NRG Energy (NRG) 10-Q 7 Nov 19 2019 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2019	Oct. 31, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-15891
Entity Registrant Name	NRG Energy, Inc
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	41-1724239
Entity Address, Address Line One	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
Title of 12(b) Security	Common Stock, par value $0.01
Trading Symbol	NRG
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		251,594,290
Entity Central Index Key	0001013871
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating Revenues
Total operating revenues	$ 2,996	$ 2,960	$ 7,626	$ 7,486
Operating Costs and Expenses
Cost of operations	2,153	2,238	5,649	5,512
Depreciation and amortization	91	99	261	331
Impairment losses	0	0	1	74
Selling, general and administrative	210	211	615	587
Reorganization costs	1	27	16	70
Development costs	1	1	5	9
Total operating costs and expenses	2,456	2,576	6,547	6,583
Gain on sale of assets	0	14	2	30
Operating Income/(Loss)	540	398	1,081	933
Other Income/(Expense)
Equity in earnings of unconsolidated affiliates	29	20	8	26
Impairment losses on investments	107	1	107	16
Other income, net	17	19	49	12
Loss on debt extinguishment, net	0	(19)	(47)	(22)
Interest expense	(99)	(122)	(318)	(361)
Total other income/(expense)	(160)	(103)	(415)	(361)
Income from Continuing Operations Before Income Taxes	380	295	666	572
Income tax expense	6	8	9	19
Income from Continuing Operations	374	287	657	553
Income/(loss) from discontinued operations, net of income tax	(2)	(336)	399	(272)
Net Income/(Loss)	372	(49)	1,056	281
Less: Net income attributable to noncontrolling interest and redeemable interests	0	23	1	1
Net income/(loss) attributable to NRG Energy, Inc.	$ 372	$ (72)	$ 1,055	$ 280
Earnings per Share Attributable to NRG Energy, Inc.
Weighted average number of common shares outstanding — basic (in shares)	254	299	266	309
Income from continuing operations per weighted average common share — basic (in usd per share)	$ 1.47	$ 0.88	$ 2.47	$ 1.79
(Loss)/income from discontinued operations per weighted average common share — basic (in usd per share)	(0.01)	(1.12)	1.50	(0.88)
Earnings/Loss per Weighted Average Common Share — Basic (in usd per share)	$ 1.46	$ (0.24)	$ 3.97	$ 0.91
Weighted average number of common shares outstanding — diluted (in shares)	256	299	268	313
Income from continuing operations per weighted average common share — diluted (in usd per share)	$ 1.46	$ 0.88	$ 2.45	$ 1.76
(Loss)/income from discontinued operations per weighted average common share — diluted (in usd per share)	(0.01)	(1.12)	1.49	(0.87)
Earnings/(Loss) per Weighted Average Common Share — Diluted (in usd per share)	$ 1.45	$ (0.24)	$ 3.94	$ 0.89

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net Income/(Loss)	$ 372	$ (49)	$ 1,056	$ 281
Other Comprehensive (Loss)/Income
Unrealized gain/(loss) on derivatives, net	0	5	0	24
Foreign currency translation adjustments	(4)	(2)	(4)	(8)
Available-for-sale securities	(14)	0	(13)	1
Defined benefit plans	(41)	(1)	(47)	(3)
Other comprehensive (loss)/income	(59)	2	(64)	14
Comprehensive Income/(Loss)	313	(47)	992	295
Less: Comprehensive income attributable to noncontrolling interest and redeemable noncontrolling interest	0	26	1	15
Comprehensive Income (Loss), Net of Tax, Attributable to Parent, Total	$ 313	$ (73)	$ 991	$ 280

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Current Assets
Cash and cash equivalents	$ 243	$ 563
Funds deposited by counterparties	30	33
Restricted cash	4	17
Accounts receivable, net	1,376	1,024
Inventory	364	412
Derivative instruments	735	764
Cash collateral paid in support of energy risk management activities	164	287
Prepayments and other current assets	271	302
Current assets - held-for-sale	0	1
Current assets - discontinued operations	0	197
Total current assets	3,187	3,600
Property, plant and equipment, net	2,615	3,048
Other Assets
Equity investments in affiliates	405	412
Operating lease right-of-use assets, net	482
Goodwill	591	573
Intangible assets, net	828	591
Nuclear decommissioning trust fund	756	663
Derivative instruments	358	317
Deferred income taxes	53	46
Other non-current assets	252	289
Non-current assets - held-for-sale	0	77
Non-current assets - discontinued operations	0	1,012
Total other assets	3,725	3,980
Total Assets	9,527	10,628
Current Liabilities
Current portion of long-term debt	302	72
Current portion of operating lease liabilities	73
Accounts payable	866	863
Derivative instruments	668	673
Cash collateral received in support of energy risk management activities	30	33
Accrued expenses and other current liabilities	625	680
Current liabilities - held-for-sale	0	5
Current liabilities - discontinued operations	0	72
Total current liabilities	2,564	2,398
Other Liabilities
Long-term debt	5,798	6,449
Non-current operating lease liabilities	500
Nuclear decommissioning reserve	294	282
Nuclear decommissioning trust liability	453	371
Derivative instruments	364	304
Deferred income taxes	70	65
Other non-current liabilities	1,036	1,274
Non-current liabilities - held-for-sale	0	65
Non-current liabilities - discontinued operations	0	635
Total other liabilities	8,515	9,445
Total Liabilities	11,079	11,843
Redeemable noncontrolling interest in subsidiaries	19	19
Commitments and Contingencies
Stockholders' Equity
Common stock; $0.01 par value; 500,000,000 shares authorized; 421,859,844 and 420,288,886 shares issued and 251,985,517 and 283,650,039 shares outstanding at September 30, 2019 and December 31, 2018, respectively	4	4
Additional paid-in-capital	8,494	8,510
Accumulated deficit	(4,991)	(6,022)
Less treasury stock, at cost - 169,874,327 and 136,638,847 shares at September 30, 2019 and December 31, 2018, respectively	(4,920)	(3,632)
Accumulated other comprehensive loss	(158)	(94)
Total Stockholders' Equity	(1,571)	(1,234)
Total Liabilities and Stockholders' Equity	$ 9,527	$ 10,628
Common stock, par or value (in usd per share)	$ 0.01
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	421,859,844	420,288,886
Treasury stock, shares (in shares)	169,874,327	136,638,847
Common stock, shares outstanding (in shares)	251,985,517	283,650,039

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par or value (in usd per share)	$ 0.01
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	421,859,844	420,288,886
Common stock, shares outstanding (in shares)	251,985,517	283,650,039
Treasury stock, shares (in shares)	169,874,327	136,638,847

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash Flows from Operating Activities
Net Income/(Loss)	$ 1,056	$ 281
Income/(loss) from discontinued operations, net of income tax	399	(272)
Income/(loss) from continuing operations	657	553
Adjustments to reconcile net income to cash provided by operating activities:
Distributions and equity earnings of unconsolidated affiliates	(5)	10
Depreciation, amortization and accretion	289	364
Provision for bad debts	87	57
Amortization of nuclear fuel	40	38
Amortization of financing costs and debt discount/premiums	20	21
Loss on debt extinguishment, net	47	22
Amortization of emissions allowances and out-of-market contracts	28	21
Amortization of unearned equity compensation	15	21
Gain on sale and disposal of assets	(20)	(50)
Impairment losses	108	90
Changes in derivative instruments	36	(17)
Changes in deferred income taxes and liability for uncertain tax benefits	(3)	(6)
Changes in collateral deposits in support of energy risk management activities	129	(30)
Changes in nuclear decommissioning trust liability	27	50
GenOn settlement	0	(125)
Loss on deconsolidation of Agua Caliente and Ivanpah projects	0	13
Changes in other working capital	(602)	(361)
Cash provided/(used) by continuing operations	853	671
Cash provided by discontinued operations	8	396
Net Cash Provided/(Used) by Operating Activities	861	1,067
Cash Flows from Investing Activities
Payments for acquisitions of businesses	(348)	(209)
Capital expenditures	(183)	(343)
Net proceeds from notes receivable	2	0
Net proceeds from sale of emission allowances	14	24
Investments in nuclear decommissioning trust fund securities	(295)	(449)
Proceeds from the sale of nuclear decommissioning trust fund securities	271	398
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees	1,293	1,555
Deconsolidation of Agua Caliente and Ivanpah projects	0	(268)
Net contributions to investments in unconsolidated affiliates	(94)	(39)
Contributions to discontinued operations	(44)	(23)
Cash (used)/provided by continuing operations	616	646
Cash used by discontinued operations	(2)	(705)
Net Cash (Used)/Provided by Investing Activities	614	(59)
Cash Flows from Financing Activities
Payments of dividends to common stockholders	(24)	(28)
Payments for treasury stock	(1,286)	(1,000)
Payments for debt extinguishment costs	(24)	0
Distributions to noncontrolling interests from subsidiaries	(1)	(17)
Proceeds from issuance of common stock	3	15
Proceeds from issuance of short and long-term debt	2,048	995
Payment of debt issuance costs	(34)	(19)
Payments for short and long-term debt	(2,487)	(970)
Receivable from affiliate	0	(26)
Other	0	(4)
Cash used by continuing operations	(1,805)	(1,054)
Cash provided by discontinued operations	43	403
Net Cash Used by Financing Activities	(1,762)	(651)
Effect of exchange rate changes on cash and cash equivalents	0	1
Change in Cash from discontinued operations	49	94
Net (Decrease)/increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash	(336)	264
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period	613	1,086
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	$ 277	$ 1,350

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions		Total	NRG Yield, Inc.	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Treasury Stock	Accumulated Other Comprehensive Loss	Noncontrolling Interest	Noncontrolling InterestNRG Yield, Inc.
Beginning balance at Dec. 31, 2017		$ 1,968		$ 4	$ 8,376	$ (6,268)	$ (2,386)	$ (72)	$ 2,314
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income/(loss)		249				279			(30)
Other comprehensive (loss) income		11						11
Sale of assets to NRG Yield, Inc.		12			8				4
ESPP share purchases		3			(2)		5
Share repurchases		(93)					(93)
Equity-based compensation		(10)			(10)
Issuance of common stock		7			7
Common stock dividends	[1]	(10)				(10)
Distributions to noncontrolling interest and dividends paid		(19)	$ (30)						(19)	$ (30)
Contributions from noncontrolling interests		153							153
Adoption of new accounting standards		17				17
Ending balance at Mar. 31, 2018		2,258		4	8,379	(5,982)	(2,474)	(61)	2,392
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income/(loss)		104				72			32
Other comprehensive (loss) income		1						1
Sale of assets to NRG Yield, Inc.		(2)							(2)
ESPP share purchases		1					1
Share repurchases		(407)			(11)		(396)
Equity-based compensation		8			8
Issuance of common stock		4			4
Common stock dividends	[1]	(9)				(9)
Distributions to noncontrolling interest and dividends paid		(15)	$ (31)						(15)	$ (31)
Contributions from noncontrolling interests		150							150
Adoption of new accounting standards		(1)				(1)
Deconsolidation of Business		(89)							(89)
Equity component of convertible senior notes		101			101
Ending balance at Jun. 30, 2018		2,071		4	8,481	(5,920)	(2,871)	(60)	2,437
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income/(loss)		(48)				(72)			24
Other comprehensive (loss) income		2						2
Sale of assets to NRG Yield, Inc.		7			1				6
Share repurchases		(500)			(37)		(463)
Equity-based compensation		4			4
Issuance of common stock		4			4
Common stock dividends	[1]	(9)				(9)
Distributions to noncontrolling interest and dividends paid		(9)							(9)
Contributions from noncontrolling interests		1							1
Deconsolidation of Business		(2,459)							(2,459)
Ending balance at Sep. 30, 2018		(936)		4	8,453	(6,001)	(3,334)	(58)	$ 0
Beginning balance at Dec. 31, 2018		(1,234)		4	8,510	(6,022)	(3,632)	(94)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income/(loss)		482				482
Other comprehensive (loss) income		(2)						(2)
Share repurchases		(749)			(10)		(739)
Equity-based compensation		(32)			(32)
Issuance of common stock		5			5
Common stock dividends	[2]	(8)				(8)
Ending balance at Mar. 31, 2019		(1,538)		4	8,473	(5,548)	(4,371)	(96)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income/(loss)		201				201
Other comprehensive (loss) income		(3)						(3)
Share repurchases		(305)			10		(315)
Equity-based compensation		5			5
Common stock dividends	[2]	(8)				(8)
Ending balance at Jun. 30, 2019		(1,648)		4	8,488	(5,355)	(4,686)	(99)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income/(loss)		372				372
Other comprehensive (loss) income		(59)						(59)
Share repurchases		(234)					(234)
Equity-based compensation		5			5
Issuance of common stock		1			1
Common stock dividends	[2]	(8)				(8)
Ending balance at Sep. 30, 2019		$ (1,571)		$ 4	$ 8,494	$ (4,991)	$ (4,920)	$ (158)
[1]	Dividends per common share were $0.03 for each of the quarters ended September 30, 2018, June 30, 2018 and March 31, 2018
[2]	Dividends per common share were $0.03 for each of the quarters ended September 30, 2019, June 30, 2019 and March 31, 2019

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends (in usd per share)	$ 0.03	$ 0.03	$ 0.03	$ 0.03	$ 0.03	$ 0.03

Nature of Business and Basis of

Nature of Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business and Basis of Presentation	Nature of Business and Basis of Presentation General NRG Energy, Inc., or NRG or the Company, is an energy company built on dynamic retail brands with diverse generation assets. NRG brings the power of energy to consumers by producing, selling and delivering electricity and related products and services in major competitive power markets in the U.S. in a manner that delivers value to all of NRG's stakeholders. NRG is perfecting the integrated model by balancing retail load with generation supply within its deregulated markets, while evolving to a customer-driven business. The Company sells energy, services, and innovative, sustainable products and services directly to retail customers under the names "NRG", "Reliant" and other brand names owned by NRG, supported by approximately 23,000 MW of generation as of September 30, 2019. The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with the SEC's regulations for interim financial information and with the instructions to Form 10-Q. Accordingly, they do not include all of the information and notes required by generally accepted accounting principles for complete financial statements. The following notes should be read in conjunction with the accounting policies and other disclosures as set forth in the notes to the consolidated financial statements in the Company's 2018 Form 10-K. Interim results are not necessarily indicative of results for a full year. In the opinion of management, the accompanying unaudited interim condensed consolidated financial statements contain all material adjustments consisting of normal and recurring accruals necessary to present fairly the Company's consolidated financial position as of September 30, 2019, and the results of operations, comprehensive income, cash flows and statements of stockholders' equity for the three and nine months ended September 30, 2019 and 2018. Discontinued Operations During the fourth quarter of 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 discontinued operations, as the sale, which closed on February 4, 2019, represented a strategic shift in the business in which NRG operates. The financial information for all historical periods has been recast to reflect the presentation of these entities as discontinued operations. On August 31, 2018, as described in Note 4, Acquisitions, Discontinued Operations and Dispositions, NRG deconsolidated NRG Yield, Inc. and its Renewables Platform for financial reporting purposes. The financial information for all historical periods was recast to reflect the presentation of these entities, as well as the Carlsbad project, as discontinued operations in the third quarter of 2018. 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 also deconsolidated the Agua Caliente project from its financial results and began accounting for the project as an equity method investment. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates. Reclassifications Certain prior year amounts have been reclassified for comparative purposes.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies 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 income attributable to the noncontrolling interest and redeemable noncontrolling interest: Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 (In millions) Income from continuing operations, net of income tax $ 374 $ 274 $ 656 $ 547 (Loss)/income from discontinued operations, net of income tax (2) (346) 399 (267) Net income/(loss) attributable to NRG Energy, Inc. $ 372 $ (72) $ 1,055 $ 280 Other Balance Sheet Information The following table presents the allowance for doubtful accounts included in accounts receivable, net; accumulated depreciation included in property, plant and equipment, net; accumulated amortization included in intangible assets, net and accumulated amortization included in out-of-market contracts, net: September 30, 2019 December 31, 2018 (In millions) Accounts receivable allowance for doubtful accounts $ 57 $ 32 Property, plant and equipment accumulated depreciation 1,759 1,811 Intangible assets accumulated amortization 1,215 1,149 Out-of-market contracts accumulated amortization — 37 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: September 30, 2019 December 31, 2018 (In millions) Cash and cash equivalents $ 243 $ 563 Funds deposited by counterparties 30 33 Restricted cash 4 17 Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows $ 277 $ 613 Funds deposited by counterparties consist of cash held by the Company as a result of collateral posting obligations from its counterparties. Some amounts are segregated into separate accounts that are not contractually restricted but, based on the Company's intention, are not available for the payment of general corporate obligations. Depending on market fluctuations and the settlement of the underlying contracts, the Company will refund this collateral to the hedge counterparties pursuant to the terms and conditions of the underlying trades. Since collateral requirements fluctuate daily and the Company cannot predict if any collateral will be held for more than twelve months, the funds deposited by counterparties are classified as a current asset on the Company's balance sheet, with an offsetting liability for this cash collateral received within current liabilities. Restricted cash consists primarily of funds held to satisfy the requirements of certain debt agreements and funds held within the Company's projects that are restricted in their use. Pension Plan Amendments 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 STP defined benefit plan is further described in Note 13 , Benefit Plans and Other Postretirement Benefits , to the Company’s 2018 Form 10-K. 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 under the modified retrospective approach by applying the provisions of the new leases guidance at the effective date without adjusting the comparative periods presented. The Company assessed its leasing arrangements, evaluated the impact of applying practical expedients and accounting policy elections, and implemented lease accounting software to meet the reporting requirements of the standard. The Company established operating lease liabilities of $404 million and right-of-use assets of $321 million upon adoption, before considering deferred taxes. The adoption of Topic 842 did not have a material impact on the statements of operations or cash flows. See Note 8, Leases, for further discussion. Recent Accounting Developments - Guidance Not Yet Adopted 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 , in response to stakeholders’ observations that Topic 810, Consolidations , could be improved thereby improving general purpose financial reporting. Specifically, ASC 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 retained earnings at the beginning of the earliest period presented. The Company is evaluating the impact of adopting this guidance on the consolidated financial statements and disclosures. 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) . The guidance in ASU No. 2018-13 eliminates such disclosures as the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy. The amendments in ASU No. 2018-13 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, with early adoption permitted for any eliminated or modified disclosures. Certain disclosures in ASU No. 2018-13 are required to be applied on a retrospective basis and others on a prospective basis. As the amendment contemplates changes in disclosures only, it will have no material impact on the Company's results of operations, cash flows, or statement of financial position.

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition Performance Obligations As of September 30, 2019, estimated future fixed fee performance obligations are $136 million for the remaining three months of fiscal year 2019, and $532 million, $586 million, $297 million and $29 million for the entirety of fiscal years 2020, 2021, 2022 and 2023, respectively. These performance obligations are for cleared auction MWs in the PJM, ISO-NE, NYISO and MISO capacity auctions and are subject to penalties for non performance. Disaggregated Revenues The following tables represent the Company’s disaggregation of revenue from contracts with customers for the three and nine months ended September 30, 2019 and 2018 along with the reportable segment for each category: Three months ended September 30, 2019 Generation (In millions) Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue (a)(c) $ — $ 773 $ 237 $ 1,010 $ (568) $ 442 Capacity revenue (c) — — 151 151 1 152 Retail revenue Mass customers 2,080 — — — — 2,080 Business Solutions customers 465 — — — — 465 Total retail revenue 2,545 — — — — 2,545 Mark-to-market for economic hedging activities (a)(b) (1) (240) (16) (256) 47 (210) Other revenues (c) — 32 37 69 (2) 67 Total operating revenue 2,544 565 409 974 (522) 2,996 Less: Lease revenue 3 — 2 2 — 5 Less: Realized and unrealized ASC 815 revenue (a) (1) 944 66 1,010 (522) 487 Total revenue from contracts with customers $ 2,542 $ (379) $ 341 $ (38) $ — $ 2,504 (a) Generation includes higher revenues due to the Company's large internal transfer of power based on average annualized market prices, which are offset by higher cost of operations within Retail (b) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 (c) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue $ — $ 1,175 $ 62 $ 1,237 $ (569) $ 668 Capacity revenue — — 33 33 — 33 Other revenue — 9 (13) (4) — (4) Three months ended September 30, 2018 Generation (In millions) Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue (a)(c) $ — $ 585 $ 339 $ 924 $ (479) $ 445 Capacity revenue (c) — 1 190 191 1 192 Retail revenue Mass customers 1,768 — — — (2) 1,766 Business Solutions customers 434 — — — — 434 Total retail revenue 2,202 — — — (2) 2,200 Mark-to-market for economic hedging activities (a)(b) 1 259 36 295 (241) 55 Other revenues (c) — 8 60 68 — 68 Total operating revenue 2,203 853 625 1,478 (721) 2,960 Less: Lease revenue 3 — 3 3 — 6 Less: Realized and unrealized ASC 815 revenue (a) 1 1,159 79 1,238 (716) 523 Total revenue from contracts with customers $ 2,199 $ (306) $ 543 $ 237 $ (5) $ 2,431 (a) Generation includes higher revenues due to the Company's large internal transfer of power based on average annualized market prices, which are offset by higher cost of operations within Retail (b) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 (c) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue $ — $ 901 $ (8) $ 893 $ (475) $ 418 Capacity revenue — — 45 45 — 45 Other revenue — (1) 6 5 — 5 Nine months ended September 30, 2019 Generation (In millions) Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue (a)(c) $ — $ 1,628 $ 578 $ 2,206 $ (1,209) $ 997 Capacity revenue (c) — — 460 460 1 461 Retail revenue Mass customers 4,802 — — — (2) 4,800 Business Solutions customers 1,096 — — — — 1,096 Total retail revenue 5,898 — — — (2) 5,896 Mark-to-market for economic hedging activities (a)(b) 1 233 40 273 (223) 51 Other revenues (c) — 77 148 225 (4) 221 Total operating revenue 5,899 1,938 1,226 3,164 (1,437) 7,626 Less: Lease revenue 9 — 6 6 — 15 Less: Realized and unrealized ASC 815 revenue (a) 1 2,674 303 2,977 (1,433) 1,545 Total revenue from contracts with customers $ 5,889 $ (736) $ 917 $ 181 $ (4) $ 6,066 (a) Generation includes higher revenues due to the Company's large internal transfer of power based on average annualized market prices, which are offset by higher cost of operations within Retail (b) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 (c) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue $ — $ 2,417 $ 192 $ 2,609 $ (1,211) $ 1,398 Capacity revenue — — 80 80 1 81 Other revenue — 24 (9) 15 — 15 Nine months ended September 30, 2018 Generation (In millions) Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue (a)(c) $ — $ 1,251 $ 937 $ 2,188 $ (890) $ 1,298 Capacity revenue (c) — 1 498 499 1 500 Retail revenue Mass customers 4,321 — — — (4) 4,317 Business Solutions customers 1,181 — — — — 1,181 Total retail revenue 5,502 — — — (4) 5,498 Mark-to-market for economic hedging activities (a)(b) (5) (14) 9 (5) (21) (31) Other revenues (c) — 72 162 234 (13) 221 Total operating revenue 5,497 1,310 1,606 2,916 (927) 7,486 Less: Lease revenue 10 — 7 7 — 17 Less: Realized and unrealized ASC 815 revenue (a) (5) 1,872 211 2,083 (901) 1,177 Total revenue from contracts with customers $ 5,492 $ (562) $ 1,388 $ 826 $ (26) $ 6,292 (a) Generation includes higher revenues due to the Company's large internal transfer of power based on average annualized market prices, which are offset by higher cost of operations within Retail (b) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 (c) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue $ — $ 1,883 $ 78 $ 1,961 $ (880) $ 1,081 Capacity revenue — — 110 110 — 110 Other revenue — 3 14 17 — 17 Contract Balances The following table reflects the contract assets and liabilities included in the Company’s balance sheet as of September 30, 2019 and December 31, 2018: (In millions) September 30, 2019 December 31, 2018 Deferred customer acquisition costs $ 130 $ 111 Accounts receivable, net - Contracts with customers 1,311 999 Accounts receivable, net - Derivative instruments 63 20 Accounts receivable, net - Affiliate 4 5 Total accounts receivable, net $ 1,378 $ 1,024 Unbilled revenues (included within Accounts receivable, net - Contracts with customers) $ 486 $ 392 Deferred revenues (a) 78 67 (a) Deferred revenues from contracts with customers for the nine months ended September 30, 2019 and the year ended December 31, 2018 were approximately $25 million and $19 million, respectively The revenue recognized from contracts with customers during the nine months ended September 30, 2019 and 2018 relating to the deferred revenue balance at the beginning of each period was $13 million and $16 million, respectively. The revenue recognized from contracts with customers during the three months ended September 30, 2019 and 2018 relating to the deferred revenue balance at the beginning of each period was $21 million and $19 million, respectively. The change in deferred revenue balances during the three and nine months ended September 30, 2019 and 2018 was primarily due to the timing difference of when consideration was received and when the performance obligation was transferred.

Acquisitions, Discontinued Oper

Acquisitions, Discontinued Operations and Dispositions	9 Months Ended
	Sep. 30, 2019
Discontinued Operations and Disposal Groups [Abstract]
Acquisitions, Discontinued Operations and Dispositions	Acquisitions, Discontinued Operations and Dispositions Acquisitions Stream Energy Acquisition — On August 1, 2019, the Company completed the acquisition of Stream Energy's retail electricity and natural gas business operating in 9 states and Washington, D.C. for $329 million, including working capital and other adjustments of approximately $29 million. The acquisition increased NRG's retail portfolio by approximately 600,000 RCEs or 450,000 customers. The purchase price was provisionally allocated as follows: (In millions) Net current and non-current working capital $ 28 Other intangible assets 283 Goodwill (a) 18 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 is assigned to the Retail segment and is not deductible for tax purposes. XOOM Energy Acquisition — On June 1, 2018, the Company completed the acquisition of XOOM Energy, LLC, an electricity and natural gas retailer operating in 19 states, Washington, D.C. and Canada for $213 million, including working capital and other adjustments of $48 million. 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 Discontinued Operations Sale of South Central Portfolio On February 4, 2019, the Company completed the sale of the South Central Portfolio to Cleco for cash consideration of $1 billion excluding working capital and other adjustments. The Company concluded that the divested business met the criteria for discontinued operations as of December 31, 2018, as the disposition represented a strategic shift in the business in which NRG operates and the criteria for held-for-sale were met. As such, all current and prior period results for the operations of the South Central Portfolio, except for the Cottonwood facility as discussed below, were reclassified as discontinued operations. In connection with the transaction, NRG also entered into a transition services agreement to provide certain corporate services to the divested business. The South Central Portfolio includes the 1,153 MW Cottonwood natural gas generating facility. Upon the closing of the sale of the South Central Portfolio, NRG entered into an agreement with Cleco to leaseback the Cottonwood facility through May 2025. Due to its continuing involvement with the Cottonwood facility, NRG did not use discontinued operations treatment in accounting for historical and ongoing activity with Cottonwood. Summarized results of the South Central Portfolio discontinued operations were as follows: Three months ended Nine months ended (In millions) September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 Operating revenues $ — $ 101 $ 31 $ 310 Operating costs and expenses — (85) (23) (262) Gain from discontinued operations, net of tax — 16 8 48 (Loss)/gain on disposal of discontinued operations, net of tax (1) — 27 — (Loss)/gain from discontinued operations, including disposal, net of tax $ (1) $ 16 $ 35 $ 48 The following table summarizes the major classes of assets and liabilities classified as discontinued operations of the South Central Portfolio: (In millions) December 31, 2018 Cash and cash equivalents $ 89 Accounts receivable - trade, 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 Sale of Ownership in NRG Yield, Inc. and the Renewables Platform On August 31, 2018, the Company completed the sale of its ownership interests in NRG Yield, Inc. and the Renewables Platform to GIP for total cash consideration of $1.348 billion. The Company concluded that the divested businesses met the criteria for discontinued operations, as the dispositions represent a strategic shift in the markets in which NRG operates. As such, all prior period results for NRG Yield, Inc. and the Renewables Platform were reclassified as discontinued operations. In connection with the transaction, NRG entered into a transition services agreement to provide certain corporate services to the divested businesses. During the nine months ended September 30, 2019, the Company recorded an adjustment to reduce the purchase price by $16 million in connection with the completion of the Patriot Wind project. The Company expects to recover a portion of this adjustment in the future. During the nine months ended September 30, 2019, the Company reduced the liability related to the indemnification of NRG Yield for any increase in property taxes for certain solar properties by $22 million due to updated estimates. Carlsbad On February 6, 2018, NRG entered into an agreement with NRG Yield and GIP to sell 100% of its membership interests in Carlsbad Energy Holdings LLC, which owns the Carlsbad project, for $385 million of cash consideration, excluding working capital adjustments. The primary condition to close the Carlsbad transaction was the completion of the sale of NRG Yield and the Renewables Platform. At the time of the sale of NRG Yield and the Renewables Platform in August 2018, the Company concluded that the Carlsbad project met the criteria for discontinued operations and accordingly, all current and prior period results for Carlsbad were reclassified as discontinued operations. The transaction closed on February 27, 2019. Carlsbad continues to have a ground lease and easement agreement with NRG with an initial term ending in 2039 and two ten Summarized results of NRG Yield, Inc. and the Renewables Platform and Carlsbad discontinued operations were as follows: Three months ended Nine months ended (In millions) September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 Operating revenues $ — $ 297 $ 19 $ 925 Operating costs and expenses — (229) (9) (682) Other expenses — (42) (5) (165) Gain from operations of discontinued components, before tax — 26 5 78 Income tax expense — 9 — 4 Gain from discontinued operations, net of tax — 17 5 74 (Loss)/gain on disposal of discontinued operations, net of tax (1) (139) 330 (139) (Expense)/income from California property tax indemnification — (153) 22 (153) (Expense)/income from other commitments, indemnification and fees — (77) 5 (77) (Loss)/gain on disposal of discontinued operations, net of tax (1) (369) 357 (369) (Loss)/gain from discontinued operations, including disposal, net of tax $ (1) $ (352) $ 362 $ (295) The following table summarizes the major classes of assets and liabilities classified as discontinued operations of Carlsbad: (In millions) December 31, 2018 Restricted cash $ 4 Accounts receivable - trade, 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 Sale of Assets to NRG Yield, Inc. Prior to Discontinued Operations On June 19, 2018, the Company completed the UPMC Thermal Project and received cash consideration from NRG Yield of $84 million, plus an additional $3 million received at final completion in January 2019. On March 30, 2018, the Company sold to NRG Yield, Inc. 100% of NRG's interests in Buckthorn Renewables, LLC, which owns a 154 MW construction-stage utility-scale solar generation project located in Texas. NRG Yield, Inc. paid cash consideration of $42 million, excluding working capital adjustments, and assumed non-recourse debt of $183 million. GenOn On June 14, 2017, the GenOn Entities filed voluntary petitions for relief under Chapter 11 of the Bankruptcy Code in the Bankruptcy Court. As a result of the bankruptcy filings, NRG concluded that it no longer controlled GenOn as it was subject to the control of the Bankruptcy Court; and, accordingly, NRG deconsolidated GenOn for financial reporting purposes as of June 14, 2017. By eliminating a large portion of its operations in the PJM market with the deconsolidation of GenOn, NRG concluded that GenOn met the criteria for discontinued operations, as this represented a strategic shift in the business in which NRG operates. As such, all prior period results for GenOn were reclassified as discontinued operations. GenOn's plan of reorganization was confirmed on December 14, 2018. Summarized results of GenOn discontinued operations were as follows: Nine months ended (In millions) September 30, 2019 September 30, 2018 Interest income - affiliate $ — $ 3 Pension and post-retirement liability assumption — (2) Other 2 (26) Gain/(loss) from discontinued operations, net of tax $ 2 $ (25) GenOn Settlement Effective July 16, 2018, NRG and GenOn consummated the GenOn Settlement whereby the Company paid GenOn approximately $125 million, which included (i) the settlement consideration of $261 million, (ii) the transition services credit of $28 million and (iii) the return of $15 million of collateral posted to NRG; offset by the (i) $151 million in borrowings under the intercompany secured revolving credit facility, (ii) related accrued interest and fees of $12 million, (iii) remaining payments due under the transition services agreement of $10 million, (iv) $4 million reduction of the settlement payment related to NRG assigning to GenOn approximately $8 million of historical claims against REMA and (v) certain other balances due to NRG totaling $2 million. GenMA Settlement The Bankruptcy Court approved settlement terms agreed to among the GenOn Entities, NRG, the Consenting Holders, GenOn Mid-Atlantic, and certain of GenOn Mid-Atlantic's stakeholders, or the GenMA Settlement, and directed the settlement parties to cooperate in good faith to negotiate definitive documentation consistent with the GenMA Settlement term sheet in order to pursue consummation of the GenMA Settlement. The definitive documentation effectuating the GenMA Settlement was finalized as of April 27, 2018. Certain terms of the compromise with respect to NRG and GenOn Mid-Atlantic are as follows: • Settlement of all pending litigation and objections to the Plan (including with respect to releases and feasibility); • NRG provided $37.5 million in letters of credit as new qualifying credit support to GenOn Mid-Atlantic; and • NRG paid $6 million as reimbursement of professional fees incurred by certain of GenOn Mid- Atlantic's stakeholders in connection with the GenMA Settlement. Dispositions On August 1, 2018, the Company completed the sale of 100% of its ownership interests in BETM to Diamond Energy Trading and Marketing, LLC for $71 million, net of working capital adjustments, which resulted in a gain of $15 million on the sale. The sale also resulted in the release and return of approximately $119 million of letters of credit, $32 million of parent guarantees, and $4 million of net cash collateral to NRG. On June 29, 2018, the Company completed the sale of Canal 3 to Stonepeak Kestrel for cash proceeds of $16 million and recorded a gain of $17 million. Prior to the sale, Canal 3 entered into a financing arrangement and received cash proceeds of $167 million, of which $151 million was distributed to the Company. The related debt was non-recourse to NRG and was transferred to Stonepeak Kestrel in connection with the sale of Canal 3. The Company entered into a project management agreement in 2018 to manage construction of Canal 3, and substantial completion was reached in June 2019. The Company completed other asset sales for cash proceeds of $22 million and $21 million during the nine months ended September 30, 2019 and 2018, respectively.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 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 paid and received in support of energy risk management activities, the carrying amounts approximate fair values because of the short-term maturity of those instruments and are classified as Level 1 within the fair value hierarchy. The estimated carrying amounts and fair values of NRG's recorded financial instruments not carried at fair market value are as follows: September 30, 2019 December 31, 2018 Carrying Amount Fair Value Carrying Amount Fair Value (In millions) Assets: Notes receivable $ 11 $ 8 $ 17 $ 14 Liabilities: Long-term debt, including current portion (a) 6,168 6,706 6,591 6,697 (a) Excludes deferred financing costs, which are recorded as a reduction to long-term debt in the Company's consolidated balance sheets The fair value of the Company's publicly-traded long-term debt is based on quoted market prices and is classified as Level 2 within the fair value hierarchy. The fair value of 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 September 30, 2019 and December 31, 2018: September 30, 2019 December 31, 2018 Level 2 Level 3 Level 2 Level 3 (In millions) Long-term debt, including current portion $ 6,375 $ 331 $ 6,528 $ 169 Recurring Fair Value Measurements Debt securities, equity securities, and trust fund investments, which are comprised of various U.S. debt and equity securities, and derivative assets and liabilities, are carried at fair market value. The following tables present assets and liabilities measured and recorded at fair value on the Company's condensed consolidated balance sheets on a recurring basis and their level within the fair value hierarchy: September 30, 2019 (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and non-current assets) $ 24 $ — $ 19 $ 5 Nuclear trust fund investments: Cash and cash equivalents 20 20 — — U.S. government and federal agency obligations 51 51 — — Federal agency mortgage-backed securities 97 — 97 — Commercial mortgage-backed securities 27 — 27 — Corporate debt securities 112 — 112 — Equity securities 372 372 — — Foreign government fixed income securities 5 — 5 — Other trust fund investments: U.S. government and federal agency obligations 1 1 — — Derivative assets: Commodity contracts 1,093 92 878 123 Measured using net asset value practical expedient: Equity securities — nuclear trust fund investments 72 Equity securities 7 Total assets $ 1,881 $ 536 $ 1,138 $ 128 Derivative liabilities: Commodity contracts $ 1,032 $ 151 $ 771 $ 110 Total liabilities $ 1,032 $ 151 $ 771 $ 110 December 31, 2018 (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and 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 There were no transfers during the three and nine months ended September 30, 2019 and 2018 between Levels 1 and 2. The following tables reconcile, for the three and nine months ended September 30, 2019 and 2018, the beginning and ending balances for financial instruments that are recognized at fair value in the condensed consolidated financial statements, at least annually, using significant unobservable inputs: Fair Value Measurement Using Significant Unobservable Inputs (Level 3) Three months ended September 30, 2019 Nine months ended September 30, 2019 (In millions) Debt Securities Derivatives (a) Total Debt Securities Derivatives (a) Total Beginning balance $ 19 $ 97 $ 116 $ 19 $ 20 $ 39 Contracts added from acquisitions — (2) (2) — (3) (3) Total (losses)/gains — realized/unrealized: Included in earnings — (18) (18) 1 (45) (44) Included in OCI (14) — (14) (14) — (14) Cash received — — — (1) — (1) Purchases — 38 38 — 26 26 Transfers into Level 3 (b) — (126) (126) — 4 4 Transfers out of Level 3 (b) — 24 24 — 11 11 Ending balance as of September 30, 2019 $ 5 $ 13 $ 18 $ 5 $ 13 $ 18 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 September 30, 2019 $ — $ 44 $ 44 $ 1 $ 13 $ 14 (a) Consists of derivative assets and liabilities, net (b) Transfers into/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. All transfers in/out are with Level 2 Fair Value Measurement Using Significant Unobservable Inputs (Level 3) Three months ended September 30, 2018 Nine months ended September 30, 2018 (In millions) Debt Securities Derivatives (a) Total Debt Securities Derivatives (a) Total Beginning balance $ 19 $ 174 $ 193 $ 19 $ (15) $ 4 Contracts added in XOOM acquisition — — — — 12 12 Total (losses) — realized/unrealized — — — — (15) (15) Purchases — 12 12 — 9 9 Transfers into Level 3 (b) — (201) (201) — (4) (4) Transfers out of Level 3 (b) — 2 2 — — — Ending balance as of September 30, 2018 $ 19 $ (13) $ 6 $ 19 $ (13) $ 6 (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 September 30, 2018 $ — $ (3) $ (3) $ — $ (18) $ (18) (a) Consists of derivative assets and liabilities, net (b) Transfers into/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. All transfers in/out are with Level 2 Derivative Fair Value Measurements A portion of NRG's contracts are exchange-traded contracts with readily available quoted market prices. A majority of NRG's contracts are non-exchange-traded contracts valued using prices provided by external sources, primarily price quotations available through brokers or over-the-counter and on-line exchanges. The remainder of the assets and liabilities represent contracts for which external sources or observable market quotes are not available. These contracts are valued based on various valuation techniques including, but not limited to, internal models based on a fundamental analysis of the market and extrapolation of the observable market data with similar characteristics. As of September 30, 2019, contracts valued with prices provided by models and other valuation techniques make up 11% of derivative assets and 11% of derivative liabilities. 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 September 30, 2019 and December 31, 2018: September 30, 2019 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) Power Contracts $ 89 $ 98 Discounted Cash Flow Forward Market Price (per MWh) $ 6 $ 217 $ 22 FTRs 34 12 Discounted Cash Flow Auction Prices (per MWh) (134) 60 0 $ 123 $ 110 December 31, 2018 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) 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 September 30, 2019 and December 31, 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) The fair value of each contract is discounted using a risk-free interest rate. In addition, the Company applies a credit reserve to reflect credit risk, which is calculated based on published default probabilities. As of September 30, 2019, the credit reserve resulted in a $1 million decrease in cost of operations. As of December 31, 2018, the credit reserve did not result in a significant change in fair value in operating revenue and cost of operations. Concentration of Credit Risk In addition to the credit risk discussion as disclosed in Note 2, Summary of Significant Accounting Policies , to the Company's 2018 Form 10-K, the following is a discussion of the concentration of credit risk for the Company's contractual obligations. Credit risk relates to the risk of loss resulting from non-performance or non-payment by counterparties pursuant to the terms of their contractual obligations. NRG is exposed to counterparty credit risk through various activities including wholesale sales, fuel purchases and retail supply arrangements, as well as retail customer credit risk through its retail load activities. Counterparty Credit Risk The Company's counterparty credit risk policies are disclosed in its 2018 Form 10-K. As of September 30, 2019, counterparty credit exposure, excluding credit exposure from RTOs, ISOs, registered commodity exchanges and certain long-term agreements, was $242 million and NRG held collateral (cash and letters of credit) against those positions of $55 million, resulting in a net exposure of $226 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 42% of the Company's exposure before collateral is expected to roll off by the end of 2020. Counterparty credit exposure is valued through observable market quotes and discounted at a risk free interest rate. The following tables highlight net counterparty credit exposure by industry sector and by counterparty credit quality. Net counterparty credit exposure is defined as the aggregate net asset position for NRG with counterparties where netting is permitted under the enabling agreement and includes all cash flow, mark-to-market and NPNS, and non-derivative transactions. The exposure is shown net of collateral held and includes amounts net of receivables or payables. Net Exposure (a)(b) Category by Industry Sector (% of Total) Utilities, energy merchants, marketers and other 84 % Financial institutions 16 Total as of September 30, 2019 100 % Net Exposure (a) (b) Category by Counterparty Credit Quality (% of Total) Investment grade 54 % Non-investment grade/non-rated 46 Total as of September 30, 2019 100 % (a) Counterparty credit exposure excludes uranium and coal transportation contracts because of the unavailability of market prices (b) The figures in the tables above exclude potential counterparty credit exposure related to RTOs, ISOs, registered commodity exchanges and certain long-term contracts The Company currently has no exposure to wholesale counterparties in excess of 10% of total net exposure discussed above as of September 30, 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 its 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 the overall market and are excluded from the above exposures. Exchange Traded Transactions The Company enters into commodity transactions on registered exchanges, notably ICE, NYMEX and Nodal. These clearinghouses act as the counterparty and transactions are subject to extensive collateral and margining requirements. As a result, these commodity transactions have limited counterparty credit risk. Long-Term Contracts Counterparty credit exposure described above excludes credit risk exposure under certain long-term contracts, primarily solar PPAs. As external sources or observable market quotes are not available to estimate such exposure, the Company values these contracts based on various techniques including, but not limited to, internal models based on a fundamental analysis of the market and extrapolation of observable market data with similar characteristics. Based on these valuation techniques, as of September 30, 2019, aggregate credit risk exposure managed by NRG to these counterparties was approximately $518 million for the next five years, including exposure to PG&E as described below. NRG, through its unconsolidated affiliates Ivanpah and Agua Caliente, has exposure to PG&E of approximately $322 million for the next five years. For further discussion see Note 11, Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs . 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 non-payment of customer accounts receivable and the loss of in-the-money forward value. The Company manages retail credit risk through the use of established credit policies that include monitoring of the portfolio and the use of credit mitigation measures such as deposits or prepayment arrangements. As of September 30, 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.

Nuclear Decommissioning Trust F

Nuclear Decommissioning Trust Fund	9 Months Ended
	Sep. 30, 2019
Nuclear Decommissioning Trust Fund Disclosure [Abstract]
Nuclear Decommissioning Trust Fund	Nuclear Decommissioning Trust Fund NRG's Nuclear Decommissioning Trust Fund assets, which are for the decommissioning of its 44% interest in STP, are comprised of securities classified as available-for-sale and recorded at fair value based on actively quoted market prices. NRG accounts for the Nuclear Decommissioning Trust Fund in accordance with ASC 980, Regulated Operations , because the Company's nuclear decommissioning activities are subject to approval by the PUCT with regulated rates that are designed to recover all decommissioning costs and that can be charged to and collected from the ratepayers per PUCT mandate. Since the Company is in compliance with PUCT rules and regulations regarding decommissioning trusts and the cost of decommissioning is the responsibility of the Texas ratepayers, not NRG, all realized and unrealized gains or losses (including other-than-temporary impairments) related to the Nuclear Decommissioning Trust Fund are recorded to the Nuclear Decommissioning Trust liability and are not included in net income or accumulated OCI, consistent with regulatory treatment. The following table summarizes the aggregate fair values and unrealized gains and losses for the securities held in the trust funds, as well as information about the contractual maturities of those securities. As of September 30, 2019 As of December 31, 2018 (In millions, except maturities) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Cash and cash equivalents $ 20 $ — $ — — $ 19 $ — $ — — U.S. government and federal agency obligations 51 5 — 13 46 1 — 12 Federal agency mortgage-backed securities 97 3 — 24 100 1 2 23 Commercial mortgage-backed securities 27 1 1 24 22 — 1 22 Corporate debt securities 112 6 — 11 96 1 2 11 Equity securities 444 295 — — 376 231 1 — Foreign government fixed income securities 5 — — 10 4 — — 9 Total $ 756 $ 310 $ 1 $ 663 $ 234 $ 6 The following table summarizes proceeds from sales of available-for-sale securities held in the trust funds and the related realized gains and losses from these sales. The cost of securities sold is determined on the specific identification method. Nine months ended September 30, 2019 2018 (In millions) Realized gains $ 8 $ 8 Realized losses (7) (8) Proceeds from sale of securities 271 398

Accounting for Derivative Instr

Accounting for Derivative Instruments and Hedging Activities	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Accounting for Derivative Instruments and Hedging Activities	Accounting for Derivative Instruments and Hedging Activities Energy-Related Commodities As of September 30, 2019, NRG had energy-related derivative instruments extending through 2034. The Company marks these derivatives to market through the statement of operations. NRG has executed power purchase agreements extending through 2033 that qualified for the NPNS exception and were therefore exempt from fair value accounting treatment. 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 September 30, 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 10, 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 category, excluding those derivatives that qualified for the NPNS exception, as of September 30, 2019 and December 31, 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. Total Volume September 30, 2019 December 31, 2018 Category Units (In millions) Emissions Short Ton 2 (2) Renewable Energy Certificates Certificates 1 1 Coal Short Ton 4 13 Natural Gas MMBtu (273) (330) Oil Barrels — 1 Power MWh 37 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 sheets: Fair Value Derivative Assets Derivative Liabilities September 30, 2019 December 31, 2018 September 30, 2019 December 31, 2018 (In millions) Derivatives Not Designated as Cash Flow or Fair Value Hedges: Interest rate contracts current $ — $ 17 $ — $ — Interest rate contracts long-term — 22 — — Commodity contracts current 735 747 668 673 Commodity contracts long-term 358 295 364 304 Total Derivatives Not Designated as Cash Flow or Fair Value Hedges $ 1,093 $ 1,081 $ 1,032 $ 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 of derivatives by counterparty master agreement level and collateral received or paid: Gross Amounts Not Offset in the September 30, 2019 Balance Sheet Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount (In millions) Commodity contracts: Derivative assets $ 1,093 $ (869) $ (5) $ 219 Derivative liabilities (1,032) 869 70 (93) Total commodity contracts $ 61 $ — $ 65 $ 126 Gross Amounts Not Offset in the December 31, 2018 Balance Sheet Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount (In millions) 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 Loss The following table summarizes the effects on the Company's accumulated OCL balance attributable to cash flow hedge derivatives, net of tax: Interest Rate Contracts Three months ended Nine months ended September 30, 2018 September 30, 2018 (In millions) Accumulated OCL beginning balance $ (23) $ (54) Reclassified from accumulated OCL to income: Due to realization of previously deferred amounts 1 8 Mark-to-market of cash flow hedge accounting contracts (3) 21 Sale of NRG Yield and Renewables Platform 25 25 Accumulated OCL ending balance, net of $0 tax $ — $ — Amounts reclassified from accumulated OCL into income are recorded in discontinued operations. Impact of Derivative Instruments on the Statements of Operations Unrealized gains and losses associated with changes in the fair value of derivative instruments not accounted for as cash flow hedges are reflected in current period results of operations. The following table summarizes the pre-tax effects of economic hedges that have not been designated as cash flow hedges 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. Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 Unrealized mark-to-market results (In millions) Reversal of previously recognized unrealized (gains) on settled positions related to economic hedges $ (118) $ (84) $ (88) $ (85) Reversal of acquired (gain) positions related to economic hedges (3) (10) (4) (11) Net unrealized gains on open positions related to economic hedges 57 26 69 158 Total unrealized mark-to-market (losses)/gains for economic hedging activities (64) (68) (23) 62 Reversal of previously recognized unrealized (gains) on settled positions related to trading activity (1) (4) (8) (10) Net unrealized (losses)/gains on open positions related to trading activity (3) 8 23 27 Total unrealized mark-to-market (losses)/gains for trading activity (4) 4 15 17 Total unrealized (losses)/gains $ (68) $ (64) $ (8) $ 79 Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 (In millions) Unrealized (losses)/ gains included in operating revenues $ (214) $ 59 $ 66 $ (14) Unrealized gains/(losses) included in cost of operations 146 (123) (74) 93 Total impact to statement of operations — energy commodities $ (68) $ (64) $ (8) $ 79 Total impact to statement of operations — interest rate contracts $ — $ 2 $ (38) $ 17 The reversals of acquired gain or loss positions were valued based upon the forward prices on the acquisition date. The roll-off amounts were offset by realized gains or losses at the settled prices and are reflected in operating revenue or cost of operations during the same period. For the nine months ended September 30, 2019, the $69 million unrealized gain from open economic hedge positions was primarily the result of an increase in value of forward purchases of ERCOT heat rate due to ERCOT heat rate expansion. For the nine months ended September 30, 2018, the $158 million unrealized gain from open economic hedge positions was primarily the result of an increase in value of forward purchases of ERCOT heat rate and ERCOT electricity contracts due to ERCOT heat rate expansion and increases in ERCOT power prices. 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 with adequate assurance clauses that are in a net liability position as of September 30, 2019 was $39 million. The collateral required for contracts with credit rating contingent features that are in a net liability position as of September 30, 2019 was $18 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 $2 million as of September 30, 2019. See Note 5, Fair Value of Financial Instruments , for discussion regarding concentration of credit risk.

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	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 Topic 840 to the updated guidance in Topic 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 Topic 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 Topic 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 Topic 840. The Company elected the following practical expedients, which allow entities to: 1. not reassess whether any contracts that existed prior to the January 1, 2019 implementation date are or contain leases; 2. 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 Topic 840 will be classified as finance leases under Topic 842 and all commenced operating leases under Topic 840 will be classified as operating leases under Topic 842; 3. not reassess initial direct costs for any leases; 4. not reassess whether existing land easements, which were not previously accounted as leases under Topic 840, are or contain leases; and 5. 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) Three months ended September 30, 2019 Nine months ended September 30, 2019 Operating lease cost $ 26 $ 82 Short-term lease cost 1 2 Variable lease cost 1 4 Sublease income (4) (13) Total lease cost $ 24 $ 75 Other information: (In millions) Nine months ended September 30, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 77 Right-of-use assets obtained in exchange for new operating lease liabilities 215 Lease Term and Discount Rate for operating leases: September 30, 2019 Weighted average remaining lease term (in years) 7.9 Weighted average discount rate 5.74 % As of September 30, 2019, annual payments based on the maturities of NRG's leases are expected to be as follows: (In millions) Remainder of 2019 $ 26 2020 94 2021 86 2022 86 2023 86 Thereafter 372 Total undiscounted lease payments $ 750 Less: present value adjustment (177) Total discounted lease payments $ 573

Impairments

Impairments	9 Months Ended
	Sep. 30, 2019
Property, Plant and Equipment [Abstract]
Impairments	Impairments 2019 Impairment Losses Petra Nova — 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 has now become 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 — During the nine months ended September 30, 2019, the Company recorded $7 million of impairment losses on cost investments and intangible assets. 2018 Impairment Losses Keystone and Conemaugh — On June 29, 2018, the Company entered into an agreement to sell 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. The transaction closed on September 5, 2018. 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 NYSPSC, 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 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, which would render the project impractical. Consequently, the Company recorded an impairment loss of $46 million during the second quarter of 2018, reducing the carrying amount of the related assets to $0. Other Impairments — During the nine months ended September 30, 2018, the Company recorded impairment losses on equity method investments of $16 million.

Debt and Finance Leases

Debt and Finance Leases	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt and Finance Leases	Debt and Finance Leases Long-term debt and finance leases consisted of the following: (In millions, except rates) September 30, 2019 December 31, 2018 September 30, 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 575 575 2.750 Senior Secured First Lien Notes, due 2024 600 — 3.750 Senior Secured First Lien Notes, due 2029 500 — 4.450 Term Loan Facility (a) — 1,698 L+ 0.0175 Revolver Facility (b) 215 — L+ 0.0175 - P+ 0.0075 Tax-exempt bonds 466 466 0.04125 - 0.06 Subtotal recourse debt 6,140 6,523 Non-recourse debt: Agua Caliente Borrower 1, due 2038 83 86 5.430 Midwest Generation — 48 4.390 Other 34 34 various Subtotal all non-recourse debt 117 168 Subtotal long-term debt (including current maturities) 6,257 6,691 Finance leases — 1 6.500 Subtotal long-term debt and finance leases (including current maturities) 6,257 6,692 Less current maturities (302) (72) Less debt issuance costs (68) (70) Discounts (89) (101) Total long-term debt and finance leases $ 5,798 $ 6,449 (a) As of December 31, 2018, the interest rate was 1-month LIBOR plus 1.75% (b) As of September 30, 2019, L is equal to 1-week LIBOR and P is equal to Prime Rate Recourse Debt Senior Notes Issuance of 2029 Senior Notes On May 14, 2019, NRG issued $733 million of aggregate principal amount at par of 5.25% senior unsecured notes due 2029, or the 2029 Senior Notes. The 2029 Senior Notes are senior unsecured obligations of NRG and are guaranteed by certain of its subsidiaries. Interest will be paid semi-annually beginning on December 15, 2019, until the maturity date of June 15, 2029. The proceeds from the issuance of the 2029 Senior Notes were utilized to redeem the Company's remaining 6.25% Senior Notes due 2024. Issuance of 2024 and 2029 Senior Secured First Lien Notes On May 28, 2019, NRG issued $1.1 billion of aggregate principal amount of senior secured first lien notes, consisting of $600 million 3.75% senior secured first lien notes due 2024 and $500 million 4.45% senior secured first lien notes due 2029, or the Senior Secured First Lien Notes, at a discount. The Senior Secured First Lien Notes are guaranteed on a first-priority basis by each of NRG’s current and future subsidiaries that guarantee indebtedness under its credit agreement. The Senior Secured First Lien Notes will be secured by a first priority security interest in the same collateral that is pledged for the benefit of the lenders under NRG’s credit agreement, which consists of a substantial portion of the property and assets owned by NRG and the guarantors. The collateral securing the Senior Secured First Lien Notes will be released if the Company obtains an investment grade rating from two out of the three rating agencies, subject to an obligation to reinstate the collateral if such rating agencies withdraw the Company's investment grade rating or downgrade its rating below investment grade. Interest will be paid semi-annually beginning on December 15, 2019, until the maturity dates of June 15, 2024 and June 15, 2029. The proceeds from the issuance of the Senior Secured First Lien Notes, together with cash on hand, were used to repay the Company's 2023 Term Loan Facility. 2024 Senior Notes Redemption During the second quarter of 2019, the Company redeemed $733 million of its 6.25% Senior Notes due 2024 and recorded a loss on debt extinguishment of $29 million, which included the write-off of previously deferred debt issuance costs of $5 million. Senior Credit Facility 2023 Term Loan Facility Repayment On May 28, 2019, the Company repaid its $1.7 billion 2023 Term Loan Facility using the proceeds from the issuance of the Senior Secured First Lien Notes, as well as cash on hand, resulting in a decrease of $594 million to long-term debt outstanding. The Company recorded a loss on debt extinguishment of $17 million, which included the write-off of previously deferred debt issuance costs of $13 million. As a result of the repayment of the outstanding 2023 Term Loan Facility, the Company terminated the related interest rate swap agreements, which were in-the-money, and received $25 million that was recorded as a reduction to interest expense. Revolving Credit Facility Modification On May 28, 2019, the Company amended its existing credit agreement to, among other things, (i) provide for a $184 million increase in revolving commitments, resulting in aggregate revolving commitments under the amended credit agreement equal to $2.6 billion, (ii) extend the maturity date of the revolving loans and commitments under the amended credit agreement to May 28, 2024, (iii) provide for a release of the collateral securing the amended credit agreement if NRG obtains an investment grade rating from two out of the three rating agencies, subject to an obligation to reinstate the collateral if such rating agencies withdraw NRG’s investment grade rating or downgrade NRG’s rating below investment grade, (iv) reduce the applicable margins for borrowings under (a) ABR Revolving Loans from 1.25% to 0.75% and (b) Eurodollar Revolving Loans from 2.25% to 1.75%, (v) add a sustainability-linked pricing metric that permits an interest rate adjustment tied to NRG meeting targets related to environmental sustainability and (vi) make certain other changes to the existing covenants. As of September 30, 2019, $215 million of borrowings were outstanding, which was fully repaid as of November 7, 2019. Non-Recourse Debt Agua Caliente Borrower 1 On January 22, 2019, the lenders of the Agua Caliente Borrower 1 debt notified Agua Caliente Borrower 1, a subsidiary of the Company, of certain defaults under the financing agreement as it relates to the bankruptcy filing made by PG&E on January 29, 2019. PG&E is the offtaker of the underlying contracts, which are material to the project. The financing was entered into along with Agua Caliente Borrower 2, LLC, a subsidiary of Clearway Energy Inc., which is joint and several to the parties. On October 21, 2019, the Company repaid the outstanding amount on the notes at 102% plus accrued interest through the payment date. Cottonwood - Letters of Credit On January 4, 2019, the Company entered into an $80 million credit agreement to issue letters of credit, which is currently supporting the Cottonwood facility lease. Annual fees of 1.33% on the facility are paid quarterly in advance. As of September 30, 2019, the full $80 million was issued.

Investments Accounted for Using

Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs	9 Months Ended
	Sep. 30, 2019
Variable Interest Entities Disclosure [Abstract]
Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs	Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs Entities that are not Consolidated NRG accounts for the Company's significant investments using the equity method of accounting. NRG's carrying value of equity investments can be impacted by a number of elements including impairments, unrealized gains and losses on derivatives and movements in foreign currency exchange rates. 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 October 17, 2019, a group of unsecured creditors filed a competing plan of reorganization that would also assume all power purchase agreements, including those held by the Agua Caliente project and the two Ivanpah units. NRG's maximum exposure to loss is limited to its equity investment, which was $213 million for Agua Caliente and $28 million for Ivanpah as of September 30, 2019. See Note 10, Debt and Finance Leases, for further discussion on Agua Caliente. Variable Interest Entities that are not consolidated 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 and entered into a settlement during the second quarter of 2018. The settlement 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 during the nine months ended September 30, 2018. 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. Variable Interest Entities that are Consolidated The Company has a controlling financial interest in certain entities that have been identified as VIEs under ASC 810. These arrangements are primarily 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, to the Company's 2018 Form 10-K. The summarized financial information for the Company's consolidated VIEs consisted of the following: (In millions) September 30, 2019 December 31, 2018 Current assets $ 3 $ 3 Net property, plant and equipment 73 76 Other long-term assets 28 28 Total assets 104 107 Current liabilities 1 2 Long-term debt 28 29 Other long-term liabilities 8 7 Total liabilities 37 38 Redeemable noncontrolling interest 19 19 Net assets less noncontrolling interest $ 48 $ 50

Changes in Capital Structure

Changes in Capital Structure	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Changes in Capital Structure	Changes in Capital Structure As of September 30, 2019 and December 31, 2018, the Company had 500,000,000 shares of common stock authorized. The following table reflects the changes in NRG's common stock issued and outstanding: Issued Treasury Outstanding Balance as of December 31, 2018 420,288,886 (136,638,847) 283,650,039 Shares issued under LTIPs 1,570,958 — 1,570,958 Shares repurchased — (33,235,480) (33,235,480) Balance as of September 30, 2019 421,859,844 (169,874,327) 251,985,517 Shares issued under LTIPs subsequent to September 30, 2019 3,757 — 3,757 Shares issued under ESPP — 46,128 46,128 Shares repurchased subsequent to September 30, 2019 — (441,112) (441,112) Balance as of October 31, 2019 421,863,601 (170,269,311) 251,594,290 Share Repurchases The following repurchases have been made during the nine months ended September 30, 2019 and through October 31, 2019 under the share repurchase programs: Total number of shares purchased Average price paid per share Amounts paid for shares purchased (in millions) Board Authorized Share Repurchases 2018 program: Repurchases made during January-February to complete the 2018 program 6,153,415 $ 40.61 $ 250 2019 programs: Repurchases under February 28, 2019 Accelerated Share Repurchase Agreement- $1.0 billion share repurchase program (a) 9,438,671 400 Other repurchases under the $1.0 billion share repurchase program (a) 16,615,479 600 Total $1.0 billion share repurchase program 26,054,150 38.38 1,000 Repurchases made through September 30, 2019 under the $250 million share repurchase program (b) 1,027,915 36.99 38 Total Share Repurchases during the nine months ended September 30, 2019 33,235,480 $ 1,288 Repurchases made subsequent to September 30, 2019 under the $250 million program (b) 441,112 39.10 $ 17 Total Share Repurchases during the period ended October 31, 2019 33,676,592 $ 1,305 (a) The $1 billion share repurchase program was announced in February 2019 (b) The $250 million share repurchase program was announced in August 2019 On February 28, 2019, the Company executed an accelerated share repurchase agreement, or ASR Agreement, with a financial institution to repurchase a total of $400 million of outstanding common stock based on a volume weighted average price. The Company received initial shares of 9,086,903, which were recorded in treasury stock at fair value based on the closing price on March 12, 2019, of $390 million, with the remaining $10 million recorded in additional paid in capital, representing the value of the forward contract to purchase additional shares. In April 2019, the financial institution delivered the remaining shares pursuant to the ASR agreement and the Company received 351,768 additional shares. The average price paid for all the shares delivered under the ASR Agreement was $42.38 per share. Upon receipt of the additional shares in April 2019, the Company transferred the $10 million from additional paid in capital to treasury stock. Employee Stock Purchase Plan In March 2019, the Company reopened participation in the ESPP, which allows eligible employees to elect to withhold between 1% and 10% of their eligible compensation to purchase shares of NRG common stock at the lesser of 95% of its market value on the offering date or 95% of the fair market value on the exercise date. An offering date will occur each April 1 and October 1. An exercise date will occur each September 30 and March 31. In October 2019, 46,128 shares of common stock were issued to employee accounts from treasury stock for the offering period of April 1, 2019 to September 30, 2019. NRG Common Stock Dividends A quarterly dividend of $0.03 per share was paid on the Company's common stock during the three months ended September 30, 2019. On October 17, 2019, NRG declared a quarterly dividend on the Company's common stock of $0.03 per share, payable November 15, 2019, to stockholders of record as of November 1, 2019, representing $0.12 per share on an annualized basis. 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 will increase 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.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Basic earnings per common share is computed by dividing net income by the weighted average number of common shares outstanding. Shares issued and treasury shares repurchased during the year are weighted for the portion of the year that they were outstanding. Diluted earnings per share is computed in a manner consistent with that of basic income per share while giving effect to all potentially dilutive common shares that were outstanding during the period. The outstanding non-qualified stock options, non-vested restricted stock units, market stock units, and relative performance stock units are not considered outstanding for purposes of computing basic income per share. However, these instruments are included in the denominator for purposes of computing diluted income per share under the treasury stock method. The 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 and diluted income per share is shown in the following table: Three months ended September 30, Nine months ended September 30, (In millions, except per share data) 2019 2018 2019 2018 Basic income per share attributable to NRG Energy, Inc; Net income/(loss) attributable to NRG Energy, Inc. common stockholders $ 372 $ (72) $ 1,055 $ 280 Weighted average number of common shares outstanding - basic 254 299 266 309 Income/(loss) per weighted average common share — basic $ 1.46 $ (0.24) $ 3.97 $ 0.91 Diluted income per share attributable to NRG Energy, Inc; Net income/(loss) attributable to NRG Energy, Inc. available to common shareholders $ 372 $ (72) $ 1,055 280 Weighted average number of common shares outstanding - basic 254 299 266 309 Incremental shares attributable to the issuance of equity compensation (treasury stock method) 2 — 2 4 Weighted average number of common shares outstanding - dilutive 256 299 268 313 Income/(loss) per weighted average common share — diluted $ 1.45 $ (0.24) $ 3.94 $ 0.89 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 per share: Three months ended September 30, Nine months ended September 30, (In millions of shares) 2019 2018 2019 2018 Equity compensation plans — 4 — —

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company's segment structure reflects how management currently makes financial decisions and allocates resources. The Company's businesses are segregated into the Retail, Generation and corporate segments. Retail includes Mass customers and Business Solutions, which includes C&I customers and other distributed and reliability products. Intersegment sales are accounted for at market. Generation includes all power plant activities, domestic and international, as well as renewables. The financial information for the nine months ended September 30, 2018 has been recast to reflect the current segment structure. On February 4, 2019, as described in Note 4, Acquisitions, Discontinued Operations and Dispositions , the Company completed the sale of and deconsolidated the South Central Portfolio. On August 31, 2018, as described in Note 4, Acquisitions, Discontinued Operations and Dispositions, NRG deconsolidated NRG Yield, Inc., its Renewables Platform and Carlsbad for financial reporting purposes. The financial information presented below has been recast to reflect the presentation of these entities as discontinued operations within the corporate segment. 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. Three months ended September 30, 2019 (a) Retail Generation Corporate Eliminations Total (In millions) Operating revenues (b) $ 2,544 $ 974 $ — $ (522) $ 2,996 Depreciation and amortization 37 47 7 — 91 Reorganization costs 1 — — — 1 (Loss)/gain on sale of assets (1) 1 — — — Equity in earnings of unconsolidated affiliates — 29 — — 29 Income/(loss) from continuing operations before income taxes 422 64 (107) 1 380 Income/(loss) from continuing operations 422 63 (112) 1 374 Loss from discontinued operations, net of tax — — (2) — (2) Net income/(loss) 422 63 (114) 1 372 Net income/(loss) attributable to NRG Energy, Inc. $ 422 $ 63 $ (114) $ 1 $ 372 (a) Includes intersegment revenues and costs associated with the internal transfer of power, which is based on average annualized market prices and results in higher revenues in Generation and higher cost of operations in Retail that are eliminated in consolidation (b) Operating revenues include intersegment sales and net derivative gains and losses of: $ 1 $ 513 $ 8 $ — $ 522 Three months ended September 30, 2018 (a) Retail Generation Corporate Eliminations Total (In millions) Operating revenues (b) $ 2,203 $ 1,478 $ 1 $ (722) $ 2,960 Depreciation and amortization 30 60 7 2 99 Reorganization costs 6 3 18 — 27 Equity in earnings of unconsolidated affiliates — 20 3 (3) 20 Loss on debt extinguishment, net — — (19) — (19) (Loss)/income from continuing operations before income taxes (128) 575 (145) (7) 295 (Loss)/income from continuing operations (128) 574 (152) (7) 287 Loss from discontinued operations, net of tax — — (336) — (336) Net (loss)/income (128) 574 (488) (7) (49) Net (loss)/income attributable to NRG Energy, Inc. $ (128) $ 559 $ (498) $ (5) $ (72) (a) Includes intersegment revenues and costs associated with our internal transfer of power, which is based on average annualized market prices and results in higher revenues in Generation and higher cost of operations in Retail that are eliminated in consolidation (b) Operating revenues include intersegment sales and net derivative gains and losses of: $ 1 $ 739 $ (18) $ — $ 722 Nine months ended September 30, 2019 (a) Retail Generation Corporate Eliminations Total (In millions) Operating revenues (b) $ 5,899 $ 3,164 $ — $ (1,437) $ 7,626 Depreciation and amortization 100 138 23 — 261 Impairment losses 1 — — — 1 Reorganization costs 4 1 11 — 16 (Loss)/gain on sale of assets (1) 2 1 — 2 Equity in earnings of unconsolidated affiliates — 8 — — 8 Loss on debt extinguishment, net — — (47) — (47) Income/(loss) from continuing operations before income taxes 253 795 (382) — 666 Income/(loss) from continuing operations 252 794 (389) — 657 Income from discontinued operations, net of tax — — 399 — 399 Net income 252 794 10 — 1,056 Net income attributable to NRG Energy, Inc. common stockholders $ 251 $ 794 $ 10 $ — $ 1,055 (a) Includes intersegment revenues and costs associated with our internal transfer of power, which is based on average annualized market prices and results in higher revenues in Generation and higher cost of operations in Retail that are eliminated in consolidation (b) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 6 $ 1,375 $ 56 $ — $ 1,437 Nine months ended September 30, 2018 (a) Retail Generation Corporate Eliminations Total (In millions) Operating revenues (b) $ 5,497 $ 2,916 $ — $ (927) $ 7,486 Depreciation and amortization 86 220 25 — 331 Impairment losses — 74 — — 74 Reorganization costs 10 10 50 — 70 Gain on sale of assets — 1 29 — 30 Equity in earnings of unconsolidated affiliates — 27 4 (5) 26 Income/(loss) from continuing operations before income taxes 732 256 (412) (4) 572 Income/(loss) from continuing operations 732 255 (430) (4) 553 Loss from discontinued operations, net of tax — — (272) — (272) Net income/(loss) 732 255 (702) (4) 281 Net income/(loss) attributable to NRG Energy, Inc. common stockholders $ 731 $ 246 $ (697) $ — $ 280 (a) Includes intersegment revenues and costs associated with our internal transfer of power, which is based on average annualized market prices and results in higher revenues in Generation and higher cost of operations in Retail that are eliminated in consolidation (b) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 7 $ 944 $ (24) $ — $ 927

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Effective Income Tax Rate The income tax provision consisted of the following: Three months ended September 30, Nine months ended September 30, (In millions, except rates) 2019 2018 2019 2018 Income from continuing operations before income taxes $ 380 $ 295 $ 666 $ 572 Income tax expense from continuing operations 6 8 9 19 Effective income tax rate 1.6 % 2.7 % 1.4 % 3.3 % For the three and nine months ended September 30, 2019 and 2018, NRG's overall effective tax rates were lower than the statutory rate of 21%, primarily due to the tax benefit for the change in valuation allowance, partially offset by current state tax expense. Uncertain Tax Benefits As of September 30, 2019, NRG has recorded a non-current tax liability of $29 million for uncertain tax benefits from positions taken on various state income tax returns, including accrued interest. For the nine months ended September 30, 2019, NRG accrued an immaterial amount of interest relating to the uncertain tax benefits. As of September 30, 2019, NRG had cumulative interest and penalties related to these uncertain tax benefits of $5 million. The Company recognizes interest and penalties related to uncertain tax benefits in income tax expense. NRG is subject to examination by taxing authorities for income tax returns filed in the U.S. federal jurisdiction and various state and foreign jurisdictions including operations located in Australia. The Company is no longer subject to U.S. federal income tax examinations for years prior to 2015. With few exceptions, state and local income tax examinations are no longer open for years before 2010.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2019
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The following table summarizes NRG's material related party transactions with third party affiliates: Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 (In millions) Revenues from Related Parties Included in Operating Revenues Gladstone $ 2 $ 1 $ 3 $ 2 GenConn — 1 — 4 Ivanpah 7 8 25 13 Midway-Sunset 2 — 4 — Revenues from Related Parties recorded against selling, general and administrative expenses GenOn — 11 — 53 Total $ 11 $ 21 $ 32 $ 72 Gladstone — NRG provides services to Gladstone, an equity method investment, under an operations and maintenance agreement. Fees for services under this contract primarily include recovery of NRG's costs of operating the plant, as approved in the annual budget, as well as a base monthly fee. GenConn — NRG provides services to GenConn under operations and maintenance agreements with GenConn Devon and GenConn Middletown that began in June 2010 and June 2011, respectively. NRG no longer has an ownership interest in GenConn as a result of the sale of its ownership interests in NRG Yield, Inc. and its Renewables Platform. Ivanpah — NRG provides services to Ivanpah, an equity method investment, under an operations and maintenance agreement and a project management agreement with each project company. Fees for the services under these contracts primarily include recovery of NRG's costs of operating the plant and providing administrative services, plus a profit margin. Ivanpah became a related party to NRG upon deconsolidation in the second quarter of 2018. Midway-Sunset — NRG provides services to Midway-Sunset, an equity method investment, under an operations and maintenance agreement. Fees for the services under this contract primarily include recovery of NRG's costs of operating the plant, as approved in the annual budget, as well as a base monthly fee and an annual incentive bonus. GenOn — NRG provided various management, personnel and other services to GenOn under the transition services agreement in conjunction with the confirmation of the GenOn Entities' plan of reorganization. GenOn provided notice to NRG of its intent to terminate the transition services agreement effective August 15, 2018 and all amounts owed and payable to NRG were settled.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments First Lien Structure NRG has granted first liens to certain counterparties on a substantial portion of the Company's assets, excluding NRG's assets that have project-level financing and the assets of certain non-guarantor subsidiaries, 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 MWh equivalents. The Company's lien counterparties may have a claim on NRG's assets to the extent market prices exceed the hedged price. As of September 30, 2019, all 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 blended 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. Additionally, the lignite supply agreement obligates NRG to provide additional performance assurance if required by the Railroad Commission of Texas. 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 18, Regulatory Matters , and Note 19, 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 certain of 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. California Department of Water Resources and San Diego Gas & Electric Company v. Sunrise Power Company LLC — On January 29, 2016, CDWR and SDG&E (plaintiffs) filed a lawsuit against Sunrise Power Company, along with NRG and Chevron Power Corporation (defendants). In June 2001, CDWR and Sunrise entered into a 10-year PPA under which Sunrise would construct and operate a generating facility and provide power to CDWR. At the time the PPA was entered into, Sunrise had a transportation services agreement, or TSA, to purchase natural gas from Kern River through April 30, 2018. In August 2003, CDWR entered into an agreement with Sunrise and Kern River in which CDWR accepted assignment of the TSA through the term of the PPA. After the PPA expired, Kern River demanded that any reassignment be to a party which met certain creditworthiness standards which Sunrise did not. As such, the plaintiffs brought this lawsuit against the defendants alleging breach of contract, breach of covenant of good faith and fair dealing and improper distributions. Plaintiffs generally claim damages of $1.2 million per month for the remaining 70 months of the TSA. On April 20, 2016, the defendants filed objections in response to the plaintiffs' complaint. The objections were granted on June 14, 2016; however, the plaintiffs were allowed to file amended complaints on July 1, 2016. On July 27, 2016, defendants filed objections to the amended complaints. On November 18, 2016, the court sustained the objections and allowed plaintiffs another opportunity to file a second amended lawsuit which they did on January 13, 2017. On April 21, 2017, the court issued an order sustaining the objections without leave to amend. On July 14, 2017, plaintiffs filed a notice of appeal. On January 10, 2018, plaintiffs filed their opening appellate brief. Defendants filed their opposition brief on April 10, 2018. On May 30, 2018, plaintiffs filed their reply brief. Oral argument on the appeal occurred on October 23, 2019, and on November 4, 2019, the appellate court affirmed the trial court's decision to dismiss the lawsuit. 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. LaGen filed its answer and affirmative defenses on November 17, 2017. On September 6, 2019, the court continued the trial that had been scheduled to begin on October 21, 2019 and will reset the trial date after it addresses a pending motion regarding subject matter jurisdiction, which is scheduled to be argued on January 16, 2020. On February 4, 2019, NRG sold the South Central Portfolio, including the entities subject to this litigation. However, NRG has agreed to indemnify the purchaser for certain losses suffered in connection therewith.

Regulatory Matters

Regulatory Matters	9 Months Ended
	Sep. 30, 2019
Regulatory Matters Disclosure [Abstract]
Regulatory Matters	Regulatory Matters Environmental regulatory matters are discussed within Note 19, Environmental Matters , to this Form 10-Q . 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. 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 2019. ISO-NE — On February 5, 2019, FERC has informed the Company that it has made a preliminary finding that the Company violated FERC's market behavior rules in connection with offers made into the ISO-NE Forward Capacity Auction in 2016. On April 26, 2019, NRG responded to the preliminary findings. The Company understands that FERC is concerned that the Company was inaccurate in its communications with the Market Monitor regarding the costs and risks associated with operating certain units in the forward timeframe. NRG withdrew the bids prior to the 2016 auction in the normal course of our commercial business decision making.

Environmental Matters

Environmental Matters	9 Months Ended
	Sep. 30, 2019
Environmental Matters Disclosure [Abstract]
Environmental Matters	Environmental Matters NRG is subject to a wide range of environmental laws in the development, construction, ownership and operation of projects. These laws generally require that governmental permits and approvals be obtained before construction and during operation of power plants. NRG is also subject to laws regarding the protection of wildlife, including migratory birds, eagles and threatened and endangered species. The electric generation industry has been facing requirements regarding GHGs, combustion byproducts, water discharge and use, and threatened and endangered species that have been put in place in recent years. However, under the current U.S. presidential administration, some of these rules are being reconsidered and reviewed. In general, future laws are expected to require the addition of emissions controls or other environmental controls or to impose certain restrictions on the operations of the Company's facilities, which could have a material effect on the Company's consolidated financial position, results of operations, or cash flows. Federal and state environmental laws generally have become more stringent over time, although this trend could slow or pause in the near term with respect to federal laws under the current U.S. presidential administration. Air On July 8, 2019, EPA promulgated the ACE rule, which rescinded the 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. In February 2012, the EPA promulgated standards (the MATS rule) to control emissions of HAPs from coal and oil-fired electric generating units. The rule established limits for mercury, non-mercury metals, certain organics and acid gases, which had to be met beginning in April 2015. In December 2018, the EPA proposed a finding that regulating HAPs was not "appropriate and necessary" because the costs far exceed the benefits. Nonetheless, the EPA proposed keeping the substantive requirements of the MATS rule. While NRG cannot predict the final outcome of this rulemaking, NRG believes that because it has already invested in pollution controls and cleaner technologies, the fleet is well-positioned to comply with the MATS rule. Water Once Through Cooling Regulation — In August 2014, the EPA finalized the regulation regarding the use of water for once through cooling at existing facilities to address impingement and entrainment concerns. NRG anticipates that more stringent requirements will be incorporated into some of its water discharge permits over the next several years as NPDES permits are renewed. The Company anticipates the cost of complying with these requirements to be immaterial. 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, 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 released its opinion remanding portions of the rule to the EPA. Accordingly, 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 rule is revised. 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. 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.

Condensed Consolidating Financi

Condensed Consolidating Financial Information	9 Months Ended
	Sep. 30, 2019
Condensed Consolidating Financial Information Disclosure [Abstract]
Condensed Consolidating Financial Information	Condensed Consolidating Financial Information As of September 30, 2019, the Company had outstanding $4.4 billion of Senior Notes due from 2024 to 2048 and outstanding $1.1 billion of Senior Secured First Lien Notes due from 2024 to 2029, as shown in Note 10, 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 the Senior Secured First Lien Notes as of September 30, 2019: Ace Energy, Inc. NRG Business Services LLC NRG PacGen Inc. Allied Home Warranty GP LLC NRG Cabrillo Power Operations Inc. NRG Portable Power LLC Allied Warranty LLC NRG California Peaker Operations LLC NRG Power Marketing LLC Arthur Kill Power LLC NRG Cedar Bayou Development Company, LLC NRG Reliability Solutions LLC Astoria Gas Turbine Power LLC NRG Connected Home LLC NRG Renter's Protection LLC BidURenergy, Inc. NRG Connecticut Affiliate Services Inc. NRG Retail LLC Cabrillo Power I LLC NRG Construction LLC NRG Retail Northeast LLC Cabrillo Power II LLC NRG Curtailment Solutions, Inc NRG Rockford Acquisition LLC Carbon Management Solutions LLC NRG Development Company Inc. NRG Saguaro Operations Inc. Cirro Group, Inc. NRG Devon Operations Inc. NRG Security LLC Cirro Energy Services, Inc. NRG Dispatch Services LLC NRG Services Corporation Connecticut Jet Power LLC NRG Distributed Energy Resources Holdings LLC NRG SimplySmart Solutions LLC Devon Power LLC NRG Distributed Generation PR LLC NRG South Central Affiliate Services Inc. Dunkirk Power LLC NRG Dunkirk Operations Inc. NRG South Central Operations Inc. Eastern Sierra Energy Company LLC NRG ECOKAP Holdings LLC NRG South Texas LP El Segundo Power, LLC NRG El Segundo Operations Inc. NRG Texas C&I Supply LLC El Segundo Power II LLC NRG Energy Labor Services LLC NRG Texas Gregory LLC Energy Alternatives Wholesale, LLC NRG Energy Services Group LLC NRG Texas Holding Inc. Energy Choice Solutions LLC NRG Energy Services International Inc. NRG Texas LLC Energy Plus Holdings LLC NRG Energy Services LLC NRG Texas Power LLC Energy Plus Natural Gas LLC NRG Generation Holdings, Inc. NRG Warranty Services LLC Energy Protection Insurance Company NRG Greenco LLC NRG West Coast LLC Everything Energy LLC NRG Home & Business Solutions LLC NRG Western Affiliate Services Inc. Forward Home Security, LLC NRG Home Services LLC O'Brien Cogeneration, Inc. II GCP Funding Company, LLC NRG Home Solutions LLC ONSITE Energy, Inc. Green Mountain Energy Company NRG Home Solutions Product LLC Oswego Harbor Power LLC Gregory Partners, LLC NRG Homer City Services LLC Reliant Energy Northeast LLC Gregory Power Partners LLC NRG Huntley Operations Inc. Reliant Energy Power Supply, LLC Huntley Power LLC NRG HQ DG LLC Reliant Energy Retail Holdings, LLC Independence Energy Alliance LLC NRG Identity Protect LLC Reliant Energy Retail Services, LLC Independence Energy Group LLC NRG Ilion Limited Partnership RERH Holdings, LLC Independence Energy Natural Gas LLC NRG Ilion LP LLC Saguaro Power LLC Indian River Operations Inc. NRG International LLC Somerset Operations Inc. Indian River Power LLC NRG Maintenance Services LLC Somerset Power LLC Meriden Gas Turbines LLC NRG Mextrans Inc. Texas Genco GP, LLC Middletown Power LLC NRG MidAtlantic Affiliate Services Inc. Texas Genco Holdings, Inc. Montville Power LLC NRG Middletown Operations Inc. Texas Genco LP, LLC NEO Corporation NRG Montville Operations Inc. Texas Genco Services, LP New Genco GP, LLC NRG North Central Operations Inc. US Retailers LLC Norwalk Power LLC NRG Northeast Affiliate Services Inc. Vienna Operations Inc. NRG Advisory Services LLC NRG Norwalk Harbor Operations Inc. Vienna Power LLC NRG Affiliate Services Inc. NRG Operating Services, Inc. WCP (Generation) Holdings LLC NRG Arthur Kill Operations Inc. NRG Oswego Harbor Power Operations Inc. West Coast Power LLC NRG Astoria Gas Turbine Operations 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. However, 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 of Regulation S-X of the Securities Act. 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.
CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS QTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the three months ended September 30, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 2,473 $ 525 $ — $ (2) $ 2,996 Operating Costs and Expenses Cost of operations 1,728 421 6 (2) 2,153 Depreciation and amortization 52 32 7 — 91 Selling, general and administrative 132 28 50 — 210 Reorganization costs — — 1 — 1 Development costs — — 1 — 1 Total operating costs and expenses 1,912 481 65 (2) 2,456 Operating Income/(Loss) 561 44 (65) — 540 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 20 — 537 (557) — Equity in earnings of unconsolidated affiliates — 29 — — 29 Impairment losses on investments — (101) (6) — (107) Other income, net 11 1 5 — 17 Interest expense (4) (3) (92) — (99) Total other income/(expense) 27 (74) 444 (557) (160) Income/(Loss) from Continuing Operations Before Income Taxes 588 (30) 379 (557) 380 Income tax expense — 1 5 — 6 Income/(Loss) from Continuing Operations 588 (31) 374 (557) 374 Income/(loss) from discontinued operations, net of income tax — — (2) — (2) Net Income/(Loss) Attributable to NRG Energy, Inc. $ 588 $ (31) $ 372 $ (557) $ 372 (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS YTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the nine months ended September 30, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 6,382 $ 1,252 $ — $ (8) $ 7,626 Operating Costs and Expenses Cost of operations 4,676 956 25 (8) 5,649 Depreciation and amortization 157 81 23 — 261 Impairment losses 1 — — — 1 Selling, general and administrative 366 56 193 — 615 Reorganization costs — — 16 — 16 Development costs — 1 4 — 5 Total operating costs and expenses 5,200 1,094 261 (8) 6,547 Gain on sale of assets 1 1 — — 2 Operating Income/(Loss) 1,183 159 (261) — 1,081 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 32 — 1,266 (1,298) — Equity in earnings of unconsolidated affiliates — 8 — — 8 Impairment losses on investments — (101) (6) — (107) Other income, net 19 10 20 — 49 Loss on debt extinguishment, net — — (47) — (47) Interest expense (11) (12) (295) — (318) Total other income/(expense) 40 (95) 938 (1,298) (415) Income from Continuing Operations Before Income Taxes 1,223 64 677 (1,298) 666 Income tax expense — 2 7 — 9 Income from Continuing Operations 1,223 62 670 (1,298) 657 Income from discontinued operations, net of income tax 9 5 385 — 399 Net Income 1,232 67 1,055 (1,298) 1,056 Less: Net income attributable to redeemable noncontrolling interests — 1 — — 1 Net Income Attributable to NRG Energy, Inc. $ 1,232 $ 66 $ 1,055 $ (1,298) $ 1,055 (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) QTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) For the three months ended September 30, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Net Income/(Loss) $ 588 $ (31) $ 372 $ (557) $ 372 Other Comprehensive Loss Foreign currency translation adjustments, net (5) (4) (4) 9 (4) Available-for-sale securities, net — — (14) — (14) Defined benefit plans, net (40) — (41) 40 (41) Other comprehensive loss (45) (4) (59) 49 (59) Comprehensive Income/(Loss) Attributable to NRG Energy, Inc. $ 543 $ (35) $ 313 $ (508) $ 313 (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) YTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME For the nine months ended September 30, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Net Income $ 1,232 $ 67 $ 1,055 $ (1,298) $ 1,056 Other Comprehensive Loss Foreign currency translation adjustments, net (5) (4) (4) 9 (4) Available-for-sale securities, net — — (13) — (13) Defined benefit plans, net (40) — (47) 40 (47) Other comprehensive loss (45) (4) (64) 49 (64) Comprehensive Income 1,187 63 991 (1,249) 992 Less: Comprehensive income attributable to redeemable noncontrolling interests — 1 — — 1 Comprehensive Income Attributable to NRG Energy, Inc. $ 1,187 $ 62 $ 991 $ (1,249) $ 991 (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING BALANCE SHEETS	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS September 30, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated ASSETS (In millions) Current Assets Cash and cash equivalents $ — $ 26 $ 217 $ — $ 243 Funds deposited by counterparties 30 — — — 30 Restricted cash 2 1 1 — 4 Accounts receivable, net 2,049 194 426 (1,293) 1,376 Inventory 248 116 — — 364 Derivative instruments 740 28 — (33) 735 Cash collateral paid in support of energy risk management activities 146 18 — — 164 Prepayments and other current assets 178 15 78 — 271 Total current assets 3,393 398 722 (1,326) 3,187 Property, plant and equipment, net 1,494 965 156 — 2,615 Other Assets Investment in subsidiaries 786 — 4,677 (5,463) — Equity investments in affiliates — 405 — — 405 Operating lease right-of-use assets, net 85 271 126 — 482 Goodwill 359 232 — — 591 Intangible assets, net 390 438 — — 828 Nuclear decommissioning trust fund 756 — — — 756 Derivative instruments 356 14 — (12) 358 Deferred income taxes — 53 — — 53 Other non-current assets 151 30 71 — 252 Total other assets 2,883 1,443 4,874 (5,475) 3,725 Total Assets $ 7,770 $ 2,806 $ 5,752 $ (6,801) $ 9,527 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Current portion of long-term debt $ — $ 87 $ 215 $ — $ 302 Current portion of operating lease liabilities 21 31 21 — 73 Accounts payable 1,315 146 698 (1,293) 866 Derivative instruments 683 18 — (33) 668 Cash collateral received in support of energy risk management activities 30 — — — 30 Accrued expenses and other current liabilities 271 51 303 — 625 Total current liabilities 2,320 333 1,237 (1,326) 2,564 Other Liabilities Long-term debt 245 85 5,468 — 5,798 Non-current operating lease liabilities 70 307 123 — 500 Nuclear decommissioning reserve 294 — — — 294 Nuclear decommissioning trust liability 453 — — — 453 Derivative instruments 374 2 — (12) 364 Deferred income taxes (10) 67 13 — 70 Other non-current liabilities 412 160 464 — 1,036 Total other liabilities 1,838 621 6,068 (12) 8,515 Total Liabilities 4,158 954 7,305 (1,338) 11,079 Redeemable noncontrolling interest in subsidiaries — 19 — — 19 Stockholders’ Equity 3,612 1,833 (1,553) (5,463) (1,571) Total Liabilities and Stockholders’ Equity $ 7,770 $ 2,806 $ 5,752 $ (6,801) $ 9,527 (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 nine months ended September 30, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net income $ 1,232 $ 67 $ 1,055 $ (1,298) $ 1,056 Income from discontinued operations 9 5 385 — 399 Income from continuing operations 1,223 62 670 (1,298) 657 Adjustments to reconcile net income to net cash provided/(used) by operating activities: Distributions and equity in (earnings)/losses of unconsolidated affiliates and consolidated subsidiaries (32) (5) (1,266) 1,298 (5) Depreciation, amortization and accretion 181 85 23 — 289 Provision for bad debts 72 11 4 — 87 Amortization of nuclear fuel 40 — — — 40 Amortization of financing costs and debt discount/premiums — — 20 — 20 Loss on debt extinguishment, net — — 47 — 47 Amortization of emission allowances 21 7 — — 28 Amortization of unearned equity compensation — — 15 — 15 (Gain)/loss on sale and disposal of assets (25) 2 3 — (20) Impairment losses 1 101 6 — 108 Changes in derivative instruments 10 (12) 38 — 36 Changes in deferred income taxes and liability for uncertain tax benefits — (1) (2) — (3) Changes in collateral deposits in support of energy risk management activities 136 (7) — — 129 Changes in nuclear decommissioning trust liability 27 — — — 27 Changes in other working capital (401) (120) (81) — (602) Cash provided/(used) by continuing operations 1,253 123 (523) — 853 Cash provided/(used) by discontinued operations 17 (9) — — 8 Net Cash Provided/(Used) by Operating Activities 1,270 114 (523) — 861 Cash Flows from Investing Activities Intercompany dividends — — 1,665 (1,665) — Payments for acquisitions of businesses (348) — — — (348) Capital expenditures (135) (23) (25) — (183) Net proceeds from notes receivable — — 2 — 2 Net proceeds from sale of emission allowances 14 — — — 14 Investments in nuclear decommissioning trust fund securities (295) — — — (295) Proceeds from the sale of nuclear decommissioning trust fund securities 271 — — — 271 Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees 1 400 892 1,293 Net contributions to investments in unconsolidated affiliates — (94) — — (94) Contributions to discontinued operations — (44) — — (44) Cash (used)/provided by continuing operations (492) 239 2,534 (1,665) 616 Cash used by discontinued operations — (2) — — (2) Net Cash (Used)/Provided by Investing Activities (492) 237 2,534 (1,665) 614 Cash Flows from Financing Activities Payments from/(for) intercompany loans 784 (260) (524) — — Intercompany dividends (1,608) (57) — 1,665 — Payment of dividends to common stockholders — — (24) — (24) Payments for treasury stock — — (1,286) — (1,286) Payments for debt extinguishment costs — — (24) — (24) Distributions to noncontrolling interests from subsidiaries — (1) — — (1) Proceeds from issuance of common stock — — 3 — 3 Proceeds from issuance of long-term debt — — 2,048 — 2,048 Payment of debt issuance costs — — (34) — (34) Payments for long-term debt — (55) (2,432) — (2,487) Cash used by continuing operations (824) (373) (2,273) 1,665 (1,805) Cash provided by discontinued operations — 43 — — 43 Net Cash Used by Financing Activities (824) (330) (2,273) 1,665 (1,762) Change in cash from discontinued operations 17 32 — — 49 Net Decrease in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash (63) (11) (262) — (336) Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period 95 38 480 — 613 Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period $ 32 $ 27 $ 218 $ — $ 277 (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Prior Period for QTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the three months ended September 30, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 2,521 $ 441 $ — $ (2) $ 2,960 Operating Costs and Expenses Cost of operations 1,937 294 9 (2) 2,238 Depreciation and amortization 54 36 9 — 99 Selling, general and administrative 123 19 142 (73) 211 Reorganization costs — — 27 — 27 Development costs — (2) 3 — 1 Total operating costs and expenses 2,114 347 190 (75) 2,576 Gain on sale of assets — 14 — — 14 Operating Income/(Loss) 407 108 (190) 73 398 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 6 — 470 (476) — Equity in earnings/(losses) of unconsolidated affiliates — 21 (1) — 20 Impairment losses on investments — (1) — — (1) Other income, net 4 9 6 — 19 Loss on debt extinguishment, net — — (19) — (19) Interest expense (4) (8) (110) — (122) Total other income/(expense) 6 21 346 (476) (103) Income from Continuing Operations Before Income Taxes 413 129 156 (403) 295 Income tax expense/(benefit) 122 42 (156) — 8 Income from Continuing Operations 291 87 312 (403) 287 Income/(loss) from discontinued operations, net of income tax 16 20 (372) — (336) Net Income/(Loss) 307 107 (60) (403) (49) Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (62) 12 73 23 Net Income/(Loss) Attributable to NRG Energy, Inc. $ 307 $ 169 $ (72) $ (476) $ (72) (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Prior Period YTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the nine months ended September 30, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 6,437 $ 1,061 $ — $ (12) $ 7,486 Operating Costs and Expenses Cost of operations 4,794 713 18 (13) 5,512 Depreciation and amortization 177 128 26 — 331 Impairment losses — 74 — — 74 Selling, general and administrative 335 46 279 (73) 587 Reorganization costs 3 — 67 — 70 Development costs — — 10 (1) 9 Total operating costs and expenses 5,309 961 400 (87) 6,583 Gain on sale of assets 3 27 — — 30 Operating Income/(Loss) 1,131 127 (400) 75 933 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 14 — 1,156 (1,170) — Equity in earnings/(losses) of unconsolidated affiliates — 28 (2) — 26 Impairment losses on investments — (16) — — (16) Other income/(loss), net 12 (11) 11 — 12 Loss on debt extinguishment, net — — (22) — (22) Interest expense (11) (42) (308) — (361) Total other income/(expense) 15 (41) 835 (1,170) (361) Income from Continuing Operations Before Income Taxes 1,146 86 435 (1,095) 572 Income tax expense/(benefit) 343 26 (350) — 19 Income from Continuing Operations 803 60 785 (1,095) 553 Income/(loss) from discontinued operations, net of income tax 46 80 (398) — (272) Net Income 849 140 387 (1,095) 281 Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (181) 107 75 1 Net Income Attributable to NRG Energy, Inc. $ 849 $ 321 $ 280 $ (1,170) $ 280 (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) Prior Period QTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) For the three months ended September 30, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Net Income/(Loss) $ 307 $ 107 $ (60) $ (403) $ (49) Other Comprehensive (Loss)/Income Unrealized gain/(loss) on derivatives, net — 10 (12) 7 5 Foreign currency translation adjustments, net (2) (2) (1) 3 (2) Defined benefit plans, net — — (1) — (1) Other comprehensive (loss)/income (2) 8 (14) 10 2 Comprehensive Income/(Loss) 305 115 (74) (393) (47) Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable interests — (58) 11 73 26 Comprehensive Income/(Loss) Attributable to NRG Energy, Inc. $ 305 $ 173 $ (85) $ (466) $ (73) (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Prior Period YTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME For the nine months ended September 30, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Net Income $ 849 $ 140 $ 387 $ (1,095) $ 281 Other Comprehensive (Loss)/Income Unrealized gain on derivatives, net — 30 9 (15) 24 Foreign currency translation adjustments, net (8) (8) (9) 17 (8) Available-for-sale securities, net — — 1 — 1 Defined benefit plans, net — — (3) — (3) Other comprehensive (loss)/income (8) 22 (2) 2 14 Comprehensive Income 841 162 385 (1,093) 295 Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable interests — (167) 107 75 15 Comprehensive Income Attributable to NRG Energy, Inc. $ 841 $ 329 $ 278 $ (1,168) $ 280 (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING BALANCE SHEETS Prior Period	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2018 Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated ASSETS (In millions) 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 paid 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 Prior Period	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the nine months ended September 30, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net income $ 849 $ 140 $ 387 $ (1,095) $ 281 Income/(loss) from discontinued operations 46 80 (398) — (272) Income from continuing operations 803 60 785 (1,095) 553 Adjustments to reconcile net income to net cash provided/(used) by operating activities: Distributions and equity in (earnings)/losses of unconsolidated affiliates and consolidated subsidiaries (14) 9 (1,095) 1,110 10 Depreciation, amortization and accretion 201 137 26 — 364 Provision for bad debts 55 2 — — 57 Amortization of nuclear fuel 38 — — — 38 Amortization of financing costs and debt discount/premiums — 23 (2) — 21 Loss on debt extinguishment, net — — 22 — 22 Amortization of emission allowances and out-of-market contracts 15 6 — — 21 Amortization of unearned equity compensation — — 21 — 21 Gain on sale and disposal of assets (23) (27) — — (50) Impairment losses — 90 — — 90 Changes in derivative instruments (38) 40 (4) (15) (17) Changes in deferred income taxes and liability for uncertain tax benefits 343 11 (360) — (6) Changes in collateral deposits in support of energy risk management activities (16) (14) — — (30) Changes in nuclear decommissioning trust liability 50 — — — 50 GenOn Settlement — — (125) — (125) Loss on deconsolidation of Agua Caliente and Ivanpah projects — 13 — — 13 Changes in other working capital (385) (266) 290 — (361) Cash provided/(used) by continuing operations 1,029 84 (442) — 671 Cash provided by discontinued operations 72 324 — — 396 Net Cash Provided/(Used) by Operating Activities 1,101 408 (442) — 1,067 Cash Flows from Investing Activities Intercompany dividends — — 1,273 (1,273) — Payments for acquisitions of businesses (2) (207) — — (209) Capital expenditures (156) (150) (37) — (343) Net proceeds from sale of emission allowances 24 — — — 24 Investments in nuclear decommissioning trust fund securities (449) — — — (449) Proceeds from the sale of nuclear decommissioning trust fund securities 398 — — — 398 Proceeds from sale of assets, net of cash disposed of 10 8 1,537 — 1,555 Deconsolidation of Agua Caliente and Ivanpah projects — (268) — — (268) Net contributions to investments in unconsolidated affiliates — (39) — — (39) Contributions to discontinued operations — (23) — — (23) Cash (used)/provided by continuing operations (175) (679) 2,773 (1,273) 646 Cash used by discontinued operations (2) (703) — — (705) Net Cash (Used)/Provided by Investing Activities (177) (1,382) 2,773 (1,273) (59) Cash Flows from Financing Activities Payments from/(for) intercompany loans 476 170 (646) — — Intercompany dividends (1,273) — — 1,273 — Payment of dividends to common stockholders — — (28) — (28) Payments for treasury stock — — (1,000) — (1,000) Distributions to noncontrolling interests from subsidiaries — (17) — — (17) Proceeds from issuance of common stock — — 15 — 15 Proceeds from issuance of short and long-term debt — 163 832 — 995 Payment of debt issuance costs — — (19) — (19) Payments for short and long-term debt — (106) (864) — (970) Receivable from affiliate — — (26) — (26) Other — (4) — — (4) Cash (used)/provided by continuing operations (797) 206 (1,736) 1,273 (1,054) Cash provided by discontinued operations — 403 — — 403 Net Cash (Used)/Provided by Financing Activities (797) 609 (1,736) 1,273 (651) Effect of exchange rate changes on cash and cash equivalents — 1 — — 1 Change in cash from discontinued operations 70 24 — — 94 Net Increase/(Decrease) in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash 57 (388) 595 — 264 Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period 41 425 620 — 1,086 Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period $ 98 $ 37 $ 1,215 $ — $ 1,350 (a) All significant intercompany transactions have been eliminated in consolidation

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Use of Estimates	Use of EstimatesThe preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates.
Reclassifications	Reclassifications Certain prior year amounts have been reclassified for comparative purposes.
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 under the modified retrospective approach by applying the provisions of the new leases guidance at the effective date without adjusting the comparative periods presented. The Company assessed its leasing arrangements, evaluated the impact of applying practical expedients and accounting policy elections, and implemented lease accounting software to meet the reporting requirements of the standard. The Company established operating lease liabilities of $404 million and right-of-use assets of $321 million upon adoption, before considering deferred taxes. The adoption of Topic 842 did not have a material impact on the statements of operations or cash flows. See Note 8, Leases, for further discussion. Recent Accounting Developments - Guidance Not Yet Adopted 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 , in response to stakeholders’ observations that Topic 810, Consolidations , could be improved thereby improving general purpose financial reporting. Specifically, ASC 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 retained earnings at the beginning of the earliest period presented. The Company is evaluating the impact of adopting this guidance on the consolidated financial statements and disclosures. 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) . The guidance in ASU No. 2018-13 eliminates such disclosures as the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy. The amendments in ASU No. 2018-13 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, with early adoption permitted for any eliminated or modified disclosures. Certain disclosures in ASU No. 2018-13 are required to be applied on a retrospective basis and others on a prospective basis. As the amendment contemplates changes in disclosures only, it will have no material impact on the Company's results of operations, cash flows, or statement of financial position.
Nuclear Decommissioning	NRG's Nuclear Decommissioning Trust Fund assets, which are for the decommissioning of its 44% interest in STP, are comprised of securities classified as available-for-sale and recorded at fair value based on actively quoted market prices. NRG accounts for the Nuclear Decommissioning Trust Fund in accordance with ASC 980, Regulated Operations
Segment Reporting	The Company's segment structure reflects how management currently makes financial decisions and allocates resources. The Company's businesses are segregated into the Retail, Generation and corporate segments. Retail includes Mass customers and Business Solutions, which includes C&I customers and other distributed and reliability products. Intersegment sales are accounted for at market. Generation includes all power plant activities, domestic and international, as well as renewables. The financial information for the nine months ended September 30, 2018 has been recast to reflect the current segment structure. On February 4, 2019, as described in Note 4, Acquisitions, Discontinued Operations and Dispositions , the Company completed the sale of and deconsolidated the South Central Portfolio. On August 31, 2018, as described in Note 4, Acquisitions, Discontinued Operations and Dispositions, NRG deconsolidated NRG Yield, Inc., its Renewables Platform and Carlsbad for financial reporting purposes. The financial information presented below has been recast to reflect the presentation of these entities as discontinued operations within the corporate segment.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Net Income Attributable to NRG Energy, Inc. After Removing Net Loss from Noncontrolling Interest	The following table reflects the net income/(loss) attributable to NRG Energy, Inc. after removing the net income attributable to the noncontrolling interest and redeemable noncontrolling interest: Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 (In millions) Income from continuing operations, net of income tax $ 374 $ 274 $ 656 $ 547 (Loss)/income from discontinued operations, net of income tax (2) (346) 399 (267) Net income/(loss) attributable to NRG Energy, Inc. $ 372 $ (72) $ 1,055 $ 280
Other Balance Sheet Information	The following table presents the allowance for doubtful accounts included in accounts receivable, net; accumulated depreciation included in property, plant and equipment, net; accumulated amortization included in intangible assets, net and accumulated amortization included in out-of-market contracts, net: September 30, 2019 December 31, 2018 (In millions) Accounts receivable allowance for doubtful accounts $ 57 $ 32 Property, plant and equipment accumulated depreciation 1,759 1,811 Intangible assets accumulated amortization 1,215 1,149 Out-of-market contracts accumulated amortization — 37
Reconciliation of Cash and Cash Equivalents, Restricted Cash and Funds Deposited by Counterparties	The following table provides a reconciliation of cash and cash equivalents, restricted cash and funds deposited by counterparties reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the statements of cash flows: September 30, 2019 December 31, 2018 (In millions) Cash and cash equivalents $ 243 $ 563 Funds deposited by counterparties 30 33 Restricted cash 4 17 Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows $ 277 $ 613

Revenue Recognition (Tables)

Revenue Recognition (Tables)	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue from Contracts with Customer	Disaggregated Revenues The following tables represent the Company’s disaggregation of revenue from contracts with customers for the three and nine months ended September 30, 2019 and 2018 along with the reportable segment for each category: Three months ended September 30, 2019 Generation (In millions) Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue (a)(c) $ — $ 773 $ 237 $ 1,010 $ (568) $ 442 Capacity revenue (c) — — 151 151 1 152 Retail revenue Mass customers 2,080 — — — — 2,080 Business Solutions customers 465 — — — — 465 Total retail revenue 2,545 — — — — 2,545 Mark-to-market for economic hedging activities (a)(b) (1) (240) (16) (256) 47 (210) Other revenues (c) — 32 37 69 (2) 67 Total operating revenue 2,544 565 409 974 (522) 2,996 Less: Lease revenue 3 — 2 2 — 5 Less: Realized and unrealized ASC 815 revenue (a) (1) 944 66 1,010 (522) 487 Total revenue from contracts with customers $ 2,542 $ (379) $ 341 $ (38) $ — $ 2,504 (a) Generation includes higher revenues due to the Company's large internal transfer of power based on average annualized market prices, which are offset by higher cost of operations within Retail (b) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 (c) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue $ — $ 1,175 $ 62 $ 1,237 $ (569) $ 668 Capacity revenue — — 33 33 — 33 Other revenue — 9 (13) (4) — (4) Three months ended September 30, 2018 Generation (In millions) Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue (a)(c) $ — $ 585 $ 339 $ 924 $ (479) $ 445 Capacity revenue (c) — 1 190 191 1 192 Retail revenue Mass customers 1,768 — — — (2) 1,766 Business Solutions customers 434 — — — — 434 Total retail revenue 2,202 — — — (2) 2,200 Mark-to-market for economic hedging activities (a)(b) 1 259 36 295 (241) 55 Other revenues (c) — 8 60 68 — 68 Total operating revenue 2,203 853 625 1,478 (721) 2,960 Less: Lease revenue 3 — 3 3 — 6 Less: Realized and unrealized ASC 815 revenue (a) 1 1,159 79 1,238 (716) 523 Total revenue from contracts with customers $ 2,199 $ (306) $ 543 $ 237 $ (5) $ 2,431 (a) Generation includes higher revenues due to the Company's large internal transfer of power based on average annualized market prices, which are offset by higher cost of operations within Retail (b) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 (c) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue $ — $ 901 $ (8) $ 893 $ (475) $ 418 Capacity revenue — — 45 45 — 45 Other revenue — (1) 6 5 — 5 Nine months ended September 30, 2019 Generation (In millions) Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue (a)(c) $ — $ 1,628 $ 578 $ 2,206 $ (1,209) $ 997 Capacity revenue (c) — — 460 460 1 461 Retail revenue Mass customers 4,802 — — — (2) 4,800 Business Solutions customers 1,096 — — — — 1,096 Total retail revenue 5,898 — — — (2) 5,896 Mark-to-market for economic hedging activities (a)(b) 1 233 40 273 (223) 51 Other revenues (c) — 77 148 225 (4) 221 Total operating revenue 5,899 1,938 1,226 3,164 (1,437) 7,626 Less: Lease revenue 9 — 6 6 — 15 Less: Realized and unrealized ASC 815 revenue (a) 1 2,674 303 2,977 (1,433) 1,545 Total revenue from contracts with customers $ 5,889 $ (736) $ 917 $ 181 $ (4) $ 6,066 (a) Generation includes higher revenues due to the Company's large internal transfer of power based on average annualized market prices, which are offset by higher cost of operations within Retail (b) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 (c) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue $ — $ 2,417 $ 192 $ 2,609 $ (1,211) $ 1,398 Capacity revenue — — 80 80 1 81 Other revenue — 24 (9) 15 — 15 Nine months ended September 30, 2018 Generation (In millions) Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue (a)(c) $ — $ 1,251 $ 937 $ 2,188 $ (890) $ 1,298 Capacity revenue (c) — 1 498 499 1 500 Retail revenue Mass customers 4,321 — — — (4) 4,317 Business Solutions customers 1,181 — — — — 1,181 Total retail revenue 5,502 — — — (4) 5,498 Mark-to-market for economic hedging activities (a)(b) (5) (14) 9 (5) (21) (31) Other revenues (c) — 72 162 234 (13) 221 Total operating revenue 5,497 1,310 1,606 2,916 (927) 7,486 Less: Lease revenue 10 — 7 7 — 17 Less: Realized and unrealized ASC 815 revenue (a) (5) 1,872 211 2,083 (901) 1,177 Total revenue from contracts with customers $ 5,492 $ (562) $ 1,388 $ 826 $ (26) $ 6,292 (a) Generation includes higher revenues due to the Company's large internal transfer of power based on average annualized market prices, which are offset by higher cost of operations within Retail (b) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 (c) The following table represents the realized revenues related to derivative instruments that are accounted for under ASC 815 and included in the amounts above: Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue $ — $ 1,883 $ 78 $ 1,961 $ (880) $ 1,081 Capacity revenue — — 110 110 — 110 Other revenue — 3 14 17 — 17
Contract Asset and Liabilities	The following table reflects the contract assets and liabilities included in the Company’s balance sheet as of September 30, 2019 and December 31, 2018: (In millions) September 30, 2019 December 31, 2018 Deferred customer acquisition costs $ 130 $ 111 Accounts receivable, net - Contracts with customers 1,311 999 Accounts receivable, net - Derivative instruments 63 20 Accounts receivable, net - Affiliate 4 5 Total accounts receivable, net $ 1,378 $ 1,024 Unbilled revenues (included within Accounts receivable, net - Contracts with customers) $ 486 $ 392 Deferred revenues (a) 78 67 (a) Deferred revenues from contracts with customers for the nine months ended September 30, 2019 and the year ended December 31, 2018 were approximately $25 million and $19 million, respectively The revenue recognized from contracts with customers during the nine months ended September 30, 2019 and 2018 relating to the deferred revenue balance at the beginning of each period was $13 million and $16 million, respectively. The revenue recognized from contracts with customers during the three months ended September 30, 2019 and 2018 relating to the deferred revenue balance at the beginning of each period was $21 million and $19 million, respectively. The change in deferred revenue balances during the three and nine months ended September 30, 2019 and 2018 was primarily due to the timing difference of when consideration was received and when the performance obligation was transferred.

Acquisitions, Discontinued Op_2

Acquisitions, Discontinued Operations and Dispositions (Tables)	9 Months Ended
	Sep. 30, 2019
Discontinued Operations and Disposal Groups [Abstract]
Schedule of Purchase Price Allocation	The purchase price was provisionally allocated as follows: (In millions) Net current and non-current working capital $ 28 Other intangible assets 283 Goodwill (a) 18 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 is assigned to the Retail segment and is not deductible for tax purposes.
Schedule of Purchase Price Allocation, XOOM Acquisition	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 the South Central Portfolio discontinued operations were as follows: Three months ended Nine months ended (In millions) September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 Operating revenues $ — $ 101 $ 31 $ 310 Operating costs and expenses — (85) (23) (262) Gain from discontinued operations, net of tax — 16 8 48 (Loss)/gain on disposal of discontinued operations, net of tax (1) — 27 — (Loss)/gain from discontinued operations, including disposal, net of tax $ (1) $ 16 $ 35 $ 48
Summary of Major Classes of Assets and Liabilities Classified as Discontinued Operations	The following table summarizes the major classes of assets and liabilities classified as discontinued operations of the South Central Portfolio: (In millions) December 31, 2018 Cash and cash equivalents $ 89 Accounts receivable - trade, 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
Summary of Results of NRG Yield and Renewables Platform and Carlsbad Discontinued Operations	Summarized results of NRG Yield, Inc. and the Renewables Platform and Carlsbad discontinued operations were as follows: Three months ended Nine months ended (In millions) September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 Operating revenues $ — $ 297 $ 19 $ 925 Operating costs and expenses — (229) (9) (682) Other expenses — (42) (5) (165) Gain from operations of discontinued components, before tax — 26 5 78 Income tax expense — 9 — 4 Gain from discontinued operations, net of tax — 17 5 74 (Loss)/gain on disposal of discontinued operations, net of tax (1) (139) 330 (139) (Expense)/income from California property tax indemnification — (153) 22 (153) (Expense)/income from other commitments, indemnification and fees — (77) 5 (77) (Loss)/gain on disposal of discontinued operations, net of tax (1) (369) 357 (369) (Loss)/gain from discontinued operations, including disposal, net of tax $ (1) $ (352) $ 362 $ (295)
Summary of Major Classes of Assets And Liabilities Classified as Discontinued Operations Carlsbad	The following table summarizes the major classes of assets and liabilities classified as discontinued operations of Carlsbad: (In millions) December 31, 2018 Restricted cash $ 4 Accounts receivable - trade, 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
Summary of Results of GenOn Discontinued Operations	Summarized results of GenOn discontinued operations were as follows: Nine months ended (In millions) September 30, 2019 September 30, 2018 Interest income - affiliate $ — $ 3 Pension and post-retirement liability assumption — (2) Other 2 (26) Gain/(loss) from discontinued operations, net of tax $ 2 $ (25)

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Estimated carrying amounts and fair values of NRG's recorded financial instruments not carried at fair market value	The estimated carrying amounts and fair values of NRG's recorded financial instruments not carried at fair market value are as follows: September 30, 2019 December 31, 2018 Carrying Amount Fair Value Carrying Amount Fair Value (In millions) Assets: Notes receivable $ 11 $ 8 $ 17 $ 14 Liabilities: Long-term debt, including current portion (a) 6,168 6,706 6,591 6,697 (a) Excludes deferred financing costs, which are recorded as a reduction to long-term debt in the Company's consolidated balance sheets
Fair Value, Hierarchy for Long-term Debt	The following table presents the level within the fair value hierarchy for long-term debt, including current portion, as of September 30, 2019 and December 31, 2018: September 30, 2019 December 31, 2018 Level 2 Level 3 Level 2 Level 3 (In millions) Long-term debt, including current portion $ 6,375 $ 331 $ 6,528 $ 169
Assets and liabilities measured and recorded at fair value on the consolidated balance sheets on a recurring basis	The following tables present assets and liabilities measured and recorded at fair value on the Company's condensed consolidated balance sheets on a recurring basis and their level within the fair value hierarchy: September 30, 2019 (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and non-current assets) $ 24 $ — $ 19 $ 5 Nuclear trust fund investments: Cash and cash equivalents 20 20 — — U.S. government and federal agency obligations 51 51 — — Federal agency mortgage-backed securities 97 — 97 — Commercial mortgage-backed securities 27 — 27 — Corporate debt securities 112 — 112 — Equity securities 372 372 — — Foreign government fixed income securities 5 — 5 — Other trust fund investments: U.S. government and federal agency obligations 1 1 — — Derivative assets: Commodity contracts 1,093 92 878 123 Measured using net asset value practical expedient: Equity securities — nuclear trust fund investments 72 Equity securities 7 Total assets $ 1,881 $ 536 $ 1,138 $ 128 Derivative liabilities: Commodity contracts $ 1,032 $ 151 $ 771 $ 110 Total liabilities $ 1,032 $ 151 $ 771 $ 110 December 31, 2018 (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and 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 in the consolidated financial statements at least annually using significant unobservable inputs	There were no transfers during the three and nine months ended September 30, 2019 and 2018 between Levels 1 and 2. The following tables reconcile, for the three and nine months ended September 30, 2019 and 2018, the beginning and ending balances for financial instruments that are recognized at fair value in the condensed consolidated financial statements, at least annually, using significant unobservable inputs: Fair Value Measurement Using Significant Unobservable Inputs (Level 3) Three months ended September 30, 2019 Nine months ended September 30, 2019 (In millions) Debt Securities Derivatives (a) Total Debt Securities Derivatives (a) Total Beginning balance $ 19 $ 97 $ 116 $ 19 $ 20 $ 39 Contracts added from acquisitions — (2) (2) — (3) (3) Total (losses)/gains — realized/unrealized: Included in earnings — (18) (18) 1 (45) (44) Included in OCI (14) — (14) (14) — (14) Cash received — — — (1) — (1) Purchases — 38 38 — 26 26 Transfers into Level 3 (b) — (126) (126) — 4 4 Transfers out of Level 3 (b) — 24 24 — 11 11 Ending balance as of September 30, 2019 $ 5 $ 13 $ 18 $ 5 $ 13 $ 18 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 September 30, 2019 $ — $ 44 $ 44 $ 1 $ 13 $ 14 (a) Consists of derivative assets and liabilities, net (b) Transfers into/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. All transfers in/out are with Level 2 Fair Value Measurement Using Significant Unobservable Inputs (Level 3) Three months ended September 30, 2018 Nine months ended September 30, 2018 (In millions) Debt Securities Derivatives (a) Total Debt Securities Derivatives (a) Total Beginning balance $ 19 $ 174 $ 193 $ 19 $ (15) $ 4 Contracts added in XOOM acquisition — — — — 12 12 Total (losses) — realized/unrealized — — — — (15) (15) Purchases — 12 12 — 9 9 Transfers into Level 3 (b) — (201) (201) — (4) (4) Transfers out of Level 3 (b) — 2 2 — — — Ending balance as of September 30, 2018 $ 19 $ (13) $ 6 $ 19 $ (13) $ 6 (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 September 30, 2018 $ — $ (3) $ (3) $ — $ (18) $ (18) (a) Consists of derivative assets and liabilities, net (b) Transfers into/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. All transfers in/out are with Level 2
Significant unobservable inputs used developing fair values, Quantitative Information	The following tables quantify the significant unobservable inputs used in developing the fair value of the Company's Level 3 positions as of September 30, 2019 and December 31, 2018: September 30, 2019 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) Power Contracts $ 89 $ 98 Discounted Cash Flow Forward Market Price (per MWh) $ 6 $ 217 $ 22 FTRs 34 12 Discounted Cash Flow Auction Prices (per MWh) (134) 60 0 $ 123 $ 110 December 31, 2018 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) 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 September 30, 2019 and December 31, 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. Net Exposure (a)(b) Category by Industry Sector (% of Total) Utilities, energy merchants, marketers and other 84 % Financial institutions 16 Total as of September 30, 2019 100 % Net Exposure (a) (b) Category by Counterparty Credit Quality (% of Total) Investment grade 54 % Non-investment grade/non-rated 46 Total as of September 30, 2019 100 % (a) Counterparty credit exposure excludes uranium and coal transportation contracts because of the unavailability of market prices (b) The figures in the tables above exclude potential counterparty credit exposure related to RTOs, ISOs, registered commodity exchanges and certain long-term contracts

Nuclear Decommissioning Trust_2

Nuclear Decommissioning Trust Fund (Tables)	9 Months Ended
	Sep. 30, 2019
Nuclear Decommissioning Trust Fund Disclosure [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 September 30, 2019 As of December 31, 2018 (In millions, except maturities) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Cash and cash equivalents $ 20 $ — $ — — $ 19 $ — $ — — U.S. government and federal agency obligations 51 5 — 13 46 1 — 12 Federal agency mortgage-backed securities 97 3 — 24 100 1 2 23 Commercial mortgage-backed securities 27 1 1 24 22 — 1 22 Corporate debt securities 112 6 — 11 96 1 2 11 Equity securities 444 295 — — 376 231 1 — Foreign government fixed income securities 5 — — 10 4 — — 9 Total $ 756 $ 310 $ 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 held in the trust funds and the related realized gains and losses from these sales. The cost of securities sold is determined on the specific identification method. Nine months ended September 30, 2019 2018 (In millions) Realized gains $ 8 $ 8 Realized losses (7) (8) Proceeds from sale of securities 271 398

Accounting for Derivative Ins_2

Accounting for Derivative Instruments and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 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 category, excluding those derivatives that qualified for the NPNS exception, as of September 30, 2019 and December 31, 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. Total Volume September 30, 2019 December 31, 2018 Category Units (In millions) Emissions Short Ton 2 (2) Renewable Energy Certificates Certificates 1 1 Coal Short Ton 4 13 Natural Gas MMBtu (273) (330) Oil Barrels — 1 Power MWh 37 1 Capacity MW/Day (1) (1) Interest Dollars $ — $ 1,000
Fair value within the derivative instrument valuation on the balance sheets	The following table summarizes the fair value within the derivative instrument valuation on the balance sheets: Fair Value Derivative Assets Derivative Liabilities September 30, 2019 December 31, 2018 September 30, 2019 December 31, 2018 (In millions) Derivatives Not Designated as Cash Flow or Fair Value Hedges: Interest rate contracts current $ — $ 17 $ — $ — Interest rate contracts long-term — 22 — — Commodity contracts current 735 747 668 673 Commodity contracts long-term 358 295 364 304 Total Derivatives Not Designated as Cash Flow or Fair Value Hedges $ 1,093 $ 1,081 $ 1,032 $ 977
Offsetting of derivatives by counterparty assets	The following table summarizes the offsetting of derivatives by counterparty master agreement level and collateral received or paid: Gross Amounts Not Offset in the September 30, 2019 Balance Sheet Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount (In millions) Commodity contracts: Derivative assets $ 1,093 $ (869) $ (5) $ 219 Derivative liabilities (1,032) 869 70 (93) Total commodity contracts $ 61 $ — $ 65 $ 126 Gross Amounts Not Offset in the December 31, 2018 Balance Sheet Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount (In millions) 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
Offsetting of derivatives by counterparty, liabilities	The following table summarizes the offsetting of derivatives by counterparty master agreement level and collateral received or paid: Gross Amounts Not Offset in the September 30, 2019 Balance Sheet Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount (In millions) Commodity contracts: Derivative assets $ 1,093 $ (869) $ (5) $ 219 Derivative liabilities (1,032) 869 70 (93) Total commodity contracts $ 61 $ — $ 65 $ 126 Gross Amounts Not Offset in the December 31, 2018 Balance Sheet Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount (In millions) 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 of Accumulated OCL balance attributable to cash flow hedge derivatives, net of tax	The following table summarizes the effects on the Company's accumulated OCL balance attributable to cash flow hedge derivatives, net of tax: Interest Rate Contracts Three months ended Nine months ended September 30, 2018 September 30, 2018 (In millions) Accumulated OCL beginning balance $ (23) $ (54) Reclassified from accumulated OCL to income: Due to realization of previously deferred amounts 1 8 Mark-to-market of cash flow hedge accounting contracts (3) 21 Sale of NRG Yield and Renewables Platform 25 25 Accumulated OCL ending balance, net of $0 tax $ — $ —
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. Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 Unrealized mark-to-market results (In millions) Reversal of previously recognized unrealized (gains) on settled positions related to economic hedges $ (118) $ (84) $ (88) $ (85) Reversal of acquired (gain) positions related to economic hedges (3) (10) (4) (11) Net unrealized gains on open positions related to economic hedges 57 26 69 158 Total unrealized mark-to-market (losses)/gains for economic hedging activities (64) (68) (23) 62 Reversal of previously recognized unrealized (gains) on settled positions related to trading activity (1) (4) (8) (10) Net unrealized (losses)/gains on open positions related to trading activity (3) 8 23 27 Total unrealized mark-to-market (losses)/gains for trading activity (4) 4 15 17 Total unrealized (losses)/gains $ (68) $ (64) $ (8) $ 79 Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 (In millions) Unrealized (losses)/ gains included in operating revenues $ (214) $ 59 $ 66 $ (14) Unrealized gains/(losses) included in cost of operations 146 (123) (74) 93 Total impact to statement of operations — energy commodities $ (68) $ (64) $ (8) $ 79 Total impact to statement of operations — interest rate contracts $ — $ 2 $ (38) $ 17

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Lease, Cost and Other Information	Lease Cost: (In millions) Three months ended September 30, 2019 Nine months ended September 30, 2019 Operating lease cost $ 26 $ 82 Short-term lease cost 1 2 Variable lease cost 1 4 Sublease income (4) (13) Total lease cost $ 24 $ 75 Other information: (In millions) Nine months ended September 30, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 77 Right-of-use assets obtained in exchange for new operating lease liabilities 215 Lease Term and Discount Rate for operating leases: September 30, 2019 Weighted average remaining lease term (in years) 7.9 Weighted average discount rate 5.74 %
Schedule of Annual Payments Based on Maturities of Leases	As of September 30, 2019, annual payments based on the maturities of NRG's leases are expected to be as follows: (In millions) Remainder of 2019 $ 26 2020 94 2021 86 2022 86 2023 86 Thereafter 372 Total undiscounted lease payments $ 750 Less: present value adjustment (177) Total discounted lease payments $ 573

Debt and Finance Leases (Tables

Debt and Finance Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Long-term debt and finance leases	Long-term debt and finance leases consisted of the following: (In millions, except rates) September 30, 2019 December 31, 2018 September 30, 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 575 575 2.750 Senior Secured First Lien Notes, due 2024 600 — 3.750 Senior Secured First Lien Notes, due 2029 500 — 4.450 Term Loan Facility (a) — 1,698 L+ 0.0175 Revolver Facility (b) 215 — L+ 0.0175 - P+ 0.0075 Tax-exempt bonds 466 466 0.04125 - 0.06 Subtotal recourse debt 6,140 6,523 Non-recourse debt: Agua Caliente Borrower 1, due 2038 83 86 5.430 Midwest Generation — 48 4.390 Other 34 34 various Subtotal all non-recourse debt 117 168 Subtotal long-term debt (including current maturities) 6,257 6,691 Finance leases — 1 6.500 Subtotal long-term debt and finance leases (including current maturities) 6,257 6,692 Less current maturities (302) (72) Less debt issuance costs (68) (70) Discounts (89) (101) Total long-term debt and finance leases $ 5,798 $ 6,449 (a) As of December 31, 2018, the interest rate was 1-month LIBOR plus 1.75% (b) As of September 30, 2019, L is equal to 1-week LIBOR and P is equal to Prime Rate

Investments Accounted for Usi_2

Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs (Tables)	9 Months Ended
	Sep. 30, 2019
Variable Interest Entities Disclosure [Abstract]
Financial Information for Consolidated VIEs	The summarized financial information for the Company's consolidated VIEs consisted of the following: (In millions) September 30, 2019 December 31, 2018 Current assets $ 3 $ 3 Net property, plant and equipment 73 76 Other long-term assets 28 28 Total assets 104 107 Current liabilities 1 2 Long-term debt 28 29 Other long-term liabilities 8 7 Total liabilities 37 38 Redeemable noncontrolling interest 19 19 Net assets less noncontrolling interest $ 48 $ 50

Changes in Capital Structure (T

Changes in Capital Structure (Tables)	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Changes in NRG's common shares issued and outstanding	As of September 30, 2019 and December 31, 2018, the Company had 500,000,000 shares of common stock authorized. The following table reflects the changes in NRG's common stock issued and outstanding: Issued Treasury Outstanding Balance as of December 31, 2018 420,288,886 (136,638,847) 283,650,039 Shares issued under LTIPs 1,570,958 — 1,570,958 Shares repurchased — (33,235,480) (33,235,480) Balance as of September 30, 2019 421,859,844 (169,874,327) 251,985,517 Shares issued under LTIPs subsequent to September 30, 2019 3,757 — 3,757 Shares issued under ESPP — 46,128 46,128 Shares repurchased subsequent to September 30, 2019 — (441,112) (441,112) Balance as of October 31, 2019 421,863,601 (170,269,311) 251,594,290
Shares Repurchased	The following repurchases have been made during the nine months ended September 30, 2019 and through October 31, 2019 under the share repurchase programs: Total number of shares purchased Average price paid per share Amounts paid for shares purchased (in millions) Board Authorized Share Repurchases 2018 program: Repurchases made during January-February to complete the 2018 program 6,153,415 $ 40.61 $ 250 2019 programs: Repurchases under February 28, 2019 Accelerated Share Repurchase Agreement- $1.0 billion share repurchase program (a) 9,438,671 400 Other repurchases under the $1.0 billion share repurchase program (a) 16,615,479 600 Total $1.0 billion share repurchase program 26,054,150 38.38 1,000 Repurchases made through September 30, 2019 under the $250 million share repurchase program (b) 1,027,915 36.99 38 Total Share Repurchases during the nine months ended September 30, 2019 33,235,480 $ 1,288 Repurchases made subsequent to September 30, 2019 under the $250 million program (b) 441,112 39.10 $ 17 Total Share Repurchases during the period ended October 31, 2019 33,676,592 $ 1,305 (a) The $1 billion share repurchase program was announced in February 2019

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Reconciliation of NRG's basic and diluted earnings per share	The reconciliation of NRG's basic and diluted income per share is shown in the following table: Three months ended September 30, Nine months ended September 30, (In millions, except per share data) 2019 2018 2019 2018 Basic income per share attributable to NRG Energy, Inc; Net income/(loss) attributable to NRG Energy, Inc. common stockholders $ 372 $ (72) $ 1,055 $ 280 Weighted average number of common shares outstanding - basic 254 299 266 309 Income/(loss) per weighted average common share — basic $ 1.46 $ (0.24) $ 3.97 $ 0.91 Diluted income per share attributable to NRG Energy, Inc; Net income/(loss) attributable to NRG Energy, Inc. available to common shareholders $ 372 $ (72) $ 1,055 280 Weighted average number of common shares outstanding - basic 254 299 266 309 Incremental shares attributable to the issuance of equity compensation (treasury stock method) 2 — 2 4 Weighted average number of common shares outstanding - dilutive 256 299 268 313 Income/(loss) per weighted average common share — diluted $ 1.45 $ (0.24) $ 3.94 $ 0.89
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 per share: Three months ended September 30, Nine months ended September 30, (In millions of shares) 2019 2018 2019 2018 Equity compensation plans — 4 — —

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Schedule of segment reporting information, by segment	Three months ended September 30, 2019 (a) Retail Generation Corporate Eliminations Total (In millions) Operating revenues (b) $ 2,544 $ 974 $ — $ (522) $ 2,996 Depreciation and amortization 37 47 7 — 91 Reorganization costs 1 — — — 1 (Loss)/gain on sale of assets (1) 1 — — — Equity in earnings of unconsolidated affiliates — 29 — — 29 Income/(loss) from continuing operations before income taxes 422 64 (107) 1 380 Income/(loss) from continuing operations 422 63 (112) 1 374 Loss from discontinued operations, net of tax — — (2) — (2) Net income/(loss) 422 63 (114) 1 372 Net income/(loss) attributable to NRG Energy, Inc. $ 422 $ 63 $ (114) $ 1 $ 372 (a) Includes intersegment revenues and costs associated with the internal transfer of power, which is based on average annualized market prices and results in higher revenues in Generation and higher cost of operations in Retail that are eliminated in consolidation (b) Operating revenues include intersegment sales and net derivative gains and losses of: $ 1 $ 513 $ 8 $ — $ 522 Three months ended September 30, 2018 (a) Retail Generation Corporate Eliminations Total (In millions) Operating revenues (b) $ 2,203 $ 1,478 $ 1 $ (722) $ 2,960 Depreciation and amortization 30 60 7 2 99 Reorganization costs 6 3 18 — 27 Equity in earnings of unconsolidated affiliates — 20 3 (3) 20 Loss on debt extinguishment, net — — (19) — (19) (Loss)/income from continuing operations before income taxes (128) 575 (145) (7) 295 (Loss)/income from continuing operations (128) 574 (152) (7) 287 Loss from discontinued operations, net of tax — — (336) — (336) Net (loss)/income (128) 574 (488) (7) (49) Net (loss)/income attributable to NRG Energy, Inc. $ (128) $ 559 $ (498) $ (5) $ (72) (a) Includes intersegment revenues and costs associated with our internal transfer of power, which is based on average annualized market prices and results in higher revenues in Generation and higher cost of operations in Retail that are eliminated in consolidation (b) Operating revenues include intersegment sales and net derivative gains and losses of: $ 1 $ 739 $ (18) $ — $ 722 Nine months ended September 30, 2019 (a) Retail Generation Corporate Eliminations Total (In millions) Operating revenues (b) $ 5,899 $ 3,164 $ — $ (1,437) $ 7,626 Depreciation and amortization 100 138 23 — 261 Impairment losses 1 — — — 1 Reorganization costs 4 1 11 — 16 (Loss)/gain on sale of assets (1) 2 1 — 2 Equity in earnings of unconsolidated affiliates — 8 — — 8 Loss on debt extinguishment, net — — (47) — (47) Income/(loss) from continuing operations before income taxes 253 795 (382) — 666 Income/(loss) from continuing operations 252 794 (389) — 657 Income from discontinued operations, net of tax — — 399 — 399 Net income 252 794 10 — 1,056 Net income attributable to NRG Energy, Inc. common stockholders $ 251 $ 794 $ 10 $ — $ 1,055 (a) Includes intersegment revenues and costs associated with our internal transfer of power, which is based on average annualized market prices and results in higher revenues in Generation and higher cost of operations in Retail that are eliminated in consolidation (b) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 6 $ 1,375 $ 56 $ — $ 1,437 Nine months ended September 30, 2018 (a) Retail Generation Corporate Eliminations Total (In millions) Operating revenues (b) $ 5,497 $ 2,916 $ — $ (927) $ 7,486 Depreciation and amortization 86 220 25 — 331 Impairment losses — 74 — — 74 Reorganization costs 10 10 50 — 70 Gain on sale of assets — 1 29 — 30 Equity in earnings of unconsolidated affiliates — 27 4 (5) 26 Income/(loss) from continuing operations before income taxes 732 256 (412) (4) 572 Income/(loss) from continuing operations 732 255 (430) (4) 553 Loss from discontinued operations, net of tax — — (272) — (272) Net income/(loss) 732 255 (702) (4) 281 Net income/(loss) attributable to NRG Energy, Inc. common stockholders $ 731 $ 246 $ (697) $ — $ 280 (a) Includes intersegment revenues and costs associated with our internal transfer of power, which is based on average annualized market prices and results in higher revenues in Generation and higher cost of operations in Retail that are eliminated in consolidation (b) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 7 $ 944 $ (24) $ — $ 927

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	The income tax provision consisted of the following: Three months ended September 30, Nine months ended September 30, (In millions, except rates) 2019 2018 2019 2018 Income from continuing operations before income taxes $ 380 $ 295 $ 666 $ 572 Income tax expense from continuing operations 6 8 9 19 Effective income tax rate 1.6 % 2.7 % 1.4 % 3.3 %

Related Party Transactions (Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2019
Related Party Transactions [Abstract]
Summary of NRG's Material Related Party Transactions	The following table summarizes NRG's material related party transactions with third party affiliates: Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 (In millions) Revenues from Related Parties Included in Operating Revenues Gladstone $ 2 $ 1 $ 3 $ 2 GenConn — 1 — 4 Ivanpah 7 8 25 13 Midway-Sunset 2 — 4 — Revenues from Related Parties recorded against selling, general and administrative expenses GenOn — 11 — 53 Total $ 11 $ 21 $ 32 $ 72

Condensed Consolidating Finan_2

Condensed Consolidating Financial Information (Tables)	9 Months Ended
	Sep. 30, 2019
Condensed Consolidating 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 the Senior Secured First Lien Notes as of September 30, 2019: Ace Energy, Inc. NRG Business Services LLC NRG PacGen Inc. Allied Home Warranty GP LLC NRG Cabrillo Power Operations Inc. NRG Portable Power LLC Allied Warranty LLC NRG California Peaker Operations LLC NRG Power Marketing LLC Arthur Kill Power LLC NRG Cedar Bayou Development Company, LLC NRG Reliability Solutions LLC Astoria Gas Turbine Power LLC NRG Connected Home LLC NRG Renter's Protection LLC BidURenergy, Inc. NRG Connecticut Affiliate Services Inc. NRG Retail LLC Cabrillo Power I LLC NRG Construction LLC NRG Retail Northeast LLC Cabrillo Power II LLC NRG Curtailment Solutions, Inc NRG Rockford Acquisition LLC Carbon Management Solutions LLC NRG Development Company Inc. NRG Saguaro Operations Inc. Cirro Group, Inc. NRG Devon Operations Inc. NRG Security LLC Cirro Energy Services, Inc. NRG Dispatch Services LLC NRG Services Corporation Connecticut Jet Power LLC NRG Distributed Energy Resources Holdings LLC NRG SimplySmart Solutions LLC Devon Power LLC NRG Distributed Generation PR LLC NRG South Central Affiliate Services Inc. Dunkirk Power LLC NRG Dunkirk Operations Inc. NRG South Central Operations Inc. Eastern Sierra Energy Company LLC NRG ECOKAP Holdings LLC NRG South Texas LP El Segundo Power, LLC NRG El Segundo Operations Inc. NRG Texas C&I Supply LLC El Segundo Power II LLC NRG Energy Labor Services LLC NRG Texas Gregory LLC Energy Alternatives Wholesale, LLC NRG Energy Services Group LLC NRG Texas Holding Inc. Energy Choice Solutions LLC NRG Energy Services International Inc. NRG Texas LLC Energy Plus Holdings LLC NRG Energy Services LLC NRG Texas Power LLC Energy Plus Natural Gas LLC NRG Generation Holdings, Inc. NRG Warranty Services LLC Energy Protection Insurance Company NRG Greenco LLC NRG West Coast LLC Everything Energy LLC NRG Home & Business Solutions LLC NRG Western Affiliate Services Inc. Forward Home Security, LLC NRG Home Services LLC O'Brien Cogeneration, Inc. II GCP Funding Company, LLC NRG Home Solutions LLC ONSITE Energy, Inc. Green Mountain Energy Company NRG Home Solutions Product LLC Oswego Harbor Power LLC Gregory Partners, LLC NRG Homer City Services LLC Reliant Energy Northeast LLC Gregory Power Partners LLC NRG Huntley Operations Inc. Reliant Energy Power Supply, LLC Huntley Power LLC NRG HQ DG LLC Reliant Energy Retail Holdings, LLC Independence Energy Alliance LLC NRG Identity Protect LLC Reliant Energy Retail Services, LLC Independence Energy Group LLC NRG Ilion Limited Partnership RERH Holdings, LLC Independence Energy Natural Gas LLC NRG Ilion LP LLC Saguaro Power LLC Indian River Operations Inc. NRG International LLC Somerset Operations Inc. Indian River Power LLC NRG Maintenance Services LLC Somerset Power LLC Meriden Gas Turbines LLC NRG Mextrans Inc. Texas Genco GP, LLC Middletown Power LLC NRG MidAtlantic Affiliate Services Inc. Texas Genco Holdings, Inc. Montville Power LLC NRG Middletown Operations Inc. Texas Genco LP, LLC NEO Corporation NRG Montville Operations Inc. Texas Genco Services, LP New Genco GP, LLC NRG North Central Operations Inc. US Retailers LLC Norwalk Power LLC NRG Northeast Affiliate Services Inc. Vienna Operations Inc. NRG Advisory Services LLC NRG Norwalk Harbor Operations Inc. Vienna Power LLC NRG Affiliate Services Inc. NRG Operating Services, Inc. WCP (Generation) Holdings LLC NRG Arthur Kill Operations Inc. NRG Oswego Harbor Power Operations Inc. West Coast Power LLC NRG Astoria Gas Turbine Operations Inc.
CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Current Period QTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the three months ended September 30, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 2,473 $ 525 $ — $ (2) $ 2,996 Operating Costs and Expenses Cost of operations 1,728 421 6 (2) 2,153 Depreciation and amortization 52 32 7 — 91 Selling, general and administrative 132 28 50 — 210 Reorganization costs — — 1 — 1 Development costs — — 1 — 1 Total operating costs and expenses 1,912 481 65 (2) 2,456 Operating Income/(Loss) 561 44 (65) — 540 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 20 — 537 (557) — Equity in earnings of unconsolidated affiliates — 29 — — 29 Impairment losses on investments — (101) (6) — (107) Other income, net 11 1 5 — 17 Interest expense (4) (3) (92) — (99) Total other income/(expense) 27 (74) 444 (557) (160) Income/(Loss) from Continuing Operations Before Income Taxes 588 (30) 379 (557) 380 Income tax expense — 1 5 — 6 Income/(Loss) from Continuing Operations 588 (31) 374 (557) 374 Income/(loss) from discontinued operations, net of income tax — — (2) — (2) Net Income/(Loss) Attributable to NRG Energy, Inc. $ 588 $ (31) $ 372 $ (557) $ 372 (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Current Period YTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the nine months ended September 30, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 6,382 $ 1,252 $ — $ (8) $ 7,626 Operating Costs and Expenses Cost of operations 4,676 956 25 (8) 5,649 Depreciation and amortization 157 81 23 — 261 Impairment losses 1 — — — 1 Selling, general and administrative 366 56 193 — 615 Reorganization costs — — 16 — 16 Development costs — 1 4 — 5 Total operating costs and expenses 5,200 1,094 261 (8) 6,547 Gain on sale of assets 1 1 — — 2 Operating Income/(Loss) 1,183 159 (261) — 1,081 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 32 — 1,266 (1,298) — Equity in earnings of unconsolidated affiliates — 8 — — 8 Impairment losses on investments — (101) (6) — (107) Other income, net 19 10 20 — 49 Loss on debt extinguishment, net — — (47) — (47) Interest expense (11) (12) (295) — (318) Total other income/(expense) 40 (95) 938 (1,298) (415) Income from Continuing Operations Before Income Taxes 1,223 64 677 (1,298) 666 Income tax expense — 2 7 — 9 Income from Continuing Operations 1,223 62 670 (1,298) 657 Income from discontinued operations, net of income tax 9 5 385 — 399 Net Income 1,232 67 1,055 (1,298) 1,056 Less: Net income attributable to redeemable noncontrolling interests — 1 — — 1 Net Income Attributable to NRG Energy, Inc. $ 1,232 $ 66 $ 1,055 $ (1,298) $ 1,055 (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Current Period QTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) For the three months ended September 30, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Net Income/(Loss) $ 588 $ (31) $ 372 $ (557) $ 372 Other Comprehensive Loss Foreign currency translation adjustments, net (5) (4) (4) 9 (4) Available-for-sale securities, net — — (14) — (14) Defined benefit plans, net (40) — (41) 40 (41) Other comprehensive loss (45) (4) (59) 49 (59) Comprehensive Income/(Loss) Attributable to NRG Energy, Inc. $ 543 $ (35) $ 313 $ (508) $ 313 (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Current Period YTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME For the nine months ended September 30, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Net Income $ 1,232 $ 67 $ 1,055 $ (1,298) $ 1,056 Other Comprehensive Loss Foreign currency translation adjustments, net (5) (4) (4) 9 (4) Available-for-sale securities, net — — (13) — (13) Defined benefit plans, net (40) — (47) 40 (47) Other comprehensive loss (45) (4) (64) 49 (64) Comprehensive Income 1,187 63 991 (1,249) 992 Less: Comprehensive income attributable to redeemable noncontrolling interests — 1 — — 1 Comprehensive Income Attributable to NRG Energy, Inc. $ 1,187 $ 62 $ 991 $ (1,249) $ 991 (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING BALANCE SHEETS	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS September 30, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated ASSETS (In millions) Current Assets Cash and cash equivalents $ — $ 26 $ 217 $ — $ 243 Funds deposited by counterparties 30 — — — 30 Restricted cash 2 1 1 — 4 Accounts receivable, net 2,049 194 426 (1,293) 1,376 Inventory 248 116 — — 364 Derivative instruments 740 28 — (33) 735 Cash collateral paid in support of energy risk management activities 146 18 — — 164 Prepayments and other current assets 178 15 78 — 271 Total current assets 3,393 398 722 (1,326) 3,187 Property, plant and equipment, net 1,494 965 156 — 2,615 Other Assets Investment in subsidiaries 786 — 4,677 (5,463) — Equity investments in affiliates — 405 — — 405 Operating lease right-of-use assets, net 85 271 126 — 482 Goodwill 359 232 — — 591 Intangible assets, net 390 438 — — 828 Nuclear decommissioning trust fund 756 — — — 756 Derivative instruments 356 14 — (12) 358 Deferred income taxes — 53 — — 53 Other non-current assets 151 30 71 — 252 Total other assets 2,883 1,443 4,874 (5,475) 3,725 Total Assets $ 7,770 $ 2,806 $ 5,752 $ (6,801) $ 9,527 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Current portion of long-term debt $ — $ 87 $ 215 $ — $ 302 Current portion of operating lease liabilities 21 31 21 — 73 Accounts payable 1,315 146 698 (1,293) 866 Derivative instruments 683 18 — (33) 668 Cash collateral received in support of energy risk management activities 30 — — — 30 Accrued expenses and other current liabilities 271 51 303 — 625 Total current liabilities 2,320 333 1,237 (1,326) 2,564 Other Liabilities Long-term debt 245 85 5,468 — 5,798 Non-current operating lease liabilities 70 307 123 — 500 Nuclear decommissioning reserve 294 — — — 294 Nuclear decommissioning trust liability 453 — — — 453 Derivative instruments 374 2 — (12) 364 Deferred income taxes (10) 67 13 — 70 Other non-current liabilities 412 160 464 — 1,036 Total other liabilities 1,838 621 6,068 (12) 8,515 Total Liabilities 4,158 954 7,305 (1,338) 11,079 Redeemable noncontrolling interest in subsidiaries — 19 — — 19 Stockholders’ Equity 3,612 1,833 (1,553) (5,463) (1,571) Total Liabilities and Stockholders’ Equity $ 7,770 $ 2,806 $ 5,752 $ (6,801) $ 9,527 (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 nine months ended September 30, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net income $ 1,232 $ 67 $ 1,055 $ (1,298) $ 1,056 Income from discontinued operations 9 5 385 — 399 Income from continuing operations 1,223 62 670 (1,298) 657 Adjustments to reconcile net income to net cash provided/(used) by operating activities: Distributions and equity in (earnings)/losses of unconsolidated affiliates and consolidated subsidiaries (32) (5) (1,266) 1,298 (5) Depreciation, amortization and accretion 181 85 23 — 289 Provision for bad debts 72 11 4 — 87 Amortization of nuclear fuel 40 — — — 40 Amortization of financing costs and debt discount/premiums — — 20 — 20 Loss on debt extinguishment, net — — 47 — 47 Amortization of emission allowances 21 7 — — 28 Amortization of unearned equity compensation — — 15 — 15 (Gain)/loss on sale and disposal of assets (25) 2 3 — (20) Impairment losses 1 101 6 — 108 Changes in derivative instruments 10 (12) 38 — 36 Changes in deferred income taxes and liability for uncertain tax benefits — (1) (2) — (3) Changes in collateral deposits in support of energy risk management activities 136 (7) — — 129 Changes in nuclear decommissioning trust liability 27 — — — 27 Changes in other working capital (401) (120) (81) — (602) Cash provided/(used) by continuing operations 1,253 123 (523) — 853 Cash provided/(used) by discontinued operations 17 (9) — — 8 Net Cash Provided/(Used) by Operating Activities 1,270 114 (523) — 861 Cash Flows from Investing Activities Intercompany dividends — — 1,665 (1,665) — Payments for acquisitions of businesses (348) — — — (348) Capital expenditures (135) (23) (25) — (183) Net proceeds from notes receivable — — 2 — 2 Net proceeds from sale of emission allowances 14 — — — 14 Investments in nuclear decommissioning trust fund securities (295) — — — (295) Proceeds from the sale of nuclear decommissioning trust fund securities 271 — — — 271 Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees 1 400 892 1,293 Net contributions to investments in unconsolidated affiliates — (94) — — (94) Contributions to discontinued operations — (44) — — (44) Cash (used)/provided by continuing operations (492) 239 2,534 (1,665) 616 Cash used by discontinued operations — (2) — — (2) Net Cash (Used)/Provided by Investing Activities (492) 237 2,534 (1,665) 614 Cash Flows from Financing Activities Payments from/(for) intercompany loans 784 (260) (524) — — Intercompany dividends (1,608) (57) — 1,665 — Payment of dividends to common stockholders — — (24) — (24) Payments for treasury stock — — (1,286) — (1,286) Payments for debt extinguishment costs — — (24) — (24) Distributions to noncontrolling interests from subsidiaries — (1) — — (1) Proceeds from issuance of common stock — — 3 — 3 Proceeds from issuance of long-term debt — — 2,048 — 2,048 Payment of debt issuance costs — — (34) — (34) Payments for long-term debt — (55) (2,432) — (2,487) Cash used by continuing operations (824) (373) (2,273) 1,665 (1,805) Cash provided by discontinued operations — 43 — — 43 Net Cash Used by Financing Activities (824) (330) (2,273) 1,665 (1,762) Change in cash from discontinued operations 17 32 — — 49 Net Decrease in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash (63) (11) (262) — (336) Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period 95 38 480 — 613 Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period $ 32 $ 27 $ 218 $ — $ 277 (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Prior Period QTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the three months ended September 30, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 2,521 $ 441 $ — $ (2) $ 2,960 Operating Costs and Expenses Cost of operations 1,937 294 9 (2) 2,238 Depreciation and amortization 54 36 9 — 99 Selling, general and administrative 123 19 142 (73) 211 Reorganization costs — — 27 — 27 Development costs — (2) 3 — 1 Total operating costs and expenses 2,114 347 190 (75) 2,576 Gain on sale of assets — 14 — — 14 Operating Income/(Loss) 407 108 (190) 73 398 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 6 — 470 (476) — Equity in earnings/(losses) of unconsolidated affiliates — 21 (1) — 20 Impairment losses on investments — (1) — — (1) Other income, net 4 9 6 — 19 Loss on debt extinguishment, net — — (19) — (19) Interest expense (4) (8) (110) — (122) Total other income/(expense) 6 21 346 (476) (103) Income from Continuing Operations Before Income Taxes 413 129 156 (403) 295 Income tax expense/(benefit) 122 42 (156) — 8 Income from Continuing Operations 291 87 312 (403) 287 Income/(loss) from discontinued operations, net of income tax 16 20 (372) — (336) Net Income/(Loss) 307 107 (60) (403) (49) Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (62) 12 73 23 Net Income/(Loss) Attributable to NRG Energy, Inc. $ 307 $ 169 $ (72) $ (476) $ (72) (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Prior Period YTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the nine months ended September 30, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 6,437 $ 1,061 $ — $ (12) $ 7,486 Operating Costs and Expenses Cost of operations 4,794 713 18 (13) 5,512 Depreciation and amortization 177 128 26 — 331 Impairment losses — 74 — — 74 Selling, general and administrative 335 46 279 (73) 587 Reorganization costs 3 — 67 — 70 Development costs — — 10 (1) 9 Total operating costs and expenses 5,309 961 400 (87) 6,583 Gain on sale of assets 3 27 — — 30 Operating Income/(Loss) 1,131 127 (400) 75 933 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 14 — 1,156 (1,170) — Equity in earnings/(losses) of unconsolidated affiliates — 28 (2) — 26 Impairment losses on investments — (16) — — (16) Other income/(loss), net 12 (11) 11 — 12 Loss on debt extinguishment, net — — (22) — (22) Interest expense (11) (42) (308) — (361) Total other income/(expense) 15 (41) 835 (1,170) (361) Income from Continuing Operations Before Income Taxes 1,146 86 435 (1,095) 572 Income tax expense/(benefit) 343 26 (350) — 19 Income from Continuing Operations 803 60 785 (1,095) 553 Income/(loss) from discontinued operations, net of income tax 46 80 (398) — (272) Net Income 849 140 387 (1,095) 281 Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (181) 107 75 1 Net Income Attributable to NRG Energy, Inc. $ 849 $ 321 $ 280 $ (1,170) $ 280 (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Prior Period QTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) For the three months ended September 30, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Net Income/(Loss) $ 307 $ 107 $ (60) $ (403) $ (49) Other Comprehensive (Loss)/Income Unrealized gain/(loss) on derivatives, net — 10 (12) 7 5 Foreign currency translation adjustments, net (2) (2) (1) 3 (2) Defined benefit plans, net — — (1) — (1) Other comprehensive (loss)/income (2) 8 (14) 10 2 Comprehensive Income/(Loss) 305 115 (74) (393) (47) Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable interests — (58) 11 73 26 Comprehensive Income/(Loss) Attributable to NRG Energy, Inc. $ 305 $ 173 $ (85) $ (466) $ (73) (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Prior Period YTD	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME For the nine months ended September 30, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Net Income $ 849 $ 140 $ 387 $ (1,095) $ 281 Other Comprehensive (Loss)/Income Unrealized gain on derivatives, net — 30 9 (15) 24 Foreign currency translation adjustments, net (8) (8) (9) 17 (8) Available-for-sale securities, net — — 1 — 1 Defined benefit plans, net — — (3) — (3) Other comprehensive (loss)/income (8) 22 (2) 2 14 Comprehensive Income 841 162 385 (1,093) 295 Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable interests — (167) 107 75 15 Comprehensive Income Attributable to NRG Energy, Inc. $ 841 $ 329 $ 278 $ (1,168) $ 280 (a) All significant intercompany transactions have been eliminated in consolidation
CONDENSED CONSOLIDATING BALANCE SHEETS Prior Period	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2018 Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated ASSETS (In millions) 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 paid 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 Prior Period	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the nine months ended September 30, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net income $ 849 $ 140 $ 387 $ (1,095) $ 281 Income/(loss) from discontinued operations 46 80 (398) — (272) Income from continuing operations 803 60 785 (1,095) 553 Adjustments to reconcile net income to net cash provided/(used) by operating activities: Distributions and equity in (earnings)/losses of unconsolidated affiliates and consolidated subsidiaries (14) 9 (1,095) 1,110 10 Depreciation, amortization and accretion 201 137 26 — 364 Provision for bad debts 55 2 — — 57 Amortization of nuclear fuel 38 — — — 38 Amortization of financing costs and debt discount/premiums — 23 (2) — 21 Loss on debt extinguishment, net — — 22 — 22 Amortization of emission allowances and out-of-market contracts 15 6 — — 21 Amortization of unearned equity compensation — — 21 — 21 Gain on sale and disposal of assets (23) (27) — — (50) Impairment losses — 90 — — 90 Changes in derivative instruments (38) 40 (4) (15) (17) Changes in deferred income taxes and liability for uncertain tax benefits 343 11 (360) — (6) Changes in collateral deposits in support of energy risk management activities (16) (14) — — (30) Changes in nuclear decommissioning trust liability 50 — — — 50 GenOn Settlement — — (125) — (125) Loss on deconsolidation of Agua Caliente and Ivanpah projects — 13 — — 13 Changes in other working capital (385) (266) 290 — (361) Cash provided/(used) by continuing operations 1,029 84 (442) — 671 Cash provided by discontinued operations 72 324 — — 396 Net Cash Provided/(Used) by Operating Activities 1,101 408 (442) — 1,067 Cash Flows from Investing Activities Intercompany dividends — — 1,273 (1,273) — Payments for acquisitions of businesses (2) (207) — — (209) Capital expenditures (156) (150) (37) — (343) Net proceeds from sale of emission allowances 24 — — — 24 Investments in nuclear decommissioning trust fund securities (449) — — — (449) Proceeds from the sale of nuclear decommissioning trust fund securities 398 — — — 398 Proceeds from sale of assets, net of cash disposed of 10 8 1,537 — 1,555 Deconsolidation of Agua Caliente and Ivanpah projects — (268) — — (268) Net contributions to investments in unconsolidated affiliates — (39) — — (39) Contributions to discontinued operations — (23) — — (23) Cash (used)/provided by continuing operations (175) (679) 2,773 (1,273) 646 Cash used by discontinued operations (2) (703) — — (705) Net Cash (Used)/Provided by Investing Activities (177) (1,382) 2,773 (1,273) (59) Cash Flows from Financing Activities Payments from/(for) intercompany loans 476 170 (646) — — Intercompany dividends (1,273) — — 1,273 — Payment of dividends to common stockholders — — (28) — (28) Payments for treasury stock — — (1,000) — (1,000) Distributions to noncontrolling interests from subsidiaries — (17) — — (17) Proceeds from issuance of common stock — — 15 — 15 Proceeds from issuance of short and long-term debt — 163 832 — 995 Payment of debt issuance costs — — (19) — (19) Payments for short and long-term debt — (106) (864) — (970) Receivable from affiliate — — (26) — (26) Other — (4) — — (4) Cash (used)/provided by continuing operations (797) 206 (1,736) 1,273 (1,054) Cash provided by discontinued operations — 403 — — 403 Net Cash (Used)/Provided by Financing Activities (797) 609 (1,736) 1,273 (651) Effect of exchange rate changes on cash and cash equivalents — 1 — — 1 Change in cash from discontinued operations 70 24 — — 94 Net Increase/(Decrease) in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash 57 (388) 595 — 264 Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period 41 425 620 — 1,086 Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period $ 98 $ 37 $ 1,215 $ — $ 1,350 (a) All significant intercompany transactions have been eliminated in consolidation

Nature of Business and Basis _2

Nature of Business and Basis of Presentation - General (Details) MW in Thousands	Sep. 30, 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 (Loss)/Income Attributable to NRG Energy, Inc. After Removing Net Loss Attributable to Noncontrolling Interest (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accounting Policies [Abstract]
Income from continuing operations, net of income tax	$ 374	$ 274	$ 656	$ 547
(Loss)/income from discontinued operations, net of income tax	(2)	(346)	399	(267)
Net income/(loss) attributable to NRG Energy, Inc.	$ 372	$ (72)	$ 1,055	$ 280

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Other Balance Sheet Information (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Accounts receivable allowance for doubtful accounts	$ 57	$ 32
Property, plant and equipment accumulated depreciation	1,759	1,811
Intangible assets accumulated amortization	1,215	1,149
Out-of-market contracts accumulated amortization	$ 0	$ 37

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Restricted Cash (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Cash and cash equivalents	$ 243	$ 563
Funds deposited by counterparties	30	33
Restricted cash	4	17
Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows	$ 277	$ 613	$ 1,350	$ 1,086

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Pension Plan Amendments (Details) $ in Millions	3 Months Ended
	Sep. 30, 2019USD ($)
Accounting Policies [Abstract]
Gain from curtailment benefit	$ 8
Increase to the pension liability, due to curtailment	$ 32

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Recent Accounting Developments (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities	$ 573
Operating lease right-of-use assets	$ 482
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities		$ 404
Operating lease right-of-use assets		$ 321

Revenue Recognition - Performan

Revenue Recognition - Performance Obligations (Details) $ in Millions	Sep. 30, 2019USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-10-01
Revenue from Contract with Customer [Abstract]
Estimated future fixed fee performance obligations	$ 136
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue remaining performance obligation period	3 months
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 obligations	$ 532
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 obligations	$ 586
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 obligations	$ 297
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 obligations	$ 29
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue remaining performance obligation period	1 year

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 2,504	$ 2,431	$ 6,066	$ 6,292
Mark-to-market for economic hedging activities	(64)	(68)	(23)	62
Operating revenues	2,996	2,960	7,626	7,486
Lease revenue	5	6	15	17
Derivative revenue	(68)	(64)	(8)	79
Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	442	445	997	1,298
Derivative revenue	668	418	1,398	1,081
Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	152	192	461	500
Derivative revenue	33	45	81	110
Retail revenue | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,080	1,766	4,800	4,317
Retail revenue | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	465	434	1,096	1,181
Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,545	2,200	5,896	5,498
Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(210)	55	51	(31)
Derivative revenue	487	523	1,545	1,177
Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	67	68	221	221
Total operating revenue
Disaggregation of Revenue [Line Items]
Operating revenues	2,996	2,960	7,626	7,486
Other revenue, derivative
Disaggregation of Revenue [Line Items]
Derivative revenue	(4)	5	15	17
Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	(5)	(4)	(26)
Operating revenues	(522)	(722)	(1,437)	(927)
Lease revenue	0	0	0	0
Corporate/Eliminations | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(568)	(479)	(1,209)	(890)
Derivative revenue	(569)	(475)	(1,211)	(880)
Corporate/Eliminations | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	1	1	1
Derivative revenue	0	0	1	0
Corporate/Eliminations | Retail revenue | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	(2)	(2)	(4)
Corporate/Eliminations | Retail revenue | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Corporate/Eliminations | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	(2)	(2)	(4)
Corporate/Eliminations | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	47	(241)	(223)	(21)
Derivative revenue	(522)	(716)	(1,433)	(901)
Corporate/Eliminations | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(2)	0	(4)	(13)
Corporate/Eliminations | Total operating revenue
Disaggregation of Revenue [Line Items]
Operating revenues	(522)	(721)	(1,437)	(927)
Corporate/Eliminations | Other revenue, derivative
Disaggregation of Revenue [Line Items]
Derivative revenue	0	0	0	0
Retail | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,542	2,199	5,889	5,492
Operating revenues	2,544	2,203	5,899	5,497
Lease revenue	3	3	9	10
Retail | Operating Segments | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Derivative revenue	0	0	0	0
Retail | Operating Segments | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Derivative revenue	0	0	0	0
Retail | Operating Segments | Retail revenue | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,080	1,768	4,802	4,321
Retail | Operating Segments | Retail revenue | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	465	434	1,096	1,181
Retail | Operating Segments | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,545	2,202	5,898	5,502
Retail | Operating Segments | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(1)	1	1	(5)
Derivative revenue	(1)	1	1	(5)
Retail | Operating Segments | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Retail | Operating Segments | Total operating revenue
Disaggregation of Revenue [Line Items]
Operating revenues	2,544	2,203	5,899	5,497
Retail | Operating Segments | Other revenue, derivative
Disaggregation of Revenue [Line Items]
Derivative revenue	0	0	0	0
Retail | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Operating revenues	(1)	(1)	(6)	(7)
Generation | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(38)	237	181	826
Operating revenues	974	1,478	3,164	2,916
Lease revenue	2	3	6	7
Generation | Operating Segments | Texas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(379)	(306)	(736)	(562)
Lease revenue	0	0	0	0
Generation | Operating Segments | East/West/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	341	543	917	1,388
Lease revenue	2	3	6	7
Generation | Operating Segments | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,010	924	2,206	2,188
Derivative revenue	1,237	893	2,609	1,961
Generation | Operating Segments | Energy revenue | Texas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	773	585	1,628	1,251
Derivative revenue	1,175	901	2,417	1,883
Generation | Operating Segments | Energy revenue | East/West/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	237	339	578	937
Derivative revenue	62	(8)	192	78
Generation | Operating Segments | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	151	191	460	499
Derivative revenue	33	45	80	110
Generation | Operating Segments | Capacity revenue | Texas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	1	0	1
Derivative revenue	0	0	0	0
Generation | Operating Segments | Capacity revenue | East/West/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	151	190	460	498
Derivative revenue	33	45	80	110
Generation | Operating Segments | Retail revenue | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Generation | Operating Segments | Retail revenue | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Generation | Operating Segments | Retail revenue | Texas | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Generation | Operating Segments | Retail revenue | Texas | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Generation | Operating Segments | Retail revenue | East/West/Other | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Generation | Operating Segments | Retail revenue | East/West/Other | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Generation | Operating Segments | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Generation | Operating Segments | Total retail revenue | Texas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Generation | Operating Segments | Total retail revenue | East/West/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Generation | Operating Segments | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(256)	295	273	(5)
Derivative revenue	1,010	1,238	2,977	2,083
Generation | Operating Segments | Derivative revenue | Texas
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(240)	259	233	(14)
Derivative revenue	944	1,159	2,674	1,872
Generation | Operating Segments | Derivative revenue | East/West/Other
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(16)	36	40	9
Derivative revenue	66	79	303	211
Generation | Operating Segments | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	69	68	225	234
Generation | Operating Segments | Other revenue | Texas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	32	8	77	72
Generation | Operating Segments | Other revenue | East/West/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	37	60	148	162
Generation | Operating Segments | Total operating revenue
Disaggregation of Revenue [Line Items]
Operating revenues	974	1,478	3,164	2,916
Generation | Operating Segments | Total operating revenue | Texas
Disaggregation of Revenue [Line Items]
Operating revenues	565	853	1,938	1,310
Generation | Operating Segments | Total operating revenue | East/West/Other
Disaggregation of Revenue [Line Items]
Operating revenues	409	625	1,226	1,606
Generation | Operating Segments | Other revenue, derivative
Disaggregation of Revenue [Line Items]
Derivative revenue	(4)	5	15	17
Generation | Operating Segments | Other revenue, derivative | Texas
Disaggregation of Revenue [Line Items]
Derivative revenue	9	(1)	24	3
Generation | Operating Segments | Other revenue, derivative | East/West/Other
Disaggregation of Revenue [Line Items]
Derivative revenue	(13)	6	(9)	14
Generation | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Operating revenues	$ (513)	$ (739)	$ (1,375)	$ (944)

Revenue Recognition - Contract

Revenue Recognition - Contract Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Schedule Of Contract Assets And Liabilities [Line Items]
Deferred customer acquisition costs	$ 130		$ 130		$ 111
Total accounts receivable, net	1,378		1,378		1,024
Unbilled revenues (included within Accounts receivable, net - Contracts with customers)	486		486		392
Deferred revenues	78		78		67
Deferred revenue from contract with customers			25		19
Revenue recognized	21	$ 19	13	$ 16
Accounts receivable, net - Contracts with customers
Schedule Of Contract Assets And Liabilities [Line Items]
Total accounts receivable, net	1,311		1,311		999
Accounts receivable, net - Derivative instruments
Schedule Of Contract Assets And Liabilities [Line Items]
Total accounts receivable, net	63		63		20
Accounts receivable, net - Affiliate
Schedule Of Contract Assets And Liabilities [Line Items]
Total accounts receivable, net	$ 4		$ 4		$ 5

Acquisitions, Discontinued Op_3

Acquisitions, Discontinued Operations and Dispositions - Acquisitions (Details) customer in Thousands, $ in Millions	Aug. 01, 2019USD ($)customerstate	Jun. 01, 2018USD ($)customerstate
Stream Energy Acquisition
Business Acquisition [Line Items]
States in which entity operates | state	9
Cash paid to acquire business | $	$ 329
Working capital and other adjustment | $	$ 29
Increase in retail portfolio by RCE's acquired | customer	600
Customers acquired | customer	450
XOOM Energy, LLC
Business Acquisition [Line Items]
States in which entity operates | state		19
Cash paid to acquire business | $		$ 213
Working capital and other adjustment | $		$ 48
Increase in retail portfolio by RCE's acquired | customer		395
Customers acquired | customer		300

Acquisitions, Discontinued Op_4

Acquisitions, Discontinued Operations and Dispositions - Schedule of Purchase Price Allocation (Details) - USD ($) $ in Millions	Aug. 01, 2019	Jun. 01, 2018	Sep. 30, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill			$ 591	$ 573
Stream Energy Acquisition
Business Acquisition [Line Items]
Net current and non-current working capital	$ 28
Other intangible assets	283
Goodwill	18
Purchase price	$ 329
XOOM Energy, LLC
Business Acquisition [Line Items]
Net current and non-current working capital		$ 46
Other intangible assets		133
Goodwill		34
Purchase price		$ 213

Acquisitions, Discontinued Op_5

Acquisitions, Discontinued Operations and Dispositions - Discontinued Operations (Details) $ in Billions	Sep. 30, 2019MW	Feb. 04, 2019USD ($)	Dec. 31, 2018MW
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generation capacity (in MW)	23,000
South Central Portfolio | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration | $		$ 1
Generation capacity (in MW)			1,153

Acquisitions, Discontinued Op_6

Acquisitions, Discontinued Operations and Dispositions - Summarized Results of Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Loss)/gain on disposal of discontinued operations, net of tax			$ 0	$ (13)
(Loss)/gain from discontinued operations, net of tax	$ (2)	$ (336)	399	(272)
Discontinued Operations | South Central Portfolio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues	0	101	31	310
Operating costs and expenses	0	(85)	(23)	(262)
Gain from discontinued operations, net of tax	0	16	8	48
(Loss)/gain on disposal of discontinued operations, net of tax	(1)	0	27	0
(Loss)/gain from discontinued operations, net of tax	(1)	16	35	48
Discontinued Operations | Carlsbad Energy Holdings LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues	0	297	19	925
Operating costs and expenses	0	(229)	(9)	(682)
Other expense	0	(42)	(5)	(165)
Gain from discontinued operations, before tax	0	26	5	78
Income tax expense	0	9	0	4
Gain from discontinued operations, net of tax	0	17	5	74
(Loss)/gain on disposal of discontinued operations, net of tax	(1)	(139)	330	(139)
(Expense)/Income from California property tax indemnification	0		22	(153)
(Expense)/income from other commitments, indemnification and fees	0	(77)	5	(77)
(Loss)/gain on disposal of discontinued operations, net of tax	(1)	(369)	357	(369)
(Loss)/gain from discontinued operations, net of tax	$ (1)	$ (352)	$ 362	$ (295)

Acquisitions, Discontinued Op_7

Acquisitions, Discontinued Operations and Dispositions - Major Classes of Assets and Liabilities Classified as Discontinued Operations (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other current assets	$ 0	$ 1
Current assets - discontinued operations	0	197
Other non-current assets	0	77
Non-current assets - discontinued operations	0	1,012
Current liabilities - discontinued operations	0	72
Other non-current liabilities	0	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 - trade, 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 Project | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restricted cash		4
Accounts receivable - trade, 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
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_8

Acquisitions, Discontinued Operations and Dispositions - Sale of Ownership in NRG Yield, Inc. and the Renewables Platform (Details) - Discontinued Operations $ in Millions	Feb. 06, 2018USD ($)extension	Sep. 30, 2019USD ($)	Dec. 31, 2018USD ($)	Aug. 31, 2018USD ($)
NRG Yield and Renewables
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration				$ 1,348
NRG Yield and Renewables | Cost To Complete Construction
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Additional commitments related to project		$ 16
NRG Yield and Renewables | Property Taxes For Solar Properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Additional commitments related to project		22
Carlsbad Project
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration	$ 385
Additional commitments related to project		$ 23	$ 23
Percentage of ownership sold	100.00%
Lease and easement agreement, number of extensions | extension	2
Lease renewal term	10 years

Acquisitions, Discontinued Op_9

Acquisitions, Discontinued Operations and Dispositions - Sale of Assets to NRG Yield, Inc. Prior to Discontinued Operations (Details) $ in Millions	Sep. 30, 2019MW	Jan. 31, 2019USD ($)	Jun. 19, 2018USD ($)	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
UPMC Thermal Project
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration		$ 3	$ 84
Buckthorn Renewables, LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration				$ 42
Percentage of ownership sold				100.00%
Generation capacity (in MW) | MW				154
Debt assumed				$ 183

Acquisitions, Discontinued O_10

Acquisitions, Discontinued Operations and Dispositions - Summarized Results of GenOn (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Loss)/gain from discontinued operations, net of tax	$ (2)	$ (336)	$ 399	$ (272)
GenOn | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Interest income - affiliate			0	3
Pension and post-retirement liability assumption			0	(2)
Other			2	(26)
(Loss)/gain from discontinued operations, net of tax			$ 2	$ (25)

Acquisitions, Discontinued O_11

Acquisitions, Discontinued Operations and Dispositions - GenOn and GenMA Settlement (Details) - USD ($) $ in Millions	Jul. 16, 2018	Apr. 27, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Return of collateral posted to NRG			$ 0	$ 26
GenOn | Services Agreement | Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Return of collateral posted to NRG	$ 15
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, new credit support		$ 37.5
Affiliated Entity
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Settlement consideration	261
Professional fees		$ 6
Affiliated Entity | Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Settlement agreement, payment	125
Affiliated Entity | Services Agreement | Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Transition services credit	28
Related Party Transaction, Due from (to) Related Party	10
Affiliated Entity | Revolving Credit Facility Borrowings | Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Borrowings under intercompany agreement	151
Affiliated Entity | Accrued Interest On Borrowings | Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Borrowings under intercompany agreement	12
Affiliated Entity | Reduction Of Settlement Payment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Related Party Transaction, Due from (to) Related Party	4
Affiliated Entity | Assignment Of Historical Claims Against REMA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Related Party Transaction, Due from (to) Related Party	8
Affiliated Entity | Other | Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Related Party Transaction, Due from (to) Related Party	$ 2

Acquisitions, Discontinued O_12

Acquisitions, Discontinued Operations and Dispositions - Dispositions (Details) - USD ($) $ in Millions	Aug. 01, 2018	Jun. 29, 2018	Jun. 28, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from financing arrangements				$ 2,048	$ 995
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, net of working capital adjustments	$ 71
Gain on sale	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]
Guarantees	119
BETM | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Guarantee Type, Other
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Guarantees	$ 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		$ 17
Proceeds from other asset sales		$ 16
Proceeds from financing arrangements			$ 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]
Proceeds from other asset sales				$ 22	$ 21

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Estimated Carrying Amounts and Fair Value of Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt, including current portion	$ 6,257		$ 6,691
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Notes receivable	11	$ 17
Long-term debt, including current portion	6,168		6,591
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Notes receivable	8	$ 14
Long-term debt, including current portion	6,706		6,697
Fair Value | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt, including current portion	6,375		6,528
Fair Value | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt, including current portion	$ 331		$ 169

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Assets and Liabilities Measured and Recorded at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 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)	$ 24	$ 39
U.S. government and federal agency obligations	1	1
Total assets	1,881	1,792
Derivative liabilities	1,032	977
Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1,093	1,042
Derivative liabilities	1,032	977
Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		39
Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	20	19
U.S. government and federal agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	51	46
Federal agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	97	100
Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	27	22
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	112	96
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	372	312
Equity contracts	7	8
Foreign government fixed income securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	5	4
Equity securities — nuclear trust fund investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity contracts	72	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
U.S. government and federal agency obligations	1	1
Total assets	536	517
Derivative liabilities	151	224
Level 1 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	92	137
Derivative liabilities	151	224
Level 1 | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0
Level 1 | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	20	19
Level 1 | U.S. government and federal agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	51	46
Level 1 | Federal agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 1 | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 1 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 1 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	372	312
Level 1 | Foreign government fixed income securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	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)	19	18
U.S. government and federal agency obligations	0	0
Total assets	1,138	1,075
Derivative liabilities	771	664
Level 2 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	878	796
Derivative liabilities	771	664
Level 2 | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		39
Level 2 | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 2 | U.S. government and federal agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 2 | Federal agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	97	100
Level 2 | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	27	22
Level 2 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	112	96
Level 2 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 2 | Foreign government fixed income securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	5	4
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)	5	19
U.S. government and federal agency obligations	0	0
Total assets	128	128
Derivative liabilities	110	89
Level 3 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	123	109
Derivative liabilities	110	89
Level 3 | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0
Level 3 | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 3 | U.S. government and federal agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 3 | Federal agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 3 | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 3 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 3 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 3 | Foreign government fixed income securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	$ 0	$ 0

Fair Value of Financial Instr_5

Fair Value of Financial Instruments - Reconciliation of Level 3 Financial Instruments (Details) - Level 3 - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 116	$ 193	$ 39	$ 4
Contracts added from acquisitions	(2)	0	(3)	12
Total (losses)/gains — realized/unrealized included in earnings	(18)	0	(44)	(15)
Included in OCI	(14)
Cash received	0		(1)
Purchases	38	12	26	9
Transfers into Level 3	(126)	(201)	4	(4)
Transfers out of Level 3	24	2	11	0
Ending balance	18	6	18	6
Gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held	44	(3)	14	(18)
Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	19	19	19	19
Contracts added from acquisitions	0	0	0	0
Total (losses)/gains — realized/unrealized included in earnings	0	0	1	0
Included in OCI	(14)
Cash received	0		(1)
Purchases	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending balance	5	19	5	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	0	0	1	0
Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	97	174	20	(15)
Contracts added from acquisitions	(2)	0	(3)	12
Total (losses)/gains — realized/unrealized included in earnings	(18)	0	(45)	(15)
Included in OCI	0
Cash received	0		0
Purchases	38	12	26	9
Transfers into Level 3	(126)	(201)	4	(4)
Transfers out of Level 3	24	2	11	0
Ending balance	13	(13)	13	(13)
Gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held	$ 44	$ (3)	$ 13	$ (18)

Fair Value of Financial Instr_6

Fair Value of Financial Instruments - Derivative Fair Value Measurements, Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)
Fair Value Disclosures [Abstract]
Total derivative assets valued with prices provided by models and other valuation techniques (as a percent)	11.00%
Total derivative liabilities valued with prices provided by models and other valuation techniques (as a percent)	11.00%
Decrease in cost of operations	$ 1

Fair Value of Financial Instr_7

Fair Value of Financial Instruments - Derivative Fair Value Measurements (Details) $ in Millions	Sep. 30, 2019USD ($)$ / MWh	Dec. 31, 2018USD ($)$ / MWh
Liabilities
Derivative liabilities	$ 1,032	$ 977
Level 3
Liabilities
Derivative liabilities	110	89
Commodity contracts
Assets
Derivative assets	1,093	1,042
Liabilities
Derivative liabilities	1,032	977
Commodity contracts | Level 3
Assets
Derivative assets	123	109
Liabilities
Derivative liabilities	110	89
Commodity contracts | Level 3 | Power Contracts
Assets
Derivative assets	89	89
Liabilities
Derivative liabilities	$ 98	$ 75
Commodity contracts | Level 3 | Power Contracts | Low
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	6	1
Commodity contracts | Level 3 | Power Contracts | High
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	217	214
Commodity contracts | Level 3 | Power Contracts | Weighted Average
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	22	31
Commodity contracts | Level 3 | FTRs
Assets
Derivative assets	$ 34	$ 20
Liabilities
Derivative liabilities	$ 12	$ 14
Commodity contracts | Level 3 | FTRs | Low
Fair Value Inputs / Range
Derivative, Auction Price | $ / MWh	(134)	(90)
Commodity contracts | Level 3 | FTRs | High
Fair Value Inputs / Range
Derivative, Auction Price | $ / MWh	60	34
Commodity contracts | Level 3 | FTRs | Weighted Average
Fair Value Inputs / Range
Derivative, Auction Price | $ / MWh	0	0

Fair Value of Financial Instr_8

Fair Value of Financial Instruments - Counterparty Credit Risk (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)counterparty
Concentration of Credit Risk
Counterparty credit exposure to a portion of the Company's counterparties	$ 242
Collateral held (cash and letters of credit) against counterparty credit exposure to a portion of the Company's counterparties	55
Net counterparty credit exposure to a portion of the Company's counterparties	$ 226
Company's exposure before collateral is expected to roll off by the end of 2019 (as a percent)	42.00%
Net exposure (as a percent)	100.00%
Wholesale counterparty with net exposure | counterparty	0
Counterparty credit risk exposure to certain counterparties, threshold (as a percent)	10.00%
Period of estimated counterparty credit risk exposure, years	5 years
Ivanpau And Agua Caliente
Concentration of Credit Risk
Period of estimated counterparty credit risk exposure, years	5 years
Estimated counterparty credit risk exposure to certain counterparties	$ 322
Long-term Contract
Concentration of Credit Risk
Aggregate counterparty credit risk exposure for counterparties representing exposure above threshold percentage	$ 518
Investment grade
Concentration of Credit Risk
Net exposure (as a percent)	54.00%
Non-investment grade/non-rated
Concentration of Credit Risk
Net exposure (as a percent)	46.00%
Utilities, energy merchants, marketers and other
Concentration of Credit Risk
Net exposure (as a percent)	84.00%
Financial institutions
Concentration of Credit Risk
Net exposure (as a percent)	16.00%

Nuclear Decommissioning Trust_3

Nuclear Decommissioning Trust Fund - Narrative (Details)	Sep. 30, 2019
STP
Investment [Line Items]
Interest in generating stations	44.00%

Nuclear Decommissioning Trust_4

Nuclear Decommissioning Trust Fund - Summary of aggregate fair values and realized gains and losses (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Nuclear decommissioning trust fund
Fair Value	$ 756	$ 663
Unrealized Gains	310	234
Unrealized Losses	1	6
Cash and cash equivalents
Nuclear decommissioning trust fund
Fair Value	20	19
Unrealized Gains	0	0
Unrealized Losses	0	0
U.S. government and federal agency obligations
Nuclear decommissioning trust fund
Fair Value	51	46
Unrealized Gains	5	1
Unrealized Losses	$ 0	$ 0
Weighted-average Maturities (In years)	13 years	12 years
Federal agency mortgage-backed securities
Nuclear decommissioning trust fund
Fair Value	$ 97	$ 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
Fair Value	$ 27	$ 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
Fair Value	$ 112	$ 96
Unrealized Gains	6	1
Unrealized Losses	$ 0	$ 2
Weighted-average Maturities (In years)	11 years	11 years
Equity securities
Nuclear decommissioning trust fund
Fair Value	$ 444	$ 376
Unrealized Gains	295	231
Unrealized Losses	0	1
Foreign government fixed income securities
Nuclear decommissioning trust fund
Fair Value	5	4
Unrealized Gains	0	0
Unrealized Losses	$ 0	$ 0
Weighted-average Maturities (In years)	10 years	9 years

Nuclear Decommissioning Trust_5

Nuclear Decommissioning Trust Fund - Summary of proceeds from sales of available-for-sale securities and related gains and losses (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Nuclear Decommissioning Trust Fund Disclosure [Abstract]
Realized gains	$ 8	$ 8
Realized losses	(7)	(8)
Proceeds from sale of securities	$ 271	$ 398

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, mw_per_day in Millions, bbl in Millions, T in Millions, MWh in Millions, MMBTU in Millions, $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019USD ($)MWhMMBTUmw_per_dayTsharesbbl	Dec. 31, 2018USD ($)MWhMMBTUmw_per_dayTsharesbbl	Sep. 30, 2018USD ($)
Volumetric Underlying Derivative Transactions
Balance, tax | $			$ 0
Short | Emissions
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, mass (ton) | T	2	2
Short | Natural Gas
Volumetric Underlying Derivative Transactions
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	(273)	(330)
Short | Capacity
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, flow rate (in MW/Day) | mw_per_day	(1)	(1)
Long | Renewable Energy Certificates
Volumetric Underlying Derivative Transactions
Derivative, non-monetary notional amount (in shares) | shares	1	1
Long | Coal
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, mass (ton) | T	4	13
Long | Oil
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount (in barrels) | bbl	0	1
Long | Power
Volumetric Underlying Derivative Transactions
Derivative, Nonmonetary Notional Amount, Energy Measure | MWh	(37)	(1)
Long | Interest
Volumetric Underlying Derivative Transactions
Derivative notional amount (in usd) | $	$ 0	$ 1,000

Accounting for Derivative Ins_4

Accounting for Derivative Instruments and Hedging Activities - Fair value within the derivative instrument valuation (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative Liabilities	$ 1,032	$ 977
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Assets	1,093	1,081
Derivative Liabilities	1,032	977
Not Designated as Hedging Instrument | Interest rate contracts current
Derivative [Line Items]
Derivative Assets	0	17
Derivative Liabilities	0	0
Not Designated as Hedging Instrument | Interest rate contracts long-term
Derivative [Line Items]
Derivative Assets	0	22
Derivative Liabilities	0	0
Not Designated as Hedging Instrument | Commodity contracts current
Derivative [Line Items]
Derivative Assets	735	747
Derivative Liabilities	668	673
Not Designated as Hedging Instrument | Commodity contracts long-term
Derivative [Line Items]
Derivative Assets	358	295
Derivative Liabilities	$ 364	$ 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	Sep. 30, 2019	Dec. 31, 2018
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Cash Collateral (Held) / Posted	$ (30)	$ (33)
Derivative liabilities	(1,032)	(977)
Cash Collateral Posted	164	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	1,093	1,042
Derivative Instruments	(869)	(778)
Cash Collateral (Held) / Posted	(5)	(31)
Net Amount	219	233
Derivative liabilities	(1,032)	(977)
Derivative Instruments	869	778
Cash Collateral Posted	70	114
Net Amount	(93)	(85)
Gross Amounts of Recognized Assets / Liabilities	61	65
Derivative Instruments	0	0
Cash Collateral (Held) / Posted	65	83
Net Amount	$ 126	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 - Effects on Accumulated OCL balance attributable to hedge derivatives, net (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)
Derivative [Line Items]
Beginning balance	$ 2,071	$ 1,968
Reclassified from accumulated OCL to income:
Sale of NRG Yield and Renewables Platform	25	25
Ending balance	(936)	(936)
Balance, tax	0	0
AOCI Including Portion Attributable to Noncontrolling Interest | Interest rate contracts
Derivative [Line Items]
Beginning balance	(23)	(54)
Reclassified from accumulated OCL to income:
Ending balance	0	0
Accumulated Gain (Loss), Net, Cash Flow Hedge | Interest rate contracts
Reclassified from accumulated OCL to income:
Due to realization of previously deferred amounts	1	8
Accumulated Net Gain (Loss) from Cash Flow Hedges | Interest rate contracts
Reclassified from accumulated OCL to income:
Mark-to-market of cash flow hedge accounting contracts	$ (3)	$ 21

Accounting for Derivative Ins_7

Accounting for Derivative Instruments and Hedging Activities - Pre-tax effects of economic hedges not designated a cash flow hedges (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Unrealized mark-to-market results
Reversal of previously recognized unrealized (gains) on settled positions related to economic hedges	$ (118)	$ (84)	$ (88)	$ (85)
Reversal of acquired (gain) positions related to economic hedges	(3)	(10)	(4)	(11)
Net unrealized gains on open positions related to economic hedges	57	26	69	158
Total unrealized mark-to-market (losses)/gains for economic hedging activities	(64)	(68)	(23)	62
Reversal of previously recognized unrealized (gains) on settled positions related to trading activity	(1)	(4)	(8)	(10)
Net unrealized (losses)/gains on open positions related to trading activity	(3)	8	23	27
Total unrealized mark-to-market (losses)/gains for trading activity	(4)	4	15	17
Total unrealized (losses)/gains	(68)	(64)	(8)	79
Credit Risk Related Contingent Features
Unrealized gain (loss) from open economic hedge positions			69	158
Collateral due on net liability position that has not been called by a certain marginable agreement counterparty	2		2
Adequate Assurance Clauses
Credit Risk Related Contingent Features
Derivative net liability position, collateral required Contracts with Credit Rating Contingent Feature	39		39
Credit Rating Contingent Features
Credit Risk Related Contingent Features
Derivative net liability position, collateral required Contracts with Credit Rating Contingent Feature	18		18
Commodity contracts
Unrealized mark-to-market results
Total unrealized (losses)/gains	(68)	(64)	(8)	79
Commodity contracts | Operating revenues
Unrealized mark-to-market results
Total unrealized (losses)/gains	(214)	59	66	(14)
Commodity contracts | Cost of operations
Unrealized mark-to-market results
Total unrealized (losses)/gains	146	(123)	(74)	93
Interest rate contracts
Unrealized mark-to-market results
Total unrealized (losses)/gains	$ 0	$ 2	$ (38)	$ 17

Leases - Lease Cost and Other I

Leases - Lease Cost and Other Information (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)
Lease, Cost [Abstract]
Operating lease cost	$ 26	$ 82
Short-term lease cost	1	2
Variable lease cost	1	4
Sublease income	(4)	(13)
Total lease cost	$ 24	75
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases		77
Right-of-use assets obtained in exchange for new operating lease liabilities		$ 215
Lease Term and Discount Rate for Operating Leases
Weighted average remaining lease term (in years)	7 years 10 months 24 days	7 years 10 months 24 days
Weighted average discount rate	5.74%	5.74%

Leases - Schedule of Annual Pay

Leases - Schedule of Annual Payments Based on Maturities of Lease (Details) $ in Millions	Sep. 30, 2019USD ($)
Leases [Abstract]
Remainder of 2019	$ 26
2020	94
2021	86
2022	86
2023	86
Thereafter	372
Total undiscounted lease payments	750
Less: present value adjustment	(177)
Total discounted lease payments	$ 573

Impairments (Details)

Impairments (Details) - USD ($)	Jun. 29, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Impairment losses					$ 16,000,000
Impairment losses on cost investments and intangible assets				$ 7,000,000
Carrying amount		$ 405,000,000		405,000,000		$ 412,000,000
Petra Nova
Schedule of Equity Method Investments [Line Items]
Investment in cash		95,000,000
Letters of credit issued		12,000,000		12,000,000
Guarantor obligations (up to)		124,000,000		$ 124,000,000
Impairment losses		$ 101,000,000
Keystone
Schedule of Equity Method Investments [Line Items]
Impairment losses	$ 14,000,000
Interest in generating stations	3.70%
Conemaugh
Schedule of Equity Method Investments [Line Items]
Impairment losses	$ 14,000,000
Dunkirk
Schedule of Equity Method Investments [Line Items]
Impairment losses			$ 46,000,000
Carrying amount			$ 0		$ 0

Debt and Finance Leases - Sched

Debt and Finance Leases - Schedule of Long-term Debt and Capital Leases (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	May 28, 2019	May 14, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt amount	$ 6,257				$ 6,691
Finance leases	0				1
Subtotal long-term debt and capital leases (including current maturities)	6,257				6,692
Less current maturities	(302)				(72)
Less debt issuance costs	(68)				(70)
Discounts	(89)				(101)
Long-term debt	5,798				$ 6,449
Finance lease interest rate					6.50%
Recourse Debt
Debt Instrument [Line Items]
Debt amount	6,140				$ 6,523
Recourse Debt | Senior Notes, due 2024
Debt Instrument [Line Items]
Debt amount	$ 0				733
Interest rate, stated percentage	6.25%	6.25%
Recourse Debt | Senior Notes, due 2026
Debt Instrument [Line Items]
Debt amount	$ 1,000				1,000
Interest rate, stated percentage	7.25%
Recourse Debt | Senior Notes, due 2027
Debt Instrument [Line Items]
Debt amount	$ 1,230				1,230
Interest rate, stated percentage	6.625%
Recourse Debt | Senior Notes, due 2028
Debt Instrument [Line Items]
Debt amount	$ 821				821
Interest rate, stated percentage	5.75%
Recourse Debt | Senior Notes, due 2029
Debt Instrument [Line Items]
Debt amount	$ 733				0
Interest rate, stated percentage	5.25%			5.25%
Recourse Debt | Convertible Senior Notes, due 2048
Debt Instrument [Line Items]
Debt amount	$ 575				575
Interest rate, stated percentage	2.75%
Recourse Debt | Senior Secured First Lien Notes, due 2024
Debt Instrument [Line Items]
Debt amount	$ 600				0
Interest rate, stated percentage	3.75%		3.75%
Recourse Debt | Senior Secured First Lien Notes, due 2029
Debt Instrument [Line Items]
Debt amount	$ 500				0
Interest rate, stated percentage	4.45%		4.45%
Recourse Debt | Term loan facility
Debt Instrument [Line Items]
Debt amount	$ 0				1,698
Recourse Debt | Term loan facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%
Recourse Debt | Tax-exempt bonds
Debt Instrument [Line Items]
Debt amount	$ 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%
Line of Credit | Revolving Credit Facility | Credit Agreement
Debt Instrument [Line Items]
Debt amount	$ 215				0
Line of Credit | Revolving Credit Facility | Credit Agreement | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%
Line of Credit | Revolving Credit Facility | Credit Agreement | Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.75%
Non Recourse Debt
Debt Instrument [Line Items]
Debt amount	$ 117				168
Non Recourse Debt | Agua Caliente Borrower 1, due 2038
Debt Instrument [Line Items]
Debt amount	$ 83				86
Interest rate, stated percentage	5.43%
Non Recourse Debt | Midwest Generation
Debt Instrument [Line Items]
Debt amount	$ 0				48
Interest rate, stated percentage	4.39%
Non Recourse Debt | Other
Debt Instrument [Line Items]
Debt amount	$ 34				$ 34

Debt and Finance Leases - Senio

Debt and Finance Leases - Senior Notes (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	May 28, 2019	May 14, 2019
Debt Instrument [Line Items]
Loss on debt extinguishment	$ 0		$ 19,000,000	$ 47,000,000	$ 22,000,000
Recourse Debt
Debt Instrument [Line Items]
Debt issuance amount						$ 1,100,000,000
Recourse Debt | Senior Notes, due 2029
Debt Instrument [Line Items]
Debt issuance amount							$ 733,000,000
Interest rate, stated percentage	5.25%			5.25%			5.25%
Recourse Debt | Senior Notes, due 2024
Debt Instrument [Line Items]
Interest rate, stated percentage	6.25%	6.25%		6.25%
Senior Notes redeemed, amount		$ 733,000,000
Loss on debt extinguishment		29,000,000
Write off of previously deferred debt issuance costs		$ 5,000,000
Recourse Debt | Senior Secured First Lien Notes, due 2024
Debt Instrument [Line Items]
Debt issuance amount						$ 600,000,000
Interest rate, stated percentage	3.75%			3.75%		3.75%
Recourse Debt | Senior Secured First Lien Notes, due 2029
Debt Instrument [Line Items]
Debt issuance amount						$ 500,000,000
Interest rate, stated percentage	4.45%			4.45%		4.45%

Debt and Finance Leases - Sen_2

Debt and Finance Leases - Senior Credit Facility (Details) - USD ($)	May 28, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Debt Instrument [Line Items]
Repayment of Term Loan Facility				$ 2,487,000,000	$ 970,000,000
Decrease in long-term debt	$ 594,000,000
Loss on debt extinguishment		$ 0	$ 19,000,000	47,000,000	$ 22,000,000
Debt amount		6,257,000,000		6,257,000,000		$ 6,691,000,000
Recourse Debt
Debt Instrument [Line Items]
Debt amount		6,140,000,000		6,140,000,000		6,523,000,000
Recourse Debt | 2023 Term Loan Facility
Debt Instrument [Line Items]
Repayment of Term Loan Facility	1,700,000,000
Loss on debt extinguishment	17,000,000
Write off of previously deferred debt issuance costs	13,000,000
Debt amount		0		0		1,698,000,000
Recourse Debt | 2023 Term Loan Facility | Interest Rate Swap Agreements
Debt Instrument [Line Items]
Reduction to interest expense	$ 25,000,000
Revolving Credit Facility | Credit Agreement | Adjusted Base Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	1.25%
Revolving Credit Facility | Credit Agreement | Adjusted Base Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	0.75%
Revolving Credit Facility | Credit Agreement | Eurodollar Rate | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	2.25%
Revolving Credit Facility | Credit Agreement | Eurodollar Rate | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%
Revolving Credit Facility | Line of Credit | Credit Agreement
Debt Instrument [Line Items]
Amended credit agreement, increase in revolving commitments	$ 184,000,000
Credit agreement	$ 2,600,000,000
Debt amount		$ 215,000,000		$ 215,000,000		$ 0

Debt and Finance Leases - Non R

Debt and Finance Leases - Non Recourse Debt (Details) - USD ($)	Oct. 21, 2019	Jan. 04, 2019	Sep. 30, 2019
Agua Caliente Borrower 1 | Subsequent Event
Debt Instrument [Line Items]
Debt repaid, outstanding amount, percentage	102.00%
Credit Agreement | Letter of Credit
Debt Instrument [Line Items]
Credit agreement		$ 80,000,000
Facility fees		1.33%
Letters of credit issued			$ 80,000,000

Investments Accounted for Usi_3

Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs (Details) $ in Millions	3 Months Ended	9 Months Ended		12 Months Ended
	Mar. 31, 2018USD ($)	Sep. 30, 2019USD ($)projectMW	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Investments Accounted for by the Equity Method
Equity investments in affiliates		$ 405		$ 412
Generation capacity (in MW) | MW		23,000
Loss on deconsolidation			$ 22
Current assets		$ 3		3
Net property, plant and equipment		73		76
Other long-term assets		28		28
Total assets		104		107
Current liabilities		1		2
Long-term debt		28		29
Other long-term liabilities		8		7
Total liabilities		37		38
Redeemable noncontrolling interest		19		19
Net assets less noncontrolling interest		48		50
Agua Caliente
Investments Accounted for by the Equity Method
Equity investments in affiliates		213
Ivampah Master Holdings LLC
Investments Accounted for by the Equity Method
Equity investments in affiliates		$ 28
Economic interest in equity method investments (as a percent)		54.50%
Number of solar electric generating projects | project		3
Generation capacity (in MW) | MW		393
Release of reserve funds	$ 95
Decrease in assets due to deconsolidation				$ 1,300
Decrease in liabilities due to deconsolidation			$ 1,200

Changes in Capital Structure -

Changes in Capital Structure - Narrative (Details) - USD ($)	1 Months Ended			2 Months Ended	3 Months Ended
	Oct. 31, 2019	Apr. 30, 2019	Mar. 31, 2019	Feb. 28, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2018
Capital Structure
Common stock, shares authorized (in shares)					500,000,000						500,000,000
Stock repurchase program, authorized amount				$ 400,000,000
Shares repurchased, value					$ 234,000,000	$ 305,000,000	$ 749,000,000	$ 500,000,000	$ 407,000,000	$ 93,000,000
Employee Stock Purchase Plan, minimum percentage of eligible compensation to purchase shares			1.00%
Employee Stock Purchase Plan, maximum percentage of eligible compensation			10.00%
Employee Stock Purchase Plan, exercise price as percentage of fair value			95.00%
Subsequent Event
Capital Structure
Shares issued to employee accounts (in shares)	46,128
Additional Paid-in Capital
Capital Structure
Shares repurchased, value						$ (10,000,000)	$ 10,000,000	$ 37,000,000	$ 11,000,000
Accelerated Share Repurchase Program
Capital Structure
Shares repurchased (in shares)		351,768	9,086,903
Shares repurchased, value			$ 390,000,000
Average price paid per share (in usd per share)		$ 42.38
Accelerated Share Repurchase Program | Additional Paid-in Capital
Capital Structure
Remaining amount recorded in additional paid in capital		$ 10,000,000
2018 Plan
Capital Structure
Average price paid per share (in usd per share)				$ 40,610,000
2019 Plan
Capital Structure
Stock repurchase program, authorized amount				$ 1,000,000,000

Changes in Capital Structure _2

Changes in Capital Structure - Changes in NRG's common shares outstanding and issued (Details) - shares	1 Months Ended	9 Months Ended
	Oct. 31, 2019	Sep. 30, 2019
Schedule of Stock by Class, Equity [Roll Forward]
Balance as of beginning of period (in shares)	421,859,844	420,288,886
Treasury shares, balance as of beginning of period (in shares)	(169,874,327)	(136,638,847)
Outstanding, as of beginning of period (in shares)	251,985,517	283,650,039
Shares issued under LTIPs (in shares)		1,570,958
Shares repurchased (in shares)		(33,235,480)
Balance as of end of period (in shares)		421,859,844
Treasury shares, balance as of end of the period (in shares)		(169,874,327)
Outstanding, as of end of period (in shares)		251,985,517
Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	3,757
Shares repurchased (in shares)	(441,112)
Balance as of end of period (in shares)	421,863,601
Treasury shares, balance as of end of the period (in shares)	(170,269,311)
Outstanding, as of end of period (in shares)	251,594,290
Issued
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		1,570,958
Shares repurchased (in shares)		0
Issued | Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	3,757
Shares repurchased (in shares)	0
Treasury
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		0
Shares repurchased (in shares)		(33,235,480)
Treasury | Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	0
Shares repurchased (in shares)	(441,112)
Capital Allocation Plan
Schedule of Stock by Class, Equity [Roll Forward]
Shares repurchased (in shares)		(33,235,480)
Capital Allocation Plan | Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares repurchased (in shares)	(33,676,592)
ESPP | Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	46,128
ESPP | Issued | Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	0
ESPP | Treasury | Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)	46,128

Changes in Capital Structure _3

Changes in Capital Structure - Schedule of Repurchases Under Share Repurchase Programs (Details) - USD ($)	1 Months Ended	2 Months Ended			3 Months Ended	7 Months Ended	9 Months Ended
	Oct. 31, 2019	Sep. 30, 2019	Apr. 30, 2019	Feb. 28, 2019	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2019	Aug. 31, 2019
Schedule of Capitalization, Equity [Line Items]
Total number of shares purchased (in shares)							33,235,480
Stock repurchase program, authorized amount				$ 400,000,000
Subsequent Event
Schedule of Capitalization, Equity [Line Items]
Total number of shares purchased (in shares)	441,112
2018 Plan
Schedule of Capitalization, Equity [Line Items]
Total number of shares purchased (in shares)				6,153,415
Average price paid per share (in usd per share)				$ 40,610,000
Amounts paid for shares purchased				$ 250,000,000
Capital Allocation Plan, Accelerated Repurchase Agreement February 2019
Schedule of Capitalization, Equity [Line Items]
Total number of shares purchased (in shares)			9,438,671		16,615,479	26,054,150
Average price paid per share (in usd per share)						$ 38,380,000
Amounts paid for shares purchased			$ 400,000,000		$ 600,000,000	$ 1,000,000,000
Capital Allocation Plan August 2019
Schedule of Capitalization, Equity [Line Items]
Total number of shares purchased (in shares)		1,027,915
Average price paid per share (in usd per share)		$ 36,990,000
Amounts paid for shares purchased		$ 38,000,000
Stock repurchase program, authorized amount								$ 250,000,000
Capital Allocation Plan August 2019 | Subsequent Event
Schedule of Capitalization, Equity [Line Items]
Total number of shares purchased (in shares)	441,112
Average price paid per share (in usd per share)	$ 39,100,000
Amounts paid for shares purchased	$ 17,000,000
Capital Allocation Plan
Schedule of Capitalization, Equity [Line Items]
Total number of shares purchased (in shares)							33,235,480
Amounts paid for shares purchased							$ 1,288,000,000
Capital Allocation Plan | Subsequent Event
Schedule of Capitalization, Equity [Line Items]
Total number of shares purchased (in shares)	33,676,592
Amounts paid for shares purchased	$ 1,305,000,000

Changes in Capital Structure _4

Changes in Capital Structure - NRG Common Stock Dividends Paid (Details) - $ / shares	Nov. 01, 2019	Oct. 17, 2019	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Subsequent Event [Line Items]
Dividends Per Common Share (in usd per share)				$ 0.03	$ 0.03	$ 0.03	$ 0.03	$ 0.03	$ 0.03
Forecast
Subsequent Event [Line Items]
Common stock dividends proposed annual amount (in usd per share)			$ 1.20
Forecast | Minimum
Subsequent Event [Line Items]
Common stock, annual dividend growth rate, percentage			7.00%
Forecast | Maximum
Subsequent Event [Line Items]
Common stock, annual dividend growth rate, percentage			9.00%
Subsequent Event
Subsequent Event [Line Items]
Common stock dividends declared (in usd per share)		$ 0.03
Common stock dividends proposed annual amount (in usd per share)	$ 0.12

Earnings Per Share - Reconcilia

Earnings Per Share - Reconciliation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Basic income per share attributable to NRG Energy, Inc;
Net income/(loss) attributable to NRG Energy, Inc. common stockholders	$ 372	$ (72)	$ 1,055	$ 280
Weighted average number of common shares outstanding — basic (in shares)	254	299	266	309
Income/(loss) per weighted average common share — basic (in usd per share)	$ 1.46	$ (0.24)	$ 3.97	$ 0.91
Diluted income per share attributable to NRG Energy, Inc;
Net income/(loss) attributable to NRG Energy, Inc. available to common shareholders	$ 372	$ (72)	$ 1,055	$ 280
Weighted average number of common shares outstanding - diluted (in shares)	254	299	266	309
Incremental shares attributable to the issuance of equity compensation (treasury stock method) (in shares)	2	0	2	4
Total dilutive shares (in shares)	256	299	268	313
Income/(loss) per weighted average common share — diluted (in usd per share)	$ 1.45	$ (0.24)	$ 3.94	$ 0.89

Earnings Per Share - Anti-dilut

Earnings Per Share - Anti-dilutive Securities (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Equity compensation plans
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	4	0	0

Segment Reporting (Details)

Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information
Operating revenues	$ 2,996	$ 2,960	$ 7,626	$ 7,486
Depreciation and amortization	91	99	261	331
Impairment losses	0	0	1	74
Reorganization costs	1	27	16	70
(Loss)/gain on sale of assets	0		2	30
Equity in earnings (losses) of unconsolidated affiliates	29	20	8	26
Loss on debt extinguishment, net	0	(19)	(47)	(22)
Income/(loss) from continuing operations before income taxes	380	295	666	572
Income/(loss) from continuing operations	374	287	657	553
Loss from discontinued operations, net of income tax	(2)	(336)	399	(272)
Net Income/(Loss)	372	(49)	1,056	281
Net (loss)/income attributable to NRG Energy, Inc.	372	(72)	1,055	280
Eliminations
Segment Reporting Information
Operating revenues	(522)	(722)	(1,437)	(927)
Depreciation and amortization	0	2	0	0
Impairment losses			0	0
Reorganization costs	0	0	0	0
(Loss)/gain on sale of assets	0		0	0
Equity in earnings (losses) of unconsolidated affiliates	0	(3)	0	(5)
Loss on debt extinguishment, net		0	0
Income/(loss) from continuing operations before income taxes	1	(7)	0	(4)
Income/(loss) from continuing operations	1	(7)	0	(4)
Loss from discontinued operations, net of income tax	0	0	0	0
Net Income/(Loss)	1	(7)	0	(4)
Net (loss)/income attributable to NRG Energy, Inc.	1	(5)	0	0
Retail | Operating Segments
Segment Reporting Information
Operating revenues	2,544	2,203	5,899	5,497
Depreciation and amortization	37	30	100	86
Impairment losses			1	0
Reorganization costs	1	6	4	10
(Loss)/gain on sale of assets	(1)		(1)	0
Equity in earnings (losses) of unconsolidated affiliates	0	0	0	0
Loss on debt extinguishment, net		0	0
Income/(loss) from continuing operations before income taxes	422	(128)	253	732
Income/(loss) from continuing operations	422	(128)	252	732
Loss from discontinued operations, net of income tax	0	0	0	0
Net Income/(Loss)	422	(128)	252	732
Net (loss)/income attributable to NRG Energy, Inc.	422	(128)	251	731
Retail | Eliminations
Segment Reporting Information
Operating revenues	(1)	(1)	(6)	(7)
Generation | Operating Segments
Segment Reporting Information
Operating revenues	974	1,478	3,164	2,916
Depreciation and amortization	47	60	138	220
Impairment losses			0	74
Reorganization costs	0	3	1	10
(Loss)/gain on sale of assets	1		2	1
Equity in earnings (losses) of unconsolidated affiliates	29	20	8	27
Loss on debt extinguishment, net		0	0
Income/(loss) from continuing operations before income taxes	64	575	795	256
Income/(loss) from continuing operations	63	574	794	255
Loss from discontinued operations, net of income tax	0	0	0	0
Net Income/(Loss)	63	574	794	255
Net (loss)/income attributable to NRG Energy, Inc.	63	559	794	246
Generation | Eliminations
Segment Reporting Information
Operating revenues	(513)	(739)	(1,375)	(944)
Corporate | Operating Segments
Segment Reporting Information
Operating revenues	0	1	0	0
Depreciation and amortization	7	7	23	25
Impairment losses			0	0
Reorganization costs	0	18	11	50
(Loss)/gain on sale of assets	0		1	29
Equity in earnings (losses) of unconsolidated affiliates	0	3	0	4
Loss on debt extinguishment, net		(19)	(47)
Income/(loss) from continuing operations before income taxes	(107)	(145)	(382)	(412)
Income/(loss) from continuing operations	(112)	(152)	(389)	(430)
Loss from discontinued operations, net of income tax	(2)	(336)	399	(272)
Net Income/(Loss)	(114)	(488)	10	(702)
Net (loss)/income attributable to NRG Energy, Inc.	(114)	(498)	10	(697)
Corporate | Eliminations
Segment Reporting Information
Operating revenues	$ (8)	$ 18	$ (56)	$ 24

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Effective Tax Rate
Income from continuing operations before income taxes	$ 380	$ 295	$ 666	$ 572
Income tax expense from continuing operations	$ 6	$ 8	$ 9	$ 19
Effective income tax rate	1.60%	2.70%	1.40%	3.30%
Uncertain Tax Benefits
Non-current tax liability for uncertain tax benefits	$ 29		$ 29
Uncertain tax benefits, penalties and interest accrued	$ 5		$ 5

Related Party Transactions - Sc

Related Party Transactions - Schedule of NRG's Material Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Related Party Transaction [Line Items]
Revenue from related parties	$ 11	$ 21	$ 32	$ 72
Gladstone
Related Party Transaction [Line Items]
Revenue from related parties	2	1	3	2
GenConn
Related Party Transaction [Line Items]
Revenue from related parties	0	1	0	4
Ivanpah
Related Party Transaction [Line Items]
Revenue from related parties	7	8	25	13
Midway-Sunset
Related Party Transaction [Line Items]
Revenue from related parties	2	0	4	0
GenOn
Related Party Transaction [Line Items]
Revenue from related parties	$ 0	$ 11	$ 0	$ 53

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	Jun. 01, 2001	Jun. 30, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2018facility	Aug. 18, 2016USD ($)
Commonwealth Edison Company And Exelon Generation Company LLC
Loss Contingencies
Payment for litigation settlement		$ 26
CDWR and SDGE v Sunrise Power
Loss Contingencies
PPA period	10 years
Damages sought, amount			$ 1.2
Remaining term			70 months
Sierra Club Et Al V. Midwest Generation LLC
Loss Contingencies
Number of facilities | facility				4
Lignite Contract With Texas Westmoreland Coal Co.
Loss Contingencies
Bond obligation					$ 99

Condensed Consolidating Finan_3

Condensed Consolidating Financial Information - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Amount outstanding	$ 6,257	$ 6,691
Recourse Debt
Debt Instrument [Line Items]
Amount outstanding	6,140	$ 6,523
Senior Notes | Recourse Debt
Debt Instrument [Line Items]
Amount outstanding	4,400
Senior Secured First Lien Notes | Recourse Debt
Debt Instrument [Line Items]
Amount outstanding	$ 1,100

Condensed Consolidating Finan_4

Condensed Consolidating Financial Information - CONSOLIDATING STATEMENTS OF OPERATIONS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating Revenues
Total operating revenues	$ 2,996	$ 2,960	$ 7,626	$ 7,486
Operating Costs and Expenses
Cost of operations	2,153	2,238	5,649	5,512
Depreciation and amortization	91	99	261	331
Impairment losses	0	0	1	74
Selling, general and administrative	210	211	615	587
Reorganization costs	1	27	16	70
Development costs	1	1	5	9
Total operating costs and expenses	2,456	2,576	6,547	6,583
Gain on sale of assets	0	14	2	30
Operating Income/(Loss)	540	398	1,081	933
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries	0	0	0	0
Equity in earnings of unconsolidated affiliates	29	20	8	26
Impairment losses on investments	107	1	107	16
Other income, net	17	19	49	12
Loss on debt extinguishment, net	0	(19)	(47)	(22)
Interest expense	(99)	(122)	(318)	(361)
Total other income/(expense)	(160)	(103)	(415)	(361)
Income from Continuing Operations Before Income Taxes	380	295	666	572
Income Tax Expense (Benefit)	6	8	9	19
Income from Continuing Operations	374	287	657	553
Income/(loss) from discontinued operations, net of income tax	(2)	(336)	399	(272)
Net Income/(Loss)	372	(49)	1,056	281
Less: Net income attributable to redeemable noncontrolling interests	0	23	1	1
Net income/(loss) attributable to NRG Energy, Inc.	372	(72)	1,055	280
Eliminations
Operating Revenues
Total operating revenues	(2)	(2)	(8)	(12)
Operating Costs and Expenses
Cost of operations	(2)	(2)	(8)	(13)
Depreciation and amortization	0	0	0	0
Impairment losses			0	0
Selling, general and administrative	0	(73)	0	(73)
Reorganization costs	0	0	0	0
Development costs	0	0	0	(1)
Total operating costs and expenses	(2)	(75)	(8)	(87)
Gain on sale of assets		0	0	0
Operating Income/(Loss)	0	73	0	75
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries	(557)	(476)	(1,298)	(1,170)
Equity in earnings of unconsolidated affiliates	0	0	0	0
Impairment losses on investments	0	0	0	0
Other income, net	0	0	0	0
Loss on debt extinguishment, net		0	0	0
Interest expense	0	0	0	0
Total other income/(expense)	(557)	(476)	(1,298)	(1,170)
Income from Continuing Operations Before Income Taxes	(557)	(403)	(1,298)	(1,095)
Income Tax Expense (Benefit)	0	0	0	0
Income from Continuing Operations	(557)	(403)	(1,298)	(1,095)
Income/(loss) from discontinued operations, net of income tax	0	0	0	0
Net Income/(Loss)	(557)	(403)	(1,298)	(1,095)
Less: Net income attributable to redeemable noncontrolling interests		73	0	75
Net income/(loss) attributable to NRG Energy, Inc.	(557)	(476)	(1,298)	(1,170)
Guarantor Subsidiaries
Operating Revenues
Total operating revenues	2,473	2,521	6,382	6,437
Operating Costs and Expenses
Cost of operations	1,728	1,937	4,676	4,794
Depreciation and amortization	52	54	157	177
Impairment losses			1	0
Selling, general and administrative	132	123	366	335
Reorganization costs	0	0	0	3
Development costs	0	0	0	0
Total operating costs and expenses	1,912	2,114	5,200	5,309
Gain on sale of assets		0	1	3
Operating Income/(Loss)	561	407	1,183	1,131
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries	20	6	32	14
Equity in earnings of unconsolidated affiliates	0	0	0	0
Impairment losses on investments	0	0	0	0
Other income, net	11	4	19	12
Loss on debt extinguishment, net		0	0	0
Interest expense	(4)	(4)	(11)	(11)
Total other income/(expense)	27	6	40	15
Income from Continuing Operations Before Income Taxes	588	413	1,223	1,146
Income Tax Expense (Benefit)	0	122	0	343
Income from Continuing Operations	588	291	1,223	803
Income/(loss) from discontinued operations, net of income tax	0	16	9	46
Net Income/(Loss)	588	307	1,232	849
Less: Net income attributable to redeemable noncontrolling interests		0	0	0
Net income/(loss) attributable to NRG Energy, Inc.	588	307	1,232	849
Non-Guarantor Subsidiaries
Operating Revenues
Total operating revenues	525	441	1,252	1,061
Operating Costs and Expenses
Cost of operations	421	294	956	713
Depreciation and amortization	32	36	81	128
Impairment losses			0	74
Selling, general and administrative	28	19	56	46
Reorganization costs	0	0	0	0
Development costs	0	(2)	1	0
Total operating costs and expenses	481	347	1,094	961
Gain on sale of assets		14	1	27
Operating Income/(Loss)	44	108	159	127
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries	0	0	0	0
Equity in earnings of unconsolidated affiliates	29	21	8	28
Impairment losses on investments	101	1	101	16
Other income, net	1	9	10	(11)
Loss on debt extinguishment, net		0	0	0
Interest expense	(3)	(8)	(12)	(42)
Total other income/(expense)	(74)	21	(95)	(41)
Income from Continuing Operations Before Income Taxes	(30)	129	64	86
Income Tax Expense (Benefit)	1	42	2	26
Income from Continuing Operations	(31)	87	62	60
Income/(loss) from discontinued operations, net of income tax	0	20	5	80
Net Income/(Loss)	(31)	107	67	140
Less: Net income attributable to redeemable noncontrolling interests		(62)	1	(181)
Net income/(loss) attributable to NRG Energy, Inc.	(31)	169	66	321
NRG Energy, Inc. (Note Issuer)
Operating Revenues
Total operating revenues	0	0	0	0
Operating Costs and Expenses
Cost of operations	6	9	25	18
Depreciation and amortization	7	9	23	26
Impairment losses			0	0
Selling, general and administrative	50	142	193	279
Reorganization costs	1	27	16	67
Development costs	1	3	4	10
Total operating costs and expenses	65	190	261	400
Gain on sale of assets		0	0	0
Operating Income/(Loss)	(65)	(190)	(261)	(400)
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries	537	470	1,266	1,156
Equity in earnings of unconsolidated affiliates	0	(1)	0	(2)
Impairment losses on investments	6	0	6	0
Other income, net	5	6	20	11
Loss on debt extinguishment, net		(19)	(47)	(22)
Interest expense	(92)	(110)	(295)	(308)
Total other income/(expense)	444	346	938	835
Income from Continuing Operations Before Income Taxes	379	156	677	435
Income Tax Expense (Benefit)	5	(156)	7	(350)
Income from Continuing Operations	374	312	670	785
Income/(loss) from discontinued operations, net of income tax	(2)	(372)	385	(398)
Net Income/(Loss)	372	(60)	1,055	387
Less: Net income attributable to redeemable noncontrolling interests		12	0	107
Net income/(loss) attributable to NRG Energy, Inc.	$ 372	$ (72)	$ 1,055	$ 280

Condensed Consolidating Finan_5

Condensed Consolidating Financial Information - CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Financial Statements, Captions [Line Items]
Net Income	$ 372	$ (49)	$ 1,056	$ 281
Other Comprehensive (Loss)/Income
Unrealized gain/(loss) on derivatives, net	0	5	0	24
Foreign currency translation adjustments, net	(4)	(2)	(4)	(8)
Available-for-sale securities, net	(14)	0	(13)	1
Defined benefit plans, net	(41)	(1)	(47)	(3)
Other comprehensive (loss)/income	(59)	2	(64)	14
Comprehensive Income/(Loss)	313	(47)	992	295
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable interests	0	26	1	15
Comprehensive Income (Loss), Net of Tax, Attributable to Parent, Total	313	(73)	991	280
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net Income	(557)	(403)	(1,298)	(1,095)
Other Comprehensive (Loss)/Income
Unrealized gain/(loss) on derivatives, net		7		(15)
Foreign currency translation adjustments, net	9	3	9	17
Available-for-sale securities, net	0		0	0
Defined benefit plans, net	40	0	40	0
Other comprehensive (loss)/income	49	10	49	2
Comprehensive Income/(Loss)		(393)	(1,249)	(1,093)
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable interests		73	0	75
Comprehensive Income (Loss), Net of Tax, Attributable to Parent, Total	(508)	(466)	(1,249)	(1,168)
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net Income	588	307	1,232	849
Other Comprehensive (Loss)/Income
Unrealized gain/(loss) on derivatives, net		0		0
Foreign currency translation adjustments, net	(5)	(2)	(5)	(8)
Available-for-sale securities, net	0		0	0
Defined benefit plans, net	(40)	0	(40)	0
Other comprehensive (loss)/income	(45)	(2)	(45)	(8)
Comprehensive Income/(Loss)		305	1,187	841
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable interests		0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent, Total	543	305	1,187	841
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net Income	(31)	107	67	140
Other Comprehensive (Loss)/Income
Unrealized gain/(loss) on derivatives, net		10		30
Foreign currency translation adjustments, net	(4)	(2)	(4)	(8)
Available-for-sale securities, net	0		0	0
Defined benefit plans, net	0	0	0	0
Other comprehensive (loss)/income	(4)	8	(4)	22
Comprehensive Income/(Loss)		115	63	162
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable interests		(58)	1	(167)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent, Total	(35)	173	62	329
NRG Energy, Inc. (Note Issuer)
Condensed Financial Statements, Captions [Line Items]
Net Income	372	(60)	1,055	387
Other Comprehensive (Loss)/Income
Unrealized gain/(loss) on derivatives, net		(12)		9
Foreign currency translation adjustments, net	(4)	(1)	(4)	(9)
Available-for-sale securities, net	(14)		(13)	1
Defined benefit plans, net	(41)	(1)	(47)	(3)
Other comprehensive (loss)/income	(59)	(14)	(64)	(2)
Comprehensive Income/(Loss)		(74)	991	385
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable interests		11	0	107
Comprehensive Income (Loss), Net of Tax, Attributable to Parent, Total	$ 313	$ (85)	$ 991	$ 278

Condensed Consolidating Finan_6

Condensed Consolidating Financial Information - CONSOLIDATING BALANCE SHEETS (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 243			$ 563
Funds deposited by counterparties	30			33
Restricted cash	4			17
Accounts receivable, net	1,376			1,024
Inventory	364			412
Derivative instruments	735			764
Cash collateral paid in support of energy risk management activities	164			287
Prepayments and other current assets	271			302
Current assets - held-for-sale	0			1
Current assets - discontinued operations	0			197
Total current assets	3,187			3,600
Property, plant and equipment, net	2,615			3,048
Other Assets
Investment in subsidiaries	0			0
Equity investments in affiliates	405			412
Operating lease right-of-use assets, net	482
Goodwill	591			573
Intangible assets, net	828			591
Nuclear decommissioning trust fund	756			663
Derivative instruments	358			317
Deferred income taxes	53			46
Other non-current assets	252			289
Non-current assets - held-for-sale	0			77
Non-current assets - discontinued operations	0			1,012
Total other assets	3,725			3,980
Total Assets	9,527			10,628
Current Liabilities
Current portion of long-term debt	302			72
Current portion of operating lease liabilities	73
Accounts payable	866			863
Derivative instruments	668			673
Cash collateral received in support of energy risk management activities	30			33
Accrued expenses and other current liabilities	625			680
Current liabilities - held-for-sale	0			5
Current liabilities - discontinued operations	0			72
Total current liabilities	2,564			2,398
Other Liabilities
Long-term debt	5,798			6,449
Non-current operating lease liabilities	500
Nuclear decommissioning reserve	294			282
Nuclear decommissioning trust liability	453			371
Derivative instruments	364			304
Deferred income taxes	70			65
Other non-current liabilities	1,036			1,274
Non-current liabilities - held-for-sale	0			65
Non-current liabilities - discontinued operations	0			635
Total other liabilities	8,515			9,445
Total Liabilities	11,079			11,843
Redeemable noncontrolling interest in subsidiaries	19			19
Total Stockholders' Equity	(1,571)	$ (1,648)	$ (1,538)	(1,234)	$ (936)	$ 2,071	$ 2,258	$ 1,968
Total Liabilities and Stockholders' Equity	9,527			10,628
Eliminations
Current Assets
Cash and cash equivalents	0			0
Funds deposited by counterparties	0			0
Restricted cash	0			0
Accounts receivable, net	(1,293)			(754)
Inventory	0			0
Derivative instruments	(33)			(81)
Cash collateral paid 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	(1,326)			(835)
Property, plant and equipment, net	0			0
Other Assets
Investment in subsidiaries	(5,463)			(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	(12)			(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	(5,475)			(5,170)
Total Assets	(6,801)			(6,005)
Current Liabilities
Current portion of long-term debt	0			0
Current portion of operating lease liabilities	0
Accounts payable	(1,293)			(754)
Derivative instruments	(33)			(81)
Cash collateral received in support of energy risk management activities	0			0
Accrued expenses and other current liabilities	0			0
Current liabilities - held-for-sale				0
Current liabilities - discontinued operations				0
Total current liabilities	(1,326)			(835)
Other Liabilities
Long-term debt	0			(12)
Non-current operating lease liabilities	0
Nuclear decommissioning reserve	0			0
Nuclear decommissioning trust liability	0			0
Derivative instruments	(12)			(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	(12)			(17)
Total Liabilities	(1,338)			(852)
Redeemable noncontrolling interest in subsidiaries	0			0
Total Stockholders' Equity	(5,463)			(5,153)
Total Liabilities and Stockholders' Equity	(6,801)			(6,005)
Guarantor Subsidiaries
Current Assets
Cash and cash equivalents	0			55
Funds deposited by counterparties	30			33
Restricted cash	2			7
Accounts receivable, net	2,049			1,354
Inventory	248			278
Derivative instruments	740			779
Cash collateral paid in support of energy risk management activities	146			275
Prepayments and other current assets	178			180
Current assets - held-for-sale				0
Current assets - discontinued operations				177
Total current assets	3,393			3,138
Property, plant and equipment, net	1,494			1,938
Other Assets
Investment in subsidiaries	786			446
Equity investments in affiliates	0			0
Operating lease right-of-use assets, net	85
Goodwill	359			359
Intangible assets, net	390			422
Nuclear decommissioning trust fund	756			663
Derivative instruments	356			296
Deferred income taxes	0			6
Other non-current assets	151			133
Non-current assets - held-for-sale				0
Non-current assets - discontinued operations				405
Total other assets	2,883			2,730
Total Assets	7,770			7,806
Current Liabilities
Current portion of long-term debt	0			0
Current portion of operating lease liabilities	21
Accounts payable	1,315			1,368
Derivative instruments	683			713
Cash collateral received in support of energy risk management activities	30			33
Accrued expenses and other current liabilities	271			291
Current liabilities - held-for-sale				0
Current liabilities - discontinued operations				24
Total current liabilities	2,320			2,429
Other Liabilities
Long-term debt	245			244
Non-current operating lease liabilities	70
Nuclear decommissioning reserve	294			282
Nuclear decommissioning trust liability	453			371
Derivative instruments	374			306
Deferred income taxes	(10)			112
Other non-current liabilities	412			402
Non-current liabilities - held-for-sale				0
Non-current liabilities - discontinued operations				58
Total other liabilities	1,838			1,775
Total Liabilities	4,158			4,204
Redeemable noncontrolling interest in subsidiaries	0			0
Total Stockholders' Equity	3,612			3,602
Total Liabilities and Stockholders' Equity	7,770			7,806
Non-Guarantor Subsidiaries
Current Assets
Cash and cash equivalents	26			28
Funds deposited by counterparties	0			0
Restricted cash	1			10
Accounts receivable, net	194			115
Inventory	116			134
Derivative instruments	28			50
Cash collateral paid in support of energy risk management activities	18			12
Prepayments and other current assets	15			32
Current assets - held-for-sale				1
Current assets - discontinued operations				20
Total current assets	398			402
Property, plant and equipment, net	965			957
Other Assets
Investment in subsidiaries	0			0
Equity investments in affiliates	405			412
Operating lease right-of-use assets, net	271
Goodwill	232			214
Intangible assets, net	438			169
Nuclear decommissioning trust fund	0			0
Derivative instruments	14			4
Deferred income taxes	53			(143)
Other non-current assets	30			71
Non-current assets - held-for-sale				77
Non-current assets - discontinued operations				607
Total other assets	1,443			1,411
Total Assets	2,806			2,770
Current Liabilities
Current portion of long-term debt	87			55
Current portion of operating lease liabilities	31
Accounts payable	146			(185)
Derivative instruments	18			41
Cash collateral received in support of energy risk management activities	0			0
Accrued expenses and other current liabilities	51			36
Current liabilities - held-for-sale				5
Current liabilities - discontinued operations				48
Total current liabilities	333			0
Other Liabilities
Long-term debt	85			192
Non-current operating lease liabilities	307
Nuclear decommissioning reserve	0			0
Nuclear decommissioning trust liability	0			0
Derivative instruments	2			3
Deferred income taxes	67			61
Other non-current liabilities	160			320
Non-current liabilities - held-for-sale				65
Non-current liabilities - discontinued operations				577
Total other liabilities	621			1,218
Total Liabilities	954			1,218
Redeemable noncontrolling interest in subsidiaries	19			19
Total Stockholders' Equity	1,833			1,533
Total Liabilities and Stockholders' Equity	2,806			2,770
NRG Energy, Inc. (Note Issuer)
Current Assets
Cash and cash equivalents	217			480
Funds deposited by counterparties	0			0
Restricted cash	1			0
Accounts receivable, net	426			309
Inventory	0			0
Derivative instruments	0			16
Cash collateral paid in support of energy risk management activities	0			0
Prepayments and other current assets	78			90
Current assets - held-for-sale				0
Current assets - discontinued operations				0
Total current assets	722			895
Property, plant and equipment, net	156			153
Other Assets
Investment in subsidiaries	4,677			4,707
Equity investments in affiliates	0			0
Operating lease right-of-use assets, net	126
Goodwill	0			0
Intangible assets, net	0			0
Nuclear decommissioning trust fund	0			0
Derivative instruments	0			22
Deferred income taxes	0			183
Other non-current assets	71			97
Non-current assets - held-for-sale				0
Non-current assets - discontinued operations				0
Total other assets	4,874			5,009
Total Assets	5,752			6,057
Current Liabilities
Current portion of long-term debt	215			17
Current portion of operating lease liabilities	21
Accounts payable	698			434
Derivative instruments	0			0
Cash collateral received in support of energy risk management activities	0			0
Accrued expenses and other current liabilities	303			353
Current liabilities - held-for-sale				0
Current liabilities - discontinued operations				0
Total current liabilities	1,237			804
Other Liabilities
Long-term debt	5,468			6,025
Non-current operating lease liabilities	123
Nuclear decommissioning reserve	0			0
Nuclear decommissioning trust liability	0			0
Derivative instruments	0			0
Deferred income taxes	13			(108)
Other non-current liabilities	464			552
Non-current liabilities - held-for-sale				0
Non-current liabilities - discontinued operations				0
Total other liabilities	6,068			6,469
Total Liabilities	7,305			7,273
Redeemable noncontrolling interest in subsidiaries	0			0
Total Stockholders' Equity	(1,553)			(1,216)
Total Liabilities and Stockholders' Equity	$ 5,752			$ 6,057

Condensed Consolidating Finan_7

Condensed Consolidating Financial Information - CONSOLIDATING STATEMENTS OF CASH FLOWS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Cash Flows from Operating Activities
Net Income/(Loss)	$ 372	$ (49)	$ 1,056	$ 281
Income/(loss) from discontinued operations, net of income tax	(2)	(336)	399	(272)
Income from continuing operations	374	287	657	553
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Distributions and equity earnings of unconsolidated affiliates			(5)	10
Depreciation, amortization and accretion			289	364
Provision for bad debts			87	57
Amortization of nuclear fuel			40	38
Amortization of financing costs and debt discount/premiums			20	21
Loss on debt extinguishment, net			47	22
Amortization of emissions allowances and out-of-market contracts			28	21
Amortization of unearned equity compensation			15	21
Gain on sale and disposal of assets			(20)	(50)
Impairment losses			108	90
Changes in derivative instruments			36	(17)
Changes in deferred income taxes and liability for uncertain tax benefits			(3)	(6)
Changes in collateral deposits in support of energy risk management activities			129	(30)
Changes in nuclear decommissioning trust liability			27	50
GenOn settlement			0	(125)
Loss on deconsolidation of Agua Caliente and Ivanpah projects			0	13
Changes in other working capital			(602)	(361)
Cash provided/(used) by continuing operations			853	671
Cash provided/(used) by discontinued operations			8	396
Net Cash Provided/(Used) by Operating Activities			861	1,067
Cash Flows from Investing Activities
Intercompany dividends			0	0
Payments for acquisitions of businesses			(348)	(209)
Capital expenditures			(183)	(343)
Proceeds from Collection of Notes Receivable			2	0
Net purchases of /proceeds from emission allowances			14	24
Investments in nuclear decommissioning trust fund securities			(295)	(449)
Proceeds from the sale of nuclear decommissioning trust fund securities			271	398
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees			1,293	1,555
Deconsolidation of Agua Caliente and Ivanpah projects			0	(268)
Net contributions to investments in unconsolidated affiliates			(94)	(39)
Contributions to discontinued operations			(44)	(23)
Cash (used)/provided by continuing operations			616	646
Cash used by discontinued operations			(2)	(705)
Net Cash (Used)/Provided by Investing Activities			614	(59)
Cash Flows from Financing Activities
Payments from/(for) intercompany loans			0	0
Intercompany dividends			0	0
Payments of dividends to common stockholders			(24)	(28)
Payments for treasury stock			(1,286)	(1,000)
Payments for debt extinguishment costs			(24)	0
Distributions to noncontrolling interests from subsidiaries			(1)	(17)
Proceeds from issuance of common stock			3	15
Proceeds from issuance of short and long-term debt			2,048
Proceeds from issuance of short and long-term debt			2,048	995
Payment of debt issuance costs			(34)	(19)
Payments for short and long-term debt			(2,487)	(970)
Receivable from affiliate			0	(26)
Other			0	(4)
Cash used by continuing operations			(1,805)	(1,054)
Cash provided by discontinued operations			43	403
Net Cash Used by Financing Activities			(1,762)	(651)
Effect of exchange rate changes on cash and cash equivalents				1
Change in cash from discontinued operations			49	94
Net (Decrease)/increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash			(336)	264
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period			613	1,086
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	277	1,350	277	1,350
Eliminations
Cash Flows from Operating Activities
Net Income/(Loss)	(557)	(403)	(1,298)	(1,095)
Income/(loss) from discontinued operations, net of income tax	0	0	0	0
Income from continuing operations	(557)	(403)	(1,298)	(1,095)
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Distributions and equity earnings of unconsolidated affiliates			1,298	1,110
Depreciation, amortization and accretion			0	0
Provision for bad debts			0	0
Amortization of nuclear fuel			0	0
Amortization of financing costs and debt discount/premiums			0	0
Loss on debt extinguishment, net			0	0
Amortization of emissions allowances and out-of-market contracts			0	0
Amortization of unearned equity compensation			0	0
Gain on sale and disposal of assets			0	0
Impairment losses			0	0
Changes in derivative instruments			0	(15)
Changes in deferred income taxes and liability for uncertain tax benefits			0	0
Changes in collateral deposits in support of energy risk management activities			0	0
Changes in nuclear decommissioning trust liability			0	0
GenOn settlement				0
Loss on deconsolidation of Agua Caliente and Ivanpah projects				0
Changes in other working capital			0	0
Cash provided/(used) by continuing operations			0	0
Cash provided/(used) by discontinued operations			0	0
Net Cash Provided/(Used) by Operating Activities			0	0
Cash Flows from Investing Activities
Intercompany dividends			(1,665)	(1,273)
Payments for acquisitions of businesses			0	0
Capital expenditures			0	0
Proceeds from Collection of Notes Receivable			0
Net purchases of /proceeds from emission allowances			0	0
Investments in nuclear decommissioning trust fund securities			0	0
Proceeds from the sale of nuclear decommissioning trust fund securities			0	0
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees				0
Deconsolidation of Agua Caliente and Ivanpah projects				0
Net contributions to investments in unconsolidated affiliates			0	0
Contributions to discontinued operations			0	0
Cash (used)/provided by continuing operations			(1,665)	(1,273)
Cash used by discontinued operations			0	0
Net Cash (Used)/Provided by Investing Activities			(1,665)	(1,273)
Cash Flows from Financing Activities
Payments from/(for) intercompany loans			0	0
Intercompany dividends			1,665	1,273
Payments of dividends to common stockholders			0	0
Payments for treasury stock			0	0
Payments for debt extinguishment costs			0
Distributions to noncontrolling interests from subsidiaries			0	0
Proceeds from issuance of common stock			0	0
Proceeds from issuance of short and long-term debt			0
Proceeds from issuance of short and long-term debt				0
Payment of debt issuance costs			0	0
Payments for short and long-term debt			0	0
Receivable from affiliate				0
Other				0
Cash used by continuing operations			1,665	1,273
Cash provided by discontinued operations			0	0
Net Cash Used by Financing Activities			1,665	1,273
Effect of exchange rate changes on cash and cash equivalents				0
Change in cash from discontinued operations			0	0
Net (Decrease)/increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash			0	0
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period			0	0
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	0	0	0	0
Guarantor Subsidiaries
Cash Flows from Operating Activities
Net Income/(Loss)	588	307	1,232	849
Income/(loss) from discontinued operations, net of income tax	0	16	9	46
Income from continuing operations	588	291	1,223	803
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Distributions and equity earnings of unconsolidated affiliates			(32)	(14)
Depreciation, amortization and accretion			181	201
Provision for bad debts			72	55
Amortization of nuclear fuel			40	38
Amortization of financing costs and debt discount/premiums			0	0
Loss on debt extinguishment, net			0	0
Amortization of emissions allowances and out-of-market contracts			21	15
Amortization of unearned equity compensation			0	0
Gain on sale and disposal of assets			(25)	(23)
Impairment losses			1	0
Changes in derivative instruments			10	(38)
Changes in deferred income taxes and liability for uncertain tax benefits			0	343
Changes in collateral deposits in support of energy risk management activities			136	(16)
Changes in nuclear decommissioning trust liability			27	50
GenOn settlement				0
Loss on deconsolidation of Agua Caliente and Ivanpah projects				0
Changes in other working capital			(401)	(385)
Cash provided/(used) by continuing operations			1,253	1,029
Cash provided/(used) by discontinued operations			17	72
Net Cash Provided/(Used) by Operating Activities			1,270	1,101
Cash Flows from Investing Activities
Intercompany dividends			0	0
Payments for acquisitions of businesses			(348)	(2)
Capital expenditures			(135)	(156)
Proceeds from Collection of Notes Receivable			0
Net purchases of /proceeds from emission allowances			14	24
Investments in nuclear decommissioning trust fund securities			(295)	(449)
Proceeds from the sale of nuclear decommissioning trust fund securities			271	398
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees			1	10
Deconsolidation of Agua Caliente and Ivanpah projects				0
Net contributions to investments in unconsolidated affiliates			0	0
Contributions to discontinued operations			0	0
Cash (used)/provided by continuing operations			(492)	(175)
Cash used by discontinued operations			0	(2)
Net Cash (Used)/Provided by Investing Activities			(492)	(177)
Cash Flows from Financing Activities
Payments from/(for) intercompany loans			784	476
Intercompany dividends			(1,608)	(1,273)
Payments of dividends to common stockholders			0	0
Payments for treasury stock			0	0
Payments for debt extinguishment costs			0
Distributions to noncontrolling interests from subsidiaries			0	0
Proceeds from issuance of common stock			0	0
Proceeds from issuance of short and long-term debt			0
Proceeds from issuance of short and long-term debt				0
Payment of debt issuance costs			0	0
Payments for short and long-term debt			0	0
Receivable from affiliate				0
Other				0
Cash used by continuing operations			(824)	(797)
Cash provided by discontinued operations			0	0
Net Cash Used by Financing Activities			(824)	(797)
Effect of exchange rate changes on cash and cash equivalents				0
Change in cash from discontinued operations			17	70
Net (Decrease)/increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash			(63)	57
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period			95	41
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	32	98	32	98
Non-Guarantor Subsidiaries
Cash Flows from Operating Activities
Net Income/(Loss)	(31)	107	67	140
Income/(loss) from discontinued operations, net of income tax	0	20	5	80
Income from continuing operations	(31)	87	62	60
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Distributions and equity earnings of unconsolidated affiliates			(5)	9
Depreciation, amortization and accretion			85	137
Provision for bad debts			11	2
Amortization of nuclear fuel			0	0
Amortization of financing costs and debt discount/premiums			0	23
Loss on debt extinguishment, net			0	0
Amortization of emissions allowances and out-of-market contracts			7	6
Amortization of unearned equity compensation			0	0
Gain on sale and disposal of assets			2	(27)
Impairment losses			101	90
Changes in derivative instruments			(12)	40
Changes in deferred income taxes and liability for uncertain tax benefits			(1)	11
Changes in collateral deposits in support of energy risk management activities			(7)	(14)
Changes in nuclear decommissioning trust liability			0	0
GenOn settlement				0
Loss on deconsolidation of Agua Caliente and Ivanpah projects				13
Changes in other working capital			(120)	(266)
Cash provided/(used) by continuing operations			123	84
Cash provided/(used) by discontinued operations			(9)	324
Net Cash Provided/(Used) by Operating Activities			114	408
Cash Flows from Investing Activities
Intercompany dividends			0	0
Payments for acquisitions of businesses			0	(207)
Capital expenditures			(23)	(150)
Proceeds from Collection of Notes Receivable			0
Net purchases of /proceeds from emission allowances			0	0
Investments in nuclear decommissioning trust fund securities			0	0
Proceeds from the sale of nuclear decommissioning trust fund securities			0	0
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees			400	8
Deconsolidation of Agua Caliente and Ivanpah projects				(268)
Net contributions to investments in unconsolidated affiliates			(94)	(39)
Contributions to discontinued operations			(44)	(23)
Cash (used)/provided by continuing operations			239	(679)
Cash used by discontinued operations			(2)	(703)
Net Cash (Used)/Provided by Investing Activities			237	(1,382)
Cash Flows from Financing Activities
Payments from/(for) intercompany loans			(260)	170
Intercompany dividends			(57)	0
Payments of dividends to common stockholders			0	0
Payments for treasury stock			0	0
Payments for debt extinguishment costs			0
Distributions to noncontrolling interests from subsidiaries			(1)	(17)
Proceeds from issuance of common stock			0	0
Proceeds from issuance of short and long-term debt			0
Proceeds from issuance of short and long-term debt				163
Payment of debt issuance costs			0	0
Payments for short and long-term debt			(55)	(106)
Receivable from affiliate				0
Other				(4)
Cash used by continuing operations			(373)	206
Cash provided by discontinued operations			43	403
Net Cash Used by Financing Activities			(330)	609
Effect of exchange rate changes on cash and cash equivalents				1
Change in cash from discontinued operations			32	24
Net (Decrease)/increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash			(11)	(388)
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period			38	425
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	27	37	27	37
NRG Energy, Inc. (Note Issuer)
Cash Flows from Operating Activities
Net Income/(Loss)	372	(60)	1,055	387
Income/(loss) from discontinued operations, net of income tax	(2)	(372)	385	(398)
Income from continuing operations	374	312	670	785
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Distributions and equity earnings of unconsolidated affiliates			(1,266)	(1,095)
Depreciation, amortization and accretion			23	26
Provision for bad debts			4	0
Amortization of nuclear fuel			0	0
Amortization of financing costs and debt discount/premiums			20	(2)
Loss on debt extinguishment, net			47	22
Amortization of emissions allowances and out-of-market contracts			0	0
Amortization of unearned equity compensation			15	21
Gain on sale and disposal of assets			3	0
Impairment losses			6	0
Changes in derivative instruments			38	(4)
Changes in deferred income taxes and liability for uncertain tax benefits			(2)	(360)
Changes in collateral deposits in support of energy risk management activities			0	0
Changes in nuclear decommissioning trust liability			0	0
GenOn settlement				(125)
Loss on deconsolidation of Agua Caliente and Ivanpah projects				0
Changes in other working capital			(81)	290
Cash provided/(used) by continuing operations			(523)	(442)
Cash provided/(used) by discontinued operations			0	0
Net Cash Provided/(Used) by Operating Activities			(523)	(442)
Cash Flows from Investing Activities
Intercompany dividends			1,665	1,273
Payments for acquisitions of businesses			0	0
Capital expenditures			(25)	(37)
Proceeds from Collection of Notes Receivable			2
Net purchases of /proceeds from emission allowances			0	0
Investments in nuclear decommissioning trust fund securities			0	0
Proceeds from the sale of nuclear decommissioning trust fund securities			0	0
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees			892	1,537
Deconsolidation of Agua Caliente and Ivanpah projects				0
Net contributions to investments in unconsolidated affiliates			0	0
Contributions to discontinued operations			0	0
Cash (used)/provided by continuing operations			2,534	2,773
Cash used by discontinued operations			0	0
Net Cash (Used)/Provided by Investing Activities			2,534	2,773
Cash Flows from Financing Activities
Payments from/(for) intercompany loans			(524)	(646)
Intercompany dividends			0	0
Payments of dividends to common stockholders			(24)	(28)
Payments for treasury stock			(1,286)	(1,000)
Payments for debt extinguishment costs			(24)
Distributions to noncontrolling interests from subsidiaries			0	0
Proceeds from issuance of common stock			3	15
Proceeds from issuance of short and long-term debt			2,048
Proceeds from issuance of short and long-term debt				832
Payment of debt issuance costs			(34)	(19)
Payments for short and long-term debt			(2,432)	(864)
Receivable from affiliate				(26)
Other				0
Cash used by continuing operations			(2,273)	(1,736)
Cash provided by discontinued operations			0	0
Net Cash Used by Financing Activities			(2,273)	(1,736)
Effect of exchange rate changes on cash and cash equivalents				0
Change in cash from discontinued operations			0	0
Net (Decrease)/increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash			(262)	595
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period			480	620
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	$ 218	$ 1,215	$ 218	$ 1,215