage-backed securities 29 1 1 24 22 — 1 22 Corporate debt securities 109 6 — 11 96 1 2 11 Equity securities 466 324 — — 376 231 1 — Foreign government fixed income securities 5 — — 10 4 — — 9 Total $ 794 $ 338 $ 1 $ 663 $ 234 $ 6
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 and the related realized gains and losses from these sales. The cost of securities sold is determined using the specific identification method. Year Ended December 31, (In millions) 2019 2018 2017 Realized gains $ 18 $ 17 $ 22 Realized (losses) (9) (13) (8) Proceeds from sale of securities 381 513 501

Inventory (Tables)

Inventory (Tables)	12 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
Schedule of Inventory	Inventory consisted of: As of December 31, (In millions) 2019 2018 Fuel oil $ 73 $ 74 Coal 93 97 Natural gas 21 28 Spare parts 196 213 Total Inventory $ 383 $ 412

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
NRG's major classes of property, plant and equipment	The Company's major classes of property, plant, and equipment were as follows: As of December 31, Depreciable (In millions) 2019 2018 Lives Facilities and equipment $ 3,262 $ 3,763 1-40 years Land and improvements 324 347 Nuclear fuel 235 212 5 years Hardware and office equipment and furnishings 422 431 2-10 years Construction in progress 102 106 Total property, plant, and equipment 4,345 4,859 Accumulated depreciation (1,752) (1,811) Net property, plant, and equipment $ 2,593 $ 3,048

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Lease Cost	Lease Cost: (In millions) For the Year Ended December 31, 2019 Finance lease cost: $ — Amortization of right-of-use assets — Shares issued under ESPP — Interest on lease liabilities — Operating lease cost $ 109 Short-term lease cost 3 Variable lease cost 6 Sublease income (17) Total lease cost $ 101 Other information: (In millions) For the Year Ended December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 104 Right-of-use assets obtained in exchange for new operating lease liabilities 215 Lease Term and Discount Rate for operating leases: December 31, 2019 Weighted average remaining lease term (in years) 7.8 Weighted average discount rate 5.72 %
Schedule of Annual Payments Based on Maturities of Leases	As of December 31, 2019, annual payments based on the maturities of NRG's leases are expected to be as follows: (In millions) 2020 $ 96 2021 87 2022 87 2023 85 2024 75 Thereafter 296 Total undiscounted lease payments $ 726 Less: present value adjustment (170) Total discounted lease payments $ 556
Future minimum lease commitments under operating leases	Future minimum lease commitments under the Powerton and Joliet operating leases as of December 31, 2018 were as follows: Period (In millions) 2019 $ 1 2020 1 2021 3 2022 6 2023 6 Thereafter 222 Total (a) $ 239 (a) Termination of leases could be at a significant premium to the remaining lease payments Future minimum lease commitments under operating leases, other than Powerton and Joliet, as of December 31, 2018 were as follows: Period (a) (In millions) 2019 $ 60 2020 55 2021 43 2022 40 2023 39 Thereafter 95 Total $ 332 (a) Amounts in the table exclude future sublease income of $29 million associated with long-term leases for office locations

Goodwill and Other Intangibles

Goodwill and Other Intangibles (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of the Components of Intangible Assets Subject to Amortization	The following tables summarize the components of NRG's intangible assets subject to amortization: (In millions) Year Ended December 31, 2019 Emission Allowances Fuel Contracts Customer Relationships Marketing Partnerships Trade Names Other Total January 1, 2019 $ 659 $ 49 $ 478 $ 131 $ 345 $ 80 $ 1,742 Purchases 13 — — — — 29 42 Acquisition of businesses (a) — — 110 154 28 26 318 Usage (4) — — — — (17) (21) Write-off of fully amortized balances (8) — (13) — — (9) (30) Impairment — — (2) — — — (2) Other 2 — — — — — 2 December 31, 2019 662 49 573 285 373 109 2,051 Less accumulated amortization (539) (45) (345) (75) (220) (38) (1,262) Net carrying amount $ 123 $ 4 $ 228 $ 210 $ 153 $ 71 $ 789 (a) The weighted average life of acquired intangibles was: customer relationships 7 years, marketing partnerships 9 years, trade names 12 years, and energy supply contracts 2 years (In millions) Year Ended December 31, 2018 Emission Allowances Fuel Contracts Customer Relationships Marketing Partnerships Trade Names Other Total January 1, 2018 $ 755 $ 49 $ 768 $ 88 $ 342 $ 78 $ 2,080 Purchases 33 — — — — 28 61 Acquisition of businesses (a) — — 122 43 13 — 178 Usage (1) — — — — (26) (27) Write-off of fully amortized balances (107) — (411) — (10) — (528) Impairment (5) — (1) — — — (6) Other (16) — — — — — (16) December 31, 2018 659 49 478 131 345 80 1,742 Less accumulated amortization (515) (45) (314) (61) (195) (21) (1,151) Net carrying amount $ 144 $ 4 $ 164 $ 70 $ 150 $ 59 $ 591 (a) The weighted average life of acquired intangibles was: customer relationships 6 years, trade names 7 years, and marketing partnerships 14 years
Schedule of Amortization of Intangible Expense	The following table presents NRG's amortization of intangible assets for each of the past three years: Years Ended December 31, (In millions) 2019 2018 2017 Emission allowances $ 32 $ 39 $ 71 Customer relationships 44 32 34 Marketing partnerships 15 9 5 Trade names 25 23 23 Other 35 30 33 Total amortization $ 151 $ 133 $ 166
Schedule of Estimated Amortization of Intangible Assets for Next Five Years	The following table presents estimated amortization of NRG's intangible assets as of December 31, 2019 for each of the next five years: (In millions) Year Ended December 31, Emission Allowances Fuel Contracts Customer Relationships Marketing Partnerships Trade Names Other Total 2020 $ 36 $ 1 $ 68 $ 24 $ 27 $ 33 $ 189 2021 35 — 52 24 27 3 141 2022 38 — 36 23 27 3 127 2023 40 1 35 23 26 3 128 2024 35 — 15 23 17 3 93

Debt and Finance Leases (Tables

Debt and Finance Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Long-term Debt and Capital Leases	Long-term debt and finance leases consisted of the following: (In millions, except rates) December 31, 2019 December 31, 2018 December 31, 2019 Interest rate % Recourse debt: Senior Notes, due 2024 $ — $ 733 6.250 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 — 5.250 Convertible Senior Notes, due 2048 (a) 575 575 2.750 Senior Secured First Lien Notes, due 2024 600 — 3.750 Senior Secured First Lien Notes, due 2029 500 — 4.450 2023 Term Loan Facility (b) — 1,698 L+ 1.75 Revolving Credit Facility (c) 83 — L+ 1.75 Tax-exempt bonds 466 466 4.125 - 6.00 Subtotal recourse debt 6,008 6,523 Non-recourse debt: Agua Caliente Borrower 1, due 2038 — 86 5.430 Midwest Generation, due 2019 — 48 4.390 Other 34 34 various Subtotal all non-recourse debt 34 168 Subtotal long-term debt (including current maturities) 6,042 6,691 Finance leases — 1 various Subtotal long-term debt and finance leases (including current maturities) 6,042 6,692 Less current maturities (88) (72) Less debt issuance costs (65) (70) Discounts (86) (101) Total long-term debt and finance leases $ 5,803 $ 6,449 (a) The effective interest rate was 5.05% and 5.02% for the years ended December 31, 2019 and 2018, respectively (b) As of December 31, 2018, the interest rate was 1-month LIBOR plus 1.75% (c) As of December 31, 2019, the interest rate was 1-week LIBOR plus 1.75% Debt includes the following discounts: As of December 31, (In millions) 2019 2018 Term loan facility, due 2023 $ — $ (4) Midwest Generation, due 2019 — (1) Senior Secured First Lien Notes, due 2024 and 2029 (1) — Convertible Senior Notes, due 2048 (85) (96) Total discounts $ (86) $ (101)
Annual Payments Based On the Maturities of NRG's Debt	As of December 31, 2019, annual payments based on the maturities of NRG's debt are expected to be as follows: (In millions) 2020 (a) $ 88 2021 6 2022 5 2023 4 2024 604 Thereafter 5,335 Total $ 6,042 (a) Includes $83 million of Revolving Credit Facility balance outstanding as of December 31, 2019
Debt Redemption	(In millions, except percentages) Principal Repurchased Cash Paid (a) Average Early Redemption Percentage 5.750% senior notes due 2028 $ 29 $ 30 99.24 % 6.250% senior notes due 2022 14 15 103.25 % Total at June 30, 2018 $ 43 $ 45 6.250% senior notes due 2022 493 512 103.13 % 5.750% senior notes due 2028 20 20 99.13 % 6.625% senior notes due 2027 20 21 103.06 % Total at September 30, 2018 $ 576 $ 598 6.250% senior notes due 2022 485 508 103.13 % Total at December 31, 2018 $ 1,061 $ 1,106 (a) Includes accrued interest of $14 million Redemption Period Redemption May 15, 2021 to May 14, 2022 103.625 % May 15, 2022 to May 14, 2023 102.417 % May 15, 2023 to May 14, 2024 101.208 % May 15, 2024 and thereafter 100.000 % Redemption Period Redemption July 15, 2021 to July14, 2022 103.313 % July 15, 2022 to July 14, 2023 102.208 % July 15, 2023 to July 14, 2024 101.104 % July 15, 2024 and thereafter 100.000 % Redemption Period Redemption January 15, 2023 to January 14, 2024 102.875 % January 15, 2024 to January 14, 2025 101.917 % January 15, 2025 to January 14, 2026 100.958 % January 15, 2026 and thereafter 100.000 % Redemption Period Redemption Percentage June 15, 2024 to June 14, 2025 102.625 % June 15, 2025 to June 14, 2026 101.750 % June 15, 2026 to June 14, 2027 100.875 % June 15, 2027 and thereafter 100.000 %
Schedule of Tax Exempt Bonds	Tax Exempt Bonds As of December 31, (In millions, except rates) 2019 2018 Interest Rate % Indian River Power, tax exempt bonds, due 2040 $ 57 $ 57 6.000 Indian River Power LLC, tax exempt bonds, due 2045 190 190 5.375 Dunkirk Power LLC, tax exempt bonds, due 2042 59 59 5.875 City of Texas City, tax exempt bonds, due 2045 33 33 4.125 Fort Bend County, tax exempt bonds, due 2038 54 54 4.750 Fort Bend County, tax exempt bonds, due 2042 73 73 4.750 Total $ 466 $ 466

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2019
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Company's ARO Obligations and Related Additions, reductions and Accretion	The following table represents the balance of ARO obligations as of December 31, 2019 and 2018, along with the additions, reductions and accretion related to the Company's ARO obligations for the year ended December 31, 2019: (In millions) Nuclear Decommission Other Total Balance as of December 31, 2018 $ 282 $ 397 $ 679 Revisions in estimates for current obligations (a) — 27 27 Additions — 9 9 Spending for current obligations — (33) (33) Accretion (a) 16 30 46 Balance as of December 31, 2019 $ 298 $ 430 $ 728 (a) Total ARO accretion expense includes non-Nuclear Decommissioning Trust accretion and revised asset retirement liabilities on non-operating plants

Benefit Plans and Other Postr_2

Benefit Plans and Other Postretirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
Schedule of Net Benefit Cost (Credit) Related to Pension and Other Postretirement Benefit Plans Components	The annual net periodic benefit cost/(credit) related to NRG's pension and other postretirement benefit plans include the following components: Year Ended December 31, Pension Benefits (In millions) 2019 2018 2017 Service cost benefits earned $ 10 $ 23 $ 26 Interest cost on benefit obligation 46 44 43 Expected return on plan assets (59) (62) (58) Amortization of unrecognized net loss 3 — 4 Settlement/curtailment expense — 7 — Net periodic benefit cost $ — $ 12 $ 15 Year Ended December 31, Other Postretirement Benefits (In millions) 2019 2018 2017 Service cost benefits earned $ 1 $ 1 $ 1 Interest cost on benefit obligation 3 4 4 Amortization of unrecognized prior service credit (13) (10) (9) Amortization of unrecognized net (gain)/loss — — (1) Curtailment gain — (10) — Net periodic benefit (credit) $ (9) $ (15) $ (5)
Schedule of Comparison of Pension Benefit obligation, Other Postretirement Benefit Obligations and Related Plan Assets on a Combined Basis	A comparison of the pension benefit obligation, other postretirement benefit obligations and related plan assets for NRG's plans on a combined basis is as follows: As of December 31, Pension Benefits Other Postretirement (In millions) 2019 2018 2019 2018 Benefit obligation at January 1 $ 1,222 $ 1,329 $ 83 $ 128 Service cost 10 23 1 1 Interest cost 46 44 3 4 Plan amendments — 17 (2) (28) Actuarial (gain)/loss 207 (95) 16 (6) Employee and retiree contributions — — 4 3 Curtailment gain — (20) — (7) Benefit payments (88) (76) (12) (12) Benefit obligation at December 31 1,397 1,222 93 83 Fair value of plan assets at January 1 981 1,104 — — Actual return on plan assets 216 (80) — — Employee and retiree contributions — — 4 3 Employer contributions 41 33 7 9 Benefit payments (88) (76) (11) (12) Fair value of plan assets at December 31 1,150 981 — — Funded status at December 31 — excess of obligation over assets $ (247) $ (241) $ (93) $ (83)
Schedule of Amounts Recognized in Balance Sheet	Amounts recognized in NRG's balance sheets were as follows: As of December 31, Pension Benefits Other Postretirement Benefits (In millions) 2019 2018 2019 2018 Other current liabilities $ — $ — $ 7 $ 7 Other non-current liabilities 247 241 86 76
Schedule of Amounts Recognized in OCI Not Yet Recognized as Components of Net Periodic Benefit Costs	Amounts recognized in NRG's accumulated OCI that have not yet been recognized as components of net periodic benefit cost were as follows: As of December 31, Pension Benefits Other Postretirement Benefits (In millions) 2019 2018 2019 2018 Net loss/(gain) $ 138 $ 90 $ 7 $ (9) Prior service cost/(credit) 2 3 (43) (53) Total accumulated OCI $ 140 $ 93 $ (36) $ (62) Net accumulated OCI $ 140 $ 93 $ (36) $ (62)
Schedule of Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income	Other changes in plan assets and benefit obligations recognized in OCI were as follows: Year Ended December 31, Pension Benefits Other Postretirement Benefits (In millions) 2019 2018 2019 2018 Net actuarial loss/(gain) $ 50 $ 47 $ 16 $ (5) Amortization of net actuarial (gain)/loss (3) — — — Curtailment — (27) — 2 Prior service credit — 17 (2) (28) Amortization of prior service cost — — 12 10 Total recognized in OCI $ 47 $ 37 $ 26 $ (21) Net periodic benefit cost/(credit) — 12 (9) (15) Net recognized in net periodic pension cost/(credit) and OCI $ 47 $ 49 $ 17 $ (36)
Schedule of Benefit Obligations Significant Components	The following table presents the balances of significant components of NRG's pension plan: As of December 31, Pension Benefits (In millions) 2019 2018 Projected benefit obligation $ 1,397 $ 1,222 Accumulated benefit obligation 1,362 1,188 Fair value of plan assets 1,150 981
Schedule of Fair Value of Pension Plan Assets by Asset Category and Level within the Fair Value Hierarchy	NRG's market-related value of its plan assets is the fair value of the assets. The fair values of the Company's pension plan assets by asset category and their level within the fair value hierarchy are as follows: Fair Value Measurements as of December 31, 2019 (In millions) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Total Common/collective trust investment — U.S. equity $ — $ 233 $ 233 Common/collective trust investment — non-U.S. equity — 73 73 Common/collective trust investment — non-core assets — 143 143 Common/collective trust investment — fixed income — 272 272 Short-term investment fund 12 — 12 Subtotal fair value $ 12 $ 721 $ 733 Measured at net asset value practical expedient: Common/collective trust investment — non-U.S. equity 84 Common/collective trust investment — fixed income 279 Common/collective trust investment — non-core assets 24 Partnerships/joint ventures 30 Total fair value $ 1,150 Fair Value Measurements as of December 31, 2018 (In millions) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Total Common/collective trust investment — U.S. equity $ — $ 183 $ 183 Common/collective trust investment — non-U.S. equity — 53 53 Common/collective trust investment — non-core assets — 117 117 Common/collective trust investment — fixed income — 256 256 Short-term investment fund 12 — 12 Subtotal fair value $ 12 $ 609 $ 621 Measured at net asset value practical expedient: Common/collective trust investment — non-U.S. equity 70 Common/collective trust investment — fixed income 249 Common/collective trust investment — non-core assets 16 Partnerships/joint ventures 25 Total fair value $ 981
Schedule of Assumptions Used to Calculate Benefit Expense	The following table presents the significant assumptions used to calculate NRG's benefit obligations: As of December 31, Pension Benefits Other Postretirement Benefits Weighted-Average Assumptions 2019 2018 2019 2018 Discount rate 3.26 % 4.38 % 3.26 % 4.37 % Rate of compensation increase 3.00 % 3.00 % — % — % Health care trend rate — — 7.5% grading to 4.5% in 2028 7.8% grading to 4.5% in 2025 The following table presents the significant assumptions used to calculate NRG's benefit expense: As of December 31, Pension Benefits Other Postretirement Benefits Weighted-Average Assumptions 2019 2018 2017 2019 2018 2017 Discount rate 4.38%/4.2% 3.71%/4.04% 4.26 % 4.37% 3.71% /4.08% 4.29 % Expected return on plan assets 6.35 % 6.17 % 6.85 % — — — Rate of compensation increase 3.00 % 3.00 % 3.00 % — — — Health care trend rate — — — 7.8% grading to 4.5% in 2025 8.2% grading to 4.5% in 2025 7.0% grading to 5.0% in 2025
Schedule of Target Allocation of Pension Plan Assets	The target allocations of NRG's pension plan assets were as follows for the year ended December 31, 2019: U.S. equity 20 % Non-U.S. equity 13 % Non-core assets 17 % U.S. fixed income 50 %
Schedule of Performance Benchmarks	Performance benchmarks are composed of the following indices: Asset Class Index U.S. equities Dow Jones U.S. Total Stock Market Index Non-U.S. equities MSCI All Country World Ex-U.S. IMI Index Non-core assets (a) Various (per underlying asset class) Fixed income securities Barclays Capital Long Term Government/Credit Index & Barclays Strips 20+ Index
Schedule of Expected Benefit Payments	NRG's expected future benefit payments for each of the next five years, and in the aggregate for the five years thereafter, are as follows: Other Postretirement Benefit (In millions) Pension Benefit Payments Benefit Payments Medicare Prescription Drug Reimbursements 2020 $ 84 $ 7 $ — 2021 86 6 — 2022 86 6 — 2023 86 6 — 2024 86 6 — 2025-2029 402 19 2
Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates	Assumed health care cost trend rates have a significant effect on the amounts reported for the health care plans. The impact of a one-percentage-point change in assumed health care cost trend rates is immaterial on total service and interest costs components but would have the following effect: (In millions) 1-Percentage- Point Increase 1-Percentage- Point Decrease Effect on postretirement benefit obligation $ 7 $ (5)
Schedule of Benefit Costs and Other Changes Recognized in the Financial Statements Related to its Interest in STP	The Company has recognized the following in its statement of financial position, statement of operations and accumulated OCI related to its 44% interest in STP: As of December 31, Pension Benefits Other Postretirement Benefits (In millions) 2019 2018 2019 2018 Funded status — STPNOC benefit plans $ (77) $ (78) $ (20) $ (19) Net periodic benefit cost/(credit) 9 8 (4) (7) Other changes in plan assets and benefit obligations recognized in other comprehensive (loss)/income (13) (7) 6 2
Defined Contribution Plan Contributions	The Company's contributions to these plans were as follows: Year Ended December 31, (In millions) 2019 2018 2017 Company contributions to defined contribution plans $ 22 $ 28 $ 56

Capital Structure (Tables)

Capital Structure (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Changes in NRG's common shares issued and outstanding	The following table reflects the changes in NRG's common shares issued and outstanding for each period presented: Common Issued Treasury Outstanding Balance as of December 31, 2016 417,583,825 (102,140,814) 315,443,011 Shares issued under ESPP — 560,769 560,769 Shares issued under LTIPs 739,309 — 739,309 Balance as of December 31, 2017 418,323,134 (101,580,045) 316,743,089 Shares issued under ESPP — 175,862 175,862 Shares issued under LTIPs 1,965,752 — 1,965,752 Share repurchases — (35,234,664) (35,234,664) Balance as of December 31, 2018 420,288,886 (136,638,847) 283,650,039 Shares issued under ESPP — 46,128 46,128 Shares issued under LTIPs 1,601,904 — 1,601,904 Share repurchases — (36,301,882) (36,301,882) Balance as of December 31, 2019 421,890,790 (172,894,601) 248,996,189
Summary of shares repurchased	The following table summarizes the shares repurchases made from 2018 through February 27, 2020: Total number of shares and share equivalents purchased Average price paid per share and share equivalent Amounts paid for shares and share equivalents purchased (in millions) 2018 repurchases: Shares repurchased under May 24, 2018 Accelerated Repurchase Agreement 10,829,903 354 Shares repurchased under September 5, 2018 Accelerated Repurchase Agreement 13,307,130 500 Other repurchases 11,097,631 396 Total Share Repurchases during 2018 35,234,664 $35.48 $ 1,250 2019 repurchases: Repurchases under February 28, 2019 Accelerated Share Repurchase Agreement 9,438,671 400 Other repurchases 26,863,211 1,008 Equivalent shares purchased in lieu of tax withholdings on equity compensation issuances (a) 936,928 36 Total Share Repurchases during 2019 37,238,810 $ 38.79 $ 1,444 2020 repurchases: Repurchases made subsequent to December 31, 2019 2,428,545 92 Equivalent shares purchased in lieu of tax withholdings on equity compensation issuances (a) 709,536 27 Total share repurchases January 1, 2020 through February 27, 2020 3,138,081 $ 37.87 $ 119 (a) NRG elected to pay cash for tax withholding on equity awards instead of issuing actual shares to management. The average price per equivalent shares withheld was $38.24 and $38.78 in 2020 and 2019, respectively. See Note 21, Stock-Based Compensation , for further discussion of the equity awards

Investments Accounted for by _2

Investments Accounted for by the Equity Method and Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Summary NRG's equity method investments	The following table summarizes NRG's equity method investments as of December 31, 2019: (In millions, except percentages) Name Economic Investment Balance Agua Caliente 35.0 % 213 Gladstone 37.5 % 124 Ivanpah Master Holdings, LLC 54.5 % 20 Watson Cogeneration Company 49.0 % 15 Midway-Sunset Cogeneration Company 50.0 % 9 Other (a) Various 7 Total equity investments in affiliates $ 388 (a) Refer to Note 11, Asset Impairments
Undistributed earnings by equity investment	As of December 31, (In millions) 2019 2018 Undistributed earnings from equity investments $ 42 $ 34
Summary of Financial Information for Consolidated VIEs	The summarized financial information for the Company's consolidated VIEs consisted of the following: (In millions) December 31, 2019 December 31, 2018 Current assets $ 3 $ 3 Net property, plant and equipment 71 76 Other long-term assets 27 28 Total assets 101 107 Current liabilities 4 2 Long-term debt 24 29 Other long-term liabilities 8 7 Total liabilities 36 38 Redeemable noncontrolling interests 20 19 Net assets less noncontrolling interests $ 45 $ 50

Earnings _Loss Per Share (Table

Earnings /Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Reconciliation of NRG's basic and diluted earnings per share	The reconciliation of NRG's basic income/(loss) per share to diluted income/(loss) per share is shown in the following table: Year Ended December 31, (In millions, except per share amounts) 2019 2018 2017 Basic income/(loss) per share attributable to NRG, Inc; Net income/(loss) attributable to NRG Energy, Inc. common stockholders $ 4,438 $ 268 $ (2,153) Weighted average number of common shares outstanding-basic 262 304 317 Income/(Loss) per weighted average common share — basic $ 16.94 $ 0.88 $ (6.79) Diluted income/(loss) per share attributable to NRG, Inc; Net income/(loss) attributable to NRG Energy, Inc. common stockholders $ 4,438 $ 268 $ (2,153) Weighted average number of common shares outstanding-basic 262 304 317 Incremental shares attributable to the issuance of equity compensation (treasury stock method) 2 4 — Weighted average number of common shares outstanding-diluted 264 308 317 Income/(Loss) per weighted average common share — diluted $ 16.81 $ 0.87 $ (6.79)
Summary of NRG's outstanding equity instruments that are anti-dilutive and were not included in the computation of the Company's diluted earnings per share	The following table summarizes NRG's outstanding equity instruments that are anti-dilutive and were not included in the computation of the Company's diluted income/(loss) per share: Year Ended December 31, (In millions) 2019 2018 2017 Equity compensation plans — — 5

Segment Reporting (Tables)

Segment Reporting (Tables)	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Segment Reporting	For the Year Ended December 31, 2019 (In millions) Texas East West/Other Corporate (a) Eliminations Total Operating revenues (a) $ 7,069 $ 2,319 $ 440 $ — $ (7) $ 9,821 Operating expenses 5,818 1,895 397 50 (7) 8,153 Depreciation and amortization 188 121 33 31 — 373 Impairment losses 1 — 4 — — 5 Development costs 3 3 1 — — 7 Total operating cost and expenses 6,010 2,019 435 81 (7) 8,538 Gain on sale of assets — 1 — 6 — 7 Operating income/(loss) 1,059 301 5 (75) — 1,290 Equity in (losses)/earnings of unconsolidated affiliates (4) — 6 — — 2 Impairment losses on investments (103) — — (5) — (108) Other income, net 20 6 10 30 — 66 Loss on debt extinguishment — — (3) (48) — (51) Interest expense — (18) (10) (385) — (413) Income/(loss) from continuing operations before income taxes 972 289 8 (483) — 786 Income tax expense/(benefit) — 2 1 (3,337) — (3,334) Net income from continuing operations 972 287 7 2,854 — 4,120 Gain from discontinued operations, net of income tax — — — 321 — 321 Net Income 972 287 7 3,175 — 4,441 Less: Net income attributable to noncontrolling interests and redeemable noncontrolling interests — — 3 — — 3 Net income attributable to NRG Energy, Inc. $ 972 $ 287 $ 4 $ 3,175 $ — $ 4,438 Balance sheet Equity investments in affiliates $ 6 $ — $ 382 $ — $ — $ 388 Capital expenditures 136 30 25 37 — 228 Goodwill (b) 325 254 — — — 579 Total assets $ 5,711 $ 2,160 $ 1,190 $ 8,342 $ (4,872) $ 12,531 (a) Inter-segment sales and inter-segment net derivative gains and losses included in operating revenues $ 1 $ 8 $ (2) $ — $ — $ 7 (b) Goodwill was allocated based on the regions in which the business operates and are expected to benefit using a relative fair value approach For the Year Ended December 31, 2018 (In millions) Texas East West/Other Corporate (a) Eliminations Total Operating revenues (a) $ 6,401 $ 2,371 $ 724 $ — $ (18) $ 9,478 Operating expenses 5,399 2,024 467 125 (18) 7,997 Depreciation and amortization 156 105 127 33 — 421 Impairment losses 5 82 12 — — 99 Development costs 3 3 3 2 — 11 Total operating cost and expenses 5,563 2,214 609 160 (18) 8,528 Gain on sale of assets 4 — (2) 30 — 32 Operating income/(loss) 842 157 113 (130) — 982 Equity in (losses)/earnings of unconsolidated affiliates (3) — 13 (1) — 9 Impairment losses on investments (15) — — — — (15) Other income/(loss), net 13 2 4 (1) — 18 Loss on debt extinguishment — — — (44) — (44) Interest expense — (22) (39) (422) — (483) Income/(loss) from continuing operations before income taxes 837 137 91 (598) — 467 Income tax expense — 1 — 6 — 7 Net income/(loss) from continuing operations 837 136 91 (604) — 460 Loss from discontinued operations, net of income tax — — — (192) — (192) Net Income/(loss) 837 136 91 (796) — 268 Less: Net income/(loss) attributable to noncontrolling interests and redeemable noncontrolling interests — — 5 (5) — — Net income/(loss) attributable to NRG Energy, Inc. $ 837 $ 136 $ 86 $ (791) $ — $ 268 Balance sheet Equity investments in affiliates $ 6 $ — 406 $ — $ — $ 412 Capital expenditures 143 171 29 45 — 388 Goodwill (b) 320 253 — — — 573 Total assets $ 5,357 $ 2,187 $ 1,548 $ 6,631 $ (5,095) $ 10,628 (a) Inter-segment sales and inter-segment net derivative gains and losses included in operating revenues $ 19 $ (5) 4 $ — $ — $ 18 (b) Goodwill was allocated based on the regions in which the business operates and are expected to benefit using a relative fair value approach For the Year Ended December 31, 2017 (In millions) Texas East West/Other Corporate (a) Eliminations Total Operating revenues (a) $ 6,318 $ 2,009 $ 788 $ 6 $ (47) $ 9,074 Operating expenses 5,393 1,684 498 239 (48) 7,766 Depreciation and amortization 258 112 194 35 (3) 596 Impairment losses 1,317 106 111 — — 1,534 Development costs 4 6 6 6 — 22 Total operating costs and expenses 6,972 1,908 809 280 (51) 9,918 Other income - affiliate — — — 87 — 87 Gain/(loss) on sale of assets 5 15 (5) 1 — 16 Operating (loss)/income (649) 116 (26) (186) 4 (741) Equity in (losses)/earnings of unconsolidated affiliates (22) — 10 (2) — (14) Impairment losses on investments (69) — (6) (4) — (79) Other (expense)/income, net (2) 4 22 27 — 51 Loss on debt extinguishment — — — (49) — (49) Interest expense — (29) (77) (451) — (557) (Loss)/income from continuing operations before income taxes (742) 91 (77) (665) 4 (1,389) Income tax benefit — — (6) (38) — (44) Net (loss)/income from continuing operations (742) 91 (71) (627) 4 (1,345) Loss from discontinued operations, net of income tax — — — (992) — (992) Net (loss)/income (742) 91 (71) (1,619) 4 (2,337) Less: Net income/(loss) attributable to noncontrolling interests and redeemable noncontrolling interests — — 1 (189) 4 (184) Net (loss)/income attributable to NRG Energy, Inc. $ (742) $ 91 $ (72) $ (1,430) $ — $ (2,153) (a) Inter-segment sales and inter-segment net derivative gains and losses included in operating revenues $ 41 $ 1 (4) $ 9 $ — $ 47

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income tax provision from continuing operations	The income tax provision from continuing operations consisted of the following amounts: Year Ended December 31, (In millions, except effective income tax rate) 2019 2018 2017 Current State $ 2 $ 6 $ 19 Foreign 4 — — Total — current 6 6 19 Deferred U.S. Federal (3,000) (16) (60) State (340) 16 (5) Foreign — 1 2 Total — deferred (3,340) 1 (63) Total income tax (benefit)/expense $ (3,334) $ 7 $ (44) Effective income tax rate (424.2) % 1.5 % 3.2 %
Domestic and foreign components of income/(loss) before income tax (benefit)/expense	The following represented the domestic and foreign components of income/(loss) from continuing operations before income taxes: Year Ended December 31, (In millions) 2019 2018 2017 U.S. $ 771 $ 468 $ (1,406) Foreign 15 (1) 17 Total $ 786 $ 467 $ (1,389)
Reconciliation of the U.S. federal statutory rate to NRG's effective rate	Reconciliations of the U.S. federal statutory tax rate to NRG's effective tax rate were as follows: Year Ended December 31, (In millions, except effective income tax rate) 2019 2018 2017 Income/(loss) from continuing operations before income taxes $ 786 $ 467 $ (1,389) Tax at federal statutory tax rate 165 98 (486) State taxes 13 18 19 Foreign operations — — 2 Permanent differences (9) 7 — Valuation allowance - current period activities (3,492) (106) 455 Book goodwill impairment — — 30 Deferred impact of state tax rate changes 12 — — Production tax credits ("PTC") — (7) (8) Recognition of uncertain tax benefits (10) 1 (5) Alternative minimum tax ("AMT") refundable credit — (4) (64) Tax Act - corporate income tax rate change — — 665 Valuation allowance due to corporate income tax rate change — — (660) Other (13) — 8 Income tax (benefit)/expense $ (3,334) $ 7 $ (44) Effective income tax rate (424.2) % 1.5 % 3.2 %
Company's deferred tax assets and liabilities	The temporary differences, which gave rise to the Company's deferred tax assets and liabilities consisted of the following: As of December 31, (In millions) 2019 2018 Deferred tax assets: Deferred compensation, accrued vacation and other reserves $ 81 $ 134 Difference between book and tax basis of property 548 554 Goodwill — 11 Differences between book and tax basis of contracts — 38 Pension and other postretirement benefits 86 87 Equity compensation 11 9 Bad debt reserve 13 14 U.S. Federal net operating loss carryforwards 2,116 2,241 Foreign net operating loss carryforwards 105 63 State net operating loss carryforwards 360 379 Federal and state tax credit carryforwards 384 381 Federal benefit on state uncertain tax positions 4 6 Intangibles amortization (excluding goodwill) — 21 Interest disallowance carryforward per §163(j) of the Tax Act 82 102 Inventory obsolescence 7 7 Other 3 — Discontinued operations — 17 Total deferred tax assets 3,800 4,064 Deferred tax liabilities: Emissions allowances 19 15 Derivatives, net 27 37 Goodwill 8 — Intangibles amortization (excluding goodwill) 15 — Equity method investments 201 180 Convertible Debt 19 21 Other — 1 Discontinued operations — 36 Total deferred tax liabilities 289 290 Total deferred tax assets less deferred tax liabilities 3,511 3,774 Valuation allowance (242) (3,812) Discontinued operations — 19 Total deferred tax assets/(liabilities), net of valuation allowance $ 3,269 $ (19)
Summary of NRG's net deferred tax position	The following table summarizes NRG's net deferred tax position as presented in the consolidated balance sheets: As of December 31, (In millions) 2019 2018 Deferred tax asset $ 3,286 $ 46 Deferred tax liability (17) (65) Net deferred tax asset/(liability) $ 3,269 $ (19)
Reconciliation of total amounts of uncertain tax benefits	The following table summarizes uncertain tax benefits activity: As of December 31, (In millions) 2019 2018 Balance as of January 1 $ 26 $ 30 Increase due to current year positions 2 4 Settlements, payments and statute closure (13) (8) Uncertain tax benefits as of December 31 $ 15 $ 26

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement, Noncash Expense [Abstract]
Summary of Company's non-vested RSU awards and changes during the year	The following table summarizes the Company's non-vested RSU awards and changes during the year: Units Weighted Average Grant Date Fair Value per Unit Non-vested at December 31, 2018 1,458,082 $ 16.16 Granted 266,938 37.37 Forfeited (73,905) 24.73 Vested (933,876) 14.20 Non-vested at December 31, 2019 717,239 25.56
Summary of Company's Non-vested DSU awards and changes during the year	The following table summarizes the Company's outstanding DSU awards and changes during the year: Units Weighted Average Grant Date Fair Value per Unit Outstanding at December 31, 2018 331,915 $ 22.94 Granted 57,630 34.84 Converted to Common Stock (58,322) 28.93 Outstanding at December 31, 2019 331,223 23.98 The following table summarizes the Company's non-vested PSU awards and changes during the year: Units Weighted Average Grant-Date Fair Value per Unit Non-vested at December 31, 2018 1,710,634 $ 19.12 Granted (a) 936,889 22.50 Forfeited (37,526) 23.04 Vested (b) (1,409,456) 14.72 Non-vested at December 31, 2019 (c) 1,200,541 26.65 (a) The weighted average grant date fair value per unit includes RPSUs that were granted during 2019 with grant date fair value of $45.77 and MSUs with 2016 grant date fair value of $14.72, that due to vesting at 200%, were considered additional grants in 2019 (b) MSUs granted during 2016 vested during 2019 at 200% (c) Non-vested units includes 8,645 MSUs
Summary of Company's PSU awards and changes during the year	The following table summarizes the Company's outstanding DSU awards and changes during the year: Units Weighted Average Grant Date Fair Value per Unit Outstanding at December 31, 2018 331,915 $ 22.94 Granted 57,630 34.84 Converted to Common Stock (58,322) 28.93 Outstanding at December 31, 2019 331,223 23.98 The following table summarizes the Company's non-vested PSU awards and changes during the year: Units Weighted Average Grant-Date Fair Value per Unit Non-vested at December 31, 2018 1,710,634 $ 19.12 Granted (a) 936,889 22.50 Forfeited (37,526) 23.04 Vested (b) (1,409,456) 14.72 Non-vested at December 31, 2019 (c) 1,200,541 26.65 (a) The weighted average grant date fair value per unit includes RPSUs that were granted during 2019 with grant date fair value of $45.77 and MSUs with 2016 grant date fair value of $14.72, that due to vesting at 200%, were considered additional grants in 2019 (b) MSUs granted during 2016 vested during 2019 at 200% (c) Non-vested units includes 8,645 MSUs
Schedule of Assumptions used in Fair Value Model	Significant assumptions used in the fair value model with respect to the Company's PSUs are summarized below: 2019 2018 2017 2016 RPSUs RPSUs RPSUs MSUs Expected volatility 40.72 % 47.52 % 43.96 % 34.33 % Expected term (in years) 3 3 3 3 Risk free rate 2.45 % 2.01 % 1.5 % 1.31 %
Summary of Company's NQSO activity, and changes during the year	The following table summarizes the Company's NQSO activity and changes during the year: Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in millions) Outstanding at December 31, 2018 279,934 $ 25.04 2 $ 4 Expired (8,254) 26.76 Exercised (137,282) 24.67 Outstanding at December 31, 2019 134,398 25.31 1 2 Exercisable at December 31, 2019 134,398 25.31 1 2
Summary of the total intrinsic value of options exercised and the cash received from the exercises of options	The following table summarizes the total intrinsic value of options exercised and the cash received from the exercises of options: Year Ended December 31, (In millions) 2019 2018 2017 Total intrinsic value of options exercised $ 2 $ 10 $ 1 Cash received from options exercised 3 24 4
Summary of NRG's total compensation expense recognized and total non-vested compensation costs not yet recognized and the period over which this expense is expected to be recognized	The following table summarizes NRG's total compensation expense recognized for the years presented, as well as total non-vested compensation costs not yet recognized and the period over which this expense is expected to be recognized as of December 31, 2019, for each of the types of awards issued under the LTIPs. Minimum tax withholdings of $36 million, $19 million, and $5 million for the years ended December 31, 2019, 2018, and 2017, respectively, are reflected as a reduction to additional paid-in capital on the Company's consolidated balance sheets. Non-vested Compensation Cost (In millions, except weighted average data) Compensation Expense Unrecognized Total Cost Weighted Average Recognition Period Remaining (In years) Year Ended December 31, As of December 31, Award 2019 2018 2017 2019 2019 RSUs 9 12 15 8 1.06 DSUs 2 2 2 — 0.00 MSUs — 4 5 — 0.50 RPSUs 10 7 3 9 0.71 PRSUs (a) 11 16 13 10 1.05 Total (b) $ 32 $ 41 $ 38 $ 27 Tax detriment recognized $ (12) $ (4) $ (5) (a) Phantom Restricted Stock Units, PRSUs, are liability-classified time-based awards that typically vest ratably over a three

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Summary of NRG's material related-party transactions with affiliates	The following table summarizes NRG's material related party transactions with third party affiliates: Year Ended December 31, (In millions) 2019 2018 2017 Revenues from Related Parties Included in Operating Revenues Gladstone $ 4 $ 3 $ 3 GenConn (a) — 4 5 Ivanpah (b) 35 20 — Midway-Sunset 5 5 — Total $ 44 $ 32 $ 8

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments under coal, gas and transportation contractual agreements	As of December 31, 2019, the Company's minimum commitments under such outstanding agreements are estimated as follows: Period (In millions) 2020 $ 124 2021 125 2022 73 2023 53 2024 62 Thereafter 139 Total (a) $ 576
Minimum purchase commitment obligations under purchased power agreements	These contracts are not included in the consolidated balance sheet as of December 31, 2019. Minimum purchase commitment obligations are as follows as of December 31, 2019: Period (In millions) 2020 $ 35 2021 49 2022 68 2023 56 2024 56 Thereafter 349 Total $ 613

Cash Flow Information (Tables)

Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2019
Supplemental Cash Flow Information [Abstract]
Details of supplemental disclosures of cash flow and non-cash investing and financing information	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. Year Ended December 31, (In millions) 2019 2018 2017 Cash and cash equivalents $ 345 $ 563 $ 770 Funds deposited by counterparties 32 33 37 Restricted cash 8 17 279 Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statements of cash flows $ 385 $ 613 $ 1,086 Detail of supplemental disclosures of cash flow and non-cash investing and financing information was: Year Ended December 31, (In millions) 2019 2018 2017 Interest paid, net of amount capitalized $ 372 $ 436 $ 543 Income taxes paid, net of refunds 8 9 9 Non-cash investing activities: Additions to fixed assets for accrued capital expenditures 1 20 19

Guarantees (Tables)

Guarantees (Tables)	12 Months Ended
	Dec. 31, 2019
Guarantees [Abstract]
Summary of NRG's estimated guarantees, indemnity, and other contingent liability	The following table summarizes the maximum potential exposures that can be estimated for NRG's guarantees, indemnities, and other contingent liabilities by maturity: By Remaining Maturity at December 31, (In millions) 2019 Guarantees Under 1 Year 1-3 Years 3-5 Years Over 5 Years Total 2018 Total Letters of credit and surety bonds (a) $ 878 $ 115 $ 31 $ — $ 1,024 $ 1,253 Asset sales guarantee obligations 4 490 — 204 698 793 Other guarantees 77 5 — 206 288 721 Total guarantees $ 959 $ 610 $ 31 $ 410 $ 2,010 $ 2,767 (a) December 31, 2019 includes $14 million of letter of credit and surety bonds for the benefit of GenOn where NRG holds cash or letter of credit to back stop the liability

Jointly Owned Plants (Tables)

Jointly Owned Plants (Tables)	12 Months Ended
	Dec. 31, 2019
Jointly Owned Plants Disclosure [Abstract]
Summary of NRG's proportionate ownership interest in the company's jointly-owned facilities	The following table summarizes NRG's proportionate ownership interest in the Company's jointly-owned facilities: (In millions unless otherwise stated) As of December 31, 2019 Ownership Interest Property, Plant & Equipment Accumulated Depreciation Construction in Progress South Texas Project Units 1 and 2, Bay City, TX 44.00 % $ 413 $ (206) $ 8 Cedar Bayou Unit 4, Baytown, TX 50.00 % 218 (93) 7

Unaudited Quarterly Financial_2

Unaudited Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Summary of Unaudited Quarterly Financial Data	Summarized unaudited quarterly financial data is as follows: Quarter Ended 2019 (In millions, except per share data) December 31 September 30 June 30 March 31 Operating revenues $ 2,195 $ 2,996 $ 2,465 $ 2,165 Operating income 209 540 320 221 Net income from continuing operations 3,463 374 189 94 (Loss)/income from discontinued operations (78) (2) 13 388 Net income 3,385 372 202 482 Less: Net income attributable to noncontrolling interests and redeemable noncontrolling interests 2 — 1 — Income available to Common Stockholders $ 3,383 $ 372 $ 201 $ 482 Weighted average number of common shares outstanding — basic 251 254 265 278 (Loss)/income from discontinued operations per weighted average common share — basic $ (0.31) $ (0.01) $ 0.05 $ 1.39 Net Income per weighted average common share — basic $ 13.48 $ 1.46 $ 0.76 $ 1.73 Weighted average number of common shares outstanding — diluted 253 256 267 280 (Loss)/income from discontinued operations per weighted average common share — diluted $ (0.31) $ (0.01) $ 0.05 $ 1.38 Net income per weighted average common share — diluted $ 13.37 $ 1.45 $ 0.75 $ 1.72 Quarter Ended 2018 (In millions, except per share data) December 31 September 30 June 30 March 31 Operating revenues $ 1,992 $ 2,960 $ 2,461 $ 2,065 Operating income 49 398 174 361 Net (loss)/income from continuing operations (93) 287 27 238 Income/(loss) from discontinued operations 80 (336) 69 (5) Net (loss)/income (13) (49) 96 233 Less: Net (loss)/income attributable to noncontrolling interests and redeemable noncontrolling interests (2) 23 24 (46) (Loss)/income available to Common Stockholders $ (11) $ (72) $ 72 $ 279 Weighted average number of common shares outstanding — basic 289 299 310 318 Income/(loss) from discontinued operations per weighted average common share — basic $ 0.28 $ (1.12) $ 0.22 $ (0.02) Net (loss)/income per weighted average common share — basic $ (0.04) $ (0.24) $ 0.23 $ 0.88 Weighted average number of common shares outstanding — diluted 289 299 314 322 Income/(loss) from discontinued operations per weighted average common share — diluted $ 0.28 $ (1.12) $ 0.22 $ (0.02) Net (loss)/income per weighted average common share — diluted $ (0.04) $ (0.24) $ 0.23 $ 0.87

Condensed Consolidating Finan_2

Condensed Consolidating Financial Information (Tables)	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Schedule of Guarantor Subsidiaries	Unless otherwise noted below, each of the following guarantor subsidiaries fully and unconditionally guaranteed the Senior Notes and Senior Secured First Lien Notes as of December 31, 2019: Ace Energy, Inc. NRG Astoria Gas Turbine Operations Inc. NRG Oswego Harbor Power Operations Inc. Allied Home Warranty GP LLC NRG Business Services LLC NRG PacGen Inc. Allied Warranty LLC NRG Cabrillo Power Operations Inc. NRG Portable Power LLC Arthur Kill Power LLC NRG California Peaker Operations LLC NRG Power Marketing LLC Astoria Gas Turbine Power LLC NRG Cedar Bayou Development Company, LLC NRG Reliability Solutions LLC BidURenergy, Inc. NRG Connected Home LLC NRG Renter's Protection LLC Cabrillo Power I LLC NRG Connecticut Affiliate Services Inc. NRG Retail LLC Cabrillo Power II LLC NRG Construction LLC NRG Retail Northeast LLC Carbon Management Solutions LLC NRG Curtailment Solutions, Inc NRG Rockford Acquisition LLC Cirro Group, Inc. NRG Development Company Inc. NRG Saguaro Operations Inc. Cirro Energy Services, Inc. NRG Devon Operations Inc. NRG Security LLC Connecticut Jet Power LLC NRG Dispatch Services LLC NRG Services Corporation Devon Power LLC NRG Distributed Energy Resources Holdings LLC NRG SimplySmart Solutions LLC Dunkirk Power LLC NRG Distributed Generation PR LLC NRG South Central Affiliate Services Inc. Eastern Sierra Energy Company LLC NRG Dunkirk Operations Inc. NRG South Central Operations Inc. El Segundo Power, LLC NRG ECOKAP Holdings LLC NRG South Texas LP El Segundo Power II LLC NRG El Segundo Operations Inc. NRG Texas Gregory LLC Energy Alternatives Wholesale, LLC NRG Energy Labor Services LLC NRG Texas Holding Inc. Energy Choice Solutions LLC NRG Energy Services Group LLC NRG Texas LLC Energy Plus Holdings LLC NRG Energy Services International Inc. NRG Texas Power LLC Energy Plus Natural Gas LLC NRG Energy Services LLC NRG Warranty Services LLC Energy Protection Insurance Company NRG Generation Holdings, Inc. NRG West Coast LLC Everything Energy LLC NRG Greenco LLC NRG Western Affiliate Services Inc. Forward Home Security, LLC NRG Home & Business Solutions LLC O'Brien Cogeneration, Inc. II GCP Funding Company, LLC NRG Home Services LLC Oswego Harbor Power LLC Green Mountain Energy Company NRG Home Solutions LLC Reliant Energy Northeast LLC Gregory Partners, LLC NRG Home Solutions Product LLC Reliant Energy Power Supply, LLC Gregory Power Partners LLC NRG Homer City Services LLC Reliant Energy Retail Holdings, LLC Huntley Power LLC NRG HQ DG LLC Reliant Energy Retail Services, LLC Independence Energy Alliance LLC NRG Huntley Operations Inc. RERH Holdings, LLC Independence Energy Group LLC NRG Identity Protect LLC Saguaro Power LLC Independence Energy Natural Gas LLC NRG Ilion Limited Partnership Somerset Operations Inc. Indian River Operations Inc. NRG Ilion LP LLC Somerset Power LLC Indian River Power LLC NRG International LLC Texas Genco GP, LLC Meriden Gas Turbines LLC NRG Maintenance Services LLC Texas Genco Holdings, Inc. Middletown Power LLC NRG Mextrans Inc. Texas Genco LP, LLC Montville Power LLC NRG MidAtlantic Affiliate Services Inc. Texas Genco Services, LP NEO Corporation NRG Middletown Operations Inc. US Retailers LLC New Genco GP, LLC NRG Montville Operations Inc. Vienna Operations Inc. Norwalk Power LLC NRG North Central Operations Inc. Vienna Power LLC NRG Advisory Services LLC NRG Northeast Affiliate Services Inc. WCP (Generation) Holdings LLC NRG Affiliate Services Inc. NRG Norwalk Harbor Operations Inc. West Coast Power LLC NRG Arthur Kill Operations Inc. NRG Operating Services, Inc.
Condensed Consolidating Statement of Operations	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the Year Ended December 31, 2019 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Operating Revenues Total operating revenues $ 8,041 $ 1,791 $ — $ (11) $ 9,821 Operating Costs and Expenses Cost of operations 5,936 1,351 27 (11) 7,303 Depreciation and amortization 212 130 31 — 373 Impairment losses 1 4 — — 5 Selling, general and administrative 466 83 278 — 827 Reorganization costs — — 23 — 23 Development costs — — 7 — 7 Total operating costs and expenses 6,615 1,568 366 (11) 8,538 Gain on sale of assets 1 — 6 — 7 Operating Income/(Loss) 1,427 223 (360) — 1,290 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 48 — 1,562 (1,610) — Equity in earnings of unconsolidated affiliates — 2 — — 2 Impairment losses on investments — (101) (7) — (108) Other income, net 23 12 31 — 66 Loss on debt extinguishment, net — (3) (48) — (51) Interest expense (14) (14) (385) — (413) Total other income/(expense) 57 (104) 1,153 (1,610) (504) Income from Continuing Operations Before Income Taxes 1,484 119 793 (1,610) 786 Income tax expense/(benefit) — 4 (3,338) — (3,334) Income from Continuing Operations 1,484 115 4,131 (1,610) 4,120 Income from discontinued operations, net of income tax 9 5 307 — 321 Net Income 1,493 120 4,438 (1,610) 4,441 Less: Net income attributable to redeemable noncontrolling interests — 3 — — 3 Net Income Attributable to NRG Energy, Inc. $ 1,493 $ 117 $ 4,438 $ (1,610) $ 4,438 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the Year Ended December 31, 2018 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Operating Revenues Total operating revenues $ 8,119 $ 1,385 $ — $ (26) $ 9,478 Operating Costs and Expenses Cost of operations 6,147 959 28 (26) 7,108 Depreciation and amortization 238 150 33 — 421 Impairment losses 6 93 — — 99 Selling, general and administrative 462 63 348 (74) 799 Reorganization costs 4 — 86 — 90 Development costs — 1 11 (1) 11 Total operating costs and expenses 6,857 1,266 506 (101) 8,528 Gain on sale of assets 4 28 — — 32 Operating Income/(Loss) 1,266 147 (506) 75 982 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 23 — 1,291 (1,314) — Equity in earnings/(losses) of unconsolidated affiliates — 10 (1) — 9 Impairment losses on investments — (15) — — (15) Other income/(expense), net 32 (13) (1) — 18 Loss on debt extinguishment, net — — (44) — (44) Interest expense (14) (49) (420) — (483) Total other income/(expense) 41 (67) 825 (1,314) (515) Income from Continuing Operations Before Income Taxes 1,307 80 319 (1,239) 467 Income tax expense/(benefit) 372 19 (384) — 7 Income from Continuing Operations 935 61 703 (1,239) 460 Income/(loss) from discontinued operations, net of income tax 62 75 (329) — (192) Net Income 997 136 374 (1,239) 268 Less: Net (loss)/income attributable to noncontrolling interests and redeemable noncontrolling interests — (181) 106 75 — Net Income Attributable to NRG Energy, Inc. $ 997 $ 317 $ 268 $ (1,314) $ 268 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the Year Ended December 31, 2017 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated Balance Operating Revenues Total operating revenues $ 7,818 $ 1,304 $ — $ (48) $ 9,074 Operating Costs and Expenses Cost of operations 5,998 862 72 (46) 6,886 Depreciation and amortization 343 221 32 — 596 Impairment losses 1,346 188 — — 1,534 Selling, general and administrative 410 64 364 (2) 836 Reorganization costs 6 — 38 — 44 Development costs — 4 18 — 22 Total operating costs and expenses 8,103 1,339 524 (48) 9,918 Other income - affiliate — — 87 — 87 Gain on sale of assets 4 12 — — 16 Operating Loss (281) (23) (437) — (741) Other Income/(Expense) Equity in earnings of consolidated subsidiaries 18 — 28 (46) — Equity in losses of unconsolidated affiliates — (10) (4) — (14) Impairment losses on investments — (75) (4) — (79) Other income, net 9 14 28 — 51 Loss on debt extinguishment, net — — (49) — (49) Interest expense (14) (91) (452) — (557) Total other income/(expense) 13 (162) (453) (46) (648) Loss from Continuing Operations Before Income Taxes (268) (185) (890) (46) (1,389) Income tax (benefit)/expense (598) (62) 616 — (44) Income/(Loss) from Continuing Operations 330 (123) (1,506) (46) (1,345) Income/(loss) from discontinued operations, net of income tax 91 (420) (663) — (992) Net Income/(Loss) 421 (543) (2,169) (46) (2,337) Less: Net loss attributable to noncontrolling interests and redeemable noncontrolling interests — (168) (16) — (184) Net Income/(Loss) Attributable to NRG Energy, Inc. $ 421 $ (375) $ (2,153) $ (46) $ (2,153) (a) All significant intercompany transactions have been eliminated in consolidation
Condensed Consolidating Statements of Comprehensive Income	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME For the Year Ended December 31, 2019 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Net Income $ 1,493 $ 120 $ 4,438 $ (1,610) $ 4,441 Other Comprehensive Loss, net of tax Foreign currency translation adjustments, net — (1) (1) 1 (1) Available-for-sale securities, net — — (19) — (19) Defined benefit plan, net (17) — (78) 17 (78) Other comprehensive loss (17) (1) (98) 18 (98) Comprehensive Income 1,476 119 4,340 (1,592) 4,343 Less: Comprehensive income attributable to redeemable noncontrolling interests — 3 — — 3 Comprehensive Income Attributable to NRG Energy, Inc. $ 1,476 $ 116 $ 4,340 $ (1,592) $ 4,340 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME For the Year Ended December 31, 2018 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Net Income $ 997 $ 136 $ 374 $ (1,239) $ 268 Other Comprehensive Income/(Loss), net of tax Unrealized gain on derivatives, net — 29 9 (15) 23 Foreign currency translation adjustments, net (10) (10) (13) 22 (11) Available-for-sale securities, net — — 1 — 1 Defined benefit plan, net (9) — (35) 9 (35) Other comprehensive (loss)/income (19) 19 (38) 16 (22) Comprehensive Income 978 155 336 (1,223) 246 Less: Comprehensive (loss)/income attributable to noncontrolling interests and redeemable noncontrolling interests — (166) 104 76 14 Comprehensive Income Attributable to NRG Energy, Inc. $ 978 $ 321 $ 232 $ (1,299) $ 232 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) For the Year Ended December 31, 2017 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Net Income/(Loss) $ 421 $ (543) $ (2,169) $ (46) $ (2,337) Other Comprehensive Income/(Loss), net of tax Unrealized gain on derivatives, net 1 13 25 (26) 13 Foreign currency translation adjustments, net 6 7 — (1) 12 Available-for-sale securities, net — — (8) — (8) Defined benefit plan, net (13) 30 46 (17) 46 Other comprehensive (loss)/income (6) 50 63 (44) 63 Comprehensive Income/(Loss) 415 (493) (2,106) (90) (2,274) Less: Comprehensive loss attributable to noncontrolling interest and redeemable noncontrolling interests — (103) (16) (60) (179) Comprehensive Income/(Loss) Attributable to NRG Energy, Inc. $ 415 $ (390) $ (2,090) $ (30) $ (2,095) (a) All significant intercompany transactions have been eliminated in consolidation
Condensed Consolidating Balance Sheets	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2019 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated Balance ASSETS Current Assets Cash and cash equivalents $ — $ 20 $ 325 $ — $ 345 Funds deposited by counterparties 32 — — — 32 Restricted cash 5 1 2 — 8 Accounts receivable, net 1,293 239 233 (740) 1,025 Inventory 272 111 — — 383 Derivative instruments 856 45 — (41) 860 Cash collateral posted in support of energy risk management activities 182 8 — — 190 Prepayments and other current assets 170 8 67 — 245 Total current assets 2,810 432 627 (781) 3,088 Property, plant and equipment, net 1,483 952 158 — 2,593 Other Assets Investment in subsidiaries 710 — 4,785 (5,495) — Equity investments in affiliates — 388 — — 388 Operating lease right-of-use assets, net 81 261 122 — 464 Goodwill 359 220 — — 579 Intangible assets, net 375 414 — — 789 Nuclear decommissioning trust fund 794 — — — 794 Derivative instruments 308 15 — (13) 310 Deferred income taxes 421 (19) 2,884 — 3,286 Other non-current assets 145 30 65 — 240 Total other assets 3,193 1,309 7,856 (5,508) 6,850 Total Assets $ 7,486 $ 2,693 $ 8,641 $ (6,289) $ 12,531 LIABILITIES AND STOCKHOLDERS' EQUITY Current Liabilities Current portion of long-term debt $ — $ 5 $ 83 $ — $ 88 Current portion of operating lease liabilities 20 32 21 — 73 Accounts payable 918 141 403 (740) 722 Derivative instruments 797 25 — (41) 781 Cash collateral received in support of energy risk management activities 32 — — — 32 Accrued expenses and other current liabilities 280 44 339 — 663 Total current liabilities 2,047 247 846 (781) 2,359 Other Liabilities Long-term debt 302 28 5,473 — 5,803 Non-current operating lease liabilities 64 301 118 — 483 Nuclear decommissioning reserve 298 — — — 298 Nuclear decommissioning trust liability 487 — — — 487 Derivative instruments 334 1 — (13) 322 Deferred income taxes — 17 — — 17 Other non-current liabilities 399 153 532 — 1,084 Total other liabilities 1,884 500 6,123 (13) 8,494 Total Liabilities 3,931 747 6,969 (794) 10,853 Redeemable noncontrolling interest in subsidiaries — 20 — — 20 Stockholders' Equity 3,555 1,926 1,672 (5,495) 1,658 Total Liabilities and Stockholders' Equity $ 7,486 $ 2,693 $ 8,641 $ (6,289) $ 12,531 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2018 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated Balance ASSETS Current Assets Cash and cash equivalents $ 55 $ 28 $ 480 $ — $ 563 Funds deposited by counterparties 33 — — — 33 Restricted cash 7 10 — — 17 Accounts receivable. net 1,354 115 309 (754) 1,024 Inventory 278 134 — — 412 Derivative instruments 779 50 16 (81) 764 Cash collateral posted in support of energy risk management activities 275 12 — — 287 Prepayments and other current assets 180 32 90 — 302 Current assets - held-for-sale — 1 — — 1 Current assets - discontinued operations 177 20 — — 197 Total current assets 3,138 402 895 (835) 3,600 Property, plant and equipment, net 1,938 957 153 — 3,048 Other Assets Investment in subsidiaries 446 — 4,707 (5,153) — Equity investments in affiliates — 412 — — 412 Goodwill 359 214 — — 573 Intangible assets, net 422 169 — — 591 Nuclear decommissioning trust fund 663 — — — 663 Derivative instruments 296 4 22 (5) 317 Deferred income taxes 6 (143) 183 — 46 Other non-current assets 133 71 97 (12) 289 Non-current assets - held-for-sale — 77 — — 77 Non-current assets - discontinued operations 405 607 — — 1,012 Total other assets 2,730 1,411 5,009 (5,170) 3,980 Total Assets $ 7,806 $ 2,770 $ 6,057 $ (6,005) $ 10,628 LIABILITIES AND STOCKHOLDERS' EQUITY Current Liabilities Current portion of long-term debt and finance leases $ — $ 55 $ 17 $ — $ 72 Accounts payable 1,368 (185) 434 (754) 863 Derivative instruments 713 41 — (81) 673 Cash collateral received in support of energy risk management activities 33 — — — 33 Accrued expenses and other current liabilities 291 36 353 — 680 Current liabilities - held-for-sale — 5 — — 5 Current liabilities - discontinued operations 24 48 — — 72 Total current liabilities 2,429 — 804 (835) 2,398 Other Liabilities Long-term debt and finance leases 244 192 6,025 (12) 6,449 Nuclear decommissioning reserve 282 — — — 282 Nuclear decommissioning trust liability 371 — — — 371 Derivative instruments 306 3 — (5) 304 Deferred income taxes 112 61 (108) — 65 Other non-current liabilities 402 320 552 — 1,274 Non-current liabilities - held-for-sale — 65 — — 65 Non-current liabilities - discontinued operations 58 577 — — 635 Total other liabilities 1,775 1,218 6,469 (17) 9,445 Total Liabilities 4,204 1,218 7,273 (852) 11,843 Redeemable noncontrolling interest in subsidiaries — 19 — — 19 Stockholders' Equity 3,602 1,533 (1,216) (5,153) (1,234) Total Liabilities and Stockholders' Equity $ 7,806 $ 2,770 $ 6,057 $ (6,005) $ 10,628 (a) All significant intercompany transactions have been eliminated in consolidation
Condensed Consolidating Statements of Cash Flows	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the Year Ended December 31, 2019 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Cash Flows from Operating Activities Net income $ 1,493 $ 120 $ 4,438 $ (1,610) $ 4,441 Income from discontinued operations 9 5 307 — 321 Net income from continuing operations 1,484 115 4,131 (1,610) 4,120 Adjustments to reconcile net income to net cash provided by operating activities: Distributions and equity in earnings of unconsolidated affiliates and consolidated subsidiaries (48) 14 (1,562) 1,610 14 Depreciation and amortization 212 130 31 — 373 Accretion of asset retirement obligations 43 8 — — 51 Provision for bad debts 78 17 — — 95 Amortization of nuclear fuel 52 — — — 52 Amortization of financing costs and debt discount/premiums — — 26 — 26 Adjustment for debt extinguishment — 3 48 — 51 Amortization of emission allowances 24 14 — — 38 Amortization of unearned equity compensation — — 20 — 20 Net gain on sale and disposal of assets (20) — (3) — (23) Impairment losses 1 105 7 — 113 Changes in derivative instruments 20 (24) 38 — 34 Changes in deferred income taxes and liability for uncertain tax benefits (525) (168) (2,660) — (3,353) Changes in collateral deposits in support of energy risk management activities 101 4 — — 105 Changes in nuclear decommissioning trust liability 37 — — — 37 Changes in other working capital (220) (118) (10) — (348) Cash provided by continuing operations 1,239 100 66 — 1,405 Cash provided/(used) by discontinued operations 17 (9) — — 8 Net Cash Provided by Operating Activities 1,256 91 66 — 1,413 Cash Flows from Investing Activities Intercompany dividends — — 2,513 (2,513) — Payments for acquisitions of businesses (355) — — — (355) Capital expenditures (164) (27) (37) — (228) Net proceeds from sale of emission allowances 11 — — — 11 Investments in nuclear decommissioning trust fund securities (416) — — — (416) Proceeds from sales of nuclear decommissioning trust fund securities 381 — — — 381 Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees 1 400 893 — 1,294 Changes in investments in unconsolidated affiliates — (91) — — (91) Net contributions to discontinued operations — (44) — — (44) Other — — 6 — 6 Cash (used)/provided by continuing operations (542) 238 3,375 (2,513) 558 Cash used by discontinued operations — (2) — — (2) Net Cash (Used)/Provided by Investing Activities (542) 236 3,375 (2,513) 556 Cash Flows from Financing Activities Intercompany dividends and transfers (751) (214) (1,548) 2,513 — Payments of dividends to common stockholders — — (32) — (32) Payments for share repurchase activity — — (1,440) — (1,440) Payments for debt extinguishment costs — — (26) — (26) Net distributions to redeemable noncontrolling interests from subsidiaries — (2) — — (2) Proceeds from issuance of common stock — — 3 — 3 Proceeds from issuance of long-term debt — — 1,916 — 1,916 Payments of debt issuance costs — — (35) — (35) Payments for short and long-term debt — (139) (2,432) — (2,571) Other (4) — — — (4) Cash used by continuing operations (755) (355) (3,594) 2,513 (2,191) Cash provided by discontinued operations — 43 — — 43 Net Cash Used by Financing Activities (755) (312) (3,594) 2,513 (2,148) Change in cash from discontinued operations 17 32 — — 49 Net Decrease in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties (58) (17) (153) — (228) Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at Beginning of Period 95 38 480 — 613 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at End of Period $ 37 $ 21 $ 327 $ — $ 385 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the Year Ended December 31, 2018 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Cash Flows from Operating Activities Net income $ 997 $ 136 $ 374 $ (1,239) $ 268 Income/(loss) from discontinued operations 62 75 (329) — (192) Net income from continuing operations 935 61 703 (1,239) 460 Adjustments to reconcile net income to net cash provided by operating activities: Distributions and equity in earnings of unconsolidated affiliates and consolidated subsidiaries (23) 47 (1,231) 1,253 46 Depreciation and amortization 238 150 33 — 421 Accretion of asset retirement obligations 28 10 — — 38 Provision for bad debts 79 6 — — 85 Amortization of nuclear fuel 48 — — — 48 Amortization of financing costs and debt discount/premiums — 6 23 — 29 Adjustment for debt extinguishment — — 44 — 44 Amortization of emission allowances and out-of-market contracts 36 9 — — 45 Amortization of unearned equity compensation — — 25 — 25 Net (gain)/loss on sale and disposal of assets (30) (20) 1 — (49) Impairment losses 5 109 — — 114 Changes in derivative instruments 25 15 11 (14) 37 Changes in deferred income taxes and liability for uncertain tax benefits 372 5 (372) — 5 Changes in collateral deposits in support of energy risk management activities (94) (11) — — (105) Changes in nuclear decommissioning trust liability 60 — — — 60 GenOn settlement, net of insurance proceeds — — (63) — (63) Net loss on deconsolidation of Agua Caliente and Ivanpah projects — 13 — — 13 Changes in other working capital (100) (166) 16 — (250) Cash provided/(used) by continuing operations 1,579 234 (810) — 1,003 Cash provided by discontinued operations 89 285 — — 374 Net Cash Provided/(Used) by Operating Activities 1,668 519 (810) — 1,377 Cash Flows from Investing Activities Intercompany dividends — — 2,006 (2,006) — Payments for acquisitions of businesses (40) (203) — — (243) Capital expenditures (192) (151) (45) — (388) Net proceeds from sale of emission allowances 19 — — — 19 Investments in nuclear decommissioning trust fund securities (572) — — — (572) Proceeds from sales of nuclear decommissioning trust fund securities 513 — — — 513 Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees 14 8 1,542 — 1,564 Deconsolidation of Agua Caliente and Ivanpah projects — (268) — — (268) Changes in investments in unconsolidated affiliates — (39) — — (39) Net contributions to discontinued operations — (60) — — (60) Other — — (6) — (6) Cash (used)/provided by continuing operations (258) (713) 3,497 (2,006) 520 Cash used by discontinued operations — (725) — — (725) Net Cash (Used)/Provided by Investing Activities (258) (1,438) 3,497 (2,006) (205) Cash Flows from Financing Activities Intercompany dividends and transfers (1,267) 86 (825) 2,006 — Payments of dividends to common stockholders — — (37) — (37) Payments for treasury stock — — (1,250) — (1,250) Payments for debt extinguishment costs — — (32) — (32) Net distributions to noncontrolling interests from subsidiaries — (16) — — (16) Proceeds from issuance of common stock — — 21 — 21 Proceeds from issuance of long-term debt — 163 937 — 1,100 Payments of debt issuance costs — — (19) — (19) Payments for short and long-term debt — (138) (1,596) — (1,734) Receivable from affiliate — — (26) — (26) Other — (4) — — (4) Cash (used)/provided by continuing operations (1,267) 91 (2,827) 2,006 (1,997) Cash provided by discontinued operations — 471 — — 471 Net Cash (Used)/Provided by Financing Activities (1,267) 562 (2,827) 2,006 (1,526) Effect of exchange rate changes on cash and cash equivalents — 1 — — 1 Change in cash from discontinued operations 89 31 — — 120 Net Increase/(Decrease) in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties 54 (387) (140) — (473) Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at Beginning of Period 41 425 620 — 1,086 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at End of Period $ 95 $ 38 $ 480 $ — $ 613 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the Year Ended December 31, 2017 (In millions) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated Balance Cash Flows from Operating Activities Net income/(loss) $ 421 $ (543) $ (2,169) $ (46) $ (2,337) Income/(loss) from discontinued operations 91 (420) (663) — (992) Net income/(loss) from continuing operations 330 (123) (1,506) (46) (1,345) Adjustments to reconcile net income/(loss) to net cash provided by operating activities: Distributions and equity in earnings of unconsolidated affiliates and consolidated subsidiaries (18) 12 60 48 102 Depreciation and amortization 343 221 32 — 596 Accretion of asset retirement obligations 37 7 — — 44 Provision for bad debts 56 — 12 — 68 Amortization of nuclear fuel 51 — — — 51 Amortization of financing costs and debt discount/premiums — 13 16 — 29 Adjustment for debt extinguishment — — 49 — 49 Amortization of emission allowances and out-of-market contracts 42 12 — — 54 Amortization of unearned equity compensation — — 35 — 35 Net loss/(gain) on sale and disposal of assets 2 (11) — — (9) Impairment losses 1,346 264 4 — 1,614 Changes in derivative instruments (214) 50 (4) (2) (170) Changes in deferred income taxes and liability for uncertain tax benefits (300) (9) 322 — 13 Changes in collateral deposits in support of energy risk management activities (98) 18 — — (80) Changes in nuclear decommissioning trust liability 11 — — — 11 Changes in other working capital (15) (396) 205 — (206) Cash provided/(used) by continuing operations 1,573 58 (775) — 856 Cash provided by discontinued operations 116 638 — — 754 Net Cash Provided/(Used) by Operating Activities 1,689 696 (775) — 1,610 Cash Flows from Investing Activities Intercompany dividends — — 1,665 (1,665) — Payments for acquisitions of businesses (14) — — — (14) Capital expenditures (180) (43) (31) — (254) Net proceeds from sale of emission allowances 66 — — — 66 Investments in nuclear decommissioning trust fund securities (512) — — — (512) Proceeds from sales of nuclear decommissioning trust fund securities 501 — — — 501 Proceeds from sale of assets, net of cash disposed 33 54 343 — 430 Changes in investments in unconsolidated affiliates — (57) — — (57) Net distributions from discontinued operations — — 150 — 150 Other 18 12 — — 30 Cash (used)/provided by continuing operations (88) (34) 2,127 (1,665) 340 Cash used by discontinued operations (13) (966) — — (979) Net Cash (Used)/Provided by Investing Activities (101) (1,000) 2,127 (1,665) (639) Cash Flows from Financing Activities Intercompany dividends and transfers (1,447) (4) (214) 1,665 — Payment of dividends to common stockholders — — (38) — (38) Payments for debt extinguishment costs — — (42) — (42) Net distributions to noncontrolling interests from subsidiaries — (30) — — (30) Payments for issuance of common stock — — (2) — (2) Proceeds from issuance of long-term debt — 94 1,084 — 1,178 Payment of debt issuance costs — (2) (16) — (18) Payments for short and long-term debt — (183) (1,701) — (1,884) Receivable from affiliate — — (125) — (125) Other — (8) — — (8) Cash used by continuing operations (1,447) (133) (1,054) 1,665 (969) Cash used by discontinued operations (109) (60) — — (169) Net Cash Used by Financing Activities (1,556) (193) (1,054) 1,665 (1,138) Effect of exchange rate changes on cash and cash equivalents — (1) — — (1) Change in cash from discontinued operations (6) (388) — — (394) Net Increase/(Decrease) in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties 38 (110) 298 — 226 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at Beginning of Period 3 535 322 — 860 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at End of Period $ 41 $ 425 $ 620 $ — $ 1,086 (a) All significant intercompany transactions have been eliminated in consolidation

Nature of Business (Details)

Nature of Business (Details) MW in Thousands	Dec. 31, 2019MW
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Generation capacity (in MW)	23

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Net Income/(Loss) Attributable to Continuing and Discontinued Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Income/(loss) from continuing operations, net of income tax	$ 4,117	$ 465	$ (977)
Income/(loss) from discontinued operations, net of income tax	321	(197)	(1,176)
Net Income/(Loss) Attributable to NRG Energy, Inc.	$ 4,438	$ 268	$ (2,153)

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Additional (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Funds Deposited by Counterparties
Number of months beyond which company can not predict the holding of collateral (in months)	12 months
Accounts Receivable, Net [Abstract]
Allowance for doubtful accounts	$ 43	$ 32
Project Development Costs and Capitalized Interest
Amount of interest capitalized	3	7	$ 20
Finite-Lived Intangible Assets, Net [Abstract]
Intangible assets, accumulated amortization	$ 1,262	1,151
Lease Revenue
Lease term	20 years
Lessor Accounting
Operating lease income	$ 20	21
Contingent rental income	5	104	253
Gross Receipts and Sales Taxes
Gross Receipts Tax	109	99	92
Cost of Energy for Retail Operations
Transmission and distribution charges not yet billed	103	105	107
Foreign Currency Translation and Transaction Gains and Losses
Cumulative translation adjustment	(13)	(13)	(2)
Marketing and Advertising Expense
Advertising expense	66	73	66
Reorganization Costs
Reorganization costs	23	$ 90	$ 44
Operating lease right-of-use assets, net	464			$ 404
Operating lease liability	$ 556			$ 321
South Texas Project
Property, Plant and Equipment
Ownership Interest (as a percent)	44.00%

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Restricted Cash (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Cash and cash equivalents	$ 345	$ 563	$ 770
Funds deposited by counterparties	32	33	37
Restricted cash	8	17	279
Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statements of cash flows	$ 385	$ 613	$ 1,086	$ 860

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Redeemable Non Controlling Interest (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Noncontrolling Interest [Roll Forward]
Balance at beginning of period	$ 19	$ 78	$ 46
Distributions to redeemable noncontrolling interest		(43)	(65)
Contributions from redeemable noncontrolling interest		26	99
Comprehensive loss attributable to redeemable noncontrolling interest	3	1	(72)
Net loss attributable to redeemable noncontrolling interest - discontinued operations		(27)
Sale of NRG Yield and the Renewables Platform		(2,548)
Balance at end of period	20	19	78
NRG Yield Inc. And Zephyr Renewables
Noncontrolling Interest [Roll Forward]
Sale of NRG Yield and the Renewables Platform		(48)
Redeemable noncontrolling interest
Noncontrolling Interest [Roll Forward]
Distributions to redeemable noncontrolling interest	$ (2)	(3)	(2)
Non-cash adjustments to redeemable noncontrolling interest		$ (8)	$ 7

Revenue Recognition - Adoption

Revenue Recognition - Adoption of ASC 606 (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit	$ (1,616)	$ (6,022)
ASU 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit			$ 15

Revenue Recognition - Capacity

Revenue Recognition - Capacity Revenue (Details) $ in Millions	Dec. 31, 2019USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue from Contract with Customer [Abstract]
Estimated future fixed fee performance obligation	$ 564
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue from Contract with Customer [Abstract]
Estimated future fixed fee performance obligation	$ 604
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue from Contract with Customer [Abstract]
Estimated future fixed fee performance obligation	$ 303
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue from Contract with Customer [Abstract]
Estimated future fixed fee performance obligation	$ 42
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue from Contract with Customer [Abstract]
Estimated future fixed fee performance obligation	$ 8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, period	1 year

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregated Revenues (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									$ 7,991	$ 8,148
Mark-to-market for economic hedging activities									(20)	14	$ 206
Revenues	$ 2,195	$ 2,996	$ 2,465	$ 2,165	$ 1,992	$ 2,960	$ 2,461	$ 2,065	9,821	9,478	9,074
Less: Lease revenue									20	21
Derivative revenue									0	31	195
Retail Revenue | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									6,254	5,591
Retail Revenue | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									1,279	1,303
Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									7,533	6,894
Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									1,169	1,496
Derivative revenue									1,595	1,233
Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									700	825
Derivative revenue									109	137
Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities									33	(130)
Derivative revenue									1,810	1,309
Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									386	393
Total operating revenues
Disaggregation of Revenue [Line Items]
Revenues									9,821	9,478
Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue									73	69
Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									(5)	(19)
Revenues									(7)	(18)	(47)
Less: Lease revenue									0	0
Corporate/Eliminations | Retail Revenue | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									(3)	(1)
Corporate/Eliminations | Retail Revenue | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									0	0
Corporate/Eliminations | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									(3)	(1)
Corporate/Eliminations | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									0	13
Derivative revenue									(1)	14
Corporate/Eliminations | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									0	0
Derivative revenue									0	0
Corporate/Eliminations | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities									(1)	(13)
Derivative revenue									(2)	1
Corporate/Eliminations | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									(3)	(17)
Corporate/Eliminations | Total operating revenues
Disaggregation of Revenue [Line Items]
Revenues									(7)	(18)
Corporate/Eliminations | Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue									0	1
Texas | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									5,507	5,304
Revenues									7,069	6,401	6,318
Less: Lease revenue									0	1
Texas | Operating Segments | Retail Revenue | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									5,027	4,618
Texas | Operating Segments | Retail Revenue | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									1,205	1,238
Texas | Operating Segments | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									6,232	5,856
Texas | Operating Segments | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									529	371
Derivative revenue									1,459	1,131
Texas | Operating Segments | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									0	0
Derivative revenue									0	0
Texas | Operating Segments | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities									47	(77)
Derivative revenue									1,562	1,096
Texas | Operating Segments | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									261	251
Texas | Operating Segments | Total operating revenues
Disaggregation of Revenue [Line Items]
Revenues									7,069	6,401
Texas | Operating Segments | Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue									56	42
Texas | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenues									(1)	(19)	(41)
East | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									2,135	2,160
Revenues									2,319	2,371	2,009
Less: Lease revenue									1	1
East | Operating Segments | Retail Revenue | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									1,230	974
East | Operating Segments | Retail Revenue | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									74	65
East | Operating Segments | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									1,304	1,039
East | Operating Segments | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									322	546
Derivative revenue									98	90
East | Operating Segments | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									664	746
Derivative revenue									109	137
East | Operating Segments | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities									(29)	(35)
Derivative revenue									183	210
East | Operating Segments | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									58	75
East | Operating Segments | Total operating revenues
Disaggregation of Revenue [Line Items]
Revenues									2,319	2,371
East | Operating Segments | Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue									5	17
East | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenues									(8)	5	(1)
West/Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									354	703
Revenues									440	724	788
Less: Lease revenue									19	19
West/Other | Operating Segments | Retail Revenue | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									0	0
West/Other | Operating Segments | Retail Revenue | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									0	0
West/Other | Operating Segments | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									0	0
West/Other | Operating Segments | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									318	566
Derivative revenue									39	(2)
West/Other | Operating Segments | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									36	79
Derivative revenue									0	0
West/Other | Operating Segments | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities									16	(5)
Derivative revenue									67	2
West/Other | Operating Segments | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									70	84
West/Other | Operating Segments | Total operating revenues
Disaggregation of Revenue [Line Items]
Revenues									440	724
West/Other | Operating Segments | Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue									12	9
West/Other | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenues									$ 2	$ (4)	$ 4

Revenue Recognition - Contract

Revenue Recognition - Contract Balances (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Contract Assets And Liabilities [Line Items]
Deferred customer acquisition costs	$ 133	$ 111
Accounts receivable, net	1,025	1,024
Unbilled revenues (included within Accounts receivable, net - Contracts with customers)	402	392
Deferred revenue	82	67
Deferred revenue from contract with customers	24	19
Revenue recognized	13	16
Accounts receivable, net - Contracts with customers
Schedule Of Contract Assets And Liabilities [Line Items]
Accounts receivable, net	1,002	999
Accounts receivable, net - Derivative instruments
Schedule Of Contract Assets And Liabilities [Line Items]
Accounts receivable, net	18	20
Accounts receivable, net - Affiliate
Schedule Of Contract Assets And Liabilities [Line Items]
Accounts receivable, net	$ 5	$ 5

Acquisitions, Discontinued Op_2

Acquisitions, Discontinued Operations and Dispositions - Acquisitions (Details) customer in Thousands, $ in Millions	Aug. 01, 2019USD ($)statecustomer	Jun. 01, 2018USD ($)customerstate	Dec. 31, 2019USD ($)customer	Dec. 31, 2018USD ($)customer	Dec. 31, 2017USD ($)
Business Acquisition [Line Items]
Goodwill			$ 579	$ 573
Stream Energy
Business Acquisition [Line Items]
Number of states in which the entity operates | state	9
Purchase price	$ 329
Working capital adjustments	$ 29
Residential customer equivalents acquired | customer	600
Customers acquired | customer	450
Account receivable	$ 98
Accounts payable	(73)
Other net current and non-current working capital	5
Goodwill	6
Stream Energy | Texas
Business Acquisition [Line Items]
Goodwill	5
Stream Energy | East
Business Acquisition [Line Items]
Goodwill	1
Stream Energy | Marketing Partnerships
Business Acquisition [Line Items]
Intangible assets	154
Stream Energy | Customer Relationships
Business Acquisition [Line Items]
Intangible assets	85
Stream Energy | Trade Names
Business Acquisition [Line Items]
Intangible assets	28
Stream Energy | Other Intangible Assets
Business Acquisition [Line Items]
Intangible assets	$ 26
XOOM Energy, LLC
Business Acquisition [Line Items]
Number of states in which the entity operates | state		19
Purchase price		$ 213
Working capital adjustments		$ 48
Residential customer equivalents acquired | customer		395
Customers acquired | customer		300
Other net current and non-current working capital		$ 46
Intangible assets		133
Goodwill		34
XOOM Energy, LLC | Texas
Business Acquisition [Line Items]
Goodwill		28
XOOM Energy, LLC | East
Business Acquisition [Line Items]
Goodwill		$ 6
Small Book Acquisitions 2019
Business Acquisition [Line Items]
Purchase price			$ 17
Customers acquired | customer			72
Cash paid to acquire business			$ 13		$ 2
Small Book Acquisitions 2018
Business Acquisition [Line Items]
Purchase price				$ 44
Customers acquired | customer				115
Cash paid to acquire business			$ 2	$ 40

Acquisitions, Discontinued Op_3

Acquisitions, Discontinued Operations and Dispositions - Discontinued Operations (Details) $ in Millions	Feb. 06, 2018USD ($)extension	Dec. 31, 2019USD ($)MW	Feb. 04, 2019USD ($)MW	Dec. 31, 2018USD ($)	Aug. 31, 2018USD ($)	Mar. 30, 2018USD ($)MW
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generation capacity (in MW) | MW		23,000
Buckthorn Renewables, LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration						$ 42
Generation capacity (in MW) | MW						154
Discontinued Operations | South Central Portfolio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration			$ 1,000
Generation capacity (in MW) | MW			1,153
Discontinued Operations | NRG Yield Inc. And Zephyr Renewables
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration					$ 1,348
Discontinued Operations | NRG Yield Inc. And Zephyr Renewables | Cost To Complete Construction
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other commitment		$ 15
Discontinued Operations | NRG Yield Inc. And Zephyr Renewables | Property Taxes For Solar Properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other commitment		22
Discontinued Operations | Carlsbad Energy Holdings LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration	$ 385
Other commitment		$ 23		$ 23
Membership percentage	100.00%
Lease and easement agreement, number of extensions | extension	2
Renewal term	10 years

Acquisitions, Discontinued Op_4

Acquisitions, Discontinued Operations and Dispositions - Major Classes of Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current assets - discontinued operations	$ 0	$ 197
Non-current assets - discontinued operations	0	1,012
Current liabilities - discontinued operations	0	72
Other non-current liabilities		65
Non-current liabilities - discontinued operations	$ 0	635
South Central Portfolio | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents		89
Accounts receivable, net		49
Inventory		35
Other current assets		5
Current assets - discontinued operations		178
Property, plant and equipment, net		408
Other non-current assets		1
Non-current assets - discontinued operations		409
Accounts payable		19
Other current liabilities		5
Current liabilities - discontinued operations		24
Out-of-market contracts, net		50
Other non-current liabilities		11
Non-current liabilities - discontinued operations		61
Carlsbad Energy Holdings LLC | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restricted Cash		4
Accounts receivable, net		10
Other current assets		5
Current assets - discontinued operations		19
Property, plant and equipment, net		590
Intangible assets, net		9
Other non-current assets		4
Non-current assets - discontinued operations		603
Current portion of long term debt and capital leases		20
Accounts payable		27
Other current liabilities		1
Current liabilities - discontinued operations		48
Long-term debt and capital leases		572
Other non-current liabilities		2
Non-current liabilities - discontinued operations		$ 574

Acquisitions, Discontinued Op_5

Acquisitions, Discontinued Operations and Dispositions - Summary of Results (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(loss) on disposal of discontinued operations, net of tax									$ 0	$ (13)	$ 0
Income/(loss) from discontinued operations, net of income tax	$ (78)	$ (2)	$ 13	$ 388	$ 80	$ (336)	$ 69	$ (5)	321	(192)	(992)
Discontinued Operations | South Central Portfolio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenue									31	410	422
Operating costs and expenses									(23)	(346)	(335)
Other income									0	2	0
(Loss)/gain from operations of discontinued components, before tax									8	66	87
(Loss)/income on disposal of discontinued operations, net of tax									20	0	0
Income/(loss) from discontinued operations, net of income tax									28	66	87
Discontinued Operations | Carlsbad Energy Holdings LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenue									19	909	1,164
Operating costs and expenses									(9)	(661)	(1,114)
Other expenses									(5)	(174)	(288)
(Loss)/gain from operations of discontinued components, before tax									5	74	(238)
Income tax expense									0	4	52
Income/(loss) from discontinued operations, net of tax									5	70	(290)
Gain/(loss) on disposal of discontinued operations, net of tax									265	(134)	0
Income/(expense) from California property tax indemnification									22	(153)	0
Income/(expense) from other commitments, indemnification and fees									4	(75)	0
(Loss)/income on disposal of discontinued operations, net of tax									291	(362)	0
Income/(loss) from discontinued operations, net of income tax									296	(292)	(290)
Discontinued Operations | GenOn
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenue									0	0	646
Operating costs and expenses									0	0	(702)
Other expenses									0	0	(98)
(Loss)/gain from operations of discontinued components, before tax									0	0	(154)
Income tax expense									0	0	9
(Loss)/gain from discontinued operations									0	0	(163)
Interest income-affiliate									0	3	8
Income/(loss) from discontinued operations, net of tax									0	3	(155)
Gain/(loss) on disposal of discontinued operations, net of tax									0	0	(208)
Settlement consideration, insurance and services credit									0	63	(289)
Pension and post-retirement liability assumptions									0	21	(131)
Income/(expense) from other commitments, indemnification and fees									(3)	(53)	(6)
(Loss)/income on disposal of discontinued operations, net of tax									(3)	31	(634)
Income/(loss) from discontinued operations, net of income tax									$ (3)	$ 34	$ (789)

Acquisitions, Discontinued Op_6

Acquisitions, Discontinued Operations and Dispositions - Sale of Assets Prior to Discontinued (Details) $ in Millions	Dec. 31, 2019MW	Jan. 11, 2019USD ($)	Jun. 19, 2018USD ($)	Mar. 30, 2018USD ($)MW	Mar. 27, 2017USD ($)utility_scale_solar_projectMW
Business Acquisition [Line Items]
Generation capacity (in MW) | MW	23,000
UPMC Thermal Project
Business Acquisition [Line Items]
Cash consideration		$ 3	$ 84
Buckthorn Renewables, LLC
Business Acquisition [Line Items]
Cash consideration				$ 42
Percentage of ownership sold				10000.00%
Generation capacity (in MW) | MW				154
Debt assumed				$ 183
Agua Caliente Solar Project
Business Acquisition [Line Items]
Cash consideration					$ 130
Debt assumed					328
Working capital adjustments					$ 1
Agua Caliente Solar Project | Agua Caliente
Business Acquisition [Line Items]
Percentage of ownership sold					16.00%
Generation capacity (in MW) | MW					46
Agua Caliente Solar Project | Utah Portfolio
Business Acquisition [Line Items]
Generation capacity (in MW) | MW					265
Number Of utility scale solar projects | utility_scale_solar_project					7

Acquisitions, Discontinued Op_7

Acquisitions, Discontinued Operations and Dispositions - GenOn Settlement and Plan Confirmation (Details) - USD ($) $ in Millions	Jul. 16, 2018	Apr. 27, 2018	Dec. 31, 2017	Dec. 14, 2018
GenOn Mid-Atlantic | Restructuring Support Agreement | Letter of Credit | Intercompany Credit Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Letters of credit facility		$ 38
Services Agreement | GenOn | Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Collateral posted	$ 15
GenOn
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Settlement consideration	261
Deduction for GenOn tax losses				$ 9,500
Professional fees		$ 6
GenOn | Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Settlement payment	125
GenOn | Services Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Credit applied			$ 28
GenOn | Services Agreement | Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Credit applied	28
Remaining payments and other balances due under settlement agreement	10
GenOn | Revolving Credit Facility Borrowings | Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Intercompany secured revolving credit facility and accrued interest and fees	151
GenOn | Accrued Interest On Borrowings | Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Intercompany secured revolving credit facility and accrued interest and fees	12
GenOn | Reduction Of Settlement Payment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Remaining payments and other balances due under settlement agreement	4
GenOn | Assignment Of Historical Claims Against REMA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Remaining payments and other balances due under settlement agreement	8
GenOn | Other | Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Remaining payments and other balances due under settlement agreement	$ 2

Acquisitions, Discontinued Op_8

Acquisitions, Discontinued Operations and Dispositions - Dispositions (Details) - USD ($) $ in Millions	Aug. 01, 2018	Jun. 29, 2018	Jun. 28, 2018	Dec. 31, 2019	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Parent guarantee				$ 2,010	$ 2,767
Other guarantees
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Parent guarantee				288	721
BETM | 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	100.00%
Proceeds from sale of businesses, net of working capital adjustments	$ 71
Gain on sale of business	15
Cash collateral	4
BETM | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Letter of Credit
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Parent guarantee	119
BETM | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Other guarantees
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Parent guarantee	$ 32
Canal Three | 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]
Gain on sale of business		$ 17
Cash received		$ 16
Cash proceeds			$ 167
Proceeds distributed to Company			$ 151
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]
Cash received				$ 22	$ 28

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Estimated Carrying Amounts of Fair Value of Financial Instruments not Carried at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Liabilities
Long-term Debt	$ 6,042	$ 6,691
Level 2
Debt, Long-term and Short-term, Combined Amount [Abstract]
Long-term debt, including current portion	6,388	6,528
Level 3
Debt, Long-term and Short-term, Combined Amount [Abstract]
Long-term debt, including current portion	116	169
Carrying Amount
Assets
Notes receivable	11	17
Liabilities
Long-term Debt	5,956	6,591
Fair Value
Assets
Notes receivable	8	14
Liabilities
Long-term Debt	$ 6,504	$ 6,697

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Assets and Liabilities Measured and Recorded at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in securities (classified within other current and non-current assets)	$ 20	$ 39
Other trust fund investments:
Other trust fund investments	1	1
Measured using net asset value practical expedient:
Total assets	1,993	1,792
Derivative liabilities:
Total liabilities	1,103	977
Commodity contracts
Derivative assets:
Derivative assets	1,170	1,042
Derivative liabilities:
Commodity contracts	1,103	977
Interest rate contracts
Derivative assets:
Derivative assets		39
Cash and cash equivalents
Nuclear trust fund investments:
Nuclear trust fund investments	17	19
U.S. government and federal agency obligations
Nuclear trust fund investments:
Nuclear trust fund investments	68	46
Federal agency mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	100	100
Commercial mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	29	22
Corporate debt securities
Nuclear trust fund investments:
Nuclear trust fund investments	109	96
Equity securities
Nuclear trust fund investments:
Nuclear trust fund investments	388	312
Measured using net asset value practical expedient:
Equity contracts	8	8
Foreign government fixed income securities
Nuclear trust fund investments:
Nuclear trust fund investments	5	4
Equity securities-nuclear trust fund investments
Measured using net asset value practical expedient:
Equity contracts	78	64
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)	0	2
Other trust fund investments:
Other trust fund investments	1	1
Measured using net asset value practical expedient:
Total assets	558	517
Derivative liabilities:
Total liabilities	143	224
Level 1 | Commodity contracts
Derivative assets:
Derivative assets	84	137
Derivative liabilities:
Commodity contracts	143	224
Level 1 | Interest rate contracts
Derivative assets:
Derivative assets		0
Level 1 | Cash and cash equivalents
Nuclear trust fund investments:
Nuclear trust fund investments	17	19
Level 1 | U.S. government and federal agency obligations
Nuclear trust fund investments:
Nuclear trust fund investments	68	46
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	388	312
Measured using net asset value practical expedient:
Equity contracts	0	0
Level 1 | Foreign government fixed income securities
Nuclear trust fund investments:
Nuclear trust fund investments	0	0
Level 1 | Equity securities-nuclear trust fund investments
Measured using net asset value practical expedient:
Equity contracts	0	0
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)	20	18
Other trust fund investments:
Other trust fund investments	0	0
Measured using net asset value practical expedient:
Total assets	1,156	1,075
Derivative liabilities:
Total liabilities	805	664
Level 2 | Commodity contracts
Derivative assets:
Derivative assets	893	796
Derivative liabilities:
Commodity contracts	805	664
Level 2 | Interest rate contracts
Derivative assets:
Derivative assets		39
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	0	0
Level 2 | Federal agency mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	100	100
Level 2 | Commercial mortgage-backed securities
Nuclear trust fund investments:
Nuclear trust fund investments	29	22
Level 2 | Corporate debt securities
Nuclear trust fund investments:
Nuclear trust fund investments	109	96
Level 2 | Equity securities
Nuclear trust fund investments:
Nuclear trust fund investments	0	0
Measured using net asset value practical expedient:
Equity contracts	0	0
Level 2 | Foreign government fixed income securities
Nuclear trust fund investments:
Nuclear trust fund investments	5	4
Level 2 | Equity securities-nuclear trust fund investments
Measured using net asset value practical expedient:
Equity contracts	0	0
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	19
Other trust fund investments:
Other trust fund investments	0	0
Measured using net asset value practical expedient:
Total assets	193	128
Derivative liabilities:
Total liabilities	155	89
Level 3 | Commodity contracts
Derivative assets:
Derivative assets	193	109
Derivative liabilities:
Commodity contracts	155	89
Level 3 | Interest rate contracts
Derivative assets:
Derivative assets		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
Measured using net asset value practical expedient:
Equity contracts	0	0
Level 3 | Foreign government fixed income securities
Nuclear trust fund investments:
Nuclear trust fund investments	0	0
Level 3 | Equity securities-nuclear trust fund investments
Measured using net asset value practical expedient:
Equity contracts	$ 0	$ 0

Fair Value of Financial Instr_5

Fair Value of Financial Instruments - Reconciliation of Level 3 Financial Instruments (Details) - Level 3 - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 39	$ 4
Contracts added from acquisitions	(3)	12
Included in earnings
Included in earnings	(26)	(21)
Included in OCI	0
Purchases	40	41
Sale	(19)
Transfers into Level 3	2	5
Transfers out of Level 3	5	(2)
Ending balance	38	39
Gains (Losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held at the end of period	17	(17)
Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	19	19
Contracts added from acquisitions	0	0
Included in earnings
Included in earnings	0	0
Included in OCI	0
Purchases	0	0
Sale	(19)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance	0	19
Gains (Losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held at the end of period	0	0
Derivative
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	20	(15)
Contracts added from acquisitions	(3)	12
Included in earnings
Included in earnings	(26)	(21)
Included in OCI	0
Purchases	40	41
Sale	0
Transfers into Level 3	2	5
Transfers out of Level 3	5	(2)
Ending balance	38	20
Gains (Losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held at the end of period	$ 17	$ (17)

Fair Value of Financial Instr_6

Fair Value of Financial Instruments - Derivative Fair Value Measurements Narrative (Details)	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Total derivative assets valued with prices provided by models and other valuation techniques percentage	16.00%
Total derivative liabilities valued with prices provided by models and other valuation techniques, percentage	14.00%

Fair Value of Financial Instr_7

Fair Value of Financial Instruments - Derivative Fair Value Measurement (Details) $ in Millions	Dec. 31, 2019USD ($)$ / MWh	Dec. 31, 2018USD ($)$ / MWh
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Cash collateral posted in support of energy risk management activities	$ 190	$ 287
Cash collateral received in support of energy risk management activities	32	33
Commodity contracts
Assets
Derivative assets	1,170	1,042
Liabilities
Commodity contracts	1,103	977
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Cash collateral posted in support of energy risk management activities	73	114
Cash collateral received in support of energy risk management activities	7	31
Commodity contracts | Level 3
Assets
Derivative assets	193	109
Liabilities
Commodity contracts	155	89
Commodity contracts | Fair Value, Measurements, Recurring | Level 3
Assets
Derivative assets	193	109
Liabilities
Commodity contracts	155	89
Commodity contracts | Fair Value, Measurements, Recurring | Power Contracts | Level 3
Assets
Derivative assets	151	89
Liabilities
Commodity contracts	$ 139	$ 75
Commodity contracts | Fair Value, Measurements, Recurring | Power Contracts | Level 3 | Low
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Forward Market Price (USD per MWh) | $ / MWh	8	1
Commodity contracts | Fair Value, Measurements, Recurring | Power Contracts | Level 3 | High
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Forward Market Price (USD per MWh) | $ / MWh	218	214
Commodity contracts | Fair Value, Measurements, Recurring | Power Contracts | Level 3 | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Forward Market Price (USD per MWh) | $ / MWh	24	31
Commodity contracts | Fair Value, Measurements, Recurring | Financial Transmission Rights | Level 3
Assets
Derivative assets	$ 42	$ 20
Liabilities
Commodity contracts	$ 16	$ 14
Commodity contracts | Fair Value, Measurements, Recurring | Financial Transmission Rights | Level 3 | Low
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Auction Prices (USD per MWh) | $ / MWh	(105)	(90)
Commodity contracts | Fair Value, Measurements, Recurring | Financial Transmission Rights | Level 3 | High
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Auction Prices (USD per MWh) | $ / MWh	213	34
Commodity contracts | Fair Value, Measurements, Recurring | Financial Transmission Rights | Level 3 | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Abstract
Auction Prices (USD per MWh) | $ / MWh	0	0

Fair Value of Financial Instr_8

Fair Value of Financial Instruments - Counterparty Credit Risk (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)counterparty	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Derivative Fair Value Meaurements and Concentration of Credit Risk
Counterparty credit exposure, excluding credit risk exposure under certain long term agreements	$ 239
Counterparty credit exposure, collateral held (cash and letters of credit) against positions	51
Counterparty credit exposure, net	$ 233
Company's exposure before collateral expected to roll off (as a percent)	67.00%
Net exposure (as a percent)	100.00%
Wholesale counterparties with net exposure | counterparty	33,000,000
Counterparty credit risk exposure to certain counterparties, threshold (as a percent)	10.00%
Estimated counterparty credit risk exposure under certain long term agreements, including California tolling agreements, South Central load obligations and solar power purchase agreements for the next 5 years	$ 548
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
Provision for bad debts	$ 95	$ 85	$ 68
Investment grade
Derivative Fair Value Meaurements and Concentration of Credit Risk
Net exposure (as a percent)	56.00%
Non-Investment grade/Non-Rated
Derivative Fair Value Meaurements and Concentration of Credit Risk
Net exposure (as a percent)	44.00%
Utilities, energy merchants, marketers and other
Derivative Fair Value Meaurements and Concentration of Credit Risk
Net exposure (as a percent)	84.00%
Financial Institutions
Derivative Fair Value Meaurements and Concentration of Credit Risk
Net exposure (as a percent)	16.00%

Accounting for Derivative Ins_3

Accounting for Derivative Instruments and Hedging Activities - Net Notional Volume Buy/Sell of Open Derivative Transactions (Details) shares in Millions, bbl in Millions, T in Millions, MWh in Millions, MMBTU in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)MMBTUMWhTsharesbbl	Dec. 31, 2018USD ($)MWhMMBTUTsharesbbl
Long | Emissions
Derivative [Line Items]
Derivative, nonmonetary notional amount, mass (ton)	3
Long | Renewables Energy Certificates
Derivative [Line Items]
Derivative, non-monetary notional amount (in shares) | shares	1	1
Long | Coal
Derivative [Line Items]
Derivative, nonmonetary notional amount, mass (ton)	10	13
Long | Oil
Derivative [Line Items]
Derivative, nonmonetary notional amount, volume (in barrels) | bbl	0	1
Long | Power
Derivative [Line Items]
Derivative, nonmonetary notional amount, energy measure in (millions of btu) and (megawatt hours) | MWh	38	1
Long | Interest
Derivative [Line Items]
Derivative, Notional Amount (in usd) | $	$ 0	$ 1,000
Short | Emissions
Derivative [Line Items]
Derivative, nonmonetary notional amount, mass (ton)		2
Short | Natural Gas
Derivative [Line Items]
Derivative, nonmonetary notional amount, energy measure in (millions of btu) and (megawatt hours) | MMBTU	181	330
Short | Capacity
Derivative [Line Items]
Derivative, nonmonetary notional amount, energy measure in (millions of btu) and (megawatt hours) | MWh	1	1

Accounting for Derivative Ins_4

Accounting for Derivative Instruments and Hedging Activities - Fair Value Within the Derivative Instrument Valuation (Details) - Not Designated as Hedging Instrument - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative assets	$ 1,170	$ 1,081
Commodity contracts	1,103	977
Interest rate contracts current
Derivative [Line Items]
Derivative assets	0	17
Commodity contracts	0	0
Interest rate contracts long-term
Derivative [Line Items]
Derivative assets	0	22
Commodity contracts	0	0
Commodity contracts current
Derivative [Line Items]
Derivative assets	860	747
Commodity contracts	781	673
Commodity contracts long-term
Derivative [Line Items]
Derivative assets	310	295
Commodity contracts	$ 322	$ 304

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	Dec. 31, 2019	Dec. 31, 2018
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Cash Collateral (Held)/Posted	$ (32)	$ (33)
Cash Collateral (Held)/Posted	190	287
Gross Amounts of Recognized Assets / Liabilities		104
Derivative Instruments		0
Cash Collateral (Held) / Posted		83
Net Amount		187
Commodity contracts
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Derivative assets	1,170	1,042
Derivative Instruments	(909)	(778)
Cash Collateral (Held)/Posted	(7)	(31)
Net Amount	254	233
Derivative liabilities	(1,103)	(977)
Derivative Instruments	909	778
Cash Collateral (Held)/Posted	73	114
Net Amount	(121)	(85)
Gross Amounts of Recognized Assets / Liabilities	67	65
Derivative Instruments	0	0
Cash Collateral (Held) / Posted	66	83
Net Amount	$ 133	148
Interest rate contracts
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Derivative assets		39
Derivative Instruments		0
Cash Collateral (Held)/Posted		0
Net Amount		39
Gross Amounts of Recognized Assets / Liabilities		39
Derivative Instruments		0
Cash Collateral (Held) / Posted		0
Net Amount		$ 39

Accounting for Derivative Ins_6

Accounting for Derivative Instruments and Hedging Activities - Effect on the Company's of Accumulated OCI Balance Attributable to Cash Flow Hedge Derivatives, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Beginning balance	$ (1,234)	$ 1,968	$ 4,446
Reclassified from accumulated OCI to income:
Sale of NRG Yield and Renewables		25	0
Ending balance	1,658	(1,234)	1,968
Interest rate contracts | AOCI Including Portion Attributable to Noncontrolling Interest
Derivative [Line Items]
Beginning balance	0	(54)	(66)
Reclassified from accumulated OCI to income:
Ending balance		0	(54)
Interest rate contracts | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Reclassified from accumulated OCI to income:
Due to realization of previously deferred amounts	$ 8		12
Interest rate contracts | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent
Reclassified from accumulated OCI to income:
Mark-to-market of cash flow hedge accounting contracts		$ 21	$ 0

Accounting for Derivative Ins_7

Accounting for Derivative Instruments and Hedging Activities - Pre-tax Effects of Economic Hedges not Designated as Cash Flow Hedges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Unrealized Mark To Market Results [Abstract]
Reversal of previously recognized unrealized (gains)/losses on settled positions related to economic hedges	$ (68)	$ (73)	$ 47
Reversal of acquired loss/(gain) positions related to economic hedges	6	(10)	0
Net unrealized gains on open positions related to economic hedges	42	97	159
Total unrealized mark-to-market (losses)/gains for economic hedging activities	(20)	14	206
Reversal of previously recognized unrealized (gains) on settled positions related to trading activity	(11)	(12)	(25)
Net unrealized gains on open positions related to trading activity	31	29	14
Total unrealized mark-to-market gains/(losses) for trading activity	20	17	(11)
Total unrealized gains	0	31	195
Credit Risk Related Contingent Features [Abstract]
Collateral required contracts with credit rating contingent features in a net liability position	3
Adequate Assurance Clauses
Credit Risk Related Contingent Features [Abstract]
Collateral required for contracts in net liability positions that have adequate assurance clauses	14
Credit Rating Contingent Features
Credit Risk Related Contingent Features [Abstract]
Collateral required for contracts in net liability positions that have adequate assurance clauses	24
Commodity contracts
Unrealized Mark To Market Results [Abstract]
Total unrealized gains	0	31	195
Commodity contracts | Operating revenue
Unrealized Mark To Market Results [Abstract]
Total unrealized gains	53	(113)	241
Commodity contracts | Cost of operations
Unrealized Mark To Market Results [Abstract]
Total unrealized gains	(53)	144	(46)
Interest rate contracts
Unrealized Mark To Market Results [Abstract]
Total unrealized gains	$ (38)	$ 0	$ 4

Nuclear Decommissioning Trust_3

Nuclear Decommissioning Trust Fund - Summary of Aggregate Fair Values and Realized Gains and Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Nuclear decommissioning trust fund disclosure
Fair Value	$ 794	$ 663
Unrealized Gains	338	234
Unrealized Losses	1	6
Cash and cash equivalents
Nuclear decommissioning trust fund disclosure
Fair Value	17	19
Unrealized Gains	0	0
Unrealized Losses	0	0
U.S. government and federal agency obligations
Nuclear decommissioning trust fund disclosure
Fair Value	68	46
Unrealized Gains	4	1
Unrealized Losses	$ 0	$ 0
Weighted- average maturities (in years)	11 years	12 years
Federal agency mortgage-backed securities
Nuclear decommissioning trust fund disclosure
Fair Value	$ 100	$ 100
Unrealized Gains	3	1
Unrealized Losses	$ 0	$ 2
Weighted- average maturities (in years)	24 years	23 years
Commercial mortgage-backed securities
Nuclear decommissioning trust fund disclosure
Fair Value	$ 29	$ 22
Unrealized Gains	1	0
Unrealized Losses	$ 1	$ 1
Weighted- average maturities (in years)	24 years	22 years
Corporate debt securities
Nuclear decommissioning trust fund disclosure
Fair Value	$ 109	$ 96
Unrealized Gains	6	1
Unrealized Losses	$ 0	$ 2
Weighted- average maturities (in years)	11 years	11 years
Equity securities
Nuclear decommissioning trust fund disclosure
Fair Value	$ 466	$ 376
Unrealized Gains	324	231
Unrealized Losses	0	1
Foreign government fixed income securities
Nuclear decommissioning trust fund disclosure
Fair Value	5	4
Unrealized Gains	0	0
Unrealized Losses	$ 0	$ 0
Weighted- average maturities (in years)	10 years	9 years
South Texas Project
Nuclear decommissioning trust fund disclosure
Ownership Interest (as a percent)	44.00%

Nuclear Decommissioning Trust_4

Nuclear Decommissioning Trust Fund - Summary of Proceeds from Sale of Available -for-sale Securities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Regulated Operations [Abstract]
Realized gains	$ 18	$ 17	$ 22
Realized (losses)	(9)	(13)	(8)
Proceeds from sales of nuclear decommissioning trust fund securities	$ 381	$ 513	$ 501

Inventory (Details)

Inventory (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Fuel oil	$ 73	$ 74
Coal	93	97
Natural gas	21	28
Spare parts	196	213
Total Inventory	$ 383	$ 412

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment
Total property, plant, and equipment	$ 4,345	$ 4,859
Accumulated depreciation	(1,752)	(1,811)
Net property, plant, and equipment	2,593	3,048
Facilities and equipment
Property, Plant and Equipment
Total property, plant, and equipment	$ 3,262	3,763
Facilities and equipment | Minimum
Property, Plant and Equipment
Depreciable lives (in years)	1 year
Facilities and equipment | Maximum
Property, Plant and Equipment
Depreciable lives (in years)	40 years
Land and improvements
Property, Plant and Equipment
Total property, plant, and equipment	$ 324	347
Nuclear fuel
Property, Plant and Equipment
Total property, plant, and equipment	$ 235	212
Depreciable lives (in years)	5 years
Hardware and office equipment and furnishings
Property, Plant and Equipment
Total property, plant, and equipment	$ 422	431
Hardware and office equipment and furnishings | Minimum
Property, Plant and Equipment
Depreciable lives (in years)	2 years
Hardware and office equipment and furnishings | Maximum
Property, Plant and Equipment
Depreciable lives (in years)	10 years
Construction in progress
Property, Plant and Equipment
Total property, plant, and equipment	$ 102	$ 106

Leases - Lease Cost and Other I

Leases - Lease Cost and Other Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Lease, Cost [Abstract]
Operating lease cost	$ 109
Short-term lease cost	3
Variable lease cost	6
Sublease income	17
Total lease cost	101
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	104
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 215
Leases, Weighted Average Discount Rate [Abstract]
Weighted average remaining lease term (in years)	7 years 9 months 18 days
Weighted average discount rate	5.72%

Leases - Annual Payments Based

Leases - Annual Payments Based on the Maturities of Leases (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019
Leases [Abstract]
2020	$ 96
2021	87
2022	87
2023	85
2024	75
Thereafter	296
Total undiscounted lease payments	726
Less present value adjustment	(170)
Operating lease liability	$ 556	$ 321

Leases - 2018 Operating Lease C

Leases - 2018 Operating Lease Commitments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2014
Other Operating Leases
Long-term Purchase Commitment [Line Items]
Lease expense	$ 66	$ 69
Midwest Generation, LLC
Long-term Purchase Commitment [Line Items]
Leased interest	100.00%
Out-of-market contracts, net			$ 159
Lease expense	$ 14

Leases - Future Minimum Lease C

Leases - Future Minimum Lease Commitments Before Adoption of ASU 2016-02 (Details) $ in Millions	Dec. 31, 2018USD ($)
Operating Leased Assets [Line Items]
Future sublease income	$ 29
Powerton and Joliet
Operating Leased Assets [Line Items]
2019	1
2020	1
2021	3
2022	6
2023	6
Thereafter	222
Total (a)	239
Other Leased Property
Operating Leased Assets [Line Items]
2019	60
2020	55
2021	43
2022	40
2023	39
Thereafter	95
Total (a)	$ 332

Asset Impairments (Details)

Asset Impairments (Details) - USD ($)	Sep. 05, 2018	Sep. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 20, 2019	Dec. 31, 2014
Asset Impairments
Impairment losses, other assets							$ 12,000,000
Impairment losses							5,000,000	$ 99,000,000	$ 1,534,000,000
Equity method investments			$ 412,000,000				388,000,000	412,000,000
Impairment losses on investments							$ 108,000,000	15,000,000	79,000,000
Emission Allowances
Asset Impairments
Impairment losses									20,000,000
Renewables
Asset Impairments
Impairment losses									29,000,000
Construction in Progress
Asset Impairments
Impairment losses						$ 41,000,000
Construction in progress						$ 0
Held-for-sale | NRG Solar Guam, LLC
Asset Impairments
Impairment losses			$ 12,000,000
Cash consideration										$ 8,000,000
Petra Nova
Asset Impairments
Contribution in cash		$ 95,000,000
Letter of credit		12,000,000
Guarantee (up to)		124,000,000
Impairment losses on equity method investments		$ 101,000,000
Keystone
Asset Impairments
Impairment losses on equity method investments	$ 14,000,000
Ownership percentage											3.70%
Impairment losses on investments									35,000,000
Conemaugh
Asset Impairments
Impairment losses on equity method investments	$ 14,000,000
Impairment losses on investments									35,000,000
Dunkirk
Asset Impairments
Impairment losses on equity method investments				$ 46,000,000
Equity method investments				$ 0
Other Investments
Asset Impairments
Impairment losses on equity method investments								15,000,000
Impairment losses on investments								$ 13,000,000	10,000,000
South Texas Project
Asset Impairments
Impairment losses on investments									1,248,000,000
Indian River
Asset Impairments
Impairment losses on investments									$ 36,000,000
Petra Nova Parish Holdings
Asset Impairments
Ownership percentage					50.00%				50.00%
Impairment losses on investments					$ 69,000,000

Goodwill and Other Intangible_2

Goodwill and Other Intangibles - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Goodwill and Other Intangibles
Goodwill	$ 579,000,000	$ 579,000,000	$ 573,000,000
Impairment		2,000,000	6,000,000
Emission allowances held-for-sale	6,000,000	6,000,000	12,000,000
Emission Allowances
Goodwill and Other Intangibles
Impairment		0	5,000,000
Impairment related to power purchase agreements			0
BETM | Held-for-sale
Goodwill and Other Intangibles
Goodwill	21,000,000	21,000,000
Goodwill, Impairment Loss	90,000,000
Midwest Generation
Goodwill and Other Intangibles
Goodwill	165,000,000	165,000,000
Midwest Generation | Lease Agreements
Goodwill and Other Intangibles
Out of market contracts			$ 121,000,000
Texas
Goodwill and Other Intangibles
Goodwill	$ 414,000,000	$ 414,000,000

Goodwill and Other Intangible_3

Goodwill and Other Intangibles - Components of Intangible Assets Subject to Amortization (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	$ 1,742	$ 2,080
Purchases	42	61
Acquisition of businesses	318	178
Usage	(21)	(27)
Write-off of fully amortized balances	(30)	(528)
Impairment	(2)	(6)
Other	2	(16)
Balance at end of period	2,051	1,742
Less accumulated amortization	(1,262)	(1,151)
Net carrying amount	789	591
Emission Allowances
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	659	755
Purchases	13	33
Acquisition of businesses	0	0
Usage	(4)	(1)
Write-off of fully amortized balances	(8)	(107)
Impairment	0	(5)
Other	2	(16)
Balance at end of period	662	659
Less accumulated amortization	(539)	(515)
Net carrying amount	123	144
Fuel Contracts
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	49	49
Purchases	0	0
Acquisition of businesses	0	0
Usage	0	0
Write-off of fully amortized balances	0	0
Impairment	0	0
Other	0	0
Balance at end of period	49	49
Less accumulated amortization	(45)	(45)
Net carrying amount	$ 4	4
Customer Contracts
Finite-lived Intangible Assets [Roll Forward]
Weighted average useful life, years	2 years
Customer Relationships
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	$ 478	768
Purchases	0	0
Acquisition of businesses	110	122
Usage	0	0
Write-off of fully amortized balances	(13)	(411)
Impairment	(2)	(1)
Other	0	0
Balance at end of period	573	478
Less accumulated amortization	(345)	(314)
Net carrying amount	$ 228	$ 164
Weighted average useful life, years	7 years	6 years
Marketing Partnerships
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	$ 131	$ 88
Purchases	0	0
Acquisition of businesses	154	43
Usage	0	0
Write-off of fully amortized balances	0	0
Impairment	0	0
Other	0	0
Balance at end of period	285	131
Less accumulated amortization	(75)	(61)
Net carrying amount	$ 210	$ 70
Weighted average useful life, years	9 years	14 years
Trade Names
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	$ 345	$ 342
Purchases	0	0
Acquisition of businesses	28	13
Usage	0	0
Write-off of fully amortized balances	0	(10)
Impairment	0	0
Other	0	0
Balance at end of period	373	345
Less accumulated amortization	(220)	(195)
Net carrying amount	$ 153	$ 150
Weighted average useful life, years	12 years	7 years
Other
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	$ 80	$ 78
Purchases	29	28
Acquisition of businesses	26	0
Usage	(17)	(26)
Write-off of fully amortized balances	(9)	0
Impairment	0	0
Other	0	0
Balance at end of period	109	80
Less accumulated amortization	(38)	(21)
Net carrying amount	$ 71	$ 59

Goodwill and Other Intangible_4

Goodwill and Other Intangibles - Schedule of Amortization Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Total amortization	$ 151	$ 133	$ 166
Emission Allowances
Finite-Lived Intangible Assets [Line Items]
Total amortization	32	39	71
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Total amortization	44	32	34
Marketing Partnerships
Finite-Lived Intangible Assets [Line Items]
Total amortization	15	9	5
Trade Names
Finite-Lived Intangible Assets [Line Items]
Total amortization	25	23	23
Other
Finite-Lived Intangible Assets [Line Items]
Total amortization	$ 35	$ 30	$ 33

Goodwill and Other Intangible_5

Goodwill and Other Intangibles - Schedule of Estimated Amortization of Intangible Asset for the Next Five Years (Details) $ in Millions	Dec. 31, 2019USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2020	$ 189
2021	141
2022	127
2023	128
2024	93
Emission Allowances
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2020	36
2021	35
2022	38
2023	40
2024	35
Fuel Contracts
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2020	1
2021	0
2022	0
2023	1
2024	0
Customer Relationships
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2020	68
2021	52
2022	36
2023	35
2024	15
Marketing Partnerships
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2020	24
2021	24
2022	23
2023	23
2024	23
Trade Names
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2020	27
2021	27
2022	27
2023	26
2024	17
Other
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2020	33
2021	3
2022	3
2023	3
2024	$ 3

Debt and Finance Leases - Sched

Debt and Finance Leases - Schedule of Long-term Debt and Finance Leases (Details) - USD ($) $ in Millions	Mar. 21, 2018	Jan. 24, 2017	Jun. 30, 2016	Dec. 31, 2019	Dec. 31, 2018	May 28, 2019	May 24, 2019	May 14, 2019	Nov. 05, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 07, 2017	Aug. 02, 2016	May 23, 2016
Debt Instrument [Line Items]
Long-term debt				$ 6,042	$ 6,691
Finance leases					1
Subtotal long-term debt and finance leases (including current maturities)				6,042	6,692
Less current maturities				(88)	(72)
Less debt issuance costs				(65)	(70)
Discounts				(86)	(101)
Total long-term debt and finance leases				5,803	6,449
Debt Instrument, Unamortized Discount [Abstract]
Total discounts				(86)	(101)
Recourse Debt
Debt Instrument [Line Items]
Long-term debt				6,008	6,523
Recourse Debt | Senior Notes, due 2024
Debt Instrument [Line Items]
Long-term debt				$ 0	733
Interest rate, stated percentage				6.25%
Recourse Debt | Senior Notes, due 2026
Debt Instrument [Line Items]
Long-term debt				$ 1,000	1,000
Interest rate, stated percentage				7.25%										7.25%
Recourse Debt | Senior Notes, due 2027
Debt Instrument [Line Items]
Long-term debt				$ 1,230	1,230
Interest rate, stated percentage				6.625%						6.625%			6.625%
Recourse Debt | Senior Notes, due 2028
Debt Instrument [Line Items]
Long-term debt				$ 821	821
Interest rate, stated percentage				5.75%						5.75%	5.75%	5.75%
Recourse Debt | Senior Notes due 2029
Debt Instrument [Line Items]
Long-term debt				$ 733	0
Interest rate, stated percentage				5.25%			5.25%	5.25%
Recourse Debt | Convertible Senior Notes Due 2048
Debt Instrument [Line Items]
Long-term debt				$ 575	575
Discounts				$ 85	$ 96
Interest rate, stated percentage				2.75%
Effective rate				5.05%	5.02%
Debt Instrument, Unamortized Discount [Abstract]
Total discounts				$ 85	$ 96
Recourse Debt | Senior Secured First Lien Notes, due 2024
Debt Instrument [Line Items]
Long-term debt				$ 600	0
Interest rate, stated percentage				3.75%		3.75%
Recourse Debt | Senior Secured First Lien Notes, due 2029
Debt Instrument [Line Items]
Long-term debt				$ 500	0
Interest rate, stated percentage				4.45%		4.45%
Recourse Debt | Term Loan Facility
Debt Instrument [Line Items]
Long-term debt			$ 1,900	$ 0	1,698				$ 260
Discounts				0	4
Debt Instrument, Unamortized Discount [Abstract]
Total discounts				$ 0	$ 4
Recourse Debt | Term Loan Facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.75%	2.25%	2.75%	1.75%	1.75%
Recourse Debt | Tax-exempt bonds
Debt Instrument [Line Items]
Long-term debt				$ 466	$ 466
Recourse Debt | Tax-exempt bonds | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage				4.125%
Recourse Debt | Tax-exempt bonds | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage				6.00%
Recourse Debt | Senior Secured First Lien Notes, due 2024 and 2029
Debt Instrument [Line Items]
Discounts				$ 1	0
Debt Instrument, Unamortized Discount [Abstract]
Total discounts				1	0
Line of Credit | Revolver Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt				$ 83	0
Line of Credit | Revolver Facility | Revolving Credit Facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)				1.75%
Non Recourse Debt
Debt Instrument [Line Items]
Long-term debt				$ 34	168
Non Recourse Debt | Agua Caliente Borrower 1, due 2038
Debt Instrument [Line Items]
Long-term debt				$ 0	86
Interest rate, stated percentage				5.43%
Non Recourse Debt | Midwest Generation, due 2019
Debt Instrument [Line Items]
Long-term debt				$ 0	48
Discounts				$ 0	1
Interest rate, stated percentage				4.39%
Debt Instrument, Unamortized Discount [Abstract]
Total discounts				$ 0	1
Non Recourse Debt | Other
Debt Instrument [Line Items]
Long-term debt				$ 34	$ 34

Debt and Finance Leases - Annua

Debt and Finance Leases - Annual Payments Based on the Maturities of Debt and Capital Leases (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
2020	$ 88
2021	6
2022	5
2023	4
2024	604
Thereafter	5,335
Subtotal long-term debt and finance leases (including current maturities)	6,042	$ 6,692
Revolving Credit Facility | Revolver Facility | Line of Credit
Debt Instrument [Line Items]
2020	$ 83

Debt and Finance Leases - Issua

Debt and Finance Leases - Issuance of Senior Notes (Details) - Recourse Debt - USD ($)	Dec. 31, 2019	May 28, 2019	May 24, 2019	May 14, 2019
Senior Notes due 2029
Debt Instrument [Line Items]
Aggregate principal amount				$ 733,000,000
Interest rate, stated percentage	5.25%		5.25%	5.25%
Senior Notes 2024
Debt Instrument [Line Items]
Interest rate, stated percentage	6.25%
Senior Secured First Lien Notes, Due 2024 and 2029
Debt Instrument [Line Items]
Aggregate principal amount		$ 1,100,000,000
Senior Secured First Lien Notes, Due 2024
Debt Instrument [Line Items]
Aggregate principal amount		$ 600,000,000
Interest rate, stated percentage	3.75%	3.75%
Senior Secured First Lien Notes, Due 2029
Debt Instrument [Line Items]
Aggregate principal amount		$ 500,000,000
Interest rate, stated percentage	4.45%	4.45%

Debt and Finance Leases - Iss_2

Debt and Finance Leases - Issuance of Convertible Senior Notes (Details)	3 Months Ended
	Jun. 30, 2018USD ($)$ / shares
Debt Instrument [Line Items]
Debt issuance transaction costs	$ 12,000,000
Convertible Senior Notes Due 2048 | Convertible Debt
Debt Instrument [Line Items]
Aggregate principal amount	$ 575,000,000
Interest rate, stated percentage	2.75%
Conversion price per common share (in usd per share) | $ / shares	$ 47.74
Conversion ratio	20.9479
Debt, estimated fair value	$ 472,000,000
Carrying amount of equity component	$ 103,000,000
Debt discount amortization period	7 years
Debt deferred financing costs amortization period	7 years
Convertible Senior Notes Due 2048 | Convertible Debt | Additional Paid-in Capita
Debt Instrument [Line Items]
Debt issuance transaction costs	$ 2,000,000
Convertible Senior Notes Due 2048 | Convertible Debt | Deferred Financing Costs
Debt Instrument [Line Items]
Debt issuance transaction costs	$ 10,000,000

Debt and Finance Leases - Senio

Debt and Finance Leases - Senior Notes Redemption and Repurchases (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2018	Jun. 30, 2018	Dec. 07, 2017	Aug. 02, 2016
Debt Instrument [Line Items]
Loss on debt extinguishment		$ 51	$ 44	$ 49
Senior Notes
Debt Instrument [Line Items]
Loss on debt extinguishment			38
Write off of deferred debt issuance cost			7
Recourse Debt | Senior Notes, due 2024
Debt Instrument [Line Items]
Principal amount redeemed		$ 733
Interest rate, stated percentage		6.25%
Loss on debt extinguishment		$ 29
Write off of deferred debt issuance cost		$ 5
Recourse Debt | Senior Notes
Debt Instrument [Line Items]
Principal Repurchased	$ 1,061		1,061		$ 576	$ 43
Cash Paid	1,106		1,106		$ 598	$ 45
Redemption percentage of principal		25.00%
Accrued interest	14		14
Recourse Debt | Senior Notes, due 2028
Debt Instrument [Line Items]
Interest rate, stated percentage		5.75%			5.75%	5.75%	5.75%
Principal Repurchased					$ 20
Recourse Debt | Senior Notes Due In 2022 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage		6.25%			6.25%	6.25%
Principal Repurchased	485		485		$ 493
Cash Paid	$ 508		$ 508
Redemption percentage of principal	103.13%
Recourse Debt | Senior Notes, due 2027
Debt Instrument [Line Items]
Interest rate, stated percentage		6.625%			6.625%			6.625%
Principal Repurchased					$ 20

Debt and Finance Leases - Sen_2

Debt and Finance Leases - Senior Notes Outstanding with Early Redemption Features (Details) - Recourse Debt	Dec. 31, 2019	May 24, 2019	May 14, 2019	Sep. 30, 2018	Jun. 30, 2018	Dec. 07, 2017	Aug. 02, 2016	May 23, 2016
Senior Notes due 2026
Debt Instrument [Line Items]
Interest rate, stated percentage	7.25%							7.25%
Senior Notes due 2027
Debt Instrument [Line Items]
Interest rate, stated percentage	6.625%			6.625%			6.625%
Senior Notes due 2028
Debt Instrument [Line Items]
Interest rate, stated percentage	5.75%			5.75%	5.75%	5.75%
Senior Notes due 2029
Debt Instrument [Line Items]
Interest rate, stated percentage	5.25%	5.25%	5.25%

Debt and Finance Leases - Recou

Debt and Finance Leases - Recourse Debt Redemption Period (Details) - Recourse Debt	12 Months Ended
	Dec. 31, 2019
Senior Notes
Debt Instrument [Line Items]
Average Early Redemption Percentage	25.00%
Senior Notes due 2026 | Treasury Rate
Debt Instrument [Line Items]
Premium percentage of principal amount of note discount factor (as percent)	1.00%
Treasury rate redemption (as percentage)	0.50%
Senior Notes due 2027 | Treasury Rate
Debt Instrument [Line Items]
Premium percentage of principal amount of note discount factor (as percent)	1.00%
Treasury rate redemption (as percentage)	50.00%
Senior Notes due 2028
Debt Instrument [Line Items]
Redemption percentage	35.00%
Senior Notes due 2028 | Treasury Rate
Debt Instrument [Line Items]
Premium percentage of principal amount of note discount factor (as percent)	1.00%
Treasury rate redemption (as percentage)	50.00%
Senior Notes due 2029
Debt Instrument [Line Items]
Redemption percentage	40.00%
Senior Notes due 2029 | Treasury Rate
Debt Instrument [Line Items]
Treasury rate redemption (as percentage)	0.50%
Redemption Period Prior To 15 May 2021 | Senior Notes due 2026
Debt Instrument [Line Items]
Redemption percentage	100.00%
Present value of note (as percentage)	1.03625
May 15, 2021 to May 14, 2022 | Senior Notes due 2026
Debt Instrument [Line Items]
Redemption percentage	103.625%
May 15, 2022 to May 14, 2023 | Senior Notes due 2026
Debt Instrument [Line Items]
Redemption percentage	102.417%
May 15, 2023 to May 14, 2024 | Senior Notes due 2026
Debt Instrument [Line Items]
Redemption percentage	101.208%
May 15, 2024 and thereafter | Senior Notes due 2026
Debt Instrument [Line Items]
Redemption percentage	100.00%
Redemption Period Prior To 15 July 2021 | Senior Notes due 2027
Debt Instrument [Line Items]
Redemption percentage	100.00%
Present value of note (as percentage)	1.03313
July 15, 2021 to July14, 2022 | Senior Notes due 2027
Debt Instrument [Line Items]
Redemption percentage	103.313%
July 15, 2022 to July 14, 2023 | Senior Notes due 2027
Debt Instrument [Line Items]
Redemption percentage	102.208%
July 15, 2023 to July 14, 2024 | Senior Notes due 2027
Debt Instrument [Line Items]
Redemption percentage	101.104%
July 15, 2024 and thereafter | Senior Notes due 2027
Debt Instrument [Line Items]
Redemption percentage	100.00%
Redemption Period Prior to January 15, 2021 | Senior Notes due 2028
Debt Instrument [Line Items]
Redemption percentage	105.75%
Redemption Period Prior to January 15, 2023 | Senior Notes due 2028
Debt Instrument [Line Items]
Redemption percentage	100.00%
Present value of note (as percentage)	1.02875
January 15, 2023 to January 14, 2024 | Senior Notes due 2028
Debt Instrument [Line Items]
Redemption percentage	102.875%
January 15, 2024 to January 14, 2025 | Senior Notes due 2028
Debt Instrument [Line Items]
Redemption percentage	101.917%
January 15, 2025 to January 14, 2026 | Senior Notes due 2028
Debt Instrument [Line Items]
Redemption percentage	100.958%
January 15, 2026 and thereafter | Senior Notes due 2028
Debt Instrument [Line Items]
Redemption percentage	100.00%
Redemption Period Prior to June 15, 2022 | Senior Notes due 2029
Debt Instrument [Line Items]
Redemption percentage	105.25%
Outstanding principal after redemption, percentage (at least)	50.00%
Redemption Period Prior to June 15, 2024 | Senior Notes due 2029
Debt Instrument [Line Items]
Redemption percentage	100.00%
Premium percentage of principal amount of note discount factor (as percent)	1.00%
Present value of note (as percentage)	1.02625
June 15, 2024 to June 14, 2025 | Senior Notes due 2029
Debt Instrument [Line Items]
Redemption percentage	102.625%
June 15, 2025 to June 14, 2026 | Senior Notes due 2029
Debt Instrument [Line Items]
Redemption percentage	101.75%
June 15, 2026 to June 14, 2027 | Senior Notes due 2029
Debt Instrument [Line Items]
Redemption percentage	100.875%
June 15, 2027 and thereafter | Senior Notes due 2029
Debt Instrument [Line Items]
Redemption percentage	100.00%

Debt and Finance Leases - Sen_3

Debt and Finance Leases - Senior Credit Facility and Tax Exempt Bonds (Details) - USD ($)	May 28, 2019	Nov. 05, 2018	Mar. 21, 2018	Jan. 24, 2017	Jun. 30, 2016	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt						$ 6,042,000,000	$ 6,691,000,000
Loss on debt extinguishment						51,000,000	44,000,000	$ 49,000,000
Decrease to long-term debt outstanding	$ 594,000,000
Credit Agreement | Adjusted Base Rate | Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.25%
Credit Agreement | Adjusted Base Rate | Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	0.75%
Credit Agreement | Eurodollar | Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	2.25%
Credit Agreement | Eurodollar | Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.75%
Recourse Debt
Debt Instrument [Line Items]
Long-term debt						6,008,000,000	6,523,000,000
Recourse Debt | Term Loan Facility
Debt Instrument [Line Items]
Long-term debt		$ 260,000,000			$ 1,900,000,000	$ 0	$ 1,698,000,000
Percent of face value					99.50%
Periodic payment, percentage of principal					0.0025
Payment amount		155,000,000
Loss on debt extinguishment	$ 17,000,000	3,000,000
Write off of deferred debt issuance cost	13,000,000	2,000,000
Repayment of debt	(1,700,000,000)
Recourse Debt | Term Loan Facility | Interest Rate Swap
Debt Instrument [Line Items]
Reduction to interest expense	(25,000,000)
Recourse Debt | Term Loan Facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			1.75%	2.25%	2.75%	1.75%	1.75%
Decrease in interest rate margin			0.50%	0.50%
Recourse Debt | Term Loan Facility | LIBOR floor
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			0.00%	0.75%	0.75%
Recourse Debt | Indian River Power, tax exempt bonds, due 2040
Debt Instrument [Line Items]
Long-term debt						$ 57,000,000	$ 57,000,000
Interest rate, stated percentage						6.00%
Recourse Debt | Indian River Power LLC, tax exempt bonds, due 2045
Debt Instrument [Line Items]
Long-term debt						$ 190,000,000	190,000,000
Interest rate, stated percentage						5.375%
Recourse Debt | Dunkirk Power LLC, tax exempt bonds, due 2042
Debt Instrument [Line Items]
Long-term debt						$ 59,000,000	59,000,000
Interest rate, stated percentage						5.875%
Recourse Debt | City of Texas City, tax exempt bonds, due 2045
Debt Instrument [Line Items]
Long-term debt						$ 33,000,000	33,000,000
Interest rate, stated percentage						4.125%
Recourse Debt | Fort Bend County, tax exempt bonds, due 2038
Debt Instrument [Line Items]
Long-term debt						$ 54,000,000	54,000,000
Interest rate, stated percentage						4.75%
Recourse Debt | Fort Bend County, tax exempt bonds, due 2042
Debt Instrument [Line Items]
Long-term debt						$ 73,000,000	73,000,000
Interest rate, stated percentage						4.75%
Recourse Debt | Tax-exempt bonds
Debt Instrument [Line Items]
Long-term debt						$ 466,000,000	466,000,000
Recourse Debt | Tax-exempt bonds | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage						4.125%
Recourse Debt | Tax-exempt bonds | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage						6.00%
Revolving Credit Facility | 2016 Tranche A Revolving Credit Facility due 2018
Debt Instrument [Line Items]
Revolving credit facility					$ 289,000,000
Revolving Credit Facility | 2016 Tranche B Revolving Credit Facility due 2021
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)					2.25%
Revolving credit facility					$ 2,200,000,000
Senior Credit Facility | Term Loan Facility
Debt Instrument [Line Items]
Long-term debt		$ 105,000,000
Line of Credit | Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt						$ 83,000,000	$ 0
Revolving credit facility	2,600,000,000
Increase in revolving commitments	$ 184,000,000
Line of Credit | Credit Agreement | LIBOR | Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)						1.75%

Debt and Finance Leases - Non-R

Debt and Finance Leases - Non-Recourse Debt (Details) - USD ($)	Oct. 21, 2019	Jan. 04, 2019	Apr. 07, 2016	Dec. 31, 2019
Agua Caliente Borrower 1, due 2038
Debt Instrument [Line Items]
Redemption percentage of principal	102.00%
Non Recourse Debt | Agua Caliente Borrower 1, due 2038
Debt Instrument [Line Items]
Interest rate, stated percentage				5.43%
Non Recourse Debt | Credit Agreement 2019 | Letter of Credit
Debt Instrument [Line Items]
Credit facility		$ 80,000,000
Annual facility fees, percentage		1.33%
Letter of credit				$ 80,000,000
Midwest Generation | Non Recourse Debt
Debt Instrument [Line Items]
Proceeds from sale of unforced capacity			$ 253,000,000
Interest rate, stated percentage			4.39%

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance as of December 31, 2018	$ 679
Revisions in estimates for current obligations(a)	27
Additions	9
Spending for current obligations	(33)
Accretion	46
Balance as of December 31, 2019	728
Nuclear Decommission
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance as of December 31, 2018	282
Revisions in estimates for current obligations(a)	0
Additions	0
Spending for current obligations	0
Accretion	16
Balance as of December 31, 2019	298
Other
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance as of December 31, 2018	397
Revisions in estimates for current obligations(a)	27
Additions	9
Spending for current obligations	(33)
Accretion	30
Balance as of December 31, 2019	$ 430

Benefit Plans and Other Postr_3

Benefit Plans and Other Postretirement Benefits - Narrative (Details) $ in Millions	Dec. 31, 2019USD ($)numberOfBenefitPlans	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Benefit Plans and Other Postretirement Benefits
Number of qualified pension plans | numberOfBenefitPlans	2
Pension Benefits
Benefit Plans and Other Postretirement Benefits
Expects to contribute to the pension plans	$ 56
GenOn
Benefit Plans and Other Postretirement Benefits
Pension liability retained			$ 92
Liability retained other post-employment and retiree health and welfare benefits		$ 23
GenOn | Restructuring Support Agreement
Benefit Plans and Other Postretirement Benefits
Amount of pension liability future contributions			$ 13
Expects to contribute to the pension plans	$ 21

Benefit Plans and Other Postr_4

Benefit Plans and Other Postretirement Benefits - Net Benefit Costs and Funded Status (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Annual periodic pension cost
Curtailment gain	$ (8)
Pension and other post retirement benefit obligations
Curtailment gain	$ (32)
Pension Benefits
Annual periodic pension cost
Service cost benefits earned		$ 10	$ 23	$ 26
Interest cost on benefit obligation		46	44	43
Expected return on plan assets		(59)	(62)	(58)
Amortization of unrecognized net loss		3	0	4
Curtailment gain		0	7	0
Net periodic benefit cost		0	12	15
Pension and other post retirement benefit obligations
Benefit obligation at January 1		1,222	1,329
Service cost		10	23	26
Interest cost		46	44	43
Plan amendments		0	17
Actuarial (gain)/loss		207	(95)
Employee and retiree contributions		0	0
Curtailment gain		0	(20)
Benefit payments		(88)	(76)
Benefit obligation at December 31		1,397	1,222	1,329
Fair value of plan assets for pension and other post retirement benefit
Fair value of plan assets at January 1		981	1,104
Actual return on plan assets		216	(80)
Employee and retiree contributions		0	0
Employer contributions		41	33
Benefit payments		(88)	(76)
Fair value of plan assets at December 31		1,150	981	1,104
Funded status at December 31 — excess of obligation over assets		(247)	(241)
Other Postretirement Benefits Plan
Annual periodic pension cost
Service cost benefits earned		1	1	1
Interest cost on benefit obligation		3	4	4
Amortization of unrecognized prior service credit		(13)	(10)	(9)
Amortization of unrecognized net loss		0	0	(1)
Curtailment gain		0	(10)	0
Net periodic benefit cost		(9)	(15)	(5)
Pension and other post retirement benefit obligations
Benefit obligation at January 1		83	128
Service cost		1	1	1
Interest cost		3	4	4
Plan amendments		(2)	(28)
Actuarial (gain)/loss		16	(6)
Employee and retiree contributions		4	3
Curtailment gain		0	(7)
Benefit payments		(12)	(12)
Benefit obligation at December 31		93	83	128
Fair value of plan assets for pension and other post retirement benefit
Fair value of plan assets at January 1		0	0
Actual return on plan assets		0	0
Employee and retiree contributions		4	3
Employer contributions		7	9
Benefit payments		(11)	(12)
Fair value of plan assets at December 31		0	0	$ 0
Funded status at December 31 — excess of obligation over assets		$ (93)	$ (83)

Benefit Plans and Other Postr_5

Benefit Plans and Other Postretirement Benefits - Amounts Recognized in the Balance Sheets and OCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits
Amounts recognized in balance sheet
Other current liabilities	$ 0	$ 0
Other non-current liabilities	247	241
Amounts recognized in accumulated OCI
Net loss/(gain)	138	90
Prior service cost/(credit)	2	3
Total/Net accumulated OCI	140	93
Other changes in plan assets and benefit obligations recognized in other comprehensive income
Net actuarial loss/(gain)	50	47
Amortization of net actuarial (gain)/loss	(3)	0	$ (4)
Curtailment	0	(27)
Prior service credit	0	17
Amortization of prior service cost	0	0
Total recognized in OCI	47	37
Net periodic benefit cost (credit)	0	12	15
Net recognized in net periodic pension cost/(credit) and OCI	47	49
Expected unrecognized gain that will be amortized from accumulated OCI to net periodic cost over the next fiscal year	5
Significant components of NRG's domestic pension plan
Projected benefit obligation	1,397	1,222	1,329
Accumulated benefit obligation	1,362	1,188
Fair value of plan assets	1,150	981	1,104
Other Postretirement Benefits Plan
Amounts recognized in balance sheet
Other current liabilities	7	7
Other non-current liabilities	86	76
Amounts recognized in accumulated OCI
Net loss/(gain)	7	(9)
Prior service cost/(credit)	(43)	(53)
Total/Net accumulated OCI	(36)	(62)
Other changes in plan assets and benefit obligations recognized in other comprehensive income
Net actuarial loss/(gain)	16	(5)
Amortization of net actuarial (gain)/loss	0	0	1
Curtailment	0	2
Prior service credit	(2)	(28)
Amortization of prior service cost	12	10
Total recognized in OCI	26	(21)
Net periodic benefit cost (credit)	(9)	(15)	(5)
Net recognized in net periodic pension cost/(credit) and OCI	17	(36)
Expected unrecognized gain that will be amortized from accumulated OCI to net periodic cost over the next fiscal year	1
Expected amortization of unrecognized prior service credit over the next fiscal Year		14
Significant components of NRG's domestic pension plan
Projected benefit obligation	93	83	128
Fair value of plan assets	$ 0	$ 0	$ 0

Benefit Plans and Other Postr_6

Benefit Plans and Other Postretirement Benefits - Fair Values of Pension Assets By Asset Category and Level Within the Fair Value Hierarchy (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Minimum
Significant assumptions used to calculate NRG's benefit expense
Aon Hewitt above median yield curve discount rate (in years)	6 months
Maximum
Significant assumptions used to calculate NRG's benefit expense
Aon Hewitt above median yield curve discount rate (in years)	99 years
Pension Benefits
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	$ 1,150	$ 981	$ 1,104
Significant assumptions used to calculate NRG's benefit obligations
Discount rate	3.26%	4.38%
Rate of compensation increase	3.00%	3.00%
Significant assumptions used to calculate NRG's benefit expense
Discount rate			4.26%
Expected return on plan assets	6.35%	6.17%	6.85%
Rate of compensation increase	3.00%	3.00%	3.00%
Pension Benefits | Minimum
Significant assumptions used to calculate NRG's benefit expense
Discount rate	4.38%	3.71%
Pension Benefits | Maximum
Significant assumptions used to calculate NRG's benefit expense
Discount rate	4.20%	4.04%
Pension Benefits | Common/collective trust investment — U.S. equity
Target allocations
Target allocation of pension plan assets (as percent)	20.00%
Pension Benefits | Common/collective trust investment — non-U.S. equity
Target allocations
Target allocation of pension plan assets (as percent)	13.00%
Pension Benefits | Common/collective trust investment — non-core assets
Target allocations
Target allocation of pension plan assets (as percent)	17.00%
Pension Benefits | Common/collective trust investment — fixed income
Target allocations
Target allocation of pension plan assets (as percent)	50.00%
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1)
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	$ 12	$ 12
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Common/collective trust investment — U.S. equity
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	0	0
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Common/collective trust investment — non-U.S. equity
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	0	0
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Common/collective trust investment — non-core assets
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	0	0
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Common/collective trust investment — fixed income
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	0	0
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investment fund
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	12	12
Pension Benefits | Significant Observable Inputs (Level 2)
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	721	609
Pension Benefits | Significant Observable Inputs (Level 2) | Common/collective trust investment — U.S. equity
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	233	183
Pension Benefits | Significant Observable Inputs (Level 2) | Common/collective trust investment — non-U.S. equity
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	73	53
Pension Benefits | Significant Observable Inputs (Level 2) | Common/collective trust investment — non-core assets
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	143	117
Pension Benefits | Significant Observable Inputs (Level 2) | Common/collective trust investment — fixed income
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	272	256
Pension Benefits | Significant Observable Inputs (Level 2) | Short-term investment fund
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	0	0
Pension Benefits | Total
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	733	621
Pension Benefits | Total | Common/collective trust investment — U.S. equity
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	233	183
Pension Benefits | Total | Common/collective trust investment — non-U.S. equity
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	73	53
Pension Benefits | Total | Common/collective trust investment — non-core assets
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	143	117
Pension Benefits | Total | Common/collective trust investment — fixed income
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	272	256
Pension Benefits | Total | Short-term investment fund
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	12	12
Pension Benefits | Fair Value Measured at Net Asset Value Per Share
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	1,150	981
Pension Benefits | Fair Value Measured at Net Asset Value Per Share | Common/collective trust investment — non-U.S. equity
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	84	70
Pension Benefits | Fair Value Measured at Net Asset Value Per Share | Common/collective trust investment — non-core assets
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	24	16
Pension Benefits | Fair Value Measured at Net Asset Value Per Share | Common/collective trust investment — fixed income
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	279	249
Pension Benefits | Fair Value Measured at Net Asset Value Per Share | Partnerships/joint ventures
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	30	25
Other Postretirement Benefits Plan
Benefit Plans and Other Postretirement Benefits
Fair value of plan assets	$ 0	$ 0	$ 0
Significant assumptions used to calculate NRG's benefit obligations
Discount rate	3.26%	4.37%
Rate of compensation increase	0.00%	0.00%
Significant assumptions used to calculate NRG's benefit expense
Discount rate			4.29%
Expected return on plan assets	0.00%	0.00%	0.00%
Rate of compensation increase	0.00%	0.00%	0.00%
Other Postretirement Benefits Plan | Minimum
Significant assumptions used to calculate NRG's benefit expense
Discount rate	4.37%	3.71%
Other Postretirement Benefits Plan | Maximum
Significant assumptions used to calculate NRG's benefit expense
Discount rate		4.08%
Other Postretirement Benefits Plan | Postretirement Benefit Obligation
Significant assumptions used to calculate NRG's benefit obligations
Year Health care cost trend rate reaches ultimate trend rate	2028	2025
Other Postretirement Benefits Plan | Postretirement Benefit Obligation | Before age 65
Significant assumptions used to calculate NRG's benefit obligations
Health care trend rate	7.50%	7.80%	7.00%
Other Postretirement Benefits Plan | Postretirement Benefit Obligation | Age 65 and after
Significant assumptions used to calculate NRG's benefit obligations
Health care trend rate	4.50%	4.50%
Other Postretirement Benefits Plan | Net Period Benefit Cost/Credit
Significant assumptions used to calculate NRG's benefit obligations
Year Health care cost trend rate reaches ultimate trend rate	2025	2025	2025
Other Postretirement Benefits Plan | Net Period Benefit Cost/Credit | Before age 65
Significant assumptions used to calculate NRG's benefit obligations
Health care trend rate	7.80%	8.20%
Other Postretirement Benefits Plan | Net Period Benefit Cost/Credit | Age 65 and after
Significant assumptions used to calculate NRG's benefit obligations
Health care trend rate	4.50%	4.50%	5.00%

Benefit Plans and Other Postr_7

Benefit Plans and Other Postretirement Benefits - Expected Future Benefit Payments For the Next Five Years and Other (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
One-percentage-point change in assumed health care cost trend rates
Effect on postretirement benefit obligation, 1-Percentage-Point Increase		$ 7
Effect on postretirement benefit obligation, 1-Percentage-Point Decrease		(5)
STP Defined Benefit Plans
Curtailment gain	$ 8
Increase to pension liability	$ (32)
Company's contributions to 401(k) plans
Company contributions to defined contribution plans		22	$ 28	$ 56
South Texas Project
STP Defined Benefit Plans
Amount reimbursed to STPNOC towards defined benefit plans		24	13
Expected reimbursement of contribution to retirement plan obligations to STPNOC in 2014		7
Pension Benefit Payments
NRG's expected future benefit payments
2020		84
2021		86
2022		86
2023		86
2024		86
2025-2029		402
STP Defined Benefit Plans
Curtailment gain		0	(7)	0
Increase to pension liability		0	(20)
Recognized amount in statement of financial position, statement of operations and accumulated OCI related to STP
Funded status — STPNOC benefit plans		(247)	(241)
Net periodic benefit cost (credit)		0	12	15
Total recognized in other comprehensive loss		(47)	(37)
Pension Benefit Payments | South Texas Project
Recognized amount in statement of financial position, statement of operations and accumulated OCI related to STP
Funded status — STPNOC benefit plans		(77)	(78)
Net periodic benefit cost (credit)		9	8
Total recognized in other comprehensive loss		(13)	(7)
Other Postretirement Benefits Plan
NRG's expected future benefit payments
2020		7
2021		6
2022		6
2023		6
2024		6
2025-2029		19
Medicare prescription drug reimbursements
2020		0
2021		0
2022		0
2023		0
2024		0
2025-2029		2
STP Defined Benefit Plans
Curtailment gain		0	10	0
Increase to pension liability		0	(7)
Recognized amount in statement of financial position, statement of operations and accumulated OCI related to STP
Funded status — STPNOC benefit plans		(93)	(83)
Net periodic benefit cost (credit)		(9)	(15)	$ (5)
Total recognized in other comprehensive loss		(26)	21
Other Postretirement Benefits Plan | South Texas Project
Recognized amount in statement of financial position, statement of operations and accumulated OCI related to STP
Funded status — STPNOC benefit plans		(20)	(19)
Net periodic benefit cost (credit)		(4)	(7)
Total recognized in other comprehensive loss		$ 6	$ 2
South Texas Project
STP Defined Benefit Plans
Ownership interest in STP (as a percent)		44.00%
Percentage of contribution to the retirement plan obligation reimbursed		44.00%

Capital Structure - Changes in

Capital Structure - Changes in Common Shares issued and Outstanding (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Capital Structure
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000	10,000,000	10,000,000
Common stock, shares authorized (in shares)	500,000,000	500,000,000	500,000,000	500,000,000
Increase (Decrease) in Stockholders' Equity (in shares)
Beginning balance, common shares issued (in shares)	420,288,886
Beginning balance, treasury shares(in shares)	(136,638,847)
Beginning balance, common shares outstanding (in shares)	283,650,039
Share repurchases (in shares)	(36,301,882)	(35,234,664)
Ending balance, common shares issued (in shares)	421,890,790	420,288,886
Ending balance, treasury shares (in shares)	(172,894,601)	(136,638,847)
Ending balance, common shares outstanding (in shares)	248,996,189	283,650,039
Common Stock
Increase (Decrease) in Stockholders' Equity (in shares)
Beginning balance, common shares issued (in shares)	420,288,886	418,323,134	417,583,825
Beginning balance, common shares outstanding (in shares)	283,650,039	316,743,089	315,443,011
Shares issued under ESPP (in shares)	46,128	175,862	560,769
Shares issued from LTIP (in shares)	1,601,904	1,965,752	739,309
Ending balance, common shares issued (in shares)	421,890,790	420,288,886	418,323,134
Ending balance, common shares outstanding (in shares)	248,996,189	283,650,039	316,743,089
Treasury Stock
Increase (Decrease) in Stockholders' Equity (in shares)
Beginning balance, treasury shares(in shares)	(136,638,847)	(101,580,045)	(102,140,814)
Shares issued under ESPP (in shares)	46,128	175,862	560,769
Shares issued from LTIP (in shares)	0	0	0
Share repurchases (in shares)	(36,301,882)	(35,234,664)
Ending balance, treasury shares (in shares)	(172,894,601)	(136,638,847)	(101,580,045)

Capital Structure - Common Stoc

Capital Structure - Common Stock (Details) - USD ($)	Jan. 21, 2020	Mar. 31, 2019	Feb. 27, 2020	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common Stock, Employee Stock Purchase Plan and Share Repurchases
Quarterly dividends per share (usd per share)							$ 0.03	$ 0.03	$ 0.03
Dividends paid per share (in usd per share)							$ 0.12	$ 0.12	$ 0.12
Eligible compensation withholding, minimum, percentage		1.00%
Eligible compensation withholding, maximum, percentage		10.00%					10.00%
Exercise price as a percentage of fair value (as a percent)		95.00%					85.00%
Treasury stock reserved for issuance under the ESPP (in shares)					2,885,060		2,885,060
Shares repurchased (in shares)							36,301,882	35,234,664
Long-term capital allocation policy, target allocation of cash generated allocated to growth investments, percentage					50.00%
Long-term capital allocation, target allocation, cash generated allocated returned to shareholders, percentage					50.00%
Capital Allocation Plan
Common Stock, Employee Stock Purchase Plan and Share Repurchases
Stock repurchase program, authorized amount					$ 1,250,000,000		$ 1,250,000,000	$ 1,500,000,000
Shares repurchased (in shares)							37,238,810	35,234,664
2018 Capital Allocation Plan
Common Stock, Employee Stock Purchase Plan and Share Repurchases
Shares repurchased (in shares)						250,000,000		1,250,000,000
2019 Capital Allocation Plan
Common Stock, Employee Stock Purchase Plan and Share Repurchases
Shares repurchased (in shares)							1,194,000,000
Subsequent Event
Common Stock, Employee Stock Purchase Plan and Share Repurchases
Dividends per common share (in usd per share)	$ 0.30
Subsequent Event | Capital Allocation Plan
Common Stock, Employee Stock Purchase Plan and Share Repurchases
Shares repurchased (in shares)			3,138,081
Subsequent Event | 2019 Capital Allocation Plan
Common Stock, Employee Stock Purchase Plan and Share Repurchases
Shares repurchased (in shares)			56,000,000
Scenario, Forecast
Common Stock, Employee Stock Purchase Plan and Share Repurchases
Common stock, dividends, proposed annual amount, per share (usd per share)				$ 1.20
Scenario, Forecast | Minimum
Common Stock, Employee Stock Purchase Plan and Share Repurchases
Annual dividend growth rate, percentage				700.00%
Scenario, Forecast | Maximum
Common Stock, Employee Stock Purchase Plan and Share Repurchases
Annual dividend growth rate, percentage				9.00%
Scenario, Plan | Subsequent Event
Common Stock, Employee Stock Purchase Plan and Share Repurchases
Common stock, dividends, proposed annual amount, per share (usd per share)	$ 1.20
Long-term incentive plans
Common Stock, Employee Stock Purchase Plan and Share Repurchases
Long-term incentive plans (in shares)					16,029,127		16,029,127

Capital Structure - Summary of

Capital Structure - Summary of Changes in Shares Repurchased (Details) - USD ($) $ / shares in Units, $ in Millions	2 Months Ended		12 Months Ended
	Feb. 27, 2020	Apr. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Capital Allocation Plan [Line Items]
Total number of shares purchased (in shares)				36,301,882	35,234,664
Shares repurchased under May 24, 2018 Accelerated Repurchase Agreement
Capital Allocation Plan [Line Items]
Total number of shares purchased (in shares)					10,829,903
Amounts paid for shares and share equivalents purchased (in millions)					$ 354
Shares repurchased under September 5, 2018 Accelerated Repurchase Agreement
Capital Allocation Plan [Line Items]
Total number of shares purchased (in shares)					13,307,130
Amounts paid for shares and share equivalents purchased (in millions)					$ 500
Other repurchases
Capital Allocation Plan [Line Items]
Total number of shares purchased (in shares)				26,863,211	11,097,631
Amounts paid for shares and share equivalents purchased (in millions)				$ 1,008	$ 396
Repurchases under February 28, 2019 Accelerated Share Repurchase Agreement
Capital Allocation Plan [Line Items]
Total number of shares purchased (in shares)		9,438,671
Amounts paid for shares and share equivalents purchased (in millions)		$ 400
Equivalent shares purchased in lieu of tax withholding on equity compensation issuances
Capital Allocation Plan [Line Items]
Total number of shares purchased (in shares)				936,928
Average price paid per share (in shares)				$ 38.78
Amounts paid for shares and share equivalents purchased (in millions)				$ 36
Capital Allocation Plan
Capital Allocation Plan [Line Items]
Total number of shares purchased (in shares)				37,238,810	35,234,664
Average price paid per share (in shares)				$ 38.79	$ 35.48
Amounts paid for shares and share equivalents purchased (in millions)				$ 1,444	$ 1,250
Subsequent Event | Other repurchases
Capital Allocation Plan [Line Items]
Total number of shares purchased (in shares)	2,428,545
Amounts paid for shares and share equivalents purchased (in millions)	$ 92
Subsequent Event | Equivalent shares purchased in lieu of tax withholding on equity compensation issuances
Capital Allocation Plan [Line Items]
Total number of shares purchased (in shares)	709,536
Average price paid per share (in shares)			$ 38.24
Amounts paid for shares and share equivalents purchased (in millions)	$ 27
Subsequent Event | Capital Allocation Plan
Capital Allocation Plan [Line Items]
Total number of shares purchased (in shares)	3,138,081
Average price paid per share (in shares)	$ 37.87
Amounts paid for shares and share equivalents purchased (in millions)	$ 119

Investments Accounted for by _3

Investments Accounted for by the Equity Method and Variable Interest Entities - Summary of Equity Method Investments (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Investments Accounted for by the Equity Method
Equity investments in affiliates	$ 388	$ 412
Undistributed earnings by equity investment	$ 42	$ 34
Agua Caliente
Investments Accounted for by the Equity Method
Economic interest in equity method investments (as a percent)	35.00%
Equity investments in affiliates	$ 213
Gladstone
Investments Accounted for by the Equity Method
Economic interest in equity method investments (as a percent)	37.50%
Equity investments in affiliates	$ 124
Ivanpah Master Holdings, LLC
Investments Accounted for by the Equity Method
Economic interest in equity method investments (as a percent)	54.50%
Equity investments in affiliates	$ 20
Watson Cogeneration Company
Investments Accounted for by the Equity Method
Economic interest in equity method investments (as a percent)	49.00%
Equity investments in affiliates	$ 15
Midway-Sunset Cogeneration Company
Investments Accounted for by the Equity Method
Economic interest in equity method investments (as a percent)	50.00%
Equity investments in affiliates	$ 9
Other
Investments Accounted for by the Equity Method
Equity investments in affiliates	$ 7

Investments Accounted for by _4

Investments Accounted for by the Equity Method and Variable Interest Entities - PG&E Bankruptcy (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Investments Accounted for by the Equity Method
Equity investments in affiliates	$ 388	$ 412
Agua Caliente
Investments Accounted for by the Equity Method
Equity investments in affiliates	213
Ivanpah Master Holdings, LLC
Investments Accounted for by the Equity Method
Equity investments in affiliates	$ 20

Investments Accounted for by _5

Investments Accounted for by the Equity Method and Variable Interest Entities - Variable Interest Entities (Details) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2018USD ($)	Dec. 31, 2019projectMW	Dec. 31, 2018USD ($)
Schedule of Equity Method Investments [Line Items]
Generation capacity (in MW) | MW		23,000
Ivanpah Master Holdings LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage		54.50%
Number of solar electric generating projects | project		3
Generation capacity (in MW) | MW		393
Release of reserves to fund equity distributions	$ 95
Loss on deconsolidation			$ 22
Reduction of assets due to deconsolidation			1,300
Reduction of liabilities due to deconsolidation			$ 1,200
Gladstone
Schedule of Equity Method Investments [Line Items]
Ownership percentage		37.50%
Generation capacity (in MW) | MW		1,613

Investments Accounted for by _6

Investments Accounted for by the Equity Method and Variable Interest Entities - Other Equity Investments (Details) $ in Millions	Dec. 31, 2019USD ($)MW	Dec. 31, 2018USD ($)
Schedule of Equity Method Investments [Line Items]
Generation capacity (in MW) | MW	23,000
Equity investments in affiliates | $	$ 388	$ 412
Gladstone
Schedule of Equity Method Investments [Line Items]
Ownership percentage	37.50%
Generation capacity (in MW) | MW	1,613
Equity investments in affiliates | $	$ 124

Investments Accounted For by _7

Investments Accounted For by the Equity Method and Variable Interest Entities - Entities that are Consolidated (Details) - Variable Interest Entity - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Current assets	$ 3	$ 3
Net property, plant and equipment	71	76
Other long-term assets	27	28
Total assets	101	107
Current liabilities	4	2
Long-term debt	24	29
Other long-term liabilities	8	7
Total liabilities	36	38
Redeemable noncontrolling interests	20	19
Net assets less noncontrolling interests	$ 45	$ 50

Earnings _Loss Per Share (Detai

Earnings /Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Basic income/(loss) per share attributable to NRG, Inc;
Net Income/(Loss) Attributable to NRG Energy, Inc.									$ 4,438	$ 268	$ (2,153)
Weighted average number of common shares outstanding — basic (in shares)	251,000,000	254,000,000	265,000,000	278,000,000	289,000,000	299,000,000	310,000,000	318,000,000	262,000,000	304,000,000	317,000,000
Income/(Loss) per weighted average common share — basic (in usd per share)	$ 13.48	$ 1.46	$ 0.76	$ 1.73	$ (0.04)	$ (0.24)	$ 0.23	$ 0.88	$ 16.94	$ 0.88	$ (6.79)
Incremental shares attributable to the issuance of equity compensation (treasury stock method) (in shares)									2,000,000	4,000,000	0
Weighted average number of common shares outstanding — diluted (in shares)	253,000,000	256,000,000	267,000,000	280,000,000	289,000,000	299,000,000	314,000,000	322,000,000	264,000,000	308,000,000	317,000,000
Income (Loss) per weighted average common share — diluted (in usd per share)	$ 13.37	$ 1.45	$ 0.75	$ 1.72	$ (0.04)	$ (0.24)	$ 0.23	$ 0.87	$ 16.81	$ 0.87	$ (6.79)

Earnings _Loss Per Share - Summ

Earnings /Loss Per Share - Summary of Outstanding Equity Instruments that are Anti-dilutive and Excluded from Computation of Loss Per Share (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Compensation Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	0	5

Segment Reporting (Details)

Segment Reporting (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement
Revenues		$ 2,195	$ 2,996	$ 2,465	$ 2,165	$ 1,992	$ 2,960	$ 2,461	$ 2,065	$ 9,821	$ 9,478	$ 9,074
Operating expenses										8,153	7,997	7,766
Depreciation and amortization										373	421	596
Impairment losses										5	99	1,534
Development costs										7	11	22
Total operating costs and expenses										8,538	8,528	9,918
Other income - affiliate	$ 84									0	0	87
(Loss)/Gain on sale of assets										7	32	16
Operating (loss)/income		209	540	320	221	49	398	174	361	1,290	982	(741)
Equity in earnings/(losses) of unconsolidated affiliates										2	9	(14)
Impairment losses on investments										(108)	(15)	(79)
Other income, net										66	18	51
Loss on debt extinguishment										(51)	(44)	(49)
Interest expense										(413)	(483)	(557)
Income/(Loss) from Continuing Operations Before Income Taxes										786	467	(1,389)
Income tax (benefit)/expense										(3,334)	7	(44)
Income/(Loss) from Continuing Operations		3,463	374	189	94	(93)	287	27	238	4,120	460	(1,345)
Income/(loss) from discontinued operations, net of income tax		(78)	(2)	13	388	80	(336)	69	(5)	321	(192)	(992)
Net Income/(Loss)		3,385	372	202	482	(13)	(49)	96	233	4,441	268	(2,337)
Less: Net income attributable to noncontrolling interests and redeemable noncontrolling interests		2	$ 0	$ 1	$ 0	(2)	$ 23	$ 24	$ (46)	3	0	(184)
Net Income/(Loss) Attributable to NRG Energy, Inc.										4,438	268	(2,153)
Balance sheet
Equity investments in affiliates		388				412				388	412
Capital expenditures		228				388				228	388
Goodwill		579				573				579	573
Total assets		12,531				10,628				12,531	10,628
Eliminations
Income Statement
Revenues										(7)	(18)	(47)
Operating expenses										(7)	(18)	(48)
Depreciation and amortization										0	0	(3)
Impairment losses										0	0	0
Development costs										0	0	0
Total operating costs and expenses										(7)	(18)	(51)
Other income - affiliate												0
(Loss)/Gain on sale of assets										0	0	0
Operating (loss)/income										0	0	4
Equity in earnings/(losses) of unconsolidated affiliates										0	0	0
Impairment losses on investments										0	0	0
Other income, net										0	0	0
Loss on debt extinguishment										0	0	0
Interest expense										0	0	0
Income/(Loss) from Continuing Operations Before Income Taxes										0	0	4
Income tax (benefit)/expense										0	0	0
Income/(Loss) from Continuing Operations										0	0	4
Income/(loss) from discontinued operations, net of income tax										0	0	0
Net Income/(Loss)										0	0	4
Less: Net income attributable to noncontrolling interests and redeemable noncontrolling interests										0	0	4
Net Income/(Loss) Attributable to NRG Energy, Inc.										0	0	0
Balance sheet
Equity investments in affiliates		0				0				0	0
Capital expenditures		0				0				0	0
Goodwill		0				0				0	0
Total assets		(4,872)				(5,095)				(4,872)	(5,095)
Texas | Operating Segments
Income Statement
Revenues										7,069	6,401	6,318
Operating expenses										5,818	5,399	5,393
Depreciation and amortization										188	156	258
Impairment losses										1	5	1,317
Development costs										3	3	4
Total operating costs and expenses										6,010	5,563	6,972
Other income - affiliate												0
(Loss)/Gain on sale of assets										0	4	5
Operating (loss)/income										1,059	842	(649)
Equity in earnings/(losses) of unconsolidated affiliates										(4)	(3)	(22)
Impairment losses on investments										(103)	(15)	(69)
Other income, net										20	13	(2)
Loss on debt extinguishment										0	0	0
Interest expense										0	0	0
Income/(Loss) from Continuing Operations Before Income Taxes										972	837	(742)
Income tax (benefit)/expense										0	0	0
Income/(Loss) from Continuing Operations										972	837	(742)
Income/(loss) from discontinued operations, net of income tax										0	0	0
Net Income/(Loss)										972	837	(742)
Less: Net income attributable to noncontrolling interests and redeemable noncontrolling interests										0	0	0
Net Income/(Loss) Attributable to NRG Energy, Inc.										972	837	(742)
Balance sheet
Equity investments in affiliates		6				6				6	6
Capital expenditures		136				143				136	143
Goodwill		325				320				325	320
Total assets		5,711				5,357				5,711	5,357
Texas | Eliminations
Income Statement
Revenues										(1)	(19)	(41)
East | Operating Segments
Income Statement
Revenues										2,319	2,371	2,009
Operating expenses										1,895	2,024	1,684
Depreciation and amortization										121	105	112
Impairment losses										0	82	106
Development costs										3	3	6
Total operating costs and expenses										2,019	2,214	1,908
Other income - affiliate												0
(Loss)/Gain on sale of assets										1	0	15
Operating (loss)/income										301	157	116
Equity in earnings/(losses) of unconsolidated affiliates										0	0	0
Impairment losses on investments										0	0	0
Other income, net										6	2	4
Loss on debt extinguishment										0	0	0
Interest expense										(18)	(22)	(29)
Income/(Loss) from Continuing Operations Before Income Taxes										289	137	91
Income tax (benefit)/expense										2	1	0
Income/(Loss) from Continuing Operations										287	136	91
Income/(loss) from discontinued operations, net of income tax										0	0	0
Net Income/(Loss)										287	136	91
Less: Net income attributable to noncontrolling interests and redeemable noncontrolling interests										0	0	0
Net Income/(Loss) Attributable to NRG Energy, Inc.										287	136	91
Balance sheet
Equity investments in affiliates		0				0				0	0
Capital expenditures		30				171				30	171
Goodwill		254				253				254	253
Total assets		2,160				2,187				2,160	2,187
East | Eliminations
Income Statement
Revenues										(8)	5	(1)
West/Other | Operating Segments
Income Statement
Revenues										440	724	788
Operating expenses										397	467	498
Depreciation and amortization										33	127	194
Impairment losses										4	12	111
Development costs										1	3	6
Total operating costs and expenses										435	609	809
Other income - affiliate												0
(Loss)/Gain on sale of assets										0	(2)	(5)
Operating (loss)/income										5	113	(26)
Equity in earnings/(losses) of unconsolidated affiliates										6	13	10
Impairment losses on investments										0	0	(6)
Other income, net										10	4	22
Loss on debt extinguishment										(3)	0	0
Interest expense										(10)	(39)	(77)
Income/(Loss) from Continuing Operations Before Income Taxes										8	91	(77)
Income tax (benefit)/expense										1	0	(6)
Income/(Loss) from Continuing Operations										7	91	(71)
Income/(loss) from discontinued operations, net of income tax										0	0	0
Net Income/(Loss)										7	91	(71)
Less: Net income attributable to noncontrolling interests and redeemable noncontrolling interests										3	5	1
Net Income/(Loss) Attributable to NRG Energy, Inc.										4	86	(72)
Balance sheet
Equity investments in affiliates		382				406				382	406
Capital expenditures		25				29				25	29
Goodwill		0				0				0	0
Total assets		1,190				1,548				1,190	1,548
West/Other | Eliminations
Income Statement
Revenues										2	(4)	4
Corporate | Operating Segments
Income Statement
Revenues										0	0	6
Operating expenses										50	125	239
Depreciation and amortization										31	33	35
Impairment losses										0	0	0
Development costs										0	2	6
Total operating costs and expenses										81	160	280
Other income - affiliate												87
(Loss)/Gain on sale of assets										6	30	1
Operating (loss)/income										(75)	(130)	(186)
Equity in earnings/(losses) of unconsolidated affiliates										0	(1)	(2)
Impairment losses on investments										(5)	0	(4)
Other income, net										30	(1)	27
Loss on debt extinguishment										(48)	(44)	(49)
Interest expense										(385)	(422)	(451)
Income/(Loss) from Continuing Operations Before Income Taxes										(483)	(598)	(665)
Income tax (benefit)/expense										(3,337)	6	(38)
Income/(Loss) from Continuing Operations										2,854	(604)	(627)
Income/(loss) from discontinued operations, net of income tax										321	(192)	(992)
Net Income/(Loss)										3,175	(796)	(1,619)
Less: Net income attributable to noncontrolling interests and redeemable noncontrolling interests										0	(5)	(189)
Net Income/(Loss) Attributable to NRG Energy, Inc.										3,175	(791)	(1,430)
Balance sheet
Equity investments in affiliates		0				0				0	0
Capital expenditures		37				45				37	45
Goodwill		0				0				0	0
Total assets		$ 8,342				$ 6,631				8,342	6,631
Corporate | Eliminations
Income Statement
Revenues										$ 0	$ 0	$ (9)
Customer Concentration Risk | Texas
Segment Reporting Information
Concentration risk, percentage										10.00%	11.00%

Income Taxes - Income Tax Provi

Income Taxes - Income Tax Provision (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current
State	$ 2	$ 6	$ 19
Foreign	4	0	0
Total — current	6	6	19
Deferred
U.S. Federal	(3,000)	(16)	(60)
State	(340)	16	(5)
Foreign	0	1	2
Total — deferred	(3,340)	1	(63)
Income tax expense/(benefit)	(3,334)	7	(44)
Domestic and foreign components of income from continuing operations before income tax expense
U.S.	771	468	(1,406)
Foreign	15	(1)	17
Income/(Loss) from Continuing Operations Before Income Taxes	786	467	(1,389)
Reconciliation of the U.S. federal statutory rate to NRG's effective rate from continuing operations
Income/(loss) from continuing operations before income taxes	786	467	(1,389)
Tax at federal statutory tax rate	165	98	(486)
State taxes	13	18	19
Foreign operations	0	0	2
Permanent differences	(9)	7	0
Valuation allowance - current period activities	(3,492)	(106)	455
Book goodwill impairment	0	0	30
Deferred impact of state tax rate changes	12	0	0
Production tax credits ("PTC")	0	(7)	(8)
Recognition of uncertain tax benefits	(10)	1	(5)
Alternative minimum tax ("AMT") refundable credit	0	(4)	(64)
Tax Act - corporate income tax rate change	0	0	665
Valuation allowance due to corporate income tax rate change	0	0	(660)
Other	(13)	0	8
Income tax expense/(benefit)	$ (3,334)	$ 7	$ (44)
Effective income tax rate (as a percent)	(424.20%)	1.50%	3.20%

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Deferred compensation, accrued vacation and other reserves	$ 81	$ 134
Difference between book and tax basis of property	548	554
Goodwill	0	11
Differences between book and tax basis of contracts	0	38
Pension and other postretirement benefits	86	87
Equity compensation	11	9
Bad debt reserve	13	14
U.S. Federal net operating loss carryforwards	2,116	2,241
Foreign net operating loss carryforwards	105	63
State net operating loss carryforwards	360	379
Federal and state tax credit carryforwards	384	381
Federal benefit on state uncertain tax positions	4	6
Intangibles amortization (excluding goodwill)	0	21
Interest disallowance carryforward per §163(j) of the Tax Act	82	102
Inventory obsolescence	7	7
Other	3	0
Discontinued operations	0	17
Total deferred tax assets	3,800	4,064
Net deferred tax liability		(19)
Deferred Tax Liabilities, Gross [Abstract]
Emissions allowances	19	15
Derivatives, net	27	37
Goodwill	8	0
Intangibles amortization (excluding goodwill)	15	0
Equity method investments	201	180
Convertible Debt	19	21
Deferred Tax Liabilities, Other	0	1
Discontinued operations	0	36
Deferred Tax Liabilities, Gross, Total	289	290
Total deferred tax assets less deferred tax liabilities	3,511	3,774
Valuation allowance	(242)	(3,812)
Discontinued operations	0	19
Net deferred tax asset	3,269
Net deferred tax liability		(19)
NRG's net deferred tax position
Deferred tax asset	3,286	46
Deferred tax liability	(17)	(65)
Deferred tax asset	$ 3,269
Net deferred tax liability		$ (19)

Income Taxes - Deferred Tax A_2

Income Taxes - Deferred Tax Assets and Valuation Allowance, Taxes Receivable and Payable (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Taxes receivable and payable
Valuation allowance - current period activities	$ 3,492	$ 106	$ (455)
NOLs untilized	593
Deferred tax liability		19
Deferred tax asset	3,269
Net deferred tax asset	3,500	3,800
Valuation allowance	242	$ 3,812
Current taxes payable	13
Current taxes receivable	1
Federal Tax Authority
Taxes receivable and payable
Operating loss carryforwards	2,100
State and Local Jurisdiction
Taxes receivable and payable
Operating loss carryforwards	360
Foreign Tax Authority
Taxes receivable and payable
Operating loss carryforwards	$ 105

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Uncertain Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Uncertain tax benefits
Uncertain tax benefits	$ 26	$ 26	$ 15	$ 26
Liability for uncertainty in income taxes, noncurrent			17	30
Unrecognized tax benefits, income tax penalties expense	1
Accrued interest and penalties related to unrecognized tax benefits			$ 2	$ 4
Uncertain tax benefits reconciliation
Balance as of January 1	26	30
Increase due to current year positions	2	4
Settlements, payments and statute closure	(13)	(8)
Uncertain tax benefits as of December 31	$ 15	$ 26

Stock-Based Compensation - Long

Stock-Based Compensation - Long-Term Incentive Plan (Details) - shares	Apr. 27, 2017	Dec. 31, 2019	Dec. 31, 2018
NRG LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in the number of shares available for issuance (in shares)	3,000,000
Number of shares authorized for issuance under plan (in shares)		25,000,000	25,000,000
Number of shares available for grant under plan (in shares)		9,935,750	8,564,611
NRG GenOn LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance under plan (in shares)	0
Number of shares available for grant under plan (in shares)		319,264	520,182

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Units (RSUs (Details) - RSUs - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock-Based Compensation
Award vesting period	3 years
Units
Non-vested at beginning of period (in shares)	1,458,082
Granted (in shares)	266,938
Forfeited (in shares)	(73,905)
Vested (in shares)	(933,876)
Non-vested at end of period (in shares)	717,239	1,458,082
Weighted Average Grant Date Fair Value per Unit
Non-vested at beginning of period (in usd per share)	$ 16.16
Granted (in usd per share)	37.37	$ 28.90	$ 12.44
Forfeited (in usd per share)	24.73
Vested (in usd per share)	14.20
Non-vested at end of period (in usd per share)	$ 25.56	$ 16.16
Vested in period, fair value	$ 36	$ 42	$ 19
Weighted average grant date fair value (in usd per share)	$ 37.37	$ 28.90	$ 12.44

Stock-Based Compensation - Defe

Stock-Based Compensation - Deferred Stock Units, DSUs (Details) - DSUs - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Units
Balance outstanding at the beginning of the period (in shares)	331,915
Granted (in shares)	57,630
Converted to Common Stock (in shares)	(58,322)
Balance outstanding at the end of the period (in shares)	331,223	331,915
Weighted Average Grant Date Fair Value per Unit
Balance outstanding at the beginning of the period, (in usd per share)	$ 22.94
Granted (in usd per share)	34.84	$ 33.43	$ 16.76
Vested (in usd per share)	28.93
Balance outstanding at the end of the period (in usd per share)	$ 23.98	$ 22.94
Aggregate intrinsic value for DSUs outstanding	$ 13,000,000	$ 13,000,000	$ 12,000,000
Aggregate intrinsic values for DSUs converted to common stock during the period	$ 2,000,000	$ 6,000,000	$ 4,000,000
Weighted average grant date fair value (in usd per share)	$ 34.84	$ 33.43	$ 16.76

Stock -Based Compensation - Per

Stock -Based Compensation - Performance Stock Units, RPSUs and MSUs Plan description (Details)	12 Months Ended
	Dec. 31, 2019shares
RPSUs
Stock-Based Compensation
Award vesting period	3 years
Award vesting right, percentage	200.00%
RPSUs | Share-based Payment Arrangement, Tranche One
Stock-Based Compensation
Award vesting right, percentage	0.00%
RPSUs | Share-based Payment Arrangement, Tranche Two
Stock-Based Compensation
Award vesting right, percentage	25.00%
RPSUs | Share-based Payment Arrangement, Tranche Three
Stock-Based Compensation
Award vesting right, percentage	100.00%
RPSUs | Share-based Payment Arrangement, Tranche Four
Stock-Based Compensation
Award vesting right, percentage	15.00%
RPSUs | Share-based Payment Arrangement, Tranche Five
Stock-Based Compensation
Award vesting right, percentage	200.00%
MSUs
Stock-Based Compensation
Award vesting right, percentage	200.00%
MSUs | Share-based Payment Arrangement, Tranche One
Stock-Based Compensation
Award vesting right, percentage	25.00%
Vested (in shares)	0
MSUs | Share-based Payment Arrangement, Tranche Two
Stock-Based Compensation
Award vesting right, percentage	25.00%
MSUs | Share-based Payment Arrangement, Tranche Three
Stock-Based Compensation
Award vesting right, percentage	25.00%
MSUs | Share-based Payment Arrangement, Tranche Four
Stock-Based Compensation
Award vesting right, percentage	100.00%
MSUs | Share-based Payment Arrangement, Tranche Five
Stock-Based Compensation
Award vesting right, percentage	100.00%

Stock-Based Compensation - Perf

Stock-Based Compensation - Performance Stock Units (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
PSUs
Units
Non-vested at beginning of period (in shares)	1,710,634
Granted (in shares)	936,889
Forfeited (in shares)	(37,526)
Vested (in shares)	(1,409,456)
Non-vested at end of period (in shares)	1,200,541	1,710,634
Weighted Average Grant-Date Fair Value per Unit
Non-vested at beginning of period (in usd per share)	$ 19.12
Granted (in usd per share)	22.50	$ 35.36	$ 15.91
Forfeited (in usd per share)	23.04
Vested (in usd per share)	14.72
Non-vested at end of period (in usd per share)	26.65	$ 19.12
RPSUs
Weighted Average Grant-Date Fair Value per Unit
Granted (in usd per share)	$ 45.77
Award vesting, percentage	200.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected volatility	40.72%	47.52%	43.96%
Expected term (in years)	3 years	3 years	3 years
Risk free rate	2.45%	2.01%	1.50%
MSUs
Units
Non-vested at end of period (in shares)	8,645
Weighted Average Grant-Date Fair Value per Unit
Granted (in usd per share)	$ 14.72
Award vesting, percentage	200.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected volatility				34.33%
Expected term (in years)				3 years
Risk free rate				1.31%

Stock-Based Compensation - Non-

Stock-Based Compensation - Non-Qualified Stock Options (Details) - NQSOs - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock-Based Compensation
Shares granted during the period (in shares)	0	0	0
Maximum contractual term for outstanding options (in years)	10 years
NQSO activity and changes
Outstanding at the beginning of the period (in shares)	279,934
Forfeited (in shares)	(8,254)
Exercised (in shares)	(137,282)
Outstanding at the end of the period (in shares)	134,398	279,934
Exercisable at the end of the period (in shares)	134,398
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding (in usd per share)	$ 25.04
Forfeited (in usd per share)	26.76
Exercised (in usd per share)	24.67
Outstanding (in usd per share)	25.31	$ 25.04
Exercisable (in usd per share)	$ 25.31
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures
Weighted Average Remaining Contractual Term, Outstanding (in years)	1 year	2 years
Weighted Average Remaining Contractual Term, Exercisable (in years)	1 year
Aggregate Intrinsic Value	$ 2	$ 4
Aggregate Intrinsic Value, Exercisable	$ 2

Stock-Based Compensation - Intr

Stock-Based Compensation - Intrinsic Value of Options Exercised and Cash Received (Details) - NQSOs - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total intrinsic value of options exercised	$ 2	$ 10	$ 1
Cash received from options exercised	$ 3	$ 24	$ 4

Stock-Based Compensation - Supp

Stock-Based Compensation - Supplemental Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock-Based Compensation
Minimum tax withholdings	$ 36	$ 19	$ 5
Compensation Expense	32	41	38
Tax detriment recognized	(12)	(4)	(5)
Unrecognized Total Cost	27
GenOn
Stock-Based Compensation
Compensation Expense		1	6
RSUs
Stock-Based Compensation
Compensation Expense	9	12	15
Unrecognized Total Cost	$ 8
Weighted Average Recognition Period Remaining (In years)	1 year 21 days
Award vesting period	3 years
DSUs
Stock-Based Compensation
Compensation Expense	$ 2	2	2
Unrecognized Total Cost	$ 0
Weighted Average Recognition Period Remaining (In years)	0 years
MSUs
Stock-Based Compensation
Compensation Expense	$ 0	4	5
Unrecognized Total Cost	$ 0
Weighted Average Recognition Period Remaining (In years)	6 months
RPSUs
Stock-Based Compensation
Compensation Expense	$ 10	7	3
Unrecognized Total Cost	$ 9
Weighted Average Recognition Period Remaining (In years)	8 months 15 days
Award vesting period	3 years
PRSUs
Stock-Based Compensation
Compensation Expense	$ 11	$ 16	$ 13
Unrecognized Total Cost	$ 10
Weighted Average Recognition Period Remaining (In years)	1 year 18 days
Award vesting period	3 years

Related Party Transactions - Su

Related Party Transactions - Summary of Material Related Party Transactions With Third Party Affiliates (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Revenues from Related Parties Included in Operating Revenues	$ 44	$ 32	$ 8
Gladstone
Related Party Transaction [Line Items]
Revenues from Related Parties Included in Operating Revenues	4	3	3
GenConn(a)
Related Party Transaction [Line Items]
Revenues from Related Parties Included in Operating Revenues	0	4	5
Ivanpah(b)
Related Party Transaction [Line Items]
Revenues from Related Parties Included in Operating Revenues	35	20	0
Midway-Sunset
Related Party Transaction [Line Items]
Revenues from Related Parties Included in Operating Revenues	$ 5	$ 5	$ 0

Related Party Transactions - Se

Related Party Transactions - Service Agreement and Transition Service Agreement with GeOn (Details) - USD ($) $ in Millions	Jul. 16, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 12, 2017
Related Party Transaction [Line Items]
Service fees			$ 44	$ 32	$ 8
Other income - affiliate		$ 84	0	0	87
Services Agreement | GenOn
Related Party Transaction [Line Items]
Credit applied		$ 28
Services Agreement | Restructuring Support Agreement
Related Party Transaction [Line Items]
Shared services annualized rate						$ 84
Services Agreement | Restructuring Support Agreement | GenOn
Related Party Transaction [Line Items]
Credit applied	$ 28
Transition Services Agreement | Restructuring Support Agreement | GenOn
Related Party Transaction [Line Items]
Other income - affiliate					87
Shared service, selling, general and administrative				$ 53	$ 42
Management Service | Services Agreement | GenOn
Related Party Transaction [Line Items]
Service fees			$ 193

Related Party Transactions - Cr

Related Party Transactions - Credit Agreement with GenOn and Commercial Operations Agreement (Details) - Revolving Credit Facility - Intercompany Credit Agreement - GenOn - USD ($)	Dec. 31, 2019	Dec. 31, 2017
Related Party Transaction [Line Items]
Revolving credit facility	$ 500,000,000
Letters of credit outstanding under revolver	$ 14,000,000	$ 92,000,000

Commitments and Contingencies -

Commitments and Contingencies - Transportation and Purchased Power Commitments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Coal, Gas and Transportation Commitments
Commitments and Contingencies
Purchases	$ 1,200	$ 1,200	$ 1,100
Minimum purchase commitment
2020	124
2021	125
2022	73
2023	53
2024	62
Thereafter	139
Total	576
Purchases	1,200	$ 1,200	$ 1,100
Renewable Purchased Power Agreements
Minimum purchase commitment
2020	35
2021	49
2022	68
2023	56
2024	56
Thereafter	349
Total	$ 613

Commitments and Contingencies_2

Commitments and Contingencies - Narrative (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2019USD ($)facility	Dec. 31, 2019USD ($)case	Dec. 31, 2016USD ($)
Loss Contingencies [Line Items]
Nuclear insurance liability limit per incident		$ 13,900,000
Required nuclear liability insurance		450,000
Nuclear financial protection pool mandated by the Price-Anderson Act		13,500,000
Maximum assessment mandated by Price-Anderson Act per nuclear reactor for a nuclear incident		$ 138,000
Maximum assessment, administrative fee (as percent)		5.00%
Maximum assessment payment mandated by Price-Anderson Act for a nuclear incident		$ 21,000
Maximum assessment		44.00%
Nuclear operator maximum annual assessment		$ 9,000
Maximum liability per nuclear incident		61,000
Mutual property insurance additional blanket policy property coverage		1,250,000
Nuclear property insurance coverage limit per individual insured		1,500,000
Lost revenue insurance maximum weekly recovery		2,500
Accidental outage weekly recovery limit for loss revenues from a nuclear industry mutual insurance company in the event of insurable loss		$ 1,980
The number of months a nuclear industry mutual insurance company will respond to retrospective premium adjustments		24 months
Number of years board of directors of industry mutual insurance company can adjust policy after policy expires		6 years
Sierra Club Et Al V. Midwest Generation L L C
Loss Contingencies [Line Items]
Number of facilities | facility	4
Commonwealth Edison Company And Exelon Generation Company LLC
Loss Contingencies [Line Items]
Financial obligations under agreement	$ 26,000
XOOM Energy Litigation
Loss Contingencies [Line Items]
Number of class action lawsuits | case		2
High
Loss Contingencies [Line Items]
Multiplier that the industry mutual insurance company may assess against insureds premium		10
Low
Loss Contingencies [Line Items]
Multiplier that the industry mutual insurance company may assess against insureds premium		6
Nuclear Event
Loss Contingencies [Line Items]
Total nuclear property insurance coverage		$ 2,750,000
Lost revenue insurance maximum weekly recovery		274,000
Accidental outage weekly recovery limit for loss revenues from a nuclear industry mutual insurance company in the event of insurable loss		216,000
Non-nuclear Event
Loss Contingencies [Line Items]
Total nuclear property insurance coverage		1,000,000
Lost revenue insurance maximum weekly recovery		184,000
Accidental outage weekly recovery limit for loss revenues from a nuclear industry mutual insurance company in the event of insurable loss		$ 144,000
Lignite Contract with Texas Westmoreland Coal Co.
Loss Contingencies [Line Items]
Bond obligation			$ 99,000

Cash Flow Information (Details)

Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Cash Flow Information [Abstract]
Interest paid, net of amount capitalized	$ 372	$ 436	$ 543
Income taxes paid, net of refunds	8	9	9
Additions to fixed assets for accrued capital expenditures	$ 1	$ 20	$ 19

Guarantees (Details)

Guarantees (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Guarantor Obligations
Under 1 Year	$ 959
1-3 Years	610
3-5 Years	31
Over 5 Years	410
Guarantees by Remaining Maturity, Total	2,010	$ 2,767
Letters of credit and surety bonds
Guarantor Obligations
Under 1 Year	878
1-3 Years	115
3-5 Years	31
Over 5 Years	0
Guarantees by Remaining Maturity, Total	$ 1,024	1,253
Letters of credit and surety bonds, maximum expiration period (in years)	1 year
Asset sales guarantee obligations
Guarantor Obligations
Under 1 Year	$ 4
1-3 Years	490
3-5 Years	0
Over 5 Years	204
Guarantees by Remaining Maturity, Total	698	793
Other guarantees
Guarantor Obligations
Under 1 Year	77
1-3 Years	5
3-5 Years	0
Over 5 Years	206
Guarantees by Remaining Maturity, Total	288	$ 721
GenOn | Letters of credit and surety bonds
Guarantor Obligations
Guarantees by Remaining Maturity, Total	$ 14

Jointly Owned Plants (Details)

Jointly Owned Plants (Details) $ in Millions	Dec. 31, 2019USD ($)
South Texas Project Units 1 and 2, Bay City, TX
Jointly Owned Utility Plant Interests
Ownership Interest (as a percent)	44.00%
Property, Plant & Equipment	$ 413
Accumulated Depreciation	(206)
Construction in Progress	$ 8
Cedar Bayou Unit 4, Baytown, TX
Jointly Owned Utility Plant Interests
Ownership Interest (as a percent)	50.00%
Property, Plant & Equipment	$ 218
Accumulated Depreciation	(93)
Construction in Progress	$ 7

Unaudited Quarterly Financial_3

Unaudited Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 2,195	$ 2,996	$ 2,465	$ 2,165	$ 1,992	$ 2,960	$ 2,461	$ 2,065	$ 9,821	$ 9,478	$ 9,074
Operating income	209	540	320	221	49	398	174	361	1,290	982	(741)
Net income from continuing operations	3,463	374	189	94	(93)	287	27	238	4,120	460	(1,345)
Income/(loss) from discontinued operations, net of income tax	(78)	(2)	13	388	80	(336)	69	(5)	321	(192)	(992)
Net Income/(Loss)	3,385	372	202	482	(13)	(49)	96	233	4,441	268	(2,337)
Less: Net income/(loss) attributable to noncontrolling interest and redeemable interests	2	0	1	0	(2)	23	24	(46)	$ 3	$ 0	$ (184)
Income/(Loss) Available to Common Stockholders	$ 3,383	$ 372	$ 201	$ 482	$ (11)	$ (72)	$ 72	$ 279
Weighted average number of common shares outstanding — basic (in shares)	251,000,000	254,000,000	265,000,000	278,000,000	289,000,000	299,000,000	310,000,000	318,000,000	262,000,000	304,000,000	317,000,000
Income/(loss) from discontinued operations per weighted average common share — basic (in usd per share)	$ (0.31)	$ (0.01)	$ 0.05	$ 1.39	$ 0.28	$ (1.12)	$ 0.22	$ (0.02)	$ 1.23	$ (0.63)	$ (3.13)
Income/(Loss) per weighted average common share — basic (in usd per share)	$ 13.48	$ 1.46	$ 0.76	$ 1.73	$ (0.04)	$ (0.24)	$ 0.23	$ 0.88	$ 16.94	$ 0.88	$ (6.79)
Weighted average number of common shares outstanding — diluted (in shares)	253,000,000	256,000,000	267,000,000	280,000,000	289,000,000	299,000,000	314,000,000	322,000,000	264,000,000	308,000,000	317,000,000
Income/(loss) from discontinued operations per weighted average common share — diluted (in usd per share)	$ (0.31)	$ (0.01)	$ 0.05	$ 1.38	$ 0.28	$ (1.12)	$ 0.22	$ (0.02)	$ 1.22	$ (0.62)	$ (3.13)
Net (loss)/income per weighted average common share — diluted (in usd per share)	$ 13.37	$ 1.45	$ 0.75	$ 1.72	$ (0.04)	$ (0.24)	$ 0.23	$ 0.87	$ 16.81	$ 0.87	$ (6.79)

Condensed Consolidating Finan_3

Condensed Consolidating Financial Information (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument
Long-term debt	$ 6,042	$ 6,691
Recourse Debt
Debt Instrument
Long-term debt	6,008	$ 6,523
Senior Notes due 2026 To 2048 | Recourse Debt
Debt Instrument
Long-term debt	4,400
Senior Secured First Lien Notes due 2024 to 2029 | Recourse Debt
Debt Instrument
Long-term debt	$ 1,100

Condensed Consolidating Finan_4

Condensed Consolidating Financial Information - Statements of Operations (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Revenues
Total operating revenues		$ 2,195	$ 2,996	$ 2,465	$ 2,165	$ 1,992	$ 2,960	$ 2,461	$ 2,065	$ 9,821	$ 9,478	$ 9,074
Operating Costs and Expenses
Cost of operations										7,303	7,108	6,886
Depreciation and amortization										373	421	596
Impairment losses										5	99	1,534
Selling, general and administrative										827	799	836
Reorganization costs										23	90	44
Development costs										7	11	22
Total operating costs and expenses										8,538	8,528	9,918
Other income - affiliate	$ 84									0	0	87
(Loss)/Gain on sale of assets										7	32	16
Operating Income/(Loss)		209	540	320	221	49	398	174	361	1,290	982	(741)
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries										0	0	0
Equity in earnings/(losses) of unconsolidated affiliates										2	9	(14)
Impairment losses on investments										(108)	(15)	(79)
Other income, net										66	18	51
Loss on debt extinguishment, net										(51)	(44)	(49)
Interest expense										(413)	(483)	(557)
Total other expense										(504)	(515)	(648)
Income/(Loss) from Continuing Operations Before Income Taxes										786	467	(1,389)
Income/(Loss) from Continuing Operations										(3,334)	7	(44)
Income/(Loss) from Continuing Operations		3,463	374	189	94	(93)	287	27	238	4,120	460	(1,345)
Income/(loss) from discontinued operations, net of income tax		(78)	(2)	13	388	80	(336)	69	(5)	321	(192)	(992)
Net Income/(Loss)		3,385	372	202	482	(13)	(49)	96	233	4,441	268	(2,337)
Less: Net income/(loss) attributable to noncontrolling interest and redeemable interests		$ 2	$ 0	$ 1	$ 0	$ (2)	$ 23	$ 24	$ (46)	3	0	(184)
Net Income/(Loss) Attributable to NRG Energy, Inc.										4,438	268	(2,153)
Eliminations
Operating Revenues
Total operating revenues										(11)	(26)	(48)
Operating Costs and Expenses
Cost of operations										(11)	(26)	(46)
Depreciation and amortization										0	0	0
Impairment losses										0	0	0
Selling, general and administrative										0	(74)	(2)
Reorganization costs										0	0	0
Development costs										0	(1)	0
Total operating costs and expenses										(11)	(101)	(48)
Other income - affiliate												0
(Loss)/Gain on sale of assets										0	0	0
Operating Income/(Loss)										0	75	0
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries										(1,610)	(1,314)	(46)
Equity in earnings/(losses) of unconsolidated affiliates										0	0	0
Impairment losses on investments										0	0	0
Other income, net										0	0	0
Loss on debt extinguishment, net										0	0	0
Interest expense										0	0	0
Total other expense										(1,610)	(1,314)	(46)
Income/(Loss) from Continuing Operations Before Income Taxes										(1,610)	(1,239)	(46)
Income/(Loss) from Continuing Operations										0	0	0
Income/(Loss) from Continuing Operations										(1,610)	(1,239)	(46)
Income/(loss) from discontinued operations, net of income tax										0	0	0
Net Income/(Loss)										(1,610)	(1,239)	(46)
Less: Net income/(loss) attributable to noncontrolling interest and redeemable interests										0	75	0
Net Income/(Loss) Attributable to NRG Energy, Inc.										(1,610)	(1,314)	(46)
Guarantor Subsidiaries
Operating Revenues
Total operating revenues										8,041	8,119	7,818
Operating Costs and Expenses
Cost of operations										5,936	6,147	5,998
Depreciation and amortization										212	238	343
Impairment losses										1	6	1,346
Selling, general and administrative										466	462	410
Reorganization costs										0	4	6
Development costs										0	0	0
Total operating costs and expenses										6,615	6,857	8,103
Other income - affiliate												0
(Loss)/Gain on sale of assets										1	4	4
Operating Income/(Loss)										1,427	1,266	(281)
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries										48	23	18
Equity in earnings/(losses) of unconsolidated affiliates										0	0	0
Impairment losses on investments										0	0	0
Other income, net										23	32	9
Loss on debt extinguishment, net										0	0	0
Interest expense										(14)	(14)	(14)
Total other expense										57	41	13
Income/(Loss) from Continuing Operations Before Income Taxes										1,484	1,307	(268)
Income/(Loss) from Continuing Operations										0	372	(598)
Income/(Loss) from Continuing Operations										1,484	935	330
Income/(loss) from discontinued operations, net of income tax										9	62	91
Net Income/(Loss)										1,493	997	421
Less: Net income/(loss) attributable to noncontrolling interest and redeemable interests										0	0	0
Net Income/(Loss) Attributable to NRG Energy, Inc.										1,493	997	421
Non-Guarantor Subsidiaries
Operating Revenues
Total operating revenues										1,791	1,385	1,304
Operating Costs and Expenses
Cost of operations										1,351	959	862
Depreciation and amortization										130	150	221
Impairment losses										4	93	188
Selling, general and administrative										83	63	64
Reorganization costs										0	0	0
Development costs										0	1	4
Total operating costs and expenses										1,568	1,266	1,339
Other income - affiliate												0
(Loss)/Gain on sale of assets										0	28	12
Operating Income/(Loss)										223	147	(23)
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries										0	0	0
Equity in earnings/(losses) of unconsolidated affiliates										2	10	(10)
Impairment losses on investments										(101)	(15)	(75)
Other income, net										12	(13)	14
Loss on debt extinguishment, net										(3)	0	0
Interest expense										(14)	(49)	(91)
Total other expense										(104)	(67)	(162)
Income/(Loss) from Continuing Operations Before Income Taxes										119	80	(185)
Income/(Loss) from Continuing Operations										4	19	(62)
Income/(Loss) from Continuing Operations										115	61	(123)
Income/(loss) from discontinued operations, net of income tax										5	75	(420)
Net Income/(Loss)										120	136	(543)
Less: Net income/(loss) attributable to noncontrolling interest and redeemable interests										3	(181)	(168)
Net Income/(Loss) Attributable to NRG Energy, Inc.										117	317	(375)
NRG Energy, Inc. (Note Issuer)
Operating Revenues
Total operating revenues										0	0	0
Operating Costs and Expenses
Cost of operations										27	28	72
Depreciation and amortization										31	33	32
Impairment losses										0	0	0
Selling, general and administrative										278	348	364
Reorganization costs										23	86	38
Development costs										7	11	18
Total operating costs and expenses										366	506	524
Other income - affiliate												87
(Loss)/Gain on sale of assets										6	0	0
Operating Income/(Loss)										(360)	(506)	(437)
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries										1,562	1,291	28
Equity in earnings/(losses) of unconsolidated affiliates										0	(1)	(4)
Impairment losses on investments										(7)	0	(4)
Other income, net										31	(1)	28
Loss on debt extinguishment, net										(48)	(44)	(49)
Interest expense										(385)	(420)	(452)
Total other expense										1,153	825	(453)
Income/(Loss) from Continuing Operations Before Income Taxes										793	319	(890)
Income/(Loss) from Continuing Operations										(3,338)	(384)	616
Income/(Loss) from Continuing Operations										4,131	703	(1,506)
Income/(loss) from discontinued operations, net of income tax										307	(329)	(663)
Net Income/(Loss)										4,438	374	(2,169)
Less: Net income/(loss) attributable to noncontrolling interest and redeemable interests										0	106	(16)
Net Income/(Loss) Attributable to NRG Energy, Inc.										$ 4,438	$ 268	$ (2,153)

Condensed Consolidating Finan_5

Condensed Consolidating Financial Information - Statements of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net income	$ 3,385	$ 372	$ 202	$ 482	$ (13)	$ (49)	$ 96	$ 233	$ 4,441	$ 268	$ (2,337)
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unrealized gain on derivatives, net									0	23	13
Foreign currency translation adjustments, net									(1)	(11)	12
Available-for-sale securities, net									(19)	1	(8)
Defined benefit plan, net									(78)	(35)	46
Other comprehensive (loss)/income									(98)	(22)	63
Comprehensive Income/(Loss)									4,343	246	(2,274)
Less: Comprehensive income attributable to redeemable noncontrolling interests									3	14	(179)
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.									4,340	232	(2,095)
Eliminations
Net income									(1,610)	(1,239)	(46)
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unrealized gain on derivatives, net										(15)	(26)
Foreign currency translation adjustments, net									1	22	(1)
Available-for-sale securities, net									0	0	0
Defined benefit plan, net									17	9	(17)
Other comprehensive (loss)/income									18	16	(44)
Comprehensive Income/(Loss)									(1,592)	(1,223)	(90)
Less: Comprehensive income attributable to redeemable noncontrolling interests									0	76	(60)
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.									(1,592)	(1,299)	(30)
Guarantor Subsidiaries
Net income									1,493	997	421
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unrealized gain on derivatives, net										0	1
Foreign currency translation adjustments, net									0	(10)	6
Available-for-sale securities, net									0	0	0
Defined benefit plan, net									(17)	(9)	(13)
Other comprehensive (loss)/income									(17)	(19)	(6)
Comprehensive Income/(Loss)									1,476	978	415
Less: Comprehensive income attributable to redeemable noncontrolling interests									0	0	0
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.									1,476	978	415
Non-Guarantor Subsidiaries
Net income									120	136	(543)
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unrealized gain on derivatives, net										29	13
Foreign currency translation adjustments, net									(1)	(10)	7
Available-for-sale securities, net									0	0	0
Defined benefit plan, net									0	0	30
Other comprehensive (loss)/income									(1)	19	50
Comprehensive Income/(Loss)									119	155	(493)
Less: Comprehensive income attributable to redeemable noncontrolling interests									3	(166)	(103)
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.									116	321	(390)
NRG Energy, Inc. (Note Issuer)
Net income									4,438	374	(2,169)
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unrealized gain on derivatives, net										9	25
Foreign currency translation adjustments, net									(1)	(13)	0
Available-for-sale securities, net									(19)	1	(8)
Defined benefit plan, net									(78)	(35)	46
Other comprehensive (loss)/income									(98)	(38)	63
Comprehensive Income/(Loss)									4,340	336	(2,106)
Less: Comprehensive income attributable to redeemable noncontrolling interests									0	104	(16)
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.									$ 4,340	$ 232	$ (2,090)

Condensed Consolidating Finan_6

Condensed Consolidating Financial Information - Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents	$ 345		$ 563	$ 770
Funds deposited by counterparties	32		33	37
Restricted cash	8		17	279
Accounts receivable, net	1,025		1,024
Inventory	383		412
Derivative instruments	860		764
Cash collateral posted in support of energy risk management activities	190		287
Prepayments and other current assets	245		302
Current assets - held-for-sale	0		1
Current assets - discontinued operations	0		197
Total current assets	3,088		3,600
Property, plant and equipment, net	2,593		3,048
Other Assets
Investment in subsidiaries	0		0
Equity investments in affiliates	388		412
Operating lease right-of-use assets, net	464	$ 404
Goodwill	579		573
Intangible assets, net	789		591
Nuclear decommissioning trust fund	794		663
Derivative instruments	310		317
Deferred income taxes	3,286		46
Other non-current assets	240		289
Non-current assets - held-for-sale	0		77
Non-current assets - discontinued operations	0		1,012
Total other assets	6,850		3,980
Total Assets	12,531		10,628
Current Liabilities
Current portion of long-term debt and finance leases	88		72
Current portion of operating lease liabilities	73
Accounts payable	722		863
Derivative instruments	781		673
Cash collateral received in support of energy risk management activities	32		33
Accrued expenses and other current liabilities	663		680
Disposal Group, Including Discontinued Operation, Accrued Liabilities, Current			5
Current liabilities - discontinued operations	0		72
Total current liabilities	2,359		2,398
Other Liabilities
Long-term debt and finance leases	5,803		6,449
Non-current operating lease liabilities	483
Nuclear decommissioning reserve	298		282
Nuclear decommissioning trust liability	487		371
Derivative instruments	322		304
Deferred income taxes	17		65
Other non-current liabilities	1,084		1,274
Non-current liabilities - held-for-sale			65
Non-current liabilities - discontinued operations	0		635
Total other liabilities	8,494		9,445
Total Liabilities	10,853		11,843
Redeemable noncontrolling interest in subsidiaries	20		19	78	$ 46
Total Stockholders' Equity	1,658		(1,234)	$ 1,968	$ 4,446
Total Liabilities and Stockholders' Equity	12,531		10,628
Eliminations
Current Assets
Cash and cash equivalents	0		0
Funds deposited by counterparties	0		0
Restricted cash	0		0
Accounts receivable, net	(740)		(754)
Inventory	0		0
Derivative instruments	(41)		(81)
Cash collateral posted in support of energy risk management activities	0		0
Prepayments and other current assets	0		0
Current assets - held-for-sale			0
Current assets - discontinued operations			0
Total current assets	(781)		(835)
Property, plant and equipment, net	0		0
Other Assets
Investment in subsidiaries	(5,495)		(5,153)
Equity investments in affiliates	0		0
Operating lease right-of-use assets, net	0
Goodwill	0		0
Intangible assets, net	0		0
Nuclear decommissioning trust fund	0		0
Derivative instruments	(13)		(5)
Deferred income taxes	0		0
Other non-current assets	0		(12)
Non-current assets - held-for-sale			0
Non-current assets - discontinued operations			0
Total other assets	(5,508)		(5,170)
Total Assets	(6,289)		(6,005)
Current Liabilities
Current portion of long-term debt and finance leases	0		0
Current portion of operating lease liabilities	0
Accounts payable	(740)		(754)
Derivative instruments	(41)		(81)
Cash collateral received in support of energy risk management activities	0		0
Accrued expenses and other current liabilities	0		0
Disposal Group, Including Discontinued Operation, Accrued Liabilities, Current			0
Current liabilities - discontinued operations			0
Total current liabilities	(781)		(835)
Other Liabilities
Long-term debt and finance leases	0		(12)
Non-current operating lease liabilities	0
Nuclear decommissioning reserve	0		0
Nuclear decommissioning trust liability	0		0
Derivative instruments	(13)		(5)
Deferred income taxes	0		0
Other non-current liabilities	0		0
Non-current liabilities - held-for-sale			0
Non-current liabilities - discontinued operations			0
Total other liabilities	(13)		(17)
Total Liabilities	(794)		(852)
Redeemable noncontrolling interest in subsidiaries	0		0
Total Stockholders' Equity	(5,495)		(5,153)
Total Liabilities and Stockholders' Equity	(6,289)		(6,005)
Guarantor Subsidiaries
Current Assets
Cash and cash equivalents	0		55
Funds deposited by counterparties	32		33
Restricted cash	5		7
Accounts receivable, net	1,293		1,354
Inventory	272		278
Derivative instruments	856		779
Cash collateral posted in support of energy risk management activities	182		275
Prepayments and other current assets	170		180
Current assets - held-for-sale			0
Current assets - discontinued operations			177
Total current assets	2,810		3,138
Property, plant and equipment, net	1,483		1,938
Other Assets
Investment in subsidiaries	710		446
Equity investments in affiliates	0		0
Operating lease right-of-use assets, net	81
Goodwill	359		359
Intangible assets, net	375		422
Nuclear decommissioning trust fund	794		663
Derivative instruments	308		296
Deferred income taxes	421		6
Other non-current assets	145		133
Non-current assets - held-for-sale			0
Non-current assets - discontinued operations			405
Total other assets	3,193		2,730
Total Assets	7,486		7,806
Current Liabilities
Current portion of long-term debt and finance leases	0		0
Current portion of operating lease liabilities	20
Accounts payable	918		1,368
Derivative instruments	797		713
Cash collateral received in support of energy risk management activities	32		33
Accrued expenses and other current liabilities	280		291
Disposal Group, Including Discontinued Operation, Accrued Liabilities, Current			0
Current liabilities - discontinued operations			24
Total current liabilities	2,047		2,429
Other Liabilities
Long-term debt and finance leases	302		244
Non-current operating lease liabilities	64
Nuclear decommissioning reserve	298		282
Nuclear decommissioning trust liability	487		371
Derivative instruments	334		306
Deferred income taxes	0		112
Other non-current liabilities	399		402
Non-current liabilities - held-for-sale			0
Non-current liabilities - discontinued operations			58
Total other liabilities	1,884		1,775
Total Liabilities	3,931		4,204
Redeemable noncontrolling interest in subsidiaries	0		0
Total Stockholders' Equity	3,555		3,602
Total Liabilities and Stockholders' Equity	7,486		7,806
Non-Guarantor Subsidiaries
Current Assets
Cash and cash equivalents	20		28
Funds deposited by counterparties	0		0
Restricted cash	1		10
Accounts receivable, net	239		115
Inventory	111		134
Derivative instruments	45		50
Cash collateral posted in support of energy risk management activities	8		12
Prepayments and other current assets	8		32
Current assets - held-for-sale			1
Current assets - discontinued operations			20
Total current assets	432		402
Property, plant and equipment, net	952		957
Other Assets
Investment in subsidiaries	0		0
Equity investments in affiliates	388		412
Operating lease right-of-use assets, net	261
Goodwill	220		214
Intangible assets, net	414		169
Nuclear decommissioning trust fund	0		0
Derivative instruments	15		4
Deferred income taxes	(19)		(143)
Other non-current assets	30		71
Non-current assets - held-for-sale			77
Non-current assets - discontinued operations			607
Total other assets	1,309		1,411
Total Assets	2,693		2,770
Current Liabilities
Current portion of long-term debt and finance leases	5		55
Current portion of operating lease liabilities	32
Accounts payable	141		(185)
Derivative instruments	25		41
Cash collateral received in support of energy risk management activities	0		0
Accrued expenses and other current liabilities	44		36
Disposal Group, Including Discontinued Operation, Accrued Liabilities, Current			5
Current liabilities - discontinued operations			48
Total current liabilities	247		0
Other Liabilities
Long-term debt and finance leases	28		192
Non-current operating lease liabilities	301
Nuclear decommissioning reserve	0		0
Nuclear decommissioning trust liability	0		0
Derivative instruments	1		3
Deferred income taxes	17		61
Other non-current liabilities	153		320
Non-current liabilities - held-for-sale			65
Non-current liabilities - discontinued operations			577
Total other liabilities	500		1,218
Total Liabilities	747		1,218
Redeemable noncontrolling interest in subsidiaries	20		19
Total Stockholders' Equity	1,926		1,533
Total Liabilities and Stockholders' Equity	2,693		2,770
NRG Energy, Inc.
Current Assets
Cash and cash equivalents	325		480
Funds deposited by counterparties	0		0
Restricted cash	2		0
Accounts receivable, net	233		309
Inventory	0		0
Derivative instruments	0		16
Cash collateral posted in support of energy risk management activities	0		0
Prepayments and other current assets	67		90
Current assets - held-for-sale			0
Current assets - discontinued operations			0
Total current assets	627		895
Property, plant and equipment, net	158		153
Other Assets
Investment in subsidiaries	4,785		4,707
Equity investments in affiliates	0		0
Operating lease right-of-use assets, net	122
Goodwill	0		0
Intangible assets, net	0		0
Nuclear decommissioning trust fund	0		0
Derivative instruments	0		22
Deferred income taxes	2,884		183
Other non-current assets	65		97
Non-current assets - held-for-sale			0
Non-current assets - discontinued operations			0
Total other assets	7,856		5,009
Total Assets	8,641		6,057
Current Liabilities
Current portion of long-term debt and finance leases	83		17
Current portion of operating lease liabilities	21
Accounts payable	403		434
Derivative instruments	0		0
Cash collateral received in support of energy risk management activities	0		0
Accrued expenses and other current liabilities	339		353
Disposal Group, Including Discontinued Operation, Accrued Liabilities, Current			0
Current liabilities - discontinued operations			0
Total current liabilities	846		804
Other Liabilities
Long-term debt and finance leases	5,473		6,025
Non-current operating lease liabilities	118
Nuclear decommissioning reserve	0		0
Nuclear decommissioning trust liability	0		0
Derivative instruments	0		0
Deferred income taxes	0		(108)
Other non-current liabilities	532		552
Non-current liabilities - held-for-sale			0
Non-current liabilities - discontinued operations			0
Total other liabilities	6,123		6,469
Total Liabilities	6,969		7,273
Redeemable noncontrolling interest in subsidiaries	0		0
Total Stockholders' Equity	1,672		(1,216)
Total Liabilities and Stockholders' Equity	$ 8,641		$ 6,057

Condensed Consolidating Finan_7

Condensed Consolidating Financial Information - Statements of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flows from Operating Activities
Net Income/(Loss)	$ 3,385	$ 372	$ 202	$ 482	$ (13)	$ (49)	$ 96	$ 233	$ 4,441	$ 268	$ (2,337)
Income/(loss) from discontinued operations, net of income tax	(78)	(2)	13	388	80	(336)	69	(5)	321	(192)	(992)
Income/(loss) from continuing operations	3,463	$ 374	$ 189	94	(93)	$ 287	$ 27	238	4,120	460	(1,345)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions and equity in earnings of unconsolidated affiliates and consolidated subsidiaries									14	46	102
Depreciation and amortization									373	421	596
Accretion of asset retirement obligations									51	38	44
Provision for bad debts									95	85	68
Amortization of nuclear fuel									52	48	51
Amortization of financing costs and debt discount/premiums									26	29	29
Adjustment for debt extinguishment									51	44	49
Amortization of emission allowances									38	45	54
Amortization of unearned equity compensation									20	25	35
Net gain on sale of assets and disposal of assets									(23)	(49)	(9)
Impairment losses									113	114	1,614
Changes in derivative instruments									34	37	(170)
Changes in deferred income taxes and liability for uncertain tax benefits									(3,353)	5	13
Changes in collateral deposits in support of risk management activities									105	(105)	(80)
Changes in nuclear decommissioning trust liability									37	60	11
GenOn settlement, net of insurance proceeds									0	(63)	0
Net loss on deconsolidation of Agua Caliente and Ivanpah projects									0	13	0
Changes in other working capital									(348)	(250)	(206)
Cash provided by continuing operations									1,405	1,003	856
Cash provided/(used) by discontinued operations									8	374	754
Net Cash Provided by Operating Activities									1,413	1,377	1,610
Cash Flows from Investing Activities
Intercompany dividends									0	0	0
Payments for acquisitions of businesses									(355)	(243)	(14)
Capital expenditures									(228)	(388)	(254)
Net proceeds from sale of emission allowances									11	19	66
Investments in nuclear decommissioning trust fund securities									(416)	(572)	(512)
Proceeds from sales of nuclear decommissioning trust fund securities									381	513	501
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees									1,294	1,564	430
Deconsolidation of Agua Caliente and Ivanpah projects									0	(268)	0
Changes in investments in unconsolidated affiliates									(91)	(39)	(57)
Net contributions to discontinued operations									(44)	(60)	150
Other									6	(6)	30
Cash provided by continuing operations									558	520	340
Cash used by discontinued operations									(2)	(725)	(979)
Net Cash Provided/(Used) by Investing Activities									556	(205)	(639)
Cash Flows from Financing Activities
Intercompany dividends and transfers									0	0	0
Payments of dividends to common stockholders									(32)	(37)	(38)
Payment for preferred shares									(1,440)	(1,250)
Payments for debt extinguishment costs									(26)	(32)	(42)
Net distributions to redeemable noncontrolling interests from subsidiaries									(2)	(16)	(30)
Proceeds/(payments) from issuance of common stock									3	21	(2)
Proceeds from issuance of long-term debt									1,916	1,100	1,178
Payments of debt issuance costs									(35)	(19)	(18)
Payments for short and long-term debt									(2,571)	(1,734)	(1,884)
Receivable from affiliate									0	(26)	(125)
Other									(4)	(4)	(8)
Cash used by continuing operations									(2,191)	(1,997)	(969)
Cash provided/(used) by discontinued operations									43	471	(169)
Net Cash (Used)/Provided by Financing Activities									(2,148)	(1,526)	(1,138)
Effect of exchange rate changes on cash and cash equivalents									0	1	(1)
Change in Cash from discontinued operations									49	120	(394)
Net (Decrease)/Increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash									(228)	(473)	226
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	385				613				385	613	1,086
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period				613				1,086	613	1,086	860
Eliminations
Cash Flows from Operating Activities
Net Income/(Loss)									(1,610)	(1,239)	(46)
Income/(loss) from discontinued operations, net of income tax									0	0	0
Income/(loss) from continuing operations									(1,610)	(1,239)	(46)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions and equity in earnings of unconsolidated affiliates and consolidated subsidiaries									1,610	1,253	48
Depreciation and amortization									0	0	0
Accretion of asset retirement obligations									0	0	0
Provision for bad debts									0	0	0
Amortization of nuclear fuel									0	0	0
Amortization of financing costs and debt discount/premiums									0	0	0
Adjustment for debt extinguishment									0	0	0
Amortization of emission allowances									0	0	0
Amortization of unearned equity compensation									0	0	0
Net gain on sale of assets and disposal of assets									0	0	0
Impairment losses									0	0	0
Changes in derivative instruments									0	(14)	(2)
Changes in deferred income taxes and liability for uncertain tax benefits									0	0	0
Changes in collateral deposits in support of risk management activities									0	0	0
Changes in nuclear decommissioning trust liability									0	0	0
GenOn settlement, net of insurance proceeds										0
Net loss on deconsolidation of Agua Caliente and Ivanpah projects										0
Changes in other working capital									0	0	0
Cash provided by continuing operations									0	0	0
Cash provided/(used) by discontinued operations									0	0	0
Net Cash Provided by Operating Activities									0	0	0
Cash Flows from Investing Activities
Intercompany dividends									(2,513)	(2,006)	(1,665)
Payments for acquisitions of businesses									0	0	0
Capital expenditures									0	0	0
Net proceeds from sale of emission allowances									0	0	0
Investments in nuclear decommissioning trust fund securities									0	0	0
Proceeds from sales of nuclear decommissioning trust fund securities									0	0	0
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees									0	0	0
Deconsolidation of Agua Caliente and Ivanpah projects										0
Changes in investments in unconsolidated affiliates									0	0	0
Net contributions to discontinued operations									0	0	0
Other									0	0	0
Cash provided by continuing operations									(2,513)	(2,006)	(1,665)
Cash used by discontinued operations									0	0	0
Net Cash Provided/(Used) by Investing Activities									(2,513)	(2,006)	(1,665)
Cash Flows from Financing Activities
Intercompany dividends and transfers									2,513	2,006	1,665
Payments of dividends to common stockholders									0	0	0
Payment for preferred shares									0	0
Payments for debt extinguishment costs									0	0	0
Net distributions to redeemable noncontrolling interests from subsidiaries									0	0	0
Proceeds/(payments) from issuance of common stock									0	0	0
Proceeds from issuance of long-term debt									0	0	0
Payments of debt issuance costs									0	0	0
Payments for short and long-term debt									0	0	0
Receivable from affiliate										0	0
Other									0	0	0
Cash used by continuing operations									2,513	2,006	1,665
Cash provided/(used) by discontinued operations									0	0	0
Net Cash (Used)/Provided by Financing Activities									2,513	2,006	1,665
Effect of exchange rate changes on cash and cash equivalents										0	0
Change in Cash from discontinued operations									0	0	0
Net (Decrease)/Increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash									0	0	0
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	0				0				0	0	0
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period				0				0	0	0	0
Guarantor Subsidiaries
Cash Flows from Operating Activities
Net Income/(Loss)									1,493	997	421
Income/(loss) from discontinued operations, net of income tax									9	62	91
Income/(loss) from continuing operations									1,484	935	330
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions and equity in earnings of unconsolidated affiliates and consolidated subsidiaries									(48)	(23)	(18)
Depreciation and amortization									212	238	343
Accretion of asset retirement obligations									43	28	37
Provision for bad debts									78	79	56
Amortization of nuclear fuel									52	48	51
Amortization of financing costs and debt discount/premiums									0	0	0
Adjustment for debt extinguishment									0	0	0
Amortization of emission allowances									24	36	42
Amortization of unearned equity compensation									0	0	0
Net gain on sale of assets and disposal of assets									(20)	(30)	2
Impairment losses									1	5	1,346
Changes in derivative instruments									20	25	(214)
Changes in deferred income taxes and liability for uncertain tax benefits									(525)	372	(300)
Changes in collateral deposits in support of risk management activities									101	(94)	(98)
Changes in nuclear decommissioning trust liability									37	60	11
GenOn settlement, net of insurance proceeds										0
Net loss on deconsolidation of Agua Caliente and Ivanpah projects										0
Changes in other working capital									(220)	(100)	(15)
Cash provided by continuing operations									1,239	1,579	1,573
Cash provided/(used) by discontinued operations									17	89	116
Net Cash Provided by Operating Activities									1,256	1,668	1,689
Cash Flows from Investing Activities
Intercompany dividends									0	0	0
Payments for acquisitions of businesses									(355)	(40)	(14)
Capital expenditures									(164)	(192)	(180)
Net proceeds from sale of emission allowances									11	19	66
Investments in nuclear decommissioning trust fund securities									(416)	(572)
Proceeds from sales of nuclear decommissioning trust fund securities									381	513	501
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees									1	14	33
Deconsolidation of Agua Caliente and Ivanpah projects										0
Changes in investments in unconsolidated affiliates									0	0	0
Net contributions to discontinued operations									0	0	0
Other									0	0	18
Cash provided by continuing operations									(542)	(258)	(88)
Cash used by discontinued operations									0	0	(13)
Net Cash Provided/(Used) by Investing Activities									(542)	(258)	(101)
Cash Flows from Financing Activities
Intercompany dividends and transfers									(751)	(1,267)	(1,447)
Payments of dividends to common stockholders									0	0	0
Payment for preferred shares									0	0
Payments for debt extinguishment costs									0	0	0
Net distributions to redeemable noncontrolling interests from subsidiaries									0	0	0
Proceeds/(payments) from issuance of common stock									0	0	0
Proceeds from issuance of long-term debt									0	0	0
Payments of debt issuance costs									0	0	0
Payments for short and long-term debt									0	0	0
Receivable from affiliate										0	0
Other									(4)	0	0
Cash used by continuing operations									(755)	(1,267)	(1,447)
Cash provided/(used) by discontinued operations									0	0	(109)
Net Cash (Used)/Provided by Financing Activities									(755)	(1,267)	(1,556)
Effect of exchange rate changes on cash and cash equivalents										0	0
Change in Cash from discontinued operations									17	89	(6)
Net (Decrease)/Increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash									(58)	54	38
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	37				95				37	95	41
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period				95				41	95	41	3
Non-Guarantor Subsidiaries
Cash Flows from Operating Activities
Net Income/(Loss)									120	136	(543)
Income/(loss) from discontinued operations, net of income tax									5	75	(420)
Income/(loss) from continuing operations									115	61	(123)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions and equity in earnings of unconsolidated affiliates and consolidated subsidiaries									14	47	12
Depreciation and amortization									130	150	221
Accretion of asset retirement obligations									8	10	7
Provision for bad debts									17	6	0
Amortization of nuclear fuel									0	0	0
Amortization of financing costs and debt discount/premiums									0	6	13
Adjustment for debt extinguishment									3	0	0
Amortization of emission allowances									14	9	12
Amortization of unearned equity compensation									0	0	0
Net gain on sale of assets and disposal of assets									0	(20)	(11)
Impairment losses									105	109	264
Changes in derivative instruments									(24)	15	50
Changes in deferred income taxes and liability for uncertain tax benefits									(168)	5	(9)
Changes in collateral deposits in support of risk management activities									4	(11)	18
Changes in nuclear decommissioning trust liability									0	0	0
GenOn settlement, net of insurance proceeds										0
Net loss on deconsolidation of Agua Caliente and Ivanpah projects										13
Changes in other working capital									(118)	(166)	(396)
Cash provided by continuing operations									100	234	58
Cash provided/(used) by discontinued operations									(9)	285	638
Net Cash Provided by Operating Activities									91	519	696
Cash Flows from Investing Activities
Intercompany dividends									0	0	0
Payments for acquisitions of businesses									0	(203)	0
Capital expenditures									(27)	(151)	(43)
Net proceeds from sale of emission allowances									0	0	0
Investments in nuclear decommissioning trust fund securities									0	0	0
Proceeds from sales of nuclear decommissioning trust fund securities									0	0	0
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees									400	8	54
Deconsolidation of Agua Caliente and Ivanpah projects										(268)
Changes in investments in unconsolidated affiliates									(91)	(39)	(57)
Net contributions to discontinued operations									(44)	(60)	0
Other									0	0	12
Cash provided by continuing operations									238	(713)	(34)
Cash used by discontinued operations									(2)	(725)	(966)
Net Cash Provided/(Used) by Investing Activities									236	(1,438)	(1,000)
Cash Flows from Financing Activities
Intercompany dividends and transfers									(214)	86	(4)
Payments of dividends to common stockholders									0	0	0
Payment for preferred shares									0	0
Payments for debt extinguishment costs									0	0	0
Net distributions to redeemable noncontrolling interests from subsidiaries									(2)	(16)	(30)
Proceeds/(payments) from issuance of common stock									0	0	0
Proceeds from issuance of long-term debt									0	163	94
Payments of debt issuance costs									0	0	(2)
Payments for short and long-term debt									(139)	(138)	(183)
Receivable from affiliate										0	0
Other									0	(4)	(8)
Cash used by continuing operations									(355)	91	(133)
Cash provided/(used) by discontinued operations									43	471	(60)
Net Cash (Used)/Provided by Financing Activities									(312)	562	(193)
Effect of exchange rate changes on cash and cash equivalents										1	(1)
Change in Cash from discontinued operations									32	31	(388)
Net (Decrease)/Increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash									(17)	(387)	(110)
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	21				38				21	38	425
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period				38				425	38	425	535
NRG Energy, Inc. (Note Issuer)
Cash Flows from Operating Activities
Net Income/(Loss)									4,438	374	(2,169)
Income/(loss) from discontinued operations, net of income tax									307	(329)	(663)
Income/(loss) from continuing operations									4,131	703	(1,506)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions and equity in earnings of unconsolidated affiliates and consolidated subsidiaries									(1,562)	(1,231)	60
Depreciation and amortization									31	33	32
Accretion of asset retirement obligations									0	0	0
Provision for bad debts									0	0	12
Amortization of nuclear fuel									0	0	0
Amortization of financing costs and debt discount/premiums									26	23	16
Adjustment for debt extinguishment									48	44	49
Amortization of emission allowances									0	0	0
Amortization of unearned equity compensation									20	25	35
Net gain on sale of assets and disposal of assets									(3)	1	0
Impairment losses									7	0	4
Changes in derivative instruments									38	11	(4)
Changes in deferred income taxes and liability for uncertain tax benefits									(2,660)	(372)	322
Changes in collateral deposits in support of risk management activities									0	0	0
Changes in nuclear decommissioning trust liability									0	0	0
GenOn settlement, net of insurance proceeds										(63)
Net loss on deconsolidation of Agua Caliente and Ivanpah projects										0
Changes in other working capital									(10)	16	205
Cash provided by continuing operations									66	(810)	(775)
Cash provided/(used) by discontinued operations									0	0	0
Net Cash Provided by Operating Activities									66	(810)	(775)
Cash Flows from Investing Activities
Intercompany dividends									2,513	2,006	1,665
Payments for acquisitions of businesses									0	0	0
Capital expenditures									(37)	(45)	(31)
Net proceeds from sale of emission allowances									0	0	0
Investments in nuclear decommissioning trust fund securities									0	0	0
Proceeds from sales of nuclear decommissioning trust fund securities									0	0	0
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees									893	1,542	343
Deconsolidation of Agua Caliente and Ivanpah projects										0
Changes in investments in unconsolidated affiliates									0	0	0
Net contributions to discontinued operations									0	0	150
Other									6	(6)	0
Cash provided by continuing operations									3,375	3,497	2,127
Cash used by discontinued operations									0	0	0
Net Cash Provided/(Used) by Investing Activities									3,375	3,497	2,127
Cash Flows from Financing Activities
Intercompany dividends and transfers									(1,548)	(825)	(214)
Payments of dividends to common stockholders									(32)	(37)	(38)
Payment for preferred shares									(1,440)	(1,250)
Payments for debt extinguishment costs									(26)	(32)	(42)
Net distributions to redeemable noncontrolling interests from subsidiaries									0	0	0
Proceeds/(payments) from issuance of common stock									3	21	(2)
Proceeds from issuance of long-term debt									1,916	937	1,084
Payments of debt issuance costs									(35)	(19)	(16)
Payments for short and long-term debt									(2,432)	(1,596)	(1,701)
Receivable from affiliate										(26)	(125)
Other									0	0	0
Cash used by continuing operations									(3,594)	(2,827)	(1,054)
Cash provided/(used) by discontinued operations									0	0	0
Net Cash (Used)/Provided by Financing Activities									(3,594)	(2,827)	(1,054)
Effect of exchange rate changes on cash and cash equivalents										0	0
Change in Cash from discontinued operations									0	0	0
Net (Decrease)/Increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash									(153)	(140)	298
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	$ 327				$ 480				327	480	620
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period				$ 480				$ 620	$ 480	$ 620	$ 322

SCHEDULE II - VALUATION AND Q_2

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for doubtful accounts, deducted from accounts receivable
Income tax valuation allowance, deducted from deferred tax assets
Balance at Beginning of Period	$ 32	$ 28	$ 28
Charged to Costs and Expenses	95	83	57
Charged to Other Accounts	0	0	0
Deductions	(84)	(79)	(57)
Balance at End of Period	43	32	28
Income tax valuation allowance, deducted from deferred tax assets
Income tax valuation allowance, deducted from deferred tax assets
Balance at Beginning of Period	3,794	1,863	4,116
Charged to Costs and Expenses	(3,543)	1,934	(151)
Charged to Other Accounts	(9)	(128)	(15)
Deductions	0	125	(2,087)
Balance at End of Period	$ 242	$ 3,794	$ 1,863