NRG Energy (NRG) 10-Q 2 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	NRG ENERGY, INC.
Entity Central Index Key	1,013,871
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		316,641,799
Document Fiscal Year Focus	2,017
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, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating Revenues
Total operating revenues	$ 3,049	$ 3,421	$ 8,132	$ 8,328
Operating Costs and Expenses
Cost of operations	2,156	2,440	5,852	5,711
Depreciation and amortization	272	298	789	826
Impairment losses	14	9	77	65
Selling, general and administrative	213	277	697	801
Reorganization	18	0	18	0
Development activity expenses	14	21	49	65
Total operating costs and expenses	2,687	3,045	7,482	7,468
Other income - affiliate	14	48	104	144
Gain/(loss) on sale of assets	0	4	4	(79)
Operating Income/(Loss)	376	428	758	925
Other Income/(Expense)
Equity in earnings of unconsolidated affiliates	27	16	29	13
Impairment loss on investment	0	(8)	0	(147)
Other income, net	15	7	33	29
Loss on debt extinguishment, net	(1)	(50)	(3)	(119)
Interest expense	(221)	(237)	(692)	(718)
Total other (expense)/income	(180)	(272)	(633)	(942)
Income/(Loss) from Continuing Operations Before Income Taxes	196	156	125	(17)
Income tax expense	6	28	5	75
Income/(Loss) from Continuing Operations	190	128	120	(92)
(Loss)/Income from discontinued operations, net of income tax	(27)	265	(802)	256
Net Income/(Loss)	163	393	(682)	164
Less: Net loss attributable to noncontrolling interest and redeemable noncontrolling interests	(8)	(9)	(63)	(49)
Net Income/(Loss) Attributable to NRG Energy, Inc.	171	402	(619)	213
Dividends for preferred shares	0	0	0	5
Gain on redemption of preferred shares	0	0	0	(78)
Net Income/(Loss) Available for Common Stockholders	$ 171	$ 402	$ (619)	$ 286
Income/(Loss) per Share Attributable to NRG Energy, Inc. Common Stockholders
Weighted average number of common shares outstanding - basic (in shares)	317	316	317	315
Income from continuing operations per weighted average common share — basic (in usd per share)	$ 0.63	$ 0.43	$ 0.58	$ 0.10
(Loss)/Income from discontinued operations per weighted average common share — basic (in usd per share)	(0.09)	0.84	(2.53)	0.81
Income/(Loss) per Weighted Average Common Share — Basic (in usd per share)	$ 0.54	$ 1.27	$ (1.95)	$ 0.91
Weighted average number of common shares outstanding — diluted (in shares)	322	317	317	316
Income from continuing operations per weighted average common share — diluted (in usd per share)	$ 0.61	$ 0.43	$ 0.58	$ 0.10
(Loss)/Income from discontinued operations per weighted average common share — diluted (in usd per share)	(0.08)	0.84	(2.53)	0.81
Income/(Loss) per Weighted Average Common Share — Diluted (in usd per share)	0.53	1.27	(1.95)	0.91
Dividends Per Common Share (in usd per share)	$ 0.03	$ 0.03	$ 0.09	$ 0.21

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income/(Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income/(loss)	$ 163	$ 393	$ (682)	$ 164
Other comprehensive income/(loss), net of tax
Unrealized gain/(loss) on derivatives, net of income tax (benefit)/expense of $0, $(1), $1, and $1	7	27	6	(8)
Foreign currency translation adjustments, net of income tax expense of $0, $0, $0, and $0	2	3	10	6
Available-for-sale securities, net of income tax expense of $0, $0, $0, and $0	1	0	2	1
Defined benefit plans, net of income tax expense of $0, $0, $0, and $0	(1)	31	26	32
Other comprehensive income	9	61	44	31
Comprehensive income/(loss)	172	454	(638)	195
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest	(5)	(2)	(61)	(70)
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.	177	456	(577)	265
Dividends for preferred shares	0	0	0	5
Gain on redemption of preferred shares	0	0	0	(78)
Comprehensive income/(loss) available for common stockholders	$ 177	$ 456	$ (577)	$ 338

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Comprehensive Income/(Loss) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Unrealized loss on derivatives, income tax expense	$ 0	$ (1)	$ 1	$ 1
Foreign currency translation adjustments, income tax expense	0	0	0	0
Available-for-sale securities, income tax expense	0	0	0	0
Defined benefit plans, income tax expense	$ 0	$ 0	$ 0	$ 0

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents	$ 1,223	$ 938
Funds deposited by counterparties	31	2
Restricted cash	537	446
Accounts receivable, net	1,274	1,058
Inventory	630	721
Derivative instruments	475	1,067
Cash collateral posted in support of energy risk management activities	203	150
Current assets - held for sale	33	9
Prepayments and other current assets	354	404
Current assets - discontinued operations	0	1,919
Total current assets	4,760	6,714
Property, plant and equipment, net	15,332	15,369
Other Assets
Equity investments in affiliates	1,138	1,120
Notes receivable, less current portion	5	16
Goodwill	662	662
Intangible assets, net	1,838	1,973
Nuclear decommissioning trust fund	670	610
Derivative instruments	206	181
Deferred income taxes	205	225
Non-current assets held-for-sale	10	10
Other non-current assets	644	841
Non-current assets - discontinued operations	0	2,961
Total other assets	5,378	8,599
Total Assets	25,470	30,682
Current Liabilities
Current portion of long-term debt and capital leases	1,247	516
Accounts payable	911	813
Derivative instruments	522	1,092
Cash collateral received in support of energy risk management activities	31	81
Accrued expenses and other current liabilities	830	990
Accrued expenses and other current liabilities - affiliate	164	0
Current liabilities - discontinued operations	0	1,210
Total current liabilities	3,705	4,702
Other Liabilities
Long-term debt and capital leases	15,658	15,957
Nuclear decommissioning reserve	265	287
Nuclear decommissioning trust liability	397	339
Deferred income taxes	21	20
Derivative instruments	307	284
Out-of-market contracts, net	213	230
Non-current liabilities held-for-sale	13	11
Other non-current liabilities	1,116	1,176
Non-current liabilities - discontinued operations	0	3,184
Total non-current liabilities	17,990	21,488
Total Liabilities	21,695	26,190
Redeemable noncontrolling interest in subsidiaries	85	46
Commitments and Contingencies
Stockholders’ Equity
Common stock	4	4
Additional paid-in capital	8,369	8,358
Retained deficit	(4,713)	(3,787)
Less treasury stock, at cost — 101,580,045 and 102,140,814 shares, respectively	(2,386)	(2,399)
Accumulated other comprehensive loss	(91)	(135)
Noncontrolling interest	2,507	2,405
Total Stockholders’ Equity	3,690	4,446
Total Liabilities and Stockholders’ Equity	$ 25,470	$ 30,682

Condensed Consolidated Balance6

Condensed Consolidated Balance Sheets (Parenthetical) - shares	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Treasury stock, shares (in shares)	101,580,045	102,140,814

Condensed Consolidated Stateme7

Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows from Operating Activities
Net Income/(Loss)	$ (682)	$ 164
(Loss)/Income from discontinued operations, net of income tax	(802)	256
Income/(loss) from continuing operations	120	(92)
Adjustments to reconcile net (loss)/income to net cash provided by operating activities:
Distributions and equity in earnings of unconsolidated affiliates	24	44
Depreciation and amortization	789	826
Provision for bad debts	57	36
Amortization of nuclear fuel	37	39
Amortization of financing costs and debt discount/premiums	44	42
Adjustment for debt extinguishment	3	119
Amortization of intangibles and out-of-market contracts	79	131
Amortization of unearned equity compensation	27	23
Impairment losses	77	211
Changes in deferred income taxes and liability for uncertain tax benefits	26	29
Changes in nuclear decommissioning trust liability	20	24
Changes in derivative instruments	25	30
Changes in collateral posted in support of risk management activities	(103)	261
Proceeds from sale of emission allowances	21	11
(Gain)/loss on sale of assets	(22)	70
Changes in other working capital	(380)	(130)
Cash provided by continuing operations	844	1,674
Cash (used)/provided by discontinued operations	(38)	67
Net Cash Provided by Operating Activities	806	1,741
Cash Flows from Investing Activities
Acquisitions of businesses, net of cash acquired	(36)	(18)
Capital expenditures	(760)	(659)
Decrease in notes receivable	11	2
Purchases of emission allowances	(47)	(32)
Proceeds from sale of emission allowances	105	47
Investments in nuclear decommissioning trust fund securities	(402)	(378)
Proceeds from the sale of nuclear decommissioning trust fund securities	382	354
Proceeds from renewable energy grants and state rebates	8	11
Proceeds from sale of assets, net of cash disposed of	36	84
Investments in unconsolidated affiliates	(31)	(23)
Other	22	31
Cash (used)/provided by continuing operations	(712)	(581)
Cash (used)/provided by discontinued operations	(53)	326
Net Cash (Used)/Provided by Investing Activities	(765)	(255)
Cash Flows from Financing Activities
Payment of dividends to common and preferred stockholders	(28)	(66)
Payment for preferred shares	0	(226)
Net receipts from settlement of acquired derivatives that include financing elements	2	6
Proceeds from issuance of long-term debt	1,134	5,237
Payments for short and long-term debt	(712)	(5,353)
Receivable from affiliate	(125)	0
Payments for debt extinguishment costs	0	(98)
Contributions from, net of distributions to, noncontrolling interest in subsidiaries	65	(127)
Proceeds from issuance of common stock	0	1
Payment of debt issuance costs	(43)	(70)
Other - contingent consideration	(10)	(10)
Cash provided/(used) by continuing operations	283	(706)
Cash (used)/provided by discontinued operations	(224)	119
Net Cash provided/(used) by Financing Activities	59	(587)
Effect of exchange rate changes on cash and cash equivalents	(10)	(6)
Change in Cash from discontinued operations	(315)	512
Net Increase/(Decrease) in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties	405	381
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period	1,386	1,322
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	$ 1,791	$ 1,703

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation NRG Energy, Inc., or NRG or the Company, is a leading integrated power company built on the strength of a diverse competitive electric generation portfolio and leading retail electricity platform. NRG is continuously focused on excellence in operating performance of its existing assets and optimal hedging of generation assets and retail load operations, as well as serving the energy needs of end-use residential, commercial and industrial customers in competitive markets through multiple brands and channels. The Company owns and operates approximately 30,000 MW of generation; engages in the trading of wholesale energy, capacity and related products; transacts in and trades fuel and transportation services; and directly sells energy, services, and innovative, sustainable products and services to retail customers under the names “NRG”, "Reliant" and other retail brand names owned by NRG. 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 2016 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, 2017 , and the results of operations, comprehensive income/(loss) and cash flows for the three and nine months ended September 30, 2017 and 2016 . GenOn Chapter 11 Cases On June 14, 2017, or the Petition Date, GenOn, along with GenOn Americas Generation and certain of their directly and indirectly-owned subsidiaries, or collectively the GenOn Entities, filed voluntary petitions for relief under Chapter 11, or the Chapter 11 Cases, of the U.S. Bankruptcy Code, or the Bankruptcy Code, in the U.S. Bankruptcy Court for the Southern District of Texas, Houston Division, or the Bankruptcy Court. GenOn Mid-Atlantic, as well as its consolidated subsidiaries, REMA and certain other subsidiaries, did not file for relief under Chapter 11. As a result of the bankruptcy filings and beginning on June 14, 2017, GenOn and its subsidiaries were deconsolidated from NRG’s consolidated financial statements. NRG recorded its investment in GenOn under the cost method with an estimated fair value of zero . NRG determined that this disposal of GenOn and its subsidiaries is a discontinued operation; and, accordingly, the financial information for all historical periods have been recast to reflect GenOn as a discontinued operation. In connection with the disposal, NRG recorded a loss on deconsolidation of $208 million during the quarter ended June 30, 2017. See Note 3 , Discontinued Operations, Dispositions and Acquisitions , for more information. Prior to the GenOn Entities' filing the Chapter 11 Cases, on June 12, 2017, NRG entered into a restructuring support and lock-up agreement, or the Restructuring Support Agreement, with the GenOn Entities and certain holders of the GenOn and GenOn Americas Generation Senior Notes, that provides for a restructuring and recapitalization of the GenOn Entities through a prearranged plan of reorganization. The RSA was amended on October 2, 2017 to remove the requirement to conduct a rights offering in connection with the exit financing. There is no assurance that the GenOn Entities' plan will be approved by the requisite stakeholders, confirmed by the Bankruptcy Court, or successfully implemented thereafter. The principal terms of the Restructuring Support Agreement are described further in Note 3 , Discontinued Operations, Dispositions and Acquisitions . As announced on October 31, 2017, NRG and GenOn engaged in arms-length discussions to settle certain items related to the pre-petition Restructuring Support Agreement, including key topics such as: (i) timeline and transition; (ii) cooperation and co-development matters; (iii) post-employment and retiree health and welfare benefits and pension benefits; (iv) tax matters; and (v) intercompany balances. The agreements reached on these topics are expected to be incorporated into definitive documents for GenOn’s emergence from Chapter 11. Forms of definitive documents were filed with the Bankruptcy Court by the GenOn Entities; however, such definitive documents are subject to ongoing review, revision, and further negotiation by the parties to the Restructuring Support Agreement, including NRG, who have various consent rights over the final form of the plan supplement documents, and may be amended, modified, supplemented, and revised in accordance with those ongoing negotiations. Transformation Plan On July 12, 2017, NRG announced its Transformation Plan designed to significantly strengthen earnings and cost competitiveness, lower risk and volatility, and create significant shareholder value. The three-part, three -year plan is comprised of the following targets: Operations and cost excellence — Cost savings and margin enhancement of $1,065 million recurring, which consists of $590 million of annual cost savings, a $215 million net margin enhancement program, $50 million annual reduction in maintenance capital expenditures, and $210 million in permanent selling, general and administrative expense reduction associated with asset sales. Portfolio optimization — Targeting up to $4.0 billion of asset sale net cash proceeds, including divestitures of 6 GWs of conventional generation and businesses (excluding GenOn) and the expected monetization of 100% of its interest in NRG Yield, Inc. and its renewables platform. Capital structure and allocation enhancements — A prioritized capital allocation strategy that targets a reduction in consolidated debt from approximately $19.5 billion ( $18 billion net debt) to approximately $6.5 billion ( $6 billion net debt). Following the completion of the contemplated asset sales, the Company expects $4.8 - $6.3 billion in excess cash to be available for allocation through 2020, after achieving its targeted 3.0 x net debt / Adjusted EBITDA corporate credit ratio. The Company expects to fully implement the Transformation Plan by the end of 2020 with significant completion by the end of 2018. The Company expects to realize (i) $370 million of non-recurring working capital improvements through 2020 and (ii) approximately $290 million , one-time costs to achieve. 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. The reclassifications did not affect results from operations, net assets or cash flows.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies 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, 2017 December 31, 2016 (In millions) Accounts receivable allowance for doubtful accounts $ 61 $ 29 Property, plant and equipment accumulated depreciation 6,437 5,711 Intangible assets accumulated amortization 1,750 1,687 Out-of-market contracts accumulated amortization 352 457 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 sheet that sum to the total of the same such amounts shown in the statement of cash flows. September 30, 2017 December 31, 2016 September 30, 2016 December 31, 2015 (In millions) Cash and cash equivalents $ 1,223 $ 938 $ 1,217 $ 853 Funds deposited by counterparties 31 2 6 55 Restricted cash 537 446 480 414 Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows $ 1,791 $ 1,386 $ 1,703 $ 1,322 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. As of December 31, 2016, $79 million of the cash collateral received was from GenOn, previously a consolidated subsidiary, and is included in cash collateral received in current liabilities as a result of deconsolidating GenOn, with the offset included in cash and cash equivalents. 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. Noncontrolling Interest The following table reflects the changes in NRG's noncontrolling interest balance: (In millions) Balance as of December 31, 2016 $ 2,405 Contributions from noncontrolling interest 116 Non-cash adjustments to noncontrolling interest 98 Sale of assets to NRG Yield, Inc. 24 Comprehensive loss attributable to noncontrolling interest (8 ) Dividends paid to NRG Yield, Inc. public shareholders (80 ) Distributions to noncontrolling interest (48 ) Balance as of September 30, 2017 $ 2,507 Redeemable Noncontrolling Interest The following table reflects the changes in the Company's redeemable noncontrolling interest balance: (In millions) Balance as of December 31, 2016 $ 46 Contributions from redeemable noncontrolling interest 73 Non-cash adjustments to noncontrolling interest 21 Comprehensive loss attributable to redeemable noncontrolling interest (53 ) Distributions to redeemable noncontrolling interest (2 ) Balance as of September 30, 2017 $ 85 Recent Accounting Developments - Guidance Adopted in 2017 ASU 2016-18 — In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230) , Restricted Cash, or ASU No. 2016-18. The amendments of ASU No. 2016-18 require an entity to include amounts generally described as restricted cash and restricted cash equivalents, including funds deposited by counterparties with cash and cash equivalents when reconciling the beginning of period and end of period total amounts on the statement of cash flows. The amendments of ASU No. 2016-18 are effective for annual reporting periods beginning after December 15, 2017, and interim periods within those annual periods. Early adoption is permitted and the adoption of ASU No. 2016-18 will be applied retrospectively. The Company adopted the guidance in ASU No. 2016-18 during the second quarter of 2017. In connection with the adoption of the standard, the Company has applied the guidance retrospectively which resulted in a decrease in cash flows from operations of $49 million and an increase in cash flows from investing of $66 million on the statement of cash flows for the nine months ended September 30, 2016. ASU 2016-16 — In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740) , Intra-Entity Transfers of Assets Other Than Inventory, or ASU No. 2016-16. Current GAAP prohibits the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset has been sold to an outside party which has resulted in diversity in practice and increased complexity within financial reporting. The amendments of ASU No. 2016-16 would require an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The Company adopted the guidance in ASU No. 2016-16 effective January 1, 2017. In connection with the adoption of the standard, the Company recorded a reduction to non-current assets of $267 million with a corresponding reduction to cumulative retained deficit. ASU 2016-15 — In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230) , Classification of Certain Cash Receipts and Cash Payments, or ASU No. 2016-15. The amendments of ASU No. 2016-15 were issued to address eight specific cash flow issues for which stakeholders have indicated to the FASB that a diversity in practice existed in how entities were presenting and classifying these items in the statement of cash flows. The issues addressed by ASU No. 2016-15 include but are not limited to the classification of debt prepayment and debt extinguishment costs, payments made for contingent consideration for a business combination, proceeds from the settlement of insurance proceeds, distributions received from equity method investees and separately identifiable cash flows and the application of the predominance principle. The Company adopted the guidance in ASU No. 2016-15 effective January 1, 2017. In connection with the adoption of the standard, the Company has applied the guidance retrospectively which resulted in an increase in cash flows from operations of $98 million and a decrease in cash flows from financing of $98 million on the statement of cash flows for the nine months ended September 30, 2016. ASU 2016-09 — In March 2016, the FASB issued ASU No. 2016-09, Compensation - Stock Compensation (Topic 718), or ASU No. 2016-09. The amendments focused on simplification specifically with regard to share-based payment transactions, including income tax consequences, classification of awards as equity or liabilities and classification on the statement of cash flows. The Company adopted the guidance in ASU No. 2016-09 effective January 1, 2017 with no material adjustments recorded to the consolidated balance sheet. Recent Accounting Developments - Guidance Not Yet Adopted ASU 2017-12 — In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815) , Targeted Improvements to Accounting for Hedging Activities, or ASU No. 2017-12. The amendments of ASU No. 2017-12 were issued to simplify the application of hedge accounting guidance and more closely align financial reporting for hedging relationships with economic results of an entity's risk management activities. The issues addressed by ASU No. 2017-12 include but are not limited to alignment of risk management activities and financial reporting, risk component hedging, accounting for the hedged item in fair value hedges of interest rate risk, recognition and presentation of the effects of hedging instruments, amounts excluded from the assessment of hedge effectiveness, and other simplifications of hedge accounting guidance. The amendments of ASU No. 2017-12 are effective for fiscal years beginning after December 15, 2018, and interim periods therein. Early adoption is permitted in any interim period and the effect of the adoption should be reflected as of the beginning of the fiscal year of adoption. The Company does not expect the adoption of ASU No. 2017-12 will have a material impact on its consolidated results of operations, cash flows, and statement of financial position. ASU 2017-07 — In March 2017, the FASB issued ASU No. 2017-07, Compensation - Retirement Benefits (Topic 715) , Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, or ASU No. 2017-07. Current GAAP does not indicate where the amount of net benefit cost should be presented in an entity’s income statement and does not require entities to disclose the amount of net benefit cost that is included in the income statement. The amendments of ASU No. 2017-07 require an entity to report the service cost component of net benefit costs in the same line item as other compensation costs arising from services rendered by the related employees during the applicable service period. The other components of net benefit cost are required to be presented separately from the service cost component and outside the subtotal of income from operations. Further, ASU No. 2017-07 prescribes that only the service cost component of net benefit costs is eligible for capitalization. The amendments of ASU No. 2017-07 are effective for fiscal years beginning after December 15, 2017, including interim periods therein. Early adoption is permitted and must be applied on a retrospective basis, except for the amendments regarding the capitalization of the service cost component, which must be applied prospectively. The Company is currently assessing the impact that the adoption of ASU No. 2017-07 will have on its results of operations, cash flows, and statement of financial position. ASU 2016-02 — In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) , or Topic 842, 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 expects to adopt the standard effective January 1, 2019 utilizing the required modified retrospective approach for the earliest period presented. The Company expects to elect certain of the practical expedients permitted, including the expedient that permits the Company to retain its existing lease assessment and classification. The Company is currently working through an adoption plan which includes the evaluation of lease contracts compared to the new standard. While the Company is currently evaluating the impact the new guidance will have on its financial position and results of operations, the Company expects to recognize lease liabilities and right of use assets. The extent of the increase to assets and liabilities associated with these amounts remains to be determined pending the Company’s review of its existing lease contracts and service contracts which may contain embedded leases. While this review is still in process, NRG believes the adoption of Topic 842 will have a material impact on its financial statements. ASU 2014-09 — In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) , or Topic 606, which was further amended through various updates issued by the FASB thereafter. The amendments of Topic 606 completed the joint effort between the FASB and the IASB, to develop a common revenue standard for GAAP and IFRS, and to improve financial reporting. The guidance under Topic 606 provides that an entity should recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for the goods or services provided and establishes a five step model to be applied by an entity in evaluating its contracts with customers. The Company expects to adopt the standard effective January 1, 2018 and apply the guidance retrospectively to contracts at the date of adoption. The Company will recognize the cumulative effect of applying Topic 606 at the date of initial application, as prescribed under the modified retrospective transition method. The Company also expects to elect the practical expedient available under Topic 606 for measuring progress toward complete satisfaction of a performance obligation and for disclosure requirements of remaining performance obligations. The practical expedient allows an entity to recognize revenue in the amount to which the entity has the right to invoice such that the entity has a right to the consideration in an amount that corresponds directly with the value to the customer for performance completed to date by the entity. The Company continues to assess the new standard with a focus on identifying the performance obligations included within its revenue arrangements with customers and evaluating the Company’s methods of estimating the amount and timing of variable consideration. While the impact remains subject to continued review, the Company does not believe the adoption of Topic 606 will have a material impact on its financial statements.

Discontinued Operations, Dispos

Discontinued Operations, Dispositions and Acquisitions	9 Months Ended
	Sep. 30, 2017
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations, Dispositions and Acquisitions	Discontinued Operations, Dispositions and Acquisitions Discontinued Operations As described in Note 1 , Basis of Presentation , on the Petition Date, 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 controls GenOn as it is subject to the control of the Bankruptcy Court; and, accordingly, NRG no longer consolidates GenOn for financial reporting purposes. By eliminating a large portion of its operations in the PJM market with the deconsolidation of GenOn, NRG concluded that GenOn meets the criteria for discontinued operations, as this represents a strategic shift in the markets in which NRG operates. As such, all prior period results for GenOn have been reclassified as discontinued operations while NRG will record all ongoing results of GenOn as a cost method investment, which was valued at zero at the date of deconsolidation. Summarized results of discontinued operations were as follows: Three months ended September 30, 2017 (a) Three months ended September 30, 2016 Nine months ended September 30, 2017 (a) Nine months ended September 30, 2016 (In millions) Operating revenues $ — $ 532 $ 646 $ 1,509 Operating costs and expenses — (468 ) (700 ) (1,409 ) Gain on sale of assets — 262 — 294 Other expenses — (43 ) (98 ) (127 ) (Loss)/Income from operations of discontinued components, before tax — 283 (152 ) 267 Income tax expense — 21 9 20 (Loss)/Incomes from operations of discontinued components — 262 (161 ) 247 Interest income - affiliate — 3 6 9 (Loss)/Income from operations of discontinued components, net of tax — 265 (155 ) 256 Pre-tax loss on deconsolidation — — (208 ) — Settlement consideration and services credit — — (289 ) — Pension and post-retirement liability assumption (b) (25 ) — (144 ) — Other (2 ) — (6 ) — Loss on disposal of discontinued components, net of tax (27 ) — (647 ) — (Loss)/Income from discontinued operations, net of tax $ (27 ) $ 265 $ (802 ) $ 256 (a) As of June 14, 2017, NRG no longer consolidates GenOn for financial reporting purposes. (b) See Note 1 , Basis of Presentation , for further discussion regarding the October 30, 2017 proposed changes to the Restructuring Support Agreement. As part of this, NRG recorded the liability for GenOn’s post-employment and retiree health and welfare benefits, in an amount up to $25 million with a corresponding loss on discontinued operations during the third quarter of 2017. The following table summarizes the major classes of assets and liabilities classified as discontinued operations as of December 31, 2016. As of June 14, 2017, NRG no longer consolidates GenOn for financial reporting purposes. (In millions) December 31, 2016 Cash and cash equivalents $ 1,034 Other current assets 885 Current assets - discontinued operations 1,919 Property, plant and equipment, net 2,543 Other non-current assets 418 Non-current assets - discontinued operations 2,961 Current portion of long term debt and capital leases 704 Other current liabilities 506 Current liabilities - discontinued operations 1,210 Long-term debt and capital leases 2,050 Out-of-market contracts 811 Other non-current liabilities 323 Non-current liabilities - discontinued operations $ 3,184 Restructuring Support Agreement As described in Note 1 , Basis of Presentation , NRG, GenOn and certain holders representing greater than 93% in aggregate principal amount of GenOn’s Senior Notes and certain holders representing greater than 93% in aggregate principal amount of GenOn Americas Generation’s Senior Notes entered into a Restructuring Support Agreement that provides for a restructuring and recapitalization of the GenOn Entities through a prearranged plan of reorganization. Completion of the agreed upon terms is contingent upon certain milestones in the Restructuring Support Agreement. Certain principal terms of the Restructuring Support Agreement are detailed below: 1) Full releases from GenOn and GenOn Americas Generation in favor of NRG, including either a full release or indemnification in favor of NRG for any claims relating to GenOn Mid-Atlantic or REMA and the dismissal of all litigation against NRG. 2) NRG will provide settlement cash consideration to GenOn of $261.3 million , which will be paid in cash less any amounts owed to NRG under the intercompany secured revolving credit facility. As of September 30, 2017, GenOn owed NRG approximately $125 million under the intercompany secured revolving credit facility. See Note 14 , Related Party Transactions , for further discussion of the intercompany secured revolving credit facility. 3) NRG will consent to the cancellation of its interests in the equity of GenOn. The equity interests in the reorganized GenOn will be issued to the holders of the GenOn Senior Notes. 4) NRG will retain the pension liability, including payment of approximately $13 million of 2017 pension contributions, for GenOn employees for service provided prior to the completion of the reorganization, which was paid in September 2017. GenOn’s pension liability as of September 30, 2017 was approximately $106 million . 5) The shared services agreement between NRG and GenOn will be amended such that (i) NRG will provide shared services to GenOn at an annualized rate of $84 million during the pendency of the Chapter 11 Cases, (ii) if the settlement is approved by the bankruptcy court, NRG will provide shared services to GenOn at no charge for two months , and (iii) NRG will then provide an option for up to two , one -month extensions for shared services at an annualized rate of $84 million . See Note 14 , Related Party Transactions , for further discussion of the shared services agreement. 6) NRG will provide a credit of $28 million to GenOn to apply against amounts owed under the shared services agreement upon emergence from bankruptcy. Any unused amount can be paid in cash at GenOn’s request. The credit was intended to reimburse GenOn for its payment of financing costs. 7) NRG agreed to provide GenOn with a letter of credit facility during the pendency of the Chapter 11 Cases, which could be utilized for required letters of credit in lieu of the intercompany secured revolving credit facility. GenOn can no longer utilize the intercompany secured revolving credit facility and, on July 27, 2017, the letter of credit facility was terminated, as GenOn had obtained a separate letter of credit facility with a third party financial institution. See Note 14 , Related Party Transactions , for further discussion of the intercompany secured revolver credit facility and the letter of credit facility obtained in July 2017. 8) NRG and GenOn have agreed to cooperate in good faith to maximize the value of certain development projects. In addition to the Restructuring Support Agreement, additional support and other agreements are being negotiated, including a transition services agreement. See Note 1 , Basis of Presentation , for further discussion regarding the October 30, 2017 proposed changes to the Restructuring Support Agreement. Settlement Consideration NRG has determined that the payment of the settlement consideration is probable and has recorded a liability for the amount due of $261.3 million in accrued expenses and other current liabilities - affiliate with a corresponding loss from discontinued operations. NRG expects to pay this amount net of amounts due from GenOn under the intercompany secured revolving credit facility, which is further described in Note 14 , Related Party Transactions . Pension Liability NRG will retain the pension liability, including payment of approximately $13 million of 2017 pension contributions, which was paid in September 2017, for the GenOn employees for service provided prior to emergence from bankruptcy. NRG determined that the retention of this liability is probable and has recorded the estimated accumulated pension benefit obligation as of September 30, 2017 of $106 million in other non-current liabilities with a corresponding loss from discontinued operations. NRG's obligation for this liability will be revalued through and at GenOn's emergence from bankruptcy. Services Agreement NRG will continue to provide shared services to GenOn under the Services Agreement at an annualized rate of $84 million during the pendency of the Chapter 11 Cases as well as for two months post-emergence at no charge. NRG then will provide an option for up to two , one -month extensions for shared services at an annualized rate of $84 million . Beginning on June 14, 2017, NRG records operating income for the amounts earned for shared services of approximately $5 million per month. NRG has also agreed to provide GenOn with a credit of $28 million against amounts owed under the Services Agreement. Any unused amount can be paid in cash at GenOn’s request. As a result, NRG has concluded that the liability for this credit is probable and has recorded a payable to GenOn for $28 million in accrued expenses and other current liabilities - affiliate with a corresponding loss from discontinued operations. See Note 1, Basis of Presentation , for further discussion regarding the October 30, 2017 proposed changes to the Restructuring Support Agreement and Services Agreement. Commercial Operations For pre-disposal periods, NRG provided GenOn with services as described in Note 14 , Related Party Transactions . Under intercompany agreements, NRG Power Marketing LLC has entered into physical and financial intercompany commodity and hedging transactions with GenOn and certain of its subsidiaries. Subject to applicable collateral thresholds, these arrangements may provide for the bilateral exchange of credit support based upon market exposure and potential market movements. The terms and conditions of the agreements are generally consistent with industry practices and other third party arrangements. For current and pre-disposal periods, revenue and expense associated with these transactions is recorded in continuing operations. GenOn Debt As of June 14, 2017, the GenOn Senior Notes and GenOn Americas Generation Senior Notes, which totaled approximately $2.5 billion , were deconsolidated from NRG's consolidated financial statements. The filing of the Chapter 11 Cases constitutes an event of default under the following debt instruments of GenOn: 1) The intercompany secured revolving credit facility with NRG; 2) The indenture governing the GenOn 7.875% Senior Notes due 2017 (as amended or supplemented from time to time); 3) The indenture governing the GenOn 9.500% Notes due 2018 (as amended or supplemented from time to time); 4) The indenture governing the GenOn 9.875% Notes due 2020 (as amended or supplemented from time to time); 5) The indenture governing the GenOn Americas Generation 8.50% Senior Notes due 2021 (as amended or supplemented from time to time); and 6) The indenture governing the GenOn Americas Generation 9.125% Senior Notes due 2031 (as amended or supplemented from time to time). Transfer of Assets Under Common Control On November 1, 2017, NRG completed the sale of a 38 MW solar portfolio primarily comprised of assets from SPP funds, in addition to other projects developed by NRG, to NRG Yield, Inc. for cash consideration of $71 million , plus $3 million in working capital adjustments. On August 1, 2017, NRG closed on the sale of its remaining 25% interest in NRG Wind TE Holdco, a portfolio of 12 wind projects, to NRG Yield, Inc. for total cash consideration of $44 million , including working capital adjustment of $3 million . The transaction also includes potential additional payments to NRG dependent upon actual energy prices for merchant periods beginning in 2027. On March 27, 2017, the Company sold to NRG Yield, Inc.: (i) a 16% interest in the Agua Caliente solar project, representing ownership of approximately 46 net MW of capacity and (ii) NRG's interests in seven utility-scale solar projects located in Utah representing 265 net MW of capacity, which have reached commercial operations. NRG Yield, Inc. paid cash consideration of $130 million , plus $1 million in working capital adjustments, and assumed non-recourse debt of approximately $328 million . On September 1, 2016, the Company completed the sale of its remaining 51.05% interest in the CVSR project to NRG Yield, Inc. for total cash consideration of $78.5 million , plus an immaterial working capital adjustment. In addition, NRG Yield, Inc. assumed non-recourse project level debt of $496 million . Acquisitions SunEdison Utility-Scale Solar and Wind Acquisition On November 2, 2016, the Company acquired equity interests in a tax equity portfolio from SunEdison, located in Utah, comprised of 530 MW of mechanically-complete solar assets, of which NRG’s net interest based on cash to be distributed is 265 MW, for upfront cash consideration of $111 million . In connection with the acquisition, the Company assumed non-recourse debt of $222 million . The Company also borrowed additional amounts of $65 million during the fourth quarter of 2016, which effectively reduced the Company's use of liquidity related to the acquisition. The Company does not have a controlling interest in the tax equity portfolio and, accordingly, its interest is recorded as an equity method investment. The purchase price was preliminarily allocated to the equity method investment balance of approximately $328 million , current assets of $5 million and the assumed non-recourse debt of $222 million . The assets reached commercial operations during the fourth quarter of 2016 and have 20 -year PPAs with PacificCorp. The Company acquired a 110 MW portfolio of construction-ready and 71 MW of development solar assets in Hawaii from SunEdison for upfront cash consideration of $2 million on October 3, 2016 and a 154 MW construction-ready solar project in Texas for upfront cash consideration of $11 million on November 9, 2016. In addition to the total $124 million in upfront cash consideration paid for the above acquisitions, the Company expects to make an estimated $59 million in additional payments contingent upon future development milestones, of which $15 million was paid as of September 30, 2017. SunEdison Solar Distributed Generation Acquisition On October 3, 2016, the Company acquired a 29 MW portfolio of mechanically-complete and construction-ready distributed generation solar assets from SunEdison for cash consideration of approximately $67 million excluding post-closing adjustments which reduced the purchase price by $5 million . Subsequent to the acquisition, the Company sold the majority of these assets into a tax-equity financed portfolio within the DGPV Holdco partnership between NRG and NRG Yield, Inc., and expects to sell the remaining assets into a similar portfolio in 2017. The purchase price was allocated to $47 million in construction in progress and $15 million in intangible assets. Dispositions Disposition of Majority Interest in EVgo On June 17, 2016, the Company completed the sale of a majority interest in its EVgo business to Vision Ridge Partners for total consideration of approximately $39 million , including $17 million in cash received, which is net of $2.5 million in working capital adjustments, $15 million contributed as capital to the EVgo business and $7 million of future contributions by Vision Ridge Partners, all of which were determined based on forecasted cash requirements to operate the business in future periods. In addition, the Company has future earnout potential of up to $70 million based on future profitability targets. NRG will retain its original financial obligation of $102.5 million under its agreement with the CPUC whereby EVgo will build at least 200 public fast charging Freedom Station sites and perform the associated work to prepare 10,000 commercial and multi-family parking spaces for electric vehicle charging in California. As part of the sale, NRG has contracted with EVgo to continue to build the remaining required Freedom Stations and commercial and multi-family parking spaces for electric vehicle charging required under this obligation and will be directly reimbursed by NRG for the costs. As a result of the sale, the Company recorded a loss on sale of $83 million during the second quarter of 2016, which reflects the loss on the sale of the equity interest of $27 million and the accrual of NRG's remaining obligation under its agreement with the CPUC of $56 million . On February 22, 2017, the Company and CPUC entered into a second amendment to the agreement which extended the operating period commitment for the Freedom Stations to December 5, 2020. At September 30, 2017 , the Company's remaining 35% interest in EVgo of $2 million was accounted for as an equity-method investment. Rockford Disposition On May 12, 2016, the Company entered into an agreement with RA Generation, LLC to sell 100% of its interests in the Rockford I and Rockford II generating stations, or Rockford, for cash consideration of $55 million , subject to adjustments for working capital and the results of the PJM 2019/2020 base residual auction. Rockford is a 450 MW natural gas facility located in Rockford, Illinois. The transaction triggered an indicator of impairment as the sales price was less than the carrying amount of the assets, and, as a result the assets were considered to be impaired. The Company measured the impairment loss as the difference between the carrying amount of the assets and the agreed-upon sales price. The Company recorded an impairment loss of $17 million during the quarter ended June 30, 2016 to reduce the carrying amount of the assets held for sale to the fair market value. At June 30, 2016, the Company had $2 million of current assets and $54 million of non-current assets classified as held for sale for Rockford on its balance sheet. On July 12, 2016, the Company completed the sale of Rockford for cash proceeds of $56 million , including $1 million in adjustments for the PJM base residual auction results. For further discussion on this impairment, refer to Note 7 , Impairments , to this Form 10-Q.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments This footnote should be read in conjunction with the complete description under Note 4 , Fair Value of Financial Instruments , to the Company's 2016 Form 10-K. 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 amount approximates fair value because of the short-term maturity of those instruments and are classified as Level 1 within the fair value hierarchy. The estimated carrying amounts and fair values of NRG's recorded financial instruments not carried at fair market value are as follows: As of September 30, 2017 As of December 31, 2016 Carrying Amount Fair Value Carrying Amount Fair Value (In millions) Assets: Notes receivable (a) $ 22 $ 21 $ 34 $ 34 Liabilities: Long-term debt, including current portion (b) 17,097 17,423 16,655 16,620 (a) Includes the current portion of notes receivable which is recorded in prepayments and other current assets on the Company's consolidated balance sheets. (b) Excludes deferred financing costs, which are recorded as a reduction to long-term debt on the Company's consolidated balance sheets. The fair value of the Company's publicly-traded long-term debt is based on quoted market prices and is classified as Level 2 within the fair value hierarchy. The fair value of debt securities, non-publicly traded long-term debt and certain notes receivable of the Company are based on expected future cash flows discounted at market interest rates, or current interest rates for similar instruments with equivalent credit quality and are classified as Level 3 within the fair value hierarchy. The following table presents the level within the fair value hierarchy for long-term debt, including current portion as of September 30, 2017 and December 31, 2016 : As of September 30, 2017 As of December 31, 2016 Level 2 Level 3 Level 2 Level 3 (In millions) Long-term debt, including current portion $ 9,571 $ 7,852 $ 9,205 $ 7,415 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: As of September 30, 2017 Fair Value (In millions) Level 1 Level 2 Level 3 Total Investment in available-for-sale securities (classified within other non-current assets): Debt securities $ — $ — $ 19 $ 19 Available-for-sale securities 5 — — 5 Nuclear trust fund investments: Cash and cash equivalents 31 — — 31 U.S. government and federal agency obligations 43 1 — 44 Federal agency mortgage-backed securities — 74 — 74 Commercial mortgage-backed securities — 11 — 11 Corporate debt securities — 108 — 108 Equity securities 333 — 65 398 Foreign government fixed income securities — 4 — 4 Other trust fund investments: U.S. government and federal agency obligations 1 — — 1 Derivative assets: Commodity contracts 132 409 98 639 Interest rate contracts — 42 — 42 Total assets $ 545 $ 649 $ 182 $ 1,376 Derivative liabilities: Commodity contracts 201 404 146 751 Interest rate contracts — 78 — 78 Total liabilities $ 201 $ 482 $ 146 $ 829 . As of December 31, 2016 Fair Value (In millions) Level 1 Level 2 Level 3 Total Investment in available-for-sale securities (classified within other non-current assets): Debt securities $ — $ — $ 17 $ 17 Available-for-sale securities 10 — — 10 Nuclear trust fund investments: Cash and cash equivalents 25 — — 25 U.S. government and federal agency obligations 72 1 — 73 Federal agency mortgage-backed securities — 62 — 62 Commercial mortgage-backed securities — 17 — 17 Corporate debt securities — 84 — 84 Equity securities 292 — 54 346 Foreign government fixed income securities — 3 — 3 Other trust fund investments: U.S. government and federal agency obligations 1 — — 1 Derivative assets: Commodity contracts 560 549 90 1,199 Interest rate contracts — 49 — 49 Total assets $ 960 $ 765 $ 161 $ 1,886 Derivative liabilities: Commodity contracts 494 636 158 1,288 Interest rate contracts — 88 — 88 Total liabilities $ 494 $ 724 $ 158 $ 1,376 There were no transfers during the three and nine months ended September 30, 2017 and 2016 between Levels 1 and 2. The following tables reconcile, for the three and nine months ended September 30, 2017 and 2016 , 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, 2017 Nine months ended September 30, 2017 (In millions) Debt Securities Trust Fund Investments Derivatives (a) Total Debt Securities Trust Fund Investments Derivatives (a) Total Beginning balance $ 18 $ 61 $ (11 ) $ 68 $ 17 $ 54 $ (68 ) $ 3 Total gains/(losses) — realized/unrealized: Included in earnings 1 — (28 ) (27 ) 2 — 18 20 Included in nuclear decommissioning obligation — 3 — 3 — 10 — 10 Purchases — 1 (9 ) (8 ) — 1 — 1 Transfers into Level 3 (b) — — (6 ) (6 ) — — (11 ) (11 ) Transfers out of Level 3 (b) — — 6 6 — — 13 13 Ending balance as of September 30, 2017 $ 19 $ 65 $ (48 ) $ 36 $ 19 $ 65 $ (48 ) $ 36 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, 2017 $ — $ — $ (13 ) $ (13 ) $ — $ — $ (6 ) $ (6 ) (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, 2016 Nine months ended September 30, 2016 (In millions) Debt Securities Trust Fund Investments Derivatives (a) Total Debt Securities Trust Fund Investments Derivatives (a) Total Beginning balance $ 16 $ 51 $ 18 $ 85 $ 17 $ 54 $ (22 ) $ 49 Total (losses)/gains — realized/unrealized: Included in earnings — — (5 ) (5 ) — — 4 4 Included in OCI 1 — — 1 — — — — Included in nuclear decommissioning obligations — 3 — 3 — (1 ) — (1 ) Purchases — — (25 ) (25 ) — 1 2 3 Transfers into Level 3 (b) — — (13 ) (13 ) — — (6 ) (6 ) Transfers out of Level 3 (b) — — 3 3 — — — — Ending balance as of September 30, 2016 $ 17 $ 54 $ (22 ) $ 49 $ 17 $ 54 $ (22 ) $ 49 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, 2016 $ — $ — $ (4 ) $ (4 ) $ — $ — $ (11 ) $ (11 ) (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 for the whole term or for certain delivery months or the contracts are retail and load following power contracts. These contracts are valued using various valuation techniques including but not limited to internal models that apply fundamental analysis of the market and corroboration with similar markets. As of September 30, 2017 , contracts valued with prices provided by models and other valuation techniques make up 14% of the total derivative assets and 18% of the total 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, 2017 and December 31, 2016 : Significant Unobservable Inputs September 30, 2017 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) Power Contracts $ 47 $ 101 Discounted Cash Flow Forward Market Price (per MWh) $ 10 $ 88 $ 24 FTRs 51 45 Discounted Cash Flow Auction Prices (per MWh) (31 ) 36 — $ 98 $ 146 Significant Unobservable Inputs December 31, 2016 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) Power Contracts $ 39 $ 108 Discounted Cash Flow Forward Market Price (per MWh) $ 11 $ 104 $ 31 FTRs 51 50 Discounted Cash Flow Auction Prices (per MWh) (22 ) 17 — $ 90 $ 158 The following table provides sensitivity of fair value measurements to increases/(decreases) in significant unobservable inputs as of September 30, 2017 and December 31, 2016 : 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, 2017 , the credit reserve resulted in a $1 million increase in fair value in operating revenue and cost of operations. As of December 31, 2016 , the credit reserve resulted in a $10 million decrease 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 2016 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, and retail customer credit risk through its retail load activities. Counterparty Credit Risk The Company's counterparty credit risk policies are disclosed in its 2016 Form 10-K. As of September 30, 2017 , the Company's counterparty credit exposure, excluding credit risk exposure under certain long term agreements, was $134 million with net exposure of $129 million . NRG held collateral (cash and letters of credit) against those positions of $14 million . Approximately 74% of the Company's exposure before collateral is expected to roll off by the end of 2018 . 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 91 % Financial institutions 9 Total as of September 30, 2017 100 % Net Exposure (a) (b) Category by Counterparty Credit Quality (% of Total) Investment grade 79 % Non-Investment grade/Non-Rated 21 Total as of September 30, 2017 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. NRG has counterparty credit risk exposure to certain counterparties, each of which represent more than 10% of total net exposure discussed above. The aggregate of such counterparties' exposure was $50 million as of September 30, 2017 . Changes in hedge positions and market prices will affect credit exposure and counterparty concentration. Given the credit quality, diversification and term of the exposure in the portfolio, NRG does not anticipate a material impact on the Company's financial position or results of operations from nonperformance by any of NRG's counterparties. RTOs and ISOs The Company participates in the organized markets of CAISO, ERCOT, ISO-NE, MISO, NYISO and PJM, known as RTOs or ISOs. Trading in these markets is approved by FERC, or in the case of ERCOT, approved by the PUCT and includes credit policies that, under certain circumstances, require that losses arising from the default of one member on spot market transactions be shared by the remaining participants. As a result, the counterparty credit risk to these markets is limited to NRG’s share of overall market and are excluded from the above exposures. Exchange Traded Transactions The Company enters into commodity transactions on registered exchanges, notably ICE and NYMEX. These clearinghouses act as the counterparty and transactions are subject to extensive collateral and margining requirements. As a result, these commodity transactions have limited counterparty credit risk. Long Term Contracts Counterparty credit exposure described above excludes credit risk exposure under certain long term agreements, including California tolling agreements, Gulf Coast load obligations, and wind and solar PPAs. As external sources or observable market quotes are not available to estimate such exposure, the Company estimates its credit exposure for 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, 2017 , aggregate credit risk exposure managed by NRG to these counterparties was approximately $4.3 billion , including $2.8 billion related to assets of NRG Yield, Inc., for the next five years. This amount excludes potential credit exposures for projects with long-term PPAs that have not reached commercial operations. The majority of these power contracts are with utilities or public power entities with strong credit quality and public utility commission or other regulatory support. However, such regulated utility counterparties can be impacted by changes in government regulations or treatment by regulatory agencies which NRG is unable to predict. Retail Customer Credit Risk NRG is exposed to retail credit risk through the Company's retail electricity providers, which serve commercial, industrial and governmental/institutional customers and the Mass market. Retail credit risk results when a customer fails to pay for products or services rendered. The losses may result from both nonpayment of customer accounts receivable and the loss of in-the-money forward value. NRG 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, 2017 , the Company believes its retail customer credit exposure 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, 2017
Nuclear Decommissioning Trust Fund Disclosure [Abstract]
Nuclear Decommissioning Trust Fund	Nuclear Decommissioning Trust Fund This footnote should be read in conjunction with the complete description under Note 6 , Nuclear Decommissioning Trust Fund , to the Company's 2016 Form 10-K. NRG's Nuclear Decommissioning Trust Fund assets 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 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 (including other-than-temporary impairments) for the securities held in the trust funds, as well as information about the contractual maturities of those securities. As of September 30, 2017 As of December 31, 2016 (In millions, except otherwise noted) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Cash and cash equivalents $ 31 $ — $ — — $ 25 $ — $ — — U.S. government and federal agency obligations 44 2 — 10 73 1 — 11 Federal agency mortgage-backed securities 74 1 1 24 62 1 1 25 Commercial mortgage-backed securities 11 — — 23 17 — 1 26 Corporate debt securities 108 2 1 11 84 1 2 11 Equity securities 398 260 — — 346 214 — — Foreign government fixed income securities 4 — — 9 3 — — 9 Total $ 670 $ 265 $ 2 $ 610 $ 217 $ 4 The following table summarizes proceeds from sales of available-for-sale securities and the related realized gains and losses from these sales. The cost of securities sold is determined on the specific identification method. Nine months ended September 30, 2017 2016 (In millions) Realized gains $ 8 $ 7 Realized losses 6 3 Proceeds from sale of securities 382 354

Accounting for Derivative Instr

Accounting for Derivative Instruments and Hedging Activities	9 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Accounting for Derivative Instruments and Hedging Activities	Accounting for Derivative Instruments and Hedging Activities This footnote should be read in conjunction with the complete description under Note 5 , Accounting for Derivative Instruments and Hedging Activities , to the Company's 2016 Form 10-K. Energy-Related Commodities As of September 30, 2017 , NRG had energy-related derivative instruments extending through 2031 . The Company marks these derivatives to market through the statement of operations. Interest Rate Swaps NRG is 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 enters into interest rate swap agreements. As of September 30, 2017 , the Company had interest rate derivative instruments on recourse debt extending through 2021, which are not designated as cash flow hedges. The Company had interest rate swaps on non-recourse debt extending through 2041 , most of which are designated as cash flow hedges. 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, 2017 and December 31, 2016 . 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, 2017 December 31, 2016 Category Units (In millions) Emissions Short Ton (1 ) — Coal Short Ton 15 35 Natural Gas MMBtu (62 ) (53 ) Oil Barrel — 1 Power MWh 19 7 Capacity MW/Day (1 ) (1 ) Interest Dollars $ 3,806 $ 3,429 Equity Shares 1 1 The decrease in the coal position was primarily the result of the settlement of hedge positions, and the increase in the power position was primarily the result of additional retail hedge positions. 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, 2017 December 31, 2016 September 30, 2017 December 31, 2016 (In millions) Derivatives designated as cash flow hedges: Interest rate contracts current $ — $ — $ 8 $ 28 Interest rate contracts long-term 10 12 15 41 Total derivatives designated as cash flow hedges 10 12 23 69 Derivatives not designated as cash flow hedges : Interest rate contracts current 5 — 19 7 Interest rate contracts long-term 27 37 36 12 Commodity contracts current 470 1,067 495 1,057 Commodity contracts long-term 169 132 256 231 Total derivatives not designated as cash flow hedges 671 1,236 806 1,307 Total derivatives $ 681 $ 1,248 $ 829 $ 1,376 The Company has elected to present derivative assets and liabilities on the balance sheet on a trade-by-trade basis and does not offset amounts at the counterparty master agreement level. In addition, collateral received or paid on the Company's derivative assets or liabilities are recorded on a separate line item on the balance sheet. The following table summarizes the offsetting of derivatives by counterparty master agreement level and collateral received or paid: Gross Amounts Not Offset in the Statement of Financial Position Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount As of September 30, 2017 (In millions) Commodity contracts: Derivative assets $ 639 $ (546 ) $ (5 ) $ 88 Derivative liabilities (751 ) 546 83 (122 ) Total commodity contracts (112 ) — 78 (34 ) Interest rate contracts: Derivative assets 42 (2 ) — 40 Derivative liabilities (78 ) 2 — (76 ) Total interest rate contracts (36 ) — — (36 ) Total derivative instruments $ (148 ) $ — $ 78 $ (70 ) Gross Amounts Not Offset in the Statement of Financial Position Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount As of December 31, 2016 (In millions) Commodity contracts: Derivative assets $ 1,199 $ (1,021 ) $ (13 ) $ 165 Derivative liabilities (1,288 ) 1,021 13 (254 ) Total commodity contracts (89 ) — — (89 ) Interest rate contracts: Derivative assets 49 (4 ) — 45 Derivative liabilities (88 ) 4 — (84 ) Total interest rate contracts (39 ) — — (39 ) Total derivative instruments $ (128 ) $ — $ — $ (128 ) Accumulated Other Comprehensive Loss The following table summarizes the effects of ASC 815 on the Company's accumulated OCI balance attributable to cash flow hedge derivatives, net of tax: Interest Rate Contracts Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In millions) Accumulated OCI beginning balance $ (67 ) $ (165 ) $ (66 ) $ (101 ) Reclassified from accumulated OCI to income: Due to realization of previously deferred amounts 4 2 10 12 Mark-to-market of cash flow hedge accounting contracts 4 32 (3 ) (42 ) Accumulated OCI ending balance, net of $15, and $28 tax $ (59 ) $ (131 ) $ (59 ) $ (131 ) Losses expected to be realized from OCI during the next 12 months, net of $4 tax $ 14 $ 14 Amounts reclassified from accumulated OCI into income and amounts recognized in income from the ineffective portion of cash flow hedges are recorded to interest expense for interest rate contracts. There was no ineffectiveness for the three and nine months ended September 30, 2017 and 2016 . Accounting guidelines require a high degree of correlation between the derivative and the hedged item throughout the period in order to qualify as a cash flow hedge. As of December 31, 2016, the Company's regression analysis for Viento Funding II interest rate swaps, while positively correlated, did not meet the required threshold for cash flow hedge accounting. As a result, the Company de-designated the Viento Funding II cash flow hedges as of December 31, 2016, and will prospectively mark these derivatives to market through the income statement. The Company's regression analysis for Marsh Landing, Walnut Creek, and Avra Valley interest rate swaps, while positively correlated, no longer contain match terms for cash flow hedge accounting. As a result, the Company voluntarily de-designated the Marsh Landing, Walnut Creek, and Avra Valley cash flow hedges as of April 28, 2017, and will prospectively mark these derivatives to market through the income statement. 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 and ineffectiveness of hedge derivatives are reflected in current period consolidated results of operations. The following table summarizes the 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 effect of energy commodity contracts is included within operating revenues and cost of operations and the effect of interest rate contracts is included in interest expense. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Unrealized mark-to-market results (In millions) Reversal of previously recognized unrealized (gains)/losses on settled positions related to economic hedges $ (6 ) $ (30 ) $ 19 $ (75 ) Reversal of acquired gain positions related to economic hedges (2 ) (7 ) (1 ) (11 ) Net unrealized (losses)/gains on open positions related to economic hedges (16 ) (50 ) (1 ) 27 Total unrealized mark-to-market (losses)/gains for economic hedging activities (24 ) (87 ) 17 (59 ) Reversal of previously recognized unrealized (gains)/losses on settled positions related to trading activity (5 ) 3 (24 ) 13 Net unrealized (losses)/gains on open positions related to trading activity — (8 ) 17 14 Total unrealized mark-to-market (losses)/gains for trading activity (5 ) (5 ) (7 ) 27 Total unrealized (losses)/gains $ (29 ) $ (92 ) $ 10 $ (32 ) Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In millions) Unrealized gains/(losses) included in operating revenues $ 21 $ 57 $ 178 $ (333 ) Unrealized (losses)/gains included in cost of operations (50 ) (149 ) (168 ) 301 Total impact to statement of operations — energy commodities $ (29 ) $ (92 ) $ 10 $ (32 ) Total impact to statement of operations — interest rate contracts $ 11 $ 9 $ (8 ) $ (9 ) 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, 2017 , the $1 million unrealized loss from open economic hedge positions was primarily the result of a decrease in value of forward purchases of coal, natural gas, and ERCOT power due to decreases in coal, natural gas, and ERCOT electricity prices, which was largely offset by an increase in value of forward sales of PJM power and New York capacity due to decreases in PJM electricity and New York capacity prices. For the nine months ended September 30, 2016 , the $27 million unrealized gain from open economic hedge positions was primarily the result of an increase in value of forward purchases of natural gas due to increases in natural gas 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 requires 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, 2017 , was $27 million . The collateral required for contracts with credit rating contingent features as of September 30, 2017 , was $34 million . The Company is also a party to certain marginable agreements where NRG has a net liability position, but the counterparty has not called for the collateral due, which was approximately $17 million as of September 30, 2017 . See Note 4 , Fair Value of Financial Instruments , to this Form 10-Q for discussion regarding concentration of credit risk.

Impairments

Impairments	9 Months Ended
	Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Impairments	Impairments 2017 Impairment Losses Bacliff Project — On June 16, 2017, NRG Texas Power LLC provided notice to BTEC New Albany, LLC that it was exercising its right to terminate the Amended and Restated Membership Interest Purchase Agreement, or MIPA, due to the Bacliff Project, a new peaking facility at the former P.H. Robinson Electric Generating Station, not achieving commercial completion by the contractual expiration date of May 31, 2017. As a result of the MIPA termination, the Company recorded an impairment loss of $41 million to reduce the carrying amount of the related construction in progress to $0 during the second quarter of 2017. On July 14, 2017, the Company gave notice to BTEC New Albany, LLC that it owes NRG Texas Power LLC approximately $48 million under the terminated MIPA, consisting of $38 million in purchaser incurred costs and $10 million in liquidated damages. Other Impairments — During the second quarter of 2017, the Company recorded impairment losses of approximately $22 million in connection with the Company's Renewables business. During the third quarter of 2017, the Company recorded an additional $14 million in impairment losses, in connection with the Company's Renewable business. 2016 Impairment Losses Rockford — On May 12, 2016, the Company entered into an agreement with RA Generation, LLC to sell 100% of its interests in the Rockford generating stations for cash consideration of $55 million . The transaction triggered an indicator of impairment as the sale price was less than the carrying amount of the assets, and, as a result, the assets were considered to be impaired. The Company measured the impairment loss as the difference between the carrying amount of the assets and the agreed-upon sale price. The Company recorded an impairment loss of $17 million during the quarter ended June 30, 2016, to reduce the carrying amount of the assets held for sale to the fair market value. Other Impairments — During the second quarter of 2016, the Company recorded impairment losses for intangible assets of $8 million in connection with the Company's strategic change in its residential solar business as well as $10 million of deferred marketing expenses. In addition, the Company also recorded an impairment loss of $17 million to record certain previously purchased solar panels at fair market value. During the third quarter of 2016, the Company recorded an additional $9 million in impairment losses related to investments and $8 million in other impairments. Petra Nova Parish Holdings — During the first quarter of 2016, management changed its plans with respect to its future capital commitments driven in part by the continued decline in oil prices. As a result, the Company reviewed its 50% interest in Petra Nova Parish Holdings for impairment utilizing the other-than-temporary impairment model. In determining fair value, the Company utilized an income approach and considered project specific assumptions for the future project cash flows. The carrying amount of the Company's equity method investment exceeded the fair value of the investment and the Company concluded that the decline is considered to be other than temporary. As a result, the Company measured the impairment loss as the difference between the carrying amount and the fair value of the investment and recorded an impairment loss of $140 million .

Debt and Capital Leases

Debt and Capital Leases	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Debt and Capital Leases	Debt and Capital Leases This footnote should be read in conjunction with the complete description under Note 12 , Debt and Capital Leases , to the Company's 2016 Form 10-K. Long-term debt and capital leases consisted of the following: (In millions, except rates) September 30, 2017 December 31, 2016 September 30, 2017 interest rate % (a) Recourse debt: Senior notes, due 2018 $ 398 $ 398 7.625 Senior notes, due 2021 207 207 7.875 Senior notes, due 2022 992 992 6.250 Senior notes, due 2023 869 869 6.625 Senior notes, due 2024 733 733 6.250 Senior notes, due 2026 1,000 1,000 7.250 Senior notes, due 2027 1,250 1,250 6.625 Term loan facility, due 2023 1,876 1,891 L+2.25 Tax-exempt bonds 465 455 4.125 - 6.00 Subtotal NRG recourse debt 7,790 7,795 Non-recourse debt: NRG Yield Operating LLC Senior Notes, due 2024 500 500 5.375 NRG Yield Operating LLC Senior Notes, due 2026 350 350 5.000 NRG Yield, Inc. Convertible Senior Notes, due 2019 345 345 3.500 NRG Yield, Inc. Convertible Senior Notes, due 2020 288 288 3.250 El Segundo Energy Center, due 2023 400 443 L+1.75 - L+2.375 Marsh Landing, due 2017 and 2023 334 370 L+1.750 - L+1.875 Alta Wind I - V lease financing arrangements, due 2034 and 2035 940 965 5.696 - 7.015 Walnut Creek, term loans due 2023 279 310 L+1.625 Utah Portfolio, due 2022 284 287 L+2.625 Tapestry, due 2021 165 172 L+1.625 CVSR, due 2037 746 771 2.339 - 3.775 CVSR HoldCo, due 2037 194 199 4.680 Alpine, due 2022 138 145 L+1.750 Energy Center Minneapolis, due 2017 and 2025 82 96 5.95 - 7.25 Energy Center Minneapolis, due 2031 125 125 3.55 Viento, due 2023 169 178 L+3.00 NRG Yield - other 562 540 various Subtotal NRG Yield debt (non-recourse to NRG) 5,901 6,084 Ivanpah, due 2033 and 2038 1,097 1,113 2.285 - 4.256 Carlsbad Energy Project 407 — 4.120 Agua Caliente, due 2037 833 849 2.395 - 3.633 Agua Caliente Borrower 1, due 2038 89 — 5.430 Cedro Hill, due 2025 153 163 L+1.75 Midwest Generation, due 2019 173 231 4.390 NRG Other 689 468 various Subtotal other NRG non-recourse debt 3,441 2,824 Subtotal all non-recourse debt 9,342 8,908 Subtotal long-term debt (including current maturities) 17,132 16,703 Capital leases 6 6 various Subtotal long-term debt and capital leases (including current maturities) 17,138 16,709 Less current maturities (1,247 ) (516 ) Less debt issuance costs (198 ) (188 ) Discounts (35 ) (48 ) Total long-term debt and capital leases $ 15,658 $ 15,957 (a) As of September 30, 2017 , L+ equals 3 month LIBOR plus x%, with the exception of the Utah Portfolio term loans. Recourse Debt 2023 Term Loan Facility On January 24, 2017, NRG repriced the 2023 Term Loan Facility, reducing the interest rate margin by 50 basis points to LIBOR plus 2.25% . The LIBOR floor remains 0.75% . Revolving Credit Facility On June 12, 2017, NRG repaid $125 million on the Revolving Credit Facility. As of September 30, 2017 , no cash borrowings were outstanding on the revolver. Senior Notes 2017 Senior Note Redemptions On October 16, 2017, the Company redeemed $398 million of its 7.625% Senior Notes due 2018 and $206 million of its 7.875% Senior Notes due 2021 for $630 million , which included $14 million in accrued interest. 2016 Senior Note Repurchases During the nine months ended September 30, 2016, the Company repurchased $2.6 billion in aggregate principal of its Senior Notes in the open market for $2.7 billion , which included accrued interest of $67 million . In connection with the repurchases, a $94 million loss on debt extinguishment was recorded, which included the write-off of previously deferred financing costs of $15 million . Issuance of 2026 Senior Notes On May 23, 2016, NRG issued $1.0 billion in aggregate principal amount at par of 7.25% senior notes due 2026, or the 2026 Senior Notes. The 2026 Senior Notes are senior unsecured obligations of NRG and are guaranteed by certain of its subsidiaries. Interest is paid semi-annually beginning on November 15, 2016, until the maturity date of May 15, 2026. Issuance of 2027 Senior Notes On August 2, 2016, NRG issued $1.25 billion in aggregate principal amount at par of 6.625% senior notes due 2027, or the 2027 Senior Notes. The 2027 Senior Notes are senior unsecured obligations of NRG and are guaranteed by certain of its subsidiaries. Interest is paid semi-annually beginning on January 15, 2017, until the maturity date of January 15, 2027. The proceeds from the issuance of the 2027 Senior Notes were utilized to retire the Company's 8.250% senior notes due 2020 and reduce the balance of the Company's 7.875% senior notes due 2021. Non-recourse Debt NRG Yield LLC and NRG Yield Operating LLC Revolving Credit Facility NRG Yield LLC and its direct wholly owned subsidiary, NRG Yield Operating LLC, entered into a senior secured revolving credit facility, which can be used for cash and for the issuance of letters of credit. At September 30, 2017 , there was $68 million of letters of credit issued under the revolving credit facility and no borrowing outstanding on the revolver. Project Financings Agua Caliente Project Financing On February 17, 2017, Agua Caliente Borrower 1 LLC and Agua Caliente Borrower 2 LLC, or Agua Caliente Holdco, the indirect owners of 51% of the Agua Caliente solar facility, issued $130 million of senior secured notes under the Agua Caliente Holdco Financing Agreement, or 2038 Agua Caliente Holdco Notes, that bear interest at 5.43% and mature on December 31, 2038. As described in Note 3 , Discontinued Operations, Dispositions and Acquisitions , on March 27, 2017, NRG Yield, Inc. acquired Agua Caliente Borrower 2 LLC from NRG. The debt is joint and several with respect to Agua Caliente Borrower 1 LLC and Agua Caliente Borrower 2 LLC and is secured by the equity interests of each borrower in the Agua Caliente solar facility. Carlsbad Project Financing On May 26, 2017, Carlsbad Energy Holdings, LLC entered into a note payable agreement with financial institutions for the issuance of up to $407 million of senior secured notes that bear interest at a rate of 4.12% , and mature on October 31, 2038. As of September 30, 2017 , all $407 million of these notes were outstanding. Also on May 26, 2017, Carlsbad Energy Holdings, LLC entered into a credit agreement, or the Carlsbad Financing Agreement, with the issuing banks, for a $194 million construction loan, that will convert to a term loan upon completion of the project. The Carlsbad Financing Agreement also includes a letter of credit facility with an aggregate principle amount not to exceed $83 million , and a working capital loan facility with an aggregate principle amount not to exceed $4 million .

Variable Interest Entities, or

Variable Interest Entities, or VIEs	9 Months Ended
	Sep. 30, 2017
Variable Interest Entities Disclosure [Abstract]
Variable Interest Entities, or VIEs	Variable Interest Entities, or VIEs Entities that are not Consolidated NRG has interests in entities that are considered VIEs under ASC 810, Consolidation , but NRG is not considered the primary beneficiary. NRG accounts for its interests in these entities under the equity method of accounting. GenConn Energy LLC — Through its consolidated subsidiary, NRG Yield Operating LLC, the Company owns a 50% interest in GCE Holding LLC, the owner of GenConn, which owns and operates two 190 MW peaking generation facilities in Connecticut at NRG's Devon and Middletown sites. NRG's maximum exposure to loss is limited to its equity investment, which was $102 million as of September 30, 2017 . Entities that are Consolidated The Company has a controlling financial interest in certain entities which have been identified as VIEs under ASC 810. These arrangements are primarily related to tax equity arrangements entered into with third-parties in order to finance the cost of solar energy systems under operating leases and wind facilities eligible for certain tax credits as further described in Note 2 , Summary of Significant Accounting Policies to the Company's 2016 Form 10-K. For one of the tax equity arrangements, the Company has a deficit restoration obligation equal to $100 million as of September 30, 2017 , which would be required to be funded if the arrangement were to be dissolved. The summarized financial information for the Company's consolidated VIEs consisted of the following: (In millions) September 30, 2017 December 31, 2016 Current assets $ 74 $ 87 Net property, plant and equipment 1,466 1,534 Other long-term assets 1,026 954 Total assets 2,566 2,575 Current liabilities 69 59 Long-term debt 420 442 Other long-term liabilities 187 183 Total liabilities 676 684 Noncontrolling interests 578 529 Net assets less noncontrolling interests $ 1,312 $ 1,362

Changes in Capital Structure

Changes in Capital Structure	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Changes in Capital Structure	Changes in Capital Structure As of September 30, 2017 and December 31, 2016 , 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, 2016 417,583,825 (102,140,814 ) 315,443,011 Shares issued under LTIPs 634,738 — 634,738 Shares issued under ESPP — 560,769 560,769 Balance as of September 30, 2017 418,218,563 (101,580,045 ) 316,638,518 Preferred Stock On May 24, 2016, NRG entered an agreement with Credit Suisse Group to repurchase 100% of the outstanding shares of its $344.5 million 2.822% preferred stock. On June 13, 2016, the Company completed the repurchase from Credit Suisse of 100% of the outstanding shares at a price of $226 million . The transaction resulted in a gain on redemption of $78 million , measured as the difference between the fair value of the cash consideration paid upon redemption of $226 million and the carrying value of the preferred stock at the time of the redemption of $304 million . This amount is reflected in net income/(loss) available to NRG common stockholders in the calculation of earnings per share. Amended and Restated Employee Stock Purchase Plan On April 27, 2017, NRG stockholders approved an increase of 3,000,000 shares available for issuance under the ESPP. As of September 30, 2017 , there were 3,107,050 shares of treasury stock available for issuance under the ESPP. Amended and Restated Long-term Incentive Plan On April 27, 2017, NRG stockholders approved an increase of 3,000,000 shares available for issuance under the NRG Energy, Inc. Amended and Restated Long-term Incentive Plan. NRG Common Stock Dividends The following table lists the dividends paid during the nine months ended September 30, 2017 : Third Quarter 2017 Second Quarter 2017 First Quarter 2017 Dividends per Common Share $ 0.03 $ 0.03 $ 0.03 On October 18, 2017 , NRG declared a quarterly dividend on the Company's common stock of $0.03 per share, payable November 15, 2017, to stockholders of record as of November 1, 2017, 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.

Earnings_(Loss) Per Share

Earnings/(Loss) Per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Earnings/(Loss) Per Share	Earnings/(Loss) Per Share Basic earnings/(loss) per common share is computed by dividing net income/(loss) less accumulated preferred stock dividends 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/(loss) per share is computed in a manner consistent with that of basic income/(loss) per share while giving effect to all potentially dilutive common shares that were outstanding during the period. During the second quarter of 2016, the Company repurchased 100% of the outstanding shares of its 2.822% preferred stock. The reconciliation of NRG's basic and diluted earnings/(loss) per share is shown in the following table: Three months ended September 30, Nine months ended September 30, (In millions, except per share data) 2017 2016 2017 2016 Basic and diluted income/(loss) per share attributable to NRG Energy, Inc. common stockholders Net income/(loss) attributable to NRG Energy, Inc. $ 171 $ 402 $ (619 ) $ 213 Dividends for preferred shares — — — 5 Gain on redemption of 2.822% redeemable perpetual preferred stock — — — (78 ) Income/(loss) available for common stockholders $ 171 $ 402 $ (619 ) $ 286 Weighted average number of common shares outstanding - basic 317 316 317 315 Income/(loss) per weighted average common share — basic $ 0.54 $ 1.27 $ (1.95 ) $ 0.91 Diluted income/(loss) per share attributable to NRG Energy, Inc. common stockholders Weighted average number of common shares outstanding - diluted 317 316 317 315 Incremental shares attributable to the issuance of equity compensation (treasury stock method) 5 1 — 1 Total dilutive shares 322 317 317 316 Income/(loss) per weighted average common share — diluted $ 0.53 $ 1.27 $ (1.95 ) $ 0.91 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 earnings/(loss) per share: Three months ended September 30, Nine months ended September 30, (In millions of shares) 2017 2016 2017 2016 Equity compensation plans 1 2 6 3 Total 1 2 6 3

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2017
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 as follows: Generation, which includes generation, international and BETM; Retail, which includes Mass customers and Business Solutions, which includes C&I customers and other distributed and reliability products; Renewables, which includes solar and wind assets, excluding those in NRG Yield; NRG Yield; and corporate activities. The financial information for the three and nine months ended September 30, 2016 has been recast to reflect the current segment structure. On September 1, 2016, NRG Yield acquired the remaining 51.05% interest in CVSR Holdco LLC, which indirectly owns the CVSR solar facility, from the Company. On March 27, 2017, NRG Yield acquired from NRG a 16% interest in the Agua Caliente solar project, and NRG's interests in seven utility-scale solar projects located in Utah. On August 1, 2017, NRG Yield acquired the remaining 25% interest in NRG Wind TE Holdco from the Company. All three acquisitions were treated as a transfer of entities under common control and accordingly, all historical periods have been recast to reflect the acquisition as if they had occurred at the beginning of the financial statement period. On June 14, 2017, as described in Note 3 , Discontinued Operations, Dispositions and Acquisitions , NRG deconsolidated GenOn for financial reporting purposes. The financial information for all historical periods have been recast to reflect the deconsolidation of GenOn and to present 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). Generation (a) Retail (a) Renewables (a) NRG Yield Corporate (a) Eliminations Total Three months ended September 30, 2017 (In millions) Operating revenues (a) $ 1,224 $ 1,937 $ 144 $ 265 $ 2 $ (523 ) $ 3,049 Depreciation and amortization 96 29 51 88 8 — 272 Impairment losses 1 — 13 — — — 14 Equity in (losses)/earnings of unconsolidated affiliates 12 — (3 ) 28 — (10 ) 27 Loss on debt extinguishment, net — — — — (1 ) — (1 ) Income/(loss) from continuing operations before income taxes 258 69 (7 ) 49 (161 ) (12 ) 196 Income/(loss) from continuing operations 258 69 (4 ) 41 (162 ) (12 ) 190 Loss from discontinued operations, net of tax — — — — (27 ) — (27 ) Net Income/(loss) 258 69 (4 ) 41 (189 ) (12 ) 163 Net Income/(loss) attributable to NRG Energy, Inc. $ 258 — $ 69 $ 9 $ 35 $ (220 ) $ 20 $ 171 Total assets as of September 30, 2017 $ 8,585 $ 2,445 $ 5,357 $ 8,442 $ 11,090 $ (10,449 ) $ 25,470 (a) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 491 $ (8 ) $ 19 $ — $ 21 $ — $ 523 Generation (a) Retail (a) Renewables (a) NRG Yield Corporate (a) Eliminations Total Three months ended September 30, 2016 (In millions) Operating revenues (a) $ 1,536 $ 2,012 $ 139 $ 272 $ 24 $ (562 ) $ 3,421 Depreciation and amortization 134 26 48 75 15 — 298 Impairment losses 9 — — — — — 9 Equity in earnings/(losses) of unconsolidated affiliates 6 — (10 ) 16 5 (1 ) 16 Gain on sale of assets — — — 4 — 4 Loss on debt extinguishment, net — — — — (50 ) — (50 ) Income/(loss) from continuing operations before income taxes 370 (78 ) (1 ) 63 (202 ) 4 156 Income/(loss) from continuing operations 372 (78 ) 2 50 (222 ) 4 128 Income from discontinued operations, net of tax — — — — 265 — 265 Net Income/(Loss) 372 (78 ) 2 50 43 4 393 Net Income/(Loss) attributable to NRG Energy, Inc. $ 372 $ (78 ) $ (9 ) $ 55 $ 19 $ 43 $ 402 (a) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 506 $ (2 ) $ 8 $ — $ 50 $ 52 $ — $ 562 Generation (a) Retail (a) Renewables (a) NRG Yield Corporate (a) Eliminations Total Nine months ended September 30, 2017 (In millions) Operating revenues (a) $ 3,072 $ 4,875 $ 364 $ 767 $ 13 $ (959 ) $ 8,132 Depreciation and amortization 287 87 150 241 24 — 789 Impairment losses 42 — 35 — — — 77 Equity in (losses)/earnings of unconsolidated affiliates (16 ) — (6 ) 63 7 (19 ) 29 Gain on sale of assets 4 — — — — — 4 Loss on debt extinguishment, net — — (3 ) — — — (3 ) Income/(loss) from continuing operations before income taxes 202 371 (97 ) 100 (430 ) (21 ) 125 Income/(loss) from continuing operations 200 380 (84 ) 85 (440 ) (21 ) 120 Loss from discontinued operations, net of tax — — — — (802 ) — (802 ) Net Income/(Loss) 200 380 (84 ) 85 (1,242 ) (21 ) (682 ) Net Income/(Loss) attributable to NRG Energy, Inc. $ 200 $ 380 $ (18 ) $ 87 $ (1,306 ) $ 38 $ (619 ) (a) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 897 $ 3 $ 23 $ — $ 36 $ — $ 959 Generation (a) Retail (a) Renewables (a) NRG Yield (a) Corporate (a) Eliminations Total Nine months ended September 30, 2016 (In millions) Operating revenues (a) $ 3,173 $ 4,918 $ 336 $ 789 $ 54 $ (942 ) $ 8,328 Depreciation and amortization 331 83 143 224 45 — 826 Impairment losses 26 — 27 — 12 — 65 Equity in earnings/(losses) of unconsolidated affiliates 1 — (16 ) 34 11 (17 ) 13 Loss on sale of assets — — — — (79 ) — (79 ) Impairment loss on investment (142 ) — 1 — (6 ) — (147 ) Loss on debt extinguishment, net — — — — (119 ) — (119 ) (Loss)/income from continuing operations before income taxes (51 ) 735 (121 ) 141 (706 ) (15 ) (17 ) (Loss)/income from continuing operations (49 ) 734 (107 ) 116 (771 ) (15 ) (92 ) Income from discontinued operations, net of tax — — — — 256 — 256 Net (Loss)/Income (49 ) 734 (107 ) 116 (515 ) (15 ) 164 Net (Loss)/Income attributable to NRG Energy, Inc. $ (49 ) $ 734 $ (103 ) $ 113 $ (547 ) $ 65 $ 213 (a) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 836 $ 3 $ 16 $ 6 $ 81 $ — $ 942

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Effective Tax Rate The income tax provision consisted of the following: Three months ended September 30, Nine months ended September 30, (In millions except otherwise noted) 2017 2016 2017 2016 Income/(Loss) before income taxes $ 196 $ 156 $ 125 $ (17 ) Income tax expense from continuing operations 6 28 5 75 Effective tax rate 3.1 % 17.9 % 4.0 % (441.2 )% For the three months and nine months ended September 30, 2017 , NRG's overall effective tax rate was different than the statutory rate of 35% primarily due to the tax benefit for the change in valuation allowance and the generation of PTCs and ITCs from various wind and solar facilities, respectively, partially offset by the inclusion of consolidated partnerships and current state tax expense. For the three months ended September 30, 2016 , NRG's overall effective tax rate was different than the statutory rate of 35% primarily due to the tax benefit for the change in valuation allowance, partially offset by amortization of indefinite lived assets, inclusion of consolidated partnerships and state tax expense. For the nine months ended September 30, 2016 , NRG's overall effective tax rate was different than the statutory rate of 35% primarily due to the amortization of indefinite lived assets, the inclusion of consolidated partnerships, state tax expense and the expense for the change in valuation allowance. Uncertain Tax Benefits As of September 30, 2017 , NRG has recorded a non-current tax liability of $40 million for uncertain tax benefits from positions taken on various state income tax returns, including accrued interest. For the nine months ended September 30, 2017 , NRG accrued an immaterial amount of interest relating to the uncertain tax benefits. As of September 30, 2017 , NRG had cumulative interest and penalties related to these uncertain tax benefits of $4 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 not 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. The Company's primary foreign operations are also no longer subject to examination by local jurisdictions for years prior to 2010.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2017
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Services Agreement with GenOn The Company provides GenOn with various management, personnel and other services, which include human resources, regulatory and public affairs, accounting, tax, legal, information systems, treasury, risk management, commercial operations, and asset management, as set forth in the services agreement with GenOn, or the Services Agreement. The initial term of the Services Agreement was through December 31, 2013, with an automatic renewal absent a request for termination. The fee charged was determined based on a fixed amount as described in the Services Agreement and was calculated based on historical GenOn expenses prior to the NRG Merger. The annual fees under the Services Agreement were approximately $193 million and management has concluded that this method of charging overhead costs is reasonable. As described in Note 3 , Discontinued Operations, Dispositions and Acquisitions , in connection with the Restructuring Support Agreement, NRG agreed to provide shared services to GenOn under the Services Agreement for an adjusted annualized fee of $84 million through the pendency of the Chapter 11 Cases. Beginning on June 14, 2017, NRG records operating income for the amounts earned for shared services of approximately $5 million per month. Subsequent to the GenOn Entities' emergence from bankruptcy, NRG will provide shared services for two months at no charge; after which GenOn has an additional two , one -month options to provide services at an annualized fee of $84 million . NRG charges these fees on a monthly basis, less amounts incurred directly by GenOn. For the three and nine months ended September 30, 2017 , NRG recorded other income - affiliate related to these services of $14 million and $104 million , respectively. For the three and nine months ended September 30, 2016 , NRG recorded other income - affiliate related to these services of $48 million and $144 million , respectively. In addition, as described in Note 3 , Discontinued Operations, Dispositions and Acquisitions , under the Restructuring Support Agreement, NRG has agreed to provide GenOn with a $28 million credit against amounts owed to NRG prior to the Petition Date under the current Services Agreement. The credit was intended to reimburse GenOn for its payment of financing costs. In addition, the Restructuring Support Agreement provides that to the extent GenOn has paid for services during the bankruptcy proceedings and the aforementioned credit has not been applied in full, NRG shall, upon request by GenOn, reimburse such payments in cash up to the amount of any unused portion of the credit. See Note 1 , Basis of Presentation , for further discussion regarding the October 30, 2017 proposed changes to the Restructuring Support Agreement and Services Agreement, based on which NRG recorded a reserve of $15 million against affiliate receivable balances as of September 30, 2017. Credit Agreement with GenOn NRG and GenOn are party to a secured intercompany revolving credit agreement. The intercompany revolving credit agreement provided for a $500 million revolving credit facility, all of which was available for revolving loans and letters of credit. At September 30, 2017 and December 31, 2016 , $103 million and $272 million , respectively, of letters of credit were issued and outstanding under the NRG credit agreement for GenOn. Additionally, as of September 30, 2017 , there were $125 million of loans outstanding under the intercompany secured revolving credit facility. As of December 31, 2016 , no loans were outstanding under this intercompany secured revolving credit facility. In addition, the intercompany secured revolving credit facility contains customary covenants and events of default. As of September 30, 2017 , GenOn was in default under the secured intercompany revolving credit agreement due to the filing of the Chapter 11 Cases. As a result of the Chapter 11 Cases, no additional revolving loans or letters of credit are available to GenOn. In addition, NRG agreed to provide GenOn with a letter of credit facility during the pendency of the Chapter 11 Cases, which could be utilized for required letters of credit in lieu of the intercompany secured revolving credit facility. The letter of credit facility provided availability of up to $330 million less amounts borrowed and letters of credit provided are required to be cash collateralized at 103% of the letter of credit amount. On July 27, 2017, this letter of credit facility was terminated as GenOn has obtained a separate letter of credit facility with a third party financial institution. Effective with completion of the reorganization, GenOn must repay NRG for all revolving loans outstanding, with such amount to be netted against the settlement payment owed from NRG to GenOn. Accordingly, the affiliate receivable is recorded net within accrued expenses and other current liabilities - affiliate on the consolidated balance sheet as of September 30, 2017. Interest continues to accrue during the pendency of the Chapter 11 Cases and borrowings remain secured obligations. Commercial Operations Agreement NRG Power Marketing LLC has entered into physical and financial intercompany commodity and hedging transactions with GenOn and certain of its subsidiaries. Subject to applicable collateral thresholds, these arrangements may provide for the bilateral exchange of credit support based upon market exposure and potential market movements. The terms and conditions of the agreements are generally consistent with industry practices and other third party arrangements. As of September 30, 2017 , derivative assets and liabilities associated with these transactions are recorded within NRG's derivative instruments balances on the consolidated balance sheet, with related revenues and costs within operating revenues and cost of operations, respectively.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies This footnote should be read in conjunction with the complete description under Note 22 , Commitments and Contingencies , to the Company's 2016 Form 10-K. Commitments First Lien Structure — NRG has granted first liens to certain counterparties on a substantial portion of the Company's assets, excluding assets acquired in the EME (including Midwest Generation) acquisitions, assets held by NRG Yield, Inc. and NRG's assets that have project-level financing, 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, 2017 , hedges under the first liens were out-of-the-money for NRG on a counterparty aggregate basis. Lignite Contract with Texas Westmoreland Coal Co. — The Company has a contract with TWCC for reclamation activities associated with closure of the Jewett mine. NRG is responsible for reclamation costs and has recorded an adequate ARO liability. The Railroad Commission of Texas has imposed a bond obligation of $95.5 million on TWCC for the reclamation of the mine. Pursuant to the contract with TWCC, NRG supports this obligation through surety bonds. Additionally, NRG is obligated 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 reserves 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 reserve for the matters discussed below. 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 reserves and that such difference could be material. In addition to the legal proceedings noted below, NRG and its subsidiaries are party to other litigation or legal proceedings arising in the ordinary course of business. In management's opinion, the disposition of these ordinary course matters will not materially adversely affect NRG's consolidated financial position, results of operations, or cash flows. Midwest Generation Asbestos Liabilities — The Company, through its subsidiary, Midwest Generation, may be subject to potential asbestos liabilities as a result of its acquisition of EME. The Company is currently analyzing the scope of potential liability as it may relate to Midwest Generation. The Company believes that it has established an adequate reserve for these cases. Energy Plus Holdings — On August 7, 2012, Energy Plus Holdings received a subpoena from the NYAG which generally sought information and business records related to Energy Plus Holdings' sales, marketing and business practices. Energy Plus Holdings provided documents and information to the NYAG. On June 22, 2015, the NYAG issued another subpoena seeking additional information. Energy Plus Holdings provided responsive documents to this second subpoena. On August 28, 2017, the parties entered into an Assurance of Discontinuance resolving this matter. Midwest Generation New Source Review Litigation — In August 2009, the EPA and the Illinois Attorney General, or the Government Plaintiffs, filed a complaint, or the Governments’ Complaint, in the U.S. District Court for the Northern District of Illinois alleging violations of CAA PSD requirements by Midwest Generation arising from maintenance, repair or replacement projects at six Illinois coal-fired electric generating stations performed by Midwest Generation or ComEd, a prior owner of the stations, including alleged failures to obtain PSD construction permits and to comply with BACT requirements. The Government Plaintiffs also alleged violations of opacity and PM standards at the Midwest Generation plants. Finally, the Government Plaintiffs alleged that Midwest Generation violated certain operating permit requirements under Title V of the CAA allegedly arising from such claimed PSD, opacity and PM emission violations. In addition to seeking penalties of up to $37,500 per violation, per day, the complaint seeks an injunction ordering Midwest Generation to install controls sufficient to meet BACT emission rates at the units subject to the complaint and other remedies, which could go well beyond the requirements of the CPS. Several environmental groups intervened as plaintiffs in this litigation and filed a complaint, or the Intervenors’ Complaint, which alleged opacity, PM and related Title V violations. Midwest Generation filed a motion to dismiss nine of the ten PSD counts in the Governments’ Complaint, and to dismiss the tenth PSD count to the extent the Governments’ Complaint sought civil penalties for that count. The trial court granted the motion in March 2010. In June 2010, the Government Plaintiffs and Intervenors each filed an amended complaint. The Governments’ Amended Complaint again alleged that Midwest Generation violated PSD (based upon the same projects as alleged in their original complaint, but adding allegations that the Company was liable as the “successor” to ComEd), Title V and opacity and PM standards. It named EME and ComEd as additional defendants and alleged PSD violations (again, premised on the same projects) against them. The Intervenors’ Amended Complaint named only Midwest Generation as a defendant and alleged Title V and opacity/PM violations, as well as one of the ten PSD violations alleged in the Governments’ Amended Complaint. Midwest Generation again moved to dismiss all but one of the Government Plaintiffs’ PSD claims and the related Title V claims. Midwest Generation also filed a motion to dismiss the PSD claim in the Intervenors’ Amended Complaint and the related Title V claims. In March 2011, the trial court granted Midwest Generation’s partial motion to dismiss the Government Plaintiffs’ PSD claims. The trial court denied Midwest Generation’s motion to dismiss the PSD claim asserted in the Intervenors’ Amended Complaint, but noted that the plaintiffs would be required to convince the court that the statute of limitations should be equitably tolled. The trial court did not address other counts in the amended complaints that allege violations of opacity and PM emission limitations under the Illinois State Implementation Plan and related Title V claims. The trial court also granted the motions to dismiss the PSD claims asserted against EME and ComEd. Following the trial court ruling, the Government Plaintiffs appealed the trial court’s dismissals of their PSD claims, including the dismissal of nine of the ten PSD claims against Midwest Generation and of the PSD claims against the other defendants. Those PSD claim dismissals were affirmed by the U.S. Court of Appeals for the Seventh Circuit in July 2013. In addition, in 2012, all but one of the environmental groups that had intervened in the case dismissed their claims without prejudice. As a result, only one environmental group remains a plaintiff intervenor in the case. The Company does not expect the resolution of this matter to have a material impact on the Company’s consolidated financial position, results of operations or cash flows. Telephone Consumer Protection Act Purported Class Actions — Three purported class action lawsuits have been filed against NRG Residential Solar Solutions, LLC — one in California and two in New Jersey. The plaintiffs generally allege misrepresentation by the call agents and violations of the TCPA, claiming that the defendants engaged in a telemarketing campaign placing unsolicited calls to individuals on the “Do Not Call List.” The plaintiffs seek statutory damages of up to $1,500 per plaintiff, actual damages and equitable relief. On June 22, 2017, plaintiffs in the California case filed a motion for leave to file a second amended complaint to substitute new plaintiffs. Defendants’ filed an opposition to this motion on June 26, 2017. The court granted plaintiffs' motion to substitute new plaintiffs and on August 1, 2017, Defendants filed an answer to the second amended complaint. On August 31, 2017, the court in the California case agreed that the litigation should be stayed pending the New Jersey settlement. On July 12, 2017, the parties in the New Jersey action reached an agreement in principle to resolve the class allegations which was confirmed by a term sheet signed by the parties on July 28, 2017. On September 27, 2017, plaintiffs in the New Jersey case filed their motion for preliminary approval of the class settlement. California Department of Water Resources and San Diego Gas & Electric Company v. Sunrise Power Company LLC — On January 29, 2016, CDWR and SDG&E filed a lawsuit against Sunrise Power Company, along with NRG and Chevron Power Corporation. 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 demurrers in response to the plaintiffs' complaint. The demurrers 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 demurrers to the amended complaints. On November 18, 2016, the court sustained the demurrers 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 demurrers without leave to amend. On July 14, 2017, CDWR filed a notice of appeal. Braun v. NRG Yield, Inc. — On April 19, 2016, plaintiffs filed a putative class action lawsuit against NRG Yield, Inc., the current and former members of its board of directors individually, and other parties in California Superior Court in Kern County, CA. Plaintiffs allege various violations of the Securities Act due to the defendants’ alleged failure to disclose material facts related to low wind production prior to the NRG Yield, Inc.'s June 22, 2015 Class C common stock offering. Plaintiffs seek compensatory damages, rescission, attorney’s fees and costs. The Defendants filed demurrers and a motion challenging jurisdiction on October 18, 2016. On October 26, 2017, the court approved the parties' stipulation which provides the plaintiffs' opposition is due on December 6, 2017 and defendants' reply is due on February 8, 2018. Ahmed v. NRG Energy, Inc. and the NRG Yield Board of Directors — On September 15, 2016, plaintiffs filed a putative class action lawsuit against NRG Energy, Inc., the directors of NRG Yield, Inc., and other parties in the Delaware Chancery Court. The complaint alleges that the defendants breached their respective fiduciary duties with regard to the recapitalization of NRG Yield, Inc. common stock in 2015. The plaintiffs generally seek economic damages, attorney’s fees and injunctive relief. The defendants filed a motion to dismiss the lawsuit on December 21, 2016. Plaintiffs filed their objection to the motion to dismiss on February 15, 2017. The defendants' reply was filed on March 24, 2017. The court heard oral argument on defendants' motion to dismiss on June 20, 2017. On September 7, 2017, the court requested additional briefing which the parties provided on September 21, 2017. Griffoul v. NRG Residential Solar Solutions — On February 28, 2017, plaintiffs, consisting of New Jersey residential solar customers, filed a purported class action lawsuit in New Jersey state court. Plaintiffs allege violations of the New Jersey Consumer Fraud Action and Truth-in-Consumer Contracts, Warranty and Notice Act with regard to certain provisions of their residential solar contracts. The plaintiffs seek damages and injunctive relief as to the proper allocation of the solar renewable energy credits. On June 6, 2017, the defendants filed a motion to compel arbitration or dismiss the lawsuit. Plaintiffs filed their opposition on June 29, 2017. On July 14, 2017, the court denied NRG's motion to compel arbitration or dismiss the case. On July 25, 2017, NRG filed a motion for reconsideration of the appeal, which the court denied. On August 22, 2017, NRG filed a notice of appeal. NRG’s appellate brief was filed on October 25, 2017. Plaintiffs’ opposition is due on November 16, 2017. Rice v. NRG — On April 14, 2017, plaintiffs filed a purported class action lawsuit in the U.S. District Court for the Western District of Pennsylvania against NRG, First Energy Corporation and Matt Canastrale Contracting, Inc. Plaintiffs generally claim personal injury, trespass, nuisance and property damage related to the disposal of coal ash from GenOn's Elrama Power Plant and First Energy’s Mitchell and Hatfield Power Plants. Plaintiffs generally seek monetary damages, medical monitoring and remediation of their property. Plaintiffs filed an amended complaint on August 14, 2017. On October 20, 2017, NRG filed its answer and affirmative defenses. 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. On September 14, 2017, the court issued a scheduling order setting this case for trial on October 21, 2019. LaGen filed a motion for a more definite statement on September 18, 2017. GenOn Chapter 11 Cases — On the Petition Date, the GenOn Entities filed voluntary petitions for relief under Chapter 11 of the Bankruptcy Code in the Bankruptcy Court. Under the Restructuring Support Agreement to which the GenOn Entities, NRG and certain of GenOn's and GenOn Americas Generation's senior unsecured noteholders are parties, each of them has agreed to support Bankruptcy Court approval of the plan of reorganization. GenOn has a customary "fiduciary out" under the Restructuring Support Agreement. Moreover, the Bankruptcy Court may not approve the plan of reorganization. If the plan of reorganization is not approved, NRG may not be entitled to the benefits of the Settlement Agreement provided under the Restructuring Support Agreement and it will remain subject to any claims of GenOn and the noteholders, including claims relating to or arising out of any shared services and any other relationships or transactions between the companies. See Note 3 , Discontinued Operations, Dispositions and Acquisitions , for additional information related to the Chapter 11 Cases. GenOn Noteholders' Lawsuit — On December 13, 2016, certain indenture trustees for an ad hoc group of holders, or the Noteholders, of the GenOn Energy, Inc. 7.875% Senior Notes due 2017, 9.500% Notes due 2018, and 9.875% Notes due 2020, and the GenOn Americas Generation, LLC 8.50% Senior Notes due 2021 and 9.125% Senior Notes due 2031, along with certain of the Noteholders, filed a complaint in the Superior Court of the State of Delaware against NRG and GenOn alleging certain claims related to the Services Agreement between NRG and GenOn. Plaintiffs generally seek return of all monies paid under the Services Agreement and any other damages that the court deems appropriate. On February 3, 2017, the court entered an order approving a Standstill Agreement whereby the parties agreed to suspend all deadlines in the case until March 1, 2017. The Standstill Agreement terminated on March 1, 2017. On April 30, 2017, the Noteholders filed an amended complaint that asserts (i) additional fraudulent transfer claims in relation to GenOn’s sale of the Marsh Landing project to NRG Yield LLC, (ii) alleged breaches of fiduciary duty by certain current and former officers and directors of GenOn in relation to the Services Agreement and the alleged usurpation of corporate opportunities concerning the Mandalay and Canal projects and (iii) claims against NRG for allegedly aiding and abetting such claimed breaches of fiduciary duties. In addition to NRG and GenOn, the amended complaint names NRG Yield LLC and certain current and former officers and directors of GenOn as defendants. The plaintiffs, among other things, generally seek return of all monies paid under the services agreement and any other damages that the court deems appropriate. Pursuant to the terms of the Restructuring Support Agreement, this matter should ultimately be resolved if the GenOn Entities' plan of reorganization is approved by the Bankruptcy Court. Morgantown v. GenOn Mid-Atlantic — On June 8, 2017, Morgantown and Dickerson Owner Lessors filed a lawsuit against GenOn Mid-Atlantic, LLC, NRG North America LLC, GenOn Americas Generation, LLC, NRG Americas, Inc., GenOn Energy Holdings, Inc., GenOn Energy, Inc., and NRG Energy, Inc. in New York State Supreme Court. The plaintiffs allege that they were overcharged by defendants for certain services outlined in a Services Agreement and that defendants caused a Qualified Credit Support portion of a Participation Agreement, or QCS Agreement, to be violated by causing the transfer of certain money outside the allowable confines set forth in the QCS Agreement. In addition, plaintiffs claim that the transfers were unfairly executed and done so in an effort to defraud plaintiffs and hinder their ability to continue to do business. As such, plaintiffs seek, among other things, the return of certain transferred funds and service charges paid and to bar defendants from executing additional transfers on plaintiffs’ behalf. A claims estimation ruling on this matter by the Bankruptcy Court could occur as early as November 7, 2017. BTEC v. NRG Texas Power — On July 18, 2017, BTEC New Albany LLC, or BTEC, filed a lawsuit against NRG Texas Power LLC, or NRG Texas Power, in the Harris County District Court in Texas. On January 15, 2013, the parties entered into a Membership Interest and Purchase Agreement, or MIPA, whereby BTEC agreed to dismantle, transport and rebuild an electric power generation facility at the former P.H. Robinson Electric Generating Station in Bacliff, Texas. The MIPA required BTEC to meet a Guaranteed Commercial Completion Date of May 31, 2016. But even a year later, BTEC had not satisfied all of the contractually-required acceptance criteria. As a result and given that the MIPA expiration date passed on May 31, 2017, NRG elected to terminate the contract in June 2017. BTEC claims that NRG Texas Power breached the MIPA by improperly terminating it, and seeks a declaratory judgment as to the rights and obligations of the parties. In addition, BTEC seeks damages, interest and attorney’s fees. On August 14, 2017, NRG Texas Power served its answer to the lawsuit. On September 7, 2017, NRG Texas Power filed a counterclaim seeking damages in excess of $48 million . GenOn Related Contingencies Actions Pursued by MC Asset Recovery — With Mirant Corporation's emergence from bankruptcy protection in 2006, certain actions filed by GenOn Energy Holdings and some of its subsidiaries against third parties were transferred to MC Asset Recovery, a wholly owned subsidiary of GenOn Energy Holdings. MC Asset Recovery is governed by a manager who is independent of NRG and GenOn. MC Asset Recovery is a disregarded entity for income tax purposes. Under the remaining action transferred to MC Asset Recovery, MC Asset Recovery seeks to recover damages from Commerzbank AG and various other banks, or the Commerzbank Defendants, for alleged fraudulent transfers that occurred prior to Mirant's bankruptcy proceedings. In December 2010, the U.S. District Court for the Northern District of Texas dismissed MC Asset Recovery's complaint against the Commerzbank Defendants. In January 2011, MC Asset Recovery appealed the District Court's dismissal of its complaint against the Commerzbank Defendants to the U.S. Court of Appeals for the Fifth Circuit, or the Fifth Circuit. In March 2012, the Fifth Circuit reversed the District Court's dismissal and reinstated MC Asset Recovery's amended complaint against the Commerzbank Defendants. On December 10, 2015, the District Court granted summary judgment in favor of the Commerzbank Defendants. On December 29, 2015, MC Asset Recovery filed a notice to appeal this judgment with the Fifth Circuit. On June 1, 2017, the Fifth Circuit affirmed the District Court's judgment. On June 12, 2017, MC Asset Recovery petitioned the Fifth Circuit for rehearing. The petition for rehearing was denied and a court order and judgment affirming the District Court's judgments was entered on July 17, 2017. On January 17, 2018, the bankruptcy court will hear a Motion for a Final Decree in the Mirant bankruptcy. Natural Gas Litigation — GenOn is party to several lawsuits, certain of which are class action lawsuits, in state and federal courts in Kansas, Missouri, Nevada and Wisconsin. These lawsuits were filed in the aftermath of the California energy crisis in 2000 and 2001 and the resulting FERC investigations and relate to alleged conduct to increase natural gas prices in violation of state antitrust law and similar laws. The lawsuits seek treble or punitive damages, restitution and/or expenses. The lawsuits also name as parties a number of energy companies unaffiliated with NRG. In July 2011, the U.S. District Court for the District of Nevada, which was handling four of the five cases, granted the defendants' motion for summary judgment and dismissed all claims against GenOn in those cases. The plaintiffs appealed to the U.S. Court of Appeals for the Ninth Circuit, or the Ninth Circuit, which reversed the decision of the District Court. GenOn along with the other defendants in the lawsuit filed a petition for a writ of certiorari to the U.S. Supreme Court challenging the Ninth Circuit's decision and the U.S. Supreme Court granted the petition. On April 21, 2015, the U.S. Supreme Court affirmed the Ninth Circuit’s holding that plaintiffs’ state antitrust law claims are not field-preempted by the federal Natural Gas Act and the Supremacy Clause of the U.S. Constitution. The U.S. Supreme Court left open whether the claims were preempted on the basis of conflict preemption. The U.S. Supreme Court directed that the case be remanded to the U.S. District Court for the District of Nevada for further proceedings. On March 7, 2016, class plaintiffs filed their motions for class certification. Defendants filed their briefs in opposition to class plaintiffs' motions for class certification on June 24, 2016. On March 30, 2017, the court denied the plaintiffs' motions for class certification. On April 13, 2017, the plaintiffs petitioned the Ninth Circuit for interlocutory review of the court’s order denying class certification. On June 13, 2017, the Ninth Circuit granted plaintiffs' petition for interlocutory review. In May 2016 in one of the Kansas cases, the U.S. District Court for the District of Nevada granted the defendants' motion for summary judgment. Subsequently in December 2016, the plaintiffs filed a notice of appeal with the Ninth Circuit. The appeal has been fully briefed by the parties. GenOn has agreed to indemnify CenterPoint against certain losses relating to these lawsuits. In September 2012, the State of Nevada Supreme Court, which was handling the remaining case, affirmed dismissal by the Eighth Judicial District Court for Clark County, Nevada of all plaintiffs' claims against GenOn. In February 2013, the plaintiffs in the Nevada case filed a petition for a writ of certiorari to the U.S. Supreme Court. In June 2013, the U.S. Supreme Court denied the petition for a writ of certiorari, thereby ending one of the five lawsuits. Potomac River Environmental Investigation — In March 2013, NRG Potomac River LLC, a subsidiary of GenOn, received notice that the District of Columbia Department of Environment (now renamed the Department of Energy and Environment, or DOEE) was investigating potential discharges to the Potomac River originating from the Potomac River Generating facility site, a site where the generation facility is no longer in operation. In connection with that investigation, DOEE served a civil subpoena on NRG Potomac River LLC requesting information related to the site and potential discharges occurring from the site. NRG Potomac River LLC provided various responsive materials. In January 2016, DOEE advised NRG Potomac River LLC that DOEE believed various environmental violations had occurred as a result of discharges DOEE believes occurred to the Potomac River from the Potomac River Generating facility site and as a result of associated failures to accurately or sufficiently report such discharges. DOEE has indicated it believes that penalties are appropriate in light of the violations. NRG Potomac River LLC is currently reviewing the information provided by DOEE.

Regulatory Matters

Regulatory Matters	9 Months Ended
	Sep. 30, 2017
Regulatory Matters Disclosure [Abstract]
Regulatory Matters	Regulatory Matters This footnote should be read in conjunction with the complete description under Note 23 , Regulatory Matters , to the Company's 2016 Form 10-K. 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. National Zero-Emission Credits for Nuclear Plants in Illinois — In 2016, Illinois enacted a Zero Emission Credit, or ZEC, program for selected nuclear units in Illinois. In total, the program directs over $2.5 billion over ten years to nuclear plants in Illinois that would otherwise retire. Pursuant to the legislation , the Illinois Power Agency, or IPA, conducts a competitive solicitation to procure ZECs, although both the Governor of Illinois and Exelon have already announced that the ZECs will be awarded to two Exelon-owned nuclear power plants in Illinois. These ZECs are out-of-market subsidies that threaten to artificially suppress market prices and interfere with the wholesale power market. On February 14, 2017, NRG, along with other companies, filed a complaint in the U.S. District Court for the Northern District of Illinois alleging that the state program is preempted by federal law and in violation of the dormant commerce clause. Another plaintiff group filed a similar complaint on the same day. Subsequently, on March 31, 2017, NRG, along with other companies, filed a motion for preliminary injunction. On April 10, 2017, Exelon, as an intervenor defendant, and State defendants filed motions to dismiss. On July 14, 2017, Defendants' motions to dismiss were granted. On July 17, 2017, NRG, along with other companies, filed a notice of appeal to the U.S. Court of Appeals for the Seventh Circuit. On July 18, 2017, the Court of Appeals issued an order setting an expedited briefing schedule for the matter. Briefing is underway. Zero-Emission Credits for Nuclear Plants in New York — On August 1, 2016, the NYSPSC issued its Clean Energy Standard, or CES, which provided for ZECs which would provide more than $7.6 billion over 12 years in out-of-market subsidy payments to certain selected nuclear generating units in the state. These ZECs are out-of-market subsidies that threaten to artificially suppress market prices and interfere with the wholesale power market. On October 19, 2016, NRG, along with other companies, filed a complaint in the U.S. District Court for the Southern District of New York, challenging the validity of the NYSPSC action and the ZEC program. On March 29, 2017, the U.S. District Court heard oral arguments on a motion to dismiss filed by defendants. On July 25, 2017, the defendants' motions to dismiss were granted. On August 24, 2017, NRG, along with other companies, filed a notice of appeal to the U.S. Court of Appeals for the Second Circuit. On September 9, 2017, the Court of Appeals issued a briefing schedule. Briefing is underway. Department of Energy's Proposed Grid Resiliency Pricing Rule — On September 29, 2017, the Department of Energy issued a proposed rulemaking titled the "Grid Resiliency Pricing Rule." The rulemaking directs FERC to take action to reform the ISO/RTO markets to value certain reliability and resiliency attributes of electric generation resources. On October 2, 2017, FERC issued a notice inviting comments. On October 4, 2017, FERC staff issued a series of questions requesting commenters to address. On October 23, 2017, NRG filed comments encouraging FERC to act expeditiously to modernize energy and capacity markets in a manner compatible with robust competitive markets.

Environmental Matters

Environmental Matters	9 Months Ended
	Sep. 30, 2017
Environmental Matters Disclosure [Abstract]
Environmental Matters	Environmental Matters This footnote should be read in conjunction with the complete description under Note 24 , Environmental Matters , to the Company's 2016 Form 10-K. 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. The EPA finalized CSAPR in 2011, which was intended to replace CAIR in January 2012, to address certain states' obligations to reduce emissions so that downwind states can achieve federal air quality standards. In December 2011, the D.C. Circuit stayed the implementation of CSAPR and then vacated CSAPR in August 2012 but kept CAIR in place until the EPA could replace it. In April 2014, the U.S. Supreme Court reversed and remanded the D.C. Circuit's decision. In October 2014, the D.C. Circuit lifted the stay of CSAPR. In response, the EPA in November 2014 amended the CSAPR compliance dates. Accordingly, CSAPR replaced CAIR on January 1, 2015. On July 28, 2015, the D.C. Circuit held that the EPA had exceeded its authority by requiring certain reductions that were not necessary for downwind states to achieve federal standards. Although the D.C. Circuit kept the rule in place, the court ordered the EPA to revise the Phase 2 (or 2017) (i) SO 2 budgets for four states including Texas and (ii) ozone-season NOx budgets for 11 states including Maryland, New Jersey, New York, Ohio, Pennsylvania and Texas. On October 26, 2016, the EPA finalized the CSAPR Update Rule, which reduces future NOx allocations and discounts the current banked allowances to account for the more stringent 2008 Ozone NAAQS and to address the D.C. Circuit's July 2015 decision. This rule has been challenged in the D.C. Circuit. The Company believes its investment in pollution controls and cleaner technologies leave the fleet well-positioned for compliance. 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 (with some units getting a 1-year extension). In June 2015, the U.S. Supreme Court issued a decision in the case of Michigan v. EPA, and held that the EPA unreasonably refused to consider costs when it determined that it was "appropriate and necessary" to regulate HAPs emitted by electric generating units. The U.S. Supreme Court did not vacate the MATS rule but rather remanded it to the D.C. Circuit for further proceedings. In December 2015, the D.C. Circuit remanded the MATS rule to the EPA without vacatur. On April 25, 2016, the EPA released a supplemental finding that the benefits of this regulation outweigh the costs to address the U.S. Supreme Court's ruling that the EPA had not properly considered costs. This finding has been challenged in the D.C. Circuit. On April 18, 2017, the EPA asked the D.C. Circuit to postpone oral argument that had been scheduled for May 18, 2017 because the EPA is closely reviewing the supplemental finding to determine whether it should reconsider all or part of the rule. On April 27, 2017, the D.C. Circuit granted EPA's request to postpone the oral argument and hold the case in abeyance. 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 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. 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, or FGD, fly ash, bottom ash, and flue gas mercury control. In April 2017, the EPA granted two petitions to reconsider the rule and also administratively stayed some of the deadlines. On September 18, 2017, the EPA promulgated a final rule that (i) 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 and (ii) withdrew the April 2017 administrative stay. The legal challenges have been suspended while the EPA reconsiders and likely modifies the rule. Accordingly, the Company has largely 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. On September 13, 2017, the EPA granted the petition for reconsideration that the Utility Solid Waste Activities Group filed in May 2017. The Company has evaluated the impact of the new rule on the Company's consolidated financial position, results of operations, or cash flows and has accrued its environmental and asset retirement obligations under the rule based on current estimates as of September 30, 2017 . East Region Burton Island Old Ash Landfill — In January 2006, NRG's Indian River Power LLC was notified that it may be a potentially responsible party with respect to Burton Island Old Ash Landfill, a historic captive landfill located at the Indian River facility. On October 1, 2007, NRG signed an agreement with DNREC to investigate the site through the Voluntary Clean-up Program, or the VCP. On February 4, 2008, DNREC issued findings that no further action was required in relation to surface water and that a previously planned shoreline stabilization project would satisfactorily address shoreline erosion. The landfill itself required a Remedial Investigation and Feasibility Study to determine the type and scope of any additional required work. DNREC approved the Feasibility Study in December 2012. In January 2013, DNREC proposed a remediation plan based on the Feasibility Study. The remediation plan was approved in October 2013. In December 2015, DNREC approved the Company's remediation design and the Company's Long Term Stewardship Plan. In the second quarter of 2017, the Company completed the remediation requirements in the remediation plan. The cost of completing the work required by the remediation plan was within amounts budgeted in early 2016. The estimated cost to comply with the Long-Term Stewardship Plan was added to the liability in December 2016. In addition to the VCP, on May 29, 2008, DNREC requested that NRG's Indian River Power LLC participate in the development and performance of a Natural Resource Damage Assessment at the Burton Island Old Ash Landfill. NRG is working with DNREC and other trustees to close out the assessment process.

Condensed Consolidating Financi

Condensed Consolidating Financial Information	9 Months Ended
	Sep. 30, 2017
Condensed Consolidating Financial Information Disclosure [Abstract]
Condensed Consolidating Financial Information	Condensed Consolidating Financial Information As of September 30, 2017 , the Company had outstanding $5.4 billion of Senior Notes due from 2018 to 2027, as shown in Note 8 , Debt and Capital Leases . These Senior 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, and NRG Yield, Inc. and its subsidiaries. Unless otherwise noted below, each of the following guarantor subsidiaries fully and unconditionally guaranteed the Senior Notes as of September 30, 2017 : Ace Energy, Inc. New Genco GP, LLC NRG Norwalk Harbor Operations Inc. Allied Home Warranty GP LLC Norwalk Power LLC NRG Operating Services, Inc. Allied Warranty LLC NRG Advisory Services LLC NRG Oswego Harbor Power Operations Inc. Arthur Kill Power LLC NRG Affiliate Services Inc. NRG PacGen Inc. Astoria Gas Turbine Power LLC NRG Arthur Kill Operations Inc. NRG Portable Power LLC Bayou Cove Peaking Power, LLC NRG Astoria Gas Turbine Operations Inc. NRG Power Marketing LLC BidURenergy, Inc. NRG Bayou Cove LLC NRG Reliability Solutions LLC Cabrillo Power I LLC NRG Business Services LLC NRG Renter's Protection LLC Cabrillo Power II LLC NRG Cabrillo Power Operations Inc. NRG Retail LLC Carbon Management Solutions LLC NRG California Peaker Operations LLC NRG Retail Northeast LLC Cirro Group, Inc. NRG Cedar Bayou Development Company, LLC NRG Rockford Acquisition LLC Cirro Energy Services, Inc. NRG Connected Home LLC NRG Saguaro Operations Inc. Conemaugh Power LLC NRG Connecticut Affiliate Services Inc. NRG Security LLC Connecticut Jet Power LLC NRG Construction LLC NRG Services Corporation Cottonwood Development LLC NRG Curtailment Solutions, Inc NRG SimplySmart Solutions LLC Cottonwood Energy Company LP NRG Development Company Inc. NRG South Central Affiliate Services Inc. Cottonwood Generating Partners I LLC NRG Devon Operations Inc. NRG South Central Generating LLC Cottonwood Generating Partners II LLC NRG Dispatch Services LLC NRG South Central Operations Inc. Cottonwood Generating Partners III LLC NRG Distributed Energy Resources Holdings LLC NRG South Texas LP Cottonwood Technology Partners LP NRG Distributed Generation PR LLC NRG SPV #1 LLC Devon Power LLC NRG Dunkirk Operations Inc. NRG Texas C&I Supply LLC Dunkirk Power LLC NRG El Segundo Operations Inc. NRG Texas Gregory LLC Eastern Sierra Energy Company LLC NRG Energy Efficiency-L LLC NRG Texas Holding Inc. El Segundo Power, LLC NRG Energy Labor Services LLC NRG Texas LLC El Segundo Power II LLC NRG ECOKAP Holdings LLC NRG Texas Power LLC Energy Alternatives Wholesale, LLC NRG Energy Services Group LLC NRG Warranty Services LLC Energy Choice Solutions LLC NRG Energy Services International Inc. NRG West Coast LLC Energy Plus Holdings LLC NRG Energy Services LLC NRG Western Affiliate Services Inc. Energy Plus Natural Gas LLC NRG Generation Holdings, Inc. O'Brien Cogeneration, Inc. II Energy Protection Insurance Company NRG Greenco LLC ONSITE Energy, Inc. Everything Energy LLC NRG Home & Business Solutions LLC Oswego Harbor Power LLC Forward Home Security, LLC NRG Home Services LLC Reliant Energy Northeast LLC GCP Funding Company, LLC NRG Home Solutions LLC Reliant Energy Power Supply, LLC Green Mountain Energy Company NRG Home Solutions Product LLC Reliant Energy Retail Holdings, LLC Gregory Partners, LLC NRG Homer City Services LLC Reliant Energy Retail Services, LLC Gregory Power Partners LLC NRG Huntley Operations Inc. RERH Holdings, LLC Huntley Power LLC NRG HQ DG LLC Saguaro Power LLC Independence Energy Alliance LLC NRG Identity Protect LLC Somerset Operations Inc. Independence Energy Group LLC NRG Ilion Limited Partnership Somerset Power LLC Independence Energy Natural Gas LLC NRG Ilion LP LLC Texas Genco GP, LLC Indian River Operations Inc. NRG International LLC Texas Genco Holdings, Inc. Indian River Power LLC NRG Maintenance Services LLC Texas Genco LP, LLC Keystone Power LLC NRG Mextrans Inc. Texas Genco Services, LP Langford Wind Power, LLC NRG MidAtlantic Affiliate Services Inc. US Retailers LLC Louisiana Generating LLC NRG Middletown Operations Inc. Vienna Operations Inc. Meriden Gas Turbines LLC NRG Montville Operations Inc. Vienna Power LLC Middletown Power LLC NRG New Roads Holdings LLC WCP (Generation) Holdings LLC Montville Power LLC NRG North Central Operations Inc. West Coast Power LLC NEO Corporation NRG Northeast Affiliate Services Inc. NRG conducts much of its business through and derives much of its income from its subsidiaries. Therefore, the Company's ability to make required payments with respect to its indebtedness and other obligations depends on the financial results and condition of its subsidiaries and NRG's ability to receive funds from its subsidiaries. There are no restrictions on the ability of any of the guarantor subsidiaries to transfer funds to NRG. 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 under the SEC Regulation S-X. The financial information may not necessarily be indicative of results of operations or financial position had the guarantor subsidiaries or non-guarantor subsidiaries operated as independent entities. In this presentation, NRG Energy, Inc. consists of parent company operations. Guarantor subsidiaries and non-guarantor subsidiaries of NRG are reported on an equity basis. For companies acquired, the fair values of the assets and liabilities acquired have been presented on a push-down accounting basis. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the three months ended September 30, 2017 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 2,160 $ 1,021 $ — $ (132 ) $ 3,049 Operating Costs and Expenses Cost of operations 1,588 682 15 (129 ) 2,156 Depreciation and amortization 104 160 8 — 272 Impairment losses — 14 — — 14 Selling, general and administrative 97 29 88 (1 ) 213 Reorganization — — 18 — 18 Development activity expenses — 9 5 14 Total operating costs and expenses 1,789 894 134 (130 ) 2,687 Other income - affiliate — — 14 — 14 Operating Income/(Loss) 371 127 (120 ) (2 ) 376 Other Income/(Expense) Equity in losses of consolidated subsidiaries (41 ) (9 ) (134 ) 184 — Equity in (losses)/earnings of unconsolidated affiliates — (606 ) 666 (33 ) 27 Other income 7 3 5 — 15 Loss on debt extinguishment — (1 ) — — (1 ) Interest expense (4 ) (103 ) (114 ) — (221 ) Total other (expense)/income (38 ) (716 ) 423 151 (180 ) Income/(Loss) from Continuing Operations Before Income Taxes 333 (589 ) 303 149 196 Income tax expense/(benefit) 113 (209 ) 102 — 6 Income/(Loss) from Continuing Operations 220 (380 ) 201 149 190 Loss from Discontinued Operations, net of income tax — (27 ) — — (27 ) Net Income/(Loss) 220 (407 ) 201 149 163 Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests — (3 ) 30 (35 ) (8 ) Net Income/(Loss) Attributable to NRG Energy, Inc. $ 220 $ (404 ) $ 171 $ 184 $ 171 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the nine months ended September 30, 2017 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 5,517 $ 2,872 $ — $ (257 ) $ 8,132 Operating Costs and Expenses Cost of operations 4,156 1,904 46 (254 ) 5,852 Depreciation and amortization 307 458 24 — 789 Impairment losses 42 35 — — 77 Selling, general and administrative 281 115 304 (3 ) 697 Reorganization — — 18 — 18 Development activity expenses — 34 15 — 49 Total operating costs and expenses 4,786 2,546 407 (257 ) 7,482 Other income - affiliate — — 104 — 104 Gain on sale of assets 4 — — — 4 Operating Income/(Loss) 735 326 (303 ) — 758 Other Income/(Expense) Equity in losses of consolidated subsidiaries (61 ) (66 ) (182 ) 309 — Equity in earnings/(losses) of unconsolidated affiliates — 101 (3 ) (69 ) 29 Other income 8 15 10 — 33 Loss on debt extinguishment — (3 ) — — (3 ) Interest expense (11 ) (328 ) (353 ) — (692 ) Total other expense (64 ) (281 ) (528 ) 240 (633 ) Income/(Loss) from Continuing Operations Before Income Taxes 671 45 (831 ) 240 125 Income tax expense/(benefit) 244 28 (267 ) — 5 Income/(Loss) from Continuing Operations 427 17 (564 ) 240 120 Loss from Discontinued Operations, net of income tax — (802 ) — — (802 ) Net Income/(Loss) 427 (785 ) (564 ) 240 (682 ) Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests — (49 ) 55 (69 ) (63 ) Net Income/(Loss) Attributable to $ 427 $ (736 ) $ (619 ) $ 309 $ (619 ) (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) For the three months ended September 30, 2017 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Net Income/(Loss) $ 220 $ (407 ) $ 201 $ 149 $ 163 Other Comprehensive Income/(Loss), net of tax Unrealized gain on derivatives, net — 7 7 (7 ) 7 Foreign currency translation adjustments, net 2 2 2 (4 ) 2 Available-for-sale securities, net — — 1 — 1 Defined benefit plans, net — — (2 ) 1 (1 ) Other comprehensive income 2 9 8 (10 ) 9 Comprehensive Income/(Loss) 222 (398 ) 209 139 172 Less: Comprehensive income/(loss) attributable to noncontrolling interest and redeemable noncontrolling interest — — 30 (35 ) (5 ) Comprehensive Income/(Loss) Attributable to NRG Energy, Inc. $ 222 $ (398 ) $ 179 $ 174 $ 177 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) For the nine months ended September 30, 2017 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Net Income/(Loss) $ 427 $ (785 ) $ (564 ) $ 240 $ (682 ) Other Comprehensive Income/(Loss), net of tax Unrealized gain on derivatives, net — 6 7 (7 ) 6 Foreign currency translation adjustments, net 7 7 9 (13 ) 10 Available-for-sale securities, net — — 2 — 2 Defined benefit plans, net — 29 25 (28 ) 26 Other comprehensive income 7 42 43 (48 ) 44 Comprehensive Income/(Loss) 434 (743 ) (521 ) 192 (638 ) Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (47 ) 55 (69 ) (61 ) Comprehensive Income/(Loss) Attributable to NRG Energy, Inc. $ 434 $ (696 ) $ (576 ) $ 261 $ (577 ) (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS September 30, 2017 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated ASSETS (In millions) Current Assets Cash and cash equivalents $ (20 ) $ 350 $ 893 $ — $ 1,223 Funds deposited by counterparties 29 2 — — 31 Restricted cash 14 523 — — 537 Accounts receivable - trade, net 876 395 3 — 1,274 Accounts receivable - affiliate 222 191 (22 ) (337 ) 54 Inventory 406 224 — — 630 Derivative instruments 438 106 5 (74 ) 475 Cash collateral posted in support of energy risk management activities 190 13 — — 203 Prepayments and other current assets 108 147 45 — 300 Current assets - held for sale — 33 — — 33 Total current assets 2,263 1,984 924 (411 ) 4,760 Net property, plant and equipment 3,980 11,142 236 (26 ) 15,332 Other Assets Investment in subsidiaries 1,098 1,004 9,409 (11,511 ) — Equity investments in affiliates — 1,135 3 — 1,138 Notes receivable, less current portion — 5 — — 5 Goodwill 359 303 — — 662 Intangible assets, net 520 1,321 — (3 ) 1,838 Nuclear decommissioning trust fund 670 — — — 670 Derivative instruments 187 38 27 (46 ) 206 Deferred income tax (5 ) (148 ) 358 — 205 Non-current assets held-for-sale — 10 — — 10 Other non-current assets 63 520 61 — 644 Total other assets 2,892 4,188 9,858 (11,560 ) 5,378 Total Assets $ 9,135 $ 17,314 $ 11,018 $ (11,997 ) $ 25,470 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Current portion of long-term debt and capital leases $ — $ 623 $ 624 $ — $ 1,247 Accounts payable 599 285 31 — 915 Accounts payable — affiliate 528 (340 ) 146 (338 ) (4 ) Derivative instruments 418 178 — (74 ) 522 Cash collateral received in support of energy risk management activities 29 2 — — 31 Accrued expenses and other current liabilities 301 57 472 — 830 Accrued expenses and other current liabilities-affiliate — 164 — — 164 Total current liabilities 1,875 969 1,273 (412 ) 3,705 Other Liabilities Long-term debt and capital leases 244 8,644 6,770 — 15,658 Nuclear decommissioning reserve 265 — — — 265 Nuclear decommissioning trust liability 397 — — — 397 Deferred income taxes 428 — (407 ) — 21 Derivative instruments 194 159 — (46 ) 307 Out-of-market contracts, net 69 144 — — 213 Non-current liabilities held-for-sale — 13 — — 13 Other non-current liabilities 377 315 424 — 1,116 Total non-current liabilities 1,974 9,275 6,787 (46 ) 17,990 Total liabilities 3,849 10,244 8,060 (458 ) 21,695 Redeemable noncontrolling interest in subsidiaries — 85 — — 85 Stockholders’ Equity 5,286 6,985 2,958 (11,539 ) 3,690 Total Liabilities and Stockholders’ Equity $ 9,135 $ 17,314 $ 11,018 $ (11,997 ) $ 25,470 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the nine months ended September 30, 2017 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net income/(loss) $ 427 $ (785 ) $ (564 ) $ 240 $ (682 ) Loss from discontinued operations — (802 ) — — (802 ) Net income/(loss) from continuing operations 427 17 (564 ) 240 120 Adjustments to reconcile net income/(loss) to net cash provided by operating activities: Distributions from unconsolidated affiliates — 60 — (7 ) 53 Equity in losses/(earnings) of unconsolidated affiliates — (101 ) 3 69 (29 ) Depreciation and amortization 307 458 24 — 789 Provision for bad debts 40 2 15 — 57 Amortization of nuclear fuel 37 — — — 37 Amortization of financing costs and debt discount/premiums — 31 13 — 44 Adjustment for debt extinguishment — 3 — — 3 Amortization of intangibles and out-of-market contracts 20 59 — — 79 Amortization of unearned equity compensation — — 27 — 27 Impairment losses 42 35 — — 77 Changes in deferred income taxes and liability for uncertain tax benefits 244 28 (246 ) — 26 Changes in nuclear decommissioning trust liability 20 — — — 20 Changes in derivative instruments (11 ) 32 12 (8 ) 25 Changes in collateral deposits supporting energy risk management activities (126 ) 23 — — (103 ) Proceeds from sale of emission allowances 21 — — — 21 Gain on sale of assets (22 ) — — — (22 ) Cash (used)/provided by changes in other working capital (958 ) (523 ) 1,395 (294 ) (380 ) Cash provided by continuing operations 41 124 679 — 844 Cash used by discontinued operations — (38 ) — — (38 ) Net Cash Provided by Operating Activities 41 86 679 — 806 Cash Flows from Investing Activities Dividends from NRG Yield, Inc. — — 69 (69 ) — Acquisition of Drop Down Assets, net of cash acquired — (176 ) — 176 — Intercompany dividends — — 129 (129 ) — Acquisition of business, net of cash acquired — (36 ) — — (36 ) Capital expenditures (135 ) (606 ) (19 ) — (760 ) Decrease in notes receivable — 11 — — 11 Purchases of emission allowances (47 ) — — — (47 ) Proceeds from sale of emission allowances 105 — — — 105 Investments in nuclear decommissioning trust fund securities (402 ) — — — (402 ) Proceeds from sales of nuclear decommissioning trust fund securities 382 — — — 382 Proceeds from renewable energy grants and state rebates 8 — — — 8 Proceeds from sale of assets, net of cash disposed of 36 — — — 36 Investments in unconsolidated affiliates — (31 ) — — (31 ) Other 22 — — — 22 Cash (used)/provided by continuing operations (31 ) (838 ) 179 (22 ) (712 ) Cash used by discontinued operations — (53 ) — — (53 ) Net Cash (Used)/Provided by Investing Activities (31 ) (891 ) 179 (22 ) (765 ) Cash Flows from Financing Activities Dividends from NRG Yield, Inc. — (69 ) — 69 — Payments from/(for) intercompany loans 9 417 (426 ) — — Acquisition of Drop Down Assets, net of cash acquired — — 176 (176 ) — Intercompany dividends — (129 ) — 129 — Payment of dividends to common and preferred stockholders — — (28 ) — (28 ) Net receipts from settlement of acquired derivatives that include financing elements — 2 — — 2 Proceeds from issuance of long-term debt — 920 214 — 1,134 Payments for short and long-term debt — (493 ) (219 ) — (712 ) Receivable from affiliate — (125 ) — — (125 ) Contributions from, net of distributions to, noncontrolling interest in subsidiaries — 65 — — 65 Payment of debt issuance costs — (38 ) (5 ) — (43 ) Other - contingent consideration — (10 ) — — (10 ) Cash provided/(used) by continuing operations 9 540 (288 ) 22 283 Cash used by discontinued operations — (224 ) — — (224 ) Net Cash Provided/(Used) by Financing Activities 9 316 (288 ) 22 59 Change in cash from discontinued operations — (315 ) — — (315 ) Effect of exchange rate changes on cash and cash equivalents — (10 ) — — (10 ) Net Increase/(Decrease) in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties 19 (184 ) 570 — 405 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at Beginning of Period 4 1,059 323 — 1,386 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at End of Period $ 23 $ 875 $ 893 $ — $ 1,791 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the three months ended September 30, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 2,424 $ 1,090 $ — $ (93 ) $ 3,421 Operating Costs and Expenses Cost of operations 1,719 804 10 (93 ) 2,440 Depreciation and amortization 147 144 7 — 298 Impairment losses 8 1 — — 9 Selling, general and administrative 115 50 112 — 277 Development activity expenses — 10 11 — 21 Total operating costs and expenses 1,989 1,009 140 (93 ) 3,045 Other income - affiliate — — 48 — 48 Gain on sale of assets — — 4 — 4 Operating Income/(Loss) 435 81 (88 ) — 428 Other Income/(Expense) Equity in (losses)/earnings of consolidated subsidiaries (114 ) (10 ) 562 (438 ) — Equity in earnings/(losses) of unconsolidated affiliates 2 75 (12 ) (49 ) 16 Loss on investment — (8 ) — — (8 ) Other income/(loss), net 1 6 — — 7 Loss on debt extinguishment — — (50 ) — (50 ) Interest expense (4 ) (104 ) (129 ) — (237 ) Total other expense (115 ) (41 ) 371 (487 ) (272 ) Income from Continuing Operations Before Income Taxes 320 40 283 (487 ) 156 Income tax expense/(benefit) 134 45 (151 ) — 28 Income from Continuing Operations 186 (5 ) 434 (487 ) 128 Income from Discontinued Operations, net of income tax — 263 2 — 265 Net Income 186 258 436 (487 ) 393 Less: Net income/(loss) attributable to noncontrolling interest and redeemable noncontrolling interest — 6 34 (49 ) (9 ) Net Income Attributable to NRG Energy, Inc. $ 186 $ 252 $ 402 $ (438 ) $ 402 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the nine months ended September 30, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 6,079 $ 2,400 $ — $ (151 ) $ 8,328 Operating Costs and Expenses Cost of operations 4,278 1,558 29 (154 ) 5,711 Depreciation and amortization 372 435 19 — 826 Impairment losses 8 57 — — 65 Selling, general and administrative 306 144 351 — 801 Development activity expenses — 42 23 — 65 Total operating costs and expenses 4,964 2,236 422 (154 ) 7,468 Other income - affiliate — — 144 — 144 Loss on sale of assets — — (79 ) — (79 ) Operating Income/(Loss) 1,115 164 (357 ) 3 925 Other Income/(Expense) Equity in (losses)/earnings of consolidated subsidiaries (195 ) (80 ) 904 (629 ) — Equity in earnings/(losses) of unconsolidated affiliates 5 114 (2 ) (104 ) 13 Impairment loss on investment — (147 ) — — (147 ) Other income, net 3 25 2 (1 ) 29 Loss on debt extinguishment — (4 ) (115 ) — (119 ) Interest expense (11 ) (312 ) (395 ) (718 ) Total other (expense)/income (198 ) (404 ) 394 (734 ) (942 ) Income/(Loss) Before Income Taxes 917 (240 ) 37 (731 ) (17 ) Income tax expense/(benefit) 362 (49 ) (238 ) — 75 Income/(Loss) from Continuing Operations 555 (191 ) 275 (731 ) (92 ) Income from Discontinued Operations, net of income tax — 248 8 — 256 Net Income 555 57 283 (731 ) 164 Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (17 ) 70 (102 ) (49 ) Net Income Attributable to NRG Energy, Inc. $ 555 $ 74 $ 213 $ (629 ) $ 213 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) For the three months ended September 30, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Net Income $ 186 $ 258 $ 436 $ (487 ) $ 393 Other Comprehensive Income/(Loss), net of tax Unrealized income on derivatives, net — 40 26 (39 ) 27 Foreign currency translation adjustments, net 2 2 4 (5 ) 3 Defined benefit plans, net 54 — (43 ) 20 31 Other comprehensive loss 56 42 (13 ) (24 ) 61 Comprehensive Income 242 300 423 (511 ) 454 Less: Comprehensive income/(loss) attributable to noncontrolling interest and redeemable noncontrolling interest — 13 34 (49 ) (2 ) Comprehensive Income Attributable to NRG Energy, Inc. $ 242 $ 287 $ 389 $ (462 ) $ 456 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) For the nine months ended September 30, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Net Income $ 555 $ 57 $ 283 $ (731 ) $ 164 Other Comprehensive Income/(Loss), net of tax Unrealized (loss)/gain on derivatives, net — (15 ) 46 (39 ) (8 ) Foreign currency translation adjustments, net 4 4 6 (8 ) 6 Available-for-sale securities, net — — 1 — 1 Defined benefit plans, net 55 — (43 ) 20 32 Other comprehensive income/(loss) 59 (11 ) 10 (27 ) 31 Comprehensive Income 614 46 293 (758 ) 195 Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (38 ) 70 (102 ) (70 ) Comprehensive Income Attributable to NRG Energy, Inc. 614 84 223 (656 ) 265 Dividends for preferred shares — — 5 — 5 Gain on redemption of preferred shares — — (78 ) — (78 ) Comprehensive Income Available for Common Stockholders $ 614 $ 84 $ 296 $ (656 ) $ 338 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2016 Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated ASSETS (In millions) Current Assets Cash and cash equivalents $ (9 ) $ 624 $ 323 $ — $ 938 Funds deposited by counterparties 2 — — — 2 Restricted cash 11 435 — — 446 Accounts receivable - trade, net 734 321 3 — 1,058 Accounts receivable - affiliate 307 (254 ) 200 (139 ) 114 Inventory 482 239 — — 721 Derivative instruments 962 196 1 (92 ) 1,067 Cash collateral posted in support of energy risk management activities 116 34 — — 150 Current assets held-for-sale — 9 — — 9 Prepayments and other current assets 76 152 62 — 290 Current assets - discontinued operations — 1,919 — — 1,919 Total current assets 2,681 3,675 589 (231 ) 6,714 Net Property, Plant and Equipment 4,219 10,926 251 (27 ) 15,369 Other Assets Investment in subsidiaries 1,090 1,054 10,128 (12,272 ) — Equity investments in affiliates (13 ) 1,128 5 — 1,120 Notes receivable, less current portion — 16 — — 16 Goodwill 359 303 — — 662 Intangible assets, net 592 1,384 — (3 ) 1,973 Nuclear decommissioning trust fund 610 — — — 610 Derivative instruments 144 44 36 (43 ) 181 Deferred income taxes 3 — 222 — 225 Non-current assets held for sale — 10 — — 10 Other non-current assets 67 446 328 — 841 Non-current assets - discontinued operations — 2,961 — — 2,961 Total other assets 2,852 7,346 10,719 (12,318 ) 8,599 Total Assets $ 9,752 $ 21,947 $ 11,559 $ (12,576 ) $ 30,682 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Current portion of long-term debt and capital leases $ — $ 498 $ 18 $ — $ 516 Accounts payable 501 247 34 — 782 Accounts payable — affiliate 744 (452 ) (122 ) (139 ) 31 Derivative instruments 947 237 — (92 ) 1,092 Cash collateral received in support of energy risk management activities 81 — — — 81 Accrued expenses and other current liabilities 316 209 465 — 990 Current liabilities - discontinued operations — 1,210 — — 1,210 Total current liabilities 2,589 1,949 395 (231 ) 4,702 Other Liabilities Long-term debt and capital leases 244 8,252 7,461 — 15,957 Nuclear decommissioning reserve 287 — — — 287 Nuclear decommissioning trust liability 339 — — — 339 Deferred income taxes 186 125 (291 ) — 20 Derivative instruments 157 170 — (43 ) 284 Out-of-market contracts, net 80 150 — — 230 Non-current liabilities held-for-sale — 11 — — 11 Other non-current liabilities 396 456 324 — 1,176 Non-current liabilities - discontinued operations — 3,184 — — 3,184 Total non-current liabilities 1,689 12,348 7,494 (43 ) 21,488 Total Liabilities 4,278 14,297 7,889 (274 ) 26,190 Redeemable noncontrolling interest in subsidiaries — 46 — — 46 Stockholders’ Equity 5,474 7,604 3,670 (12,302 ) 4,446 Total Liabilities and Stockholders’ Equity $ 9,752 $ 21,947 $ 11,559 $ (12,576 ) $ 30,682 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the nine months ended September 30, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net Income $ 555 $ 57 $ 283 $ (731 ) $ 164 Less: Income from discontinued operations — 248 8 — 256 Net income/(loss) from continuing operations 555 (191 ) 275 (731 ) (92 ) Adjustments to reconcile net income/(loss) to net cash provided by operating activities: Distributions from unconsolidated affiliates — 65 — (8 ) 57 Equity in (earnings)/losses of unconsolidated affiliates (5 ) (20 ) 2 10 (13 ) Depreciation and amortization 372 435 19 — 826 Provision for bad debts 31 5 — — 36 Amortization of nuclear fuel 39 — — — 39 Amortization of financing costs and debt discount/premiums — 25 17 — 42 Adjustment for debt extinguishment — 102 17 — 119 Amortization of intangibles and out-of-market contracts 32 99 — — 131 Amortization of unearned equity compensation — — 23 — 23 Impairment losses 8 203 — — 211 Changes in deferred income taxes and liability for uncertain tax benefits (134 ) (90 ) 253 — 29 Changes in nuclear decommissioning trust liability 24 — — — 24 Changes in derivative instruments (173 ) 206 (3 ) — 30 Changes in collateral posted supporting energy risk management activities 268 (7 ) — — 261 Proceeds from sale of emission allowances 11 — — — 11 Loss on sale of assets — — 70 — 70 Cash (used)/provided by changes in other working capital (827 ) 168 (200 ) 729 (130 ) Net cash provided by continuing operations 201 1,000 473 — 1,674 Cash provided by discontinued operations — 67 — — 67 Net Cash Provided by Operating Activities 201 1,067 473 — 1,741 Cash Flows from Investing Activities Dividends from NRG Yield, Inc. — — 59 (59 ) — Acquisition of September 2016 Drop Down assets, net of cash acquired — (77 ) — 77 — Intercompany dividends — — 12 (12 ) — Acquisition of businesses, net of cash acquired — (18 ) — — (18 ) Capital expenditures (145 ) (474 ) (40 ) — (659 ) Increase in notes receivable — 2 — — 2 Purchases of emission allowances (32 ) — — — (32 ) Proceeds from sale of emission allowances 47 — — — 47 Investments in nuclear decommissioning trust fund securities (378 ) — — — (378 ) Proceeds from sales of nuclear decommissioning trust fund securities 354 — — — 354 Proceeds from renewable energy grants and state rebates — 11 — — 11 Proceeds from sale of assets, net of cash disposed of — 67 17 — 84 Investments in unconsolidated affiliates 2 (25 ) — — (23 ) Other 27 (4 ) 8 — 31 Net cash (used)/provided by continuing operations (125 ) (518 ) 56 6 (581 ) Cash provided by discontinued operations — 326 — — 326 Net Cash (Used)/Provided by Investing Activities (125 ) (192 ) 56 6 (255 ) Cash Flows from Financing Activities Dividends from NRG Yield, Inc. — (59 ) — 59 — Payments (for)/from intercompany loans (2 ) (134 ) 136 — — Acquisition of September 2016 Drop Down assets, net of cash acquired — — 77 (77 ) — Intercompany dividends (52 ) 40 — 12 — Payment of dividends to common and preferred stockholders — — (66 ) — (66 ) Payment for preferred shares — — (226 ) — (226 ) Net receipts for settlement of acquired derivatives that include financing elements — 6 — — 6 Proceeds from issuance of long-term debt — 1,097 4,140 — 5,237 Payments for short and long-term debt (2 ) (811 ) (4,540 ) — (5,353 ) Payments for debt extinguishment costs — (98 ) — — (98 ) Distributions from, net of contributions to, noncontrolling interest in subsidiaries — (127 ) — — (127 ) Proceeds from issuance of common stock — — 1 — 1 Payment of debt issuance costs — (17 ) (53 ) — (70 ) Other (3 ) (7 ) — — (10 ) Net cash used by continuing operations (59 ) (110 ) (531 ) (6 ) (706 ) Cash provided by discontinued operations — 119 — — 119 Net Cash (Used)/Provided by Financing Activities (59 ) 9 (531 ) (6 ) (587 ) Change in cash from discontinued operations — 512 — — 512 Effect of exchange rate changes on cash and cash equivalents — (6 ) — — (6 ) Net Increase/(Decrease) in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties 17 366 (2 ) — 381 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at Beginning of Period — 629 693 — 1,322 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at End of Period $ 17 $ 995 $ 691 $ — $ 1,703 (a) All significant intercompany transactions have been eliminated in consolidation.

Summary of Significant Accoun26

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Use of Estimates	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	Reclassifications Certain prior year amounts have been reclassified for comparative purposes. The reclassifications did not affect results from operations, net assets or cash flows.
Recent Accounting Developments	Recent Accounting Developments - Guidance Adopted in 2017 ASU 2016-18 — In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230) , Restricted Cash, or ASU No. 2016-18. The amendments of ASU No. 2016-18 require an entity to include amounts generally described as restricted cash and restricted cash equivalents, including funds deposited by counterparties with cash and cash equivalents when reconciling the beginning of period and end of period total amounts on the statement of cash flows. The amendments of ASU No. 2016-18 are effective for annual reporting periods beginning after December 15, 2017, and interim periods within those annual periods. Early adoption is permitted and the adoption of ASU No. 2016-18 will be applied retrospectively. The Company adopted the guidance in ASU No. 2016-18 during the second quarter of 2017. In connection with the adoption of the standard, the Company has applied the guidance retrospectively which resulted in a decrease in cash flows from operations of $49 million and an increase in cash flows from investing of $66 million on the statement of cash flows for the nine months ended September 30, 2016. ASU 2016-16 — In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740) , Intra-Entity Transfers of Assets Other Than Inventory, or ASU No. 2016-16. Current GAAP prohibits the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset has been sold to an outside party which has resulted in diversity in practice and increased complexity within financial reporting. The amendments of ASU No. 2016-16 would require an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The Company adopted the guidance in ASU No. 2016-16 effective January 1, 2017. In connection with the adoption of the standard, the Company recorded a reduction to non-current assets of $267 million with a corresponding reduction to cumulative retained deficit. ASU 2016-15 — In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230) , Classification of Certain Cash Receipts and Cash Payments, or ASU No. 2016-15. The amendments of ASU No. 2016-15 were issued to address eight specific cash flow issues for which stakeholders have indicated to the FASB that a diversity in practice existed in how entities were presenting and classifying these items in the statement of cash flows. The issues addressed by ASU No. 2016-15 include but are not limited to the classification of debt prepayment and debt extinguishment costs, payments made for contingent consideration for a business combination, proceeds from the settlement of insurance proceeds, distributions received from equity method investees and separately identifiable cash flows and the application of the predominance principle. The Company adopted the guidance in ASU No. 2016-15 effective January 1, 2017. In connection with the adoption of the standard, the Company has applied the guidance retrospectively which resulted in an increase in cash flows from operations of $98 million and a decrease in cash flows from financing of $98 million on the statement of cash flows for the nine months ended September 30, 2016. ASU 2016-09 — In March 2016, the FASB issued ASU No. 2016-09, Compensation - Stock Compensation (Topic 718), or ASU No. 2016-09. The amendments focused on simplification specifically with regard to share-based payment transactions, including income tax consequences, classification of awards as equity or liabilities and classification on the statement of cash flows. The Company adopted the guidance in ASU No. 2016-09 effective January 1, 2017 with no material adjustments recorded to the consolidated balance sheet. Recent Accounting Developments - Guidance Not Yet Adopted ASU 2017-12 — In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815) , Targeted Improvements to Accounting for Hedging Activities, or ASU No. 2017-12. The amendments of ASU No. 2017-12 were issued to simplify the application of hedge accounting guidance and more closely align financial reporting for hedging relationships with economic results of an entity's risk management activities. The issues addressed by ASU No. 2017-12 include but are not limited to alignment of risk management activities and financial reporting, risk component hedging, accounting for the hedged item in fair value hedges of interest rate risk, recognition and presentation of the effects of hedging instruments, amounts excluded from the assessment of hedge effectiveness, and other simplifications of hedge accounting guidance. The amendments of ASU No. 2017-12 are effective for fiscal years beginning after December 15, 2018, and interim periods therein. Early adoption is permitted in any interim period and the effect of the adoption should be reflected as of the beginning of the fiscal year of adoption. The Company does not expect the adoption of ASU No. 2017-12 will have a material impact on its consolidated results of operations, cash flows, and statement of financial position. ASU 2017-07 — In March 2017, the FASB issued ASU No. 2017-07, Compensation - Retirement Benefits (Topic 715) , Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, or ASU No. 2017-07. Current GAAP does not indicate where the amount of net benefit cost should be presented in an entity’s income statement and does not require entities to disclose the amount of net benefit cost that is included in the income statement. The amendments of ASU No. 2017-07 require an entity to report the service cost component of net benefit costs in the same line item as other compensation costs arising from services rendered by the related employees during the applicable service period. The other components of net benefit cost are required to be presented separately from the service cost component and outside the subtotal of income from operations. Further, ASU No. 2017-07 prescribes that only the service cost component of net benefit costs is eligible for capitalization. The amendments of ASU No. 2017-07 are effective for fiscal years beginning after December 15, 2017, including interim periods therein. Early adoption is permitted and must be applied on a retrospective basis, except for the amendments regarding the capitalization of the service cost component, which must be applied prospectively. The Company is currently assessing the impact that the adoption of ASU No. 2017-07 will have on its results of operations, cash flows, and statement of financial position. ASU 2016-02 — In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) , or Topic 842, 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 expects to adopt the standard effective January 1, 2019 utilizing the required modified retrospective approach for the earliest period presented. The Company expects to elect certain of the practical expedients permitted, including the expedient that permits the Company to retain its existing lease assessment and classification. The Company is currently working through an adoption plan which includes the evaluation of lease contracts compared to the new standard. While the Company is currently evaluating the impact the new guidance will have on its financial position and results of operations, the Company expects to recognize lease liabilities and right of use assets. The extent of the increase to assets and liabilities associated with these amounts remains to be determined pending the Company’s review of its existing lease contracts and service contracts which may contain embedded leases. While this review is still in process, NRG believes the adoption of Topic 842 will have a material impact on its financial statements. ASU 2014-09 — In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) , or Topic 606, which was further amended through various updates issued by the FASB thereafter. The amendments of Topic 606 completed the joint effort between the FASB and the IASB, to develop a common revenue standard for GAAP and IFRS, and to improve financial reporting. The guidance under Topic 606 provides that an entity should recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for the goods or services provided and establishes a five step model to be applied by an entity in evaluating its contracts with customers. The Company expects to adopt the standard effective January 1, 2018 and apply the guidance retrospectively to contracts at the date of adoption. The Company will recognize the cumulative effect of applying Topic 606 at the date of initial application, as prescribed under the modified retrospective transition method. The Company also expects to elect the practical expedient available under Topic 606 for measuring progress toward complete satisfaction of a performance obligation and for disclosure requirements of remaining performance obligations. The practical expedient allows an entity to recognize revenue in the amount to which the entity has the right to invoice such that the entity has a right to the consideration in an amount that corresponds directly with the value to the customer for performance completed to date by the entity. The Company continues to assess the new standard with a focus on identifying the performance obligations included within its revenue arrangements with customers and evaluating the Company’s methods of estimating the amount and timing of variable consideration. While the impact remains subject to continued review, the Company does not believe the adoption of Topic 606 will have a material impact on its financial statements.
Nuclear Decommissioning	NRG's Nuclear Decommissioning Trust Fund assets 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 nuclear decommissioning trust liability and are not included in net income or accumulated OCI, consistent with regulatory treatment.
Segment Reporting	The Company's segment structure reflects how management currently makes financial decisions and allocates resources. The Company's businesses are segregated as follows: Generation, which includes generation, international and BETM; Retail, which includes Mass customers and Business Solutions, which includes C&I customers and other distributed and reliability products; Renewables, which includes solar and wind assets, excluding those in NRG Yield; NRG Yield; and corporate activities. The financial information for the three and nine months ended September 30, 2016 has been recast to reflect the current segment structure. On September 1, 2016, NRG Yield acquired the remaining 51.05% interest in CVSR Holdco LLC, which indirectly owns the CVSR solar facility, from the Company. On March 27, 2017, NRG Yield acquired from NRG a 16% interest in the Agua Caliente solar project, and NRG's interests in seven utility-scale solar projects located in Utah. On August 1, 2017, NRG Yield acquired the remaining 25% interest in NRG Wind TE Holdco from the Company. All three acquisitions were treated as a transfer of entities under common control and accordingly, all historical periods have been recast to reflect the acquisition as if they had occurred at the beginning of the financial statement period. On June 14, 2017, as described in Note 3 , Discontinued Operations, Dispositions and Acquisitions , NRG deconsolidated GenOn for financial reporting purposes. The financial information for all historical periods have been recast to reflect the deconsolidation of GenOn and to present 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).

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
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, 2017 December 31, 2016 (In millions) Accounts receivable allowance for doubtful accounts $ 61 $ 29 Property, plant and equipment accumulated depreciation 6,437 5,711 Intangible assets accumulated amortization 1,750 1,687 Out-of-market contracts accumulated amortization 352 457
Restrictions on Cash and Cash Equivalents	The following table provides a reconciliation of cash and cash equivalents, restricted cash and funds deposited by counterparties reported within the consolidated balance sheet that sum to the total of the same such amounts shown in the statement of cash flows. September 30, 2017 December 31, 2016 September 30, 2016 December 31, 2015 (In millions) Cash and cash equivalents $ 1,223 $ 938 $ 1,217 $ 853 Funds deposited by counterparties 31 2 6 55 Restricted cash 537 446 480 414 Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows $ 1,791 $ 1,386 $ 1,703 $ 1,322
Schedule of Change in Noncontrolling Interest	The following table reflects the changes in NRG's noncontrolling interest balance: (In millions) Balance as of December 31, 2016 $ 2,405 Contributions from noncontrolling interest 116 Non-cash adjustments to noncontrolling interest 98 Sale of assets to NRG Yield, Inc. 24 Comprehensive loss attributable to noncontrolling interest (8 ) Dividends paid to NRG Yield, Inc. public shareholders (80 ) Distributions to noncontrolling interest (48 ) Balance as of September 30, 2017 $ 2,507
Redeemable Noncontrolling Interest	The following table reflects the changes in the Company's redeemable noncontrolling interest balance: (In millions) Balance as of December 31, 2016 $ 46 Contributions from redeemable noncontrolling interest 73 Non-cash adjustments to noncontrolling interest 21 Comprehensive loss attributable to redeemable noncontrolling interest (53 ) Distributions to redeemable noncontrolling interest (2 ) Balance as of September 30, 2017 $ 85

Discontinued Operations, Disp28

Discontinued Operations, Dispositions and Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2017
Discontinued Operations and Disposal Groups [Abstract]
Summary of Results of Discontinued Operations and Major Classes of Assets and Liabilities	Summarized results of discontinued operations were as follows: Three months ended September 30, 2017 (a) Three months ended September 30, 2016 Nine months ended September 30, 2017 (a) Nine months ended September 30, 2016 (In millions) Operating revenues $ — $ 532 $ 646 $ 1,509 Operating costs and expenses — (468 ) (700 ) (1,409 ) Gain on sale of assets — 262 — 294 Other expenses — (43 ) (98 ) (127 ) (Loss)/Income from operations of discontinued components, before tax — 283 (152 ) 267 Income tax expense — 21 9 20 (Loss)/Incomes from operations of discontinued components — 262 (161 ) 247 Interest income - affiliate — 3 6 9 (Loss)/Income from operations of discontinued components, net of tax — 265 (155 ) 256 Pre-tax loss on deconsolidation — — (208 ) — Settlement consideration and services credit — — (289 ) — Pension and post-retirement liability assumption (b) (25 ) — (144 ) — Other (2 ) — (6 ) — Loss on disposal of discontinued components, net of tax (27 ) — (647 ) — (Loss)/Income from discontinued operations, net of tax $ (27 ) $ 265 $ (802 ) $ 256 (a) As of June 14, 2017, NRG no longer consolidates GenOn for financial reporting purposes. (b) See Note 1 , Basis of Presentation , for further discussion regarding the October 30, 2017 proposed changes to the Restructuring Support Agreement. As part of this, NRG recorded the liability for GenOn’s post-employment and retiree health and welfare benefits, in an amount up to $25 million with a corresponding loss on discontinued operations during the third quarter of 2017. The following table summarizes the major classes of assets and liabilities classified as discontinued operations as of December 31, 2016. As of June 14, 2017, NRG no longer consolidates GenOn for financial reporting purposes. (In millions) December 31, 2016 Cash and cash equivalents $ 1,034 Other current assets 885 Current assets - discontinued operations 1,919 Property, plant and equipment, net 2,543 Other non-current assets 418 Non-current assets - discontinued operations 2,961 Current portion of long term debt and capital leases 704 Other current liabilities 506 Current liabilities - discontinued operations 1,210 Long-term debt and capital leases 2,050 Out-of-market contracts 811 Other non-current liabilities 323 Non-current liabilities - discontinued operations $ 3,184

Fair Value of Financial Instr29

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2017
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: As of September 30, 2017 As of December 31, 2016 Carrying Amount Fair Value Carrying Amount Fair Value (In millions) Assets: Notes receivable (a) $ 22 $ 21 $ 34 $ 34 Liabilities: Long-term debt, including current portion (b) 17,097 17,423 16,655 16,620 (a) Includes the current portion of notes receivable which is recorded in prepayments and other current assets on the Company's consolidated balance sheets. (b) Excludes deferred financing costs, which are recorded as a reduction to long-term debt on the Company's consolidated balance sheets. The following table presents the level within the fair value hierarchy for long-term debt, including current portion as of September 30, 2017 and December 31, 2016 : As of September 30, 2017 As of December 31, 2016 Level 2 Level 3 Level 2 Level 3 (In millions) Long-term debt, including current portion $ 9,571 $ 7,852 $ 9,205 $ 7,415
Assets and Liabilities Measured and Recorded at Fair Value 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: As of September 30, 2017 Fair Value (In millions) Level 1 Level 2 Level 3 Total Investment in available-for-sale securities (classified within other non-current assets): Debt securities $ — $ — $ 19 $ 19 Available-for-sale securities 5 — — 5 Nuclear trust fund investments: Cash and cash equivalents 31 — — 31 U.S. government and federal agency obligations 43 1 — 44 Federal agency mortgage-backed securities — 74 — 74 Commercial mortgage-backed securities — 11 — 11 Corporate debt securities — 108 — 108 Equity securities 333 — 65 398 Foreign government fixed income securities — 4 — 4 Other trust fund investments: U.S. government and federal agency obligations 1 — — 1 Derivative assets: Commodity contracts 132 409 98 639 Interest rate contracts — 42 — 42 Total assets $ 545 $ 649 $ 182 $ 1,376 Derivative liabilities: Commodity contracts 201 404 146 751 Interest rate contracts — 78 — 78 Total liabilities $ 201 $ 482 $ 146 $ 829 . As of December 31, 2016 Fair Value (In millions) Level 1 Level 2 Level 3 Total Investment in available-for-sale securities (classified within other non-current assets): Debt securities $ — $ — $ 17 $ 17 Available-for-sale securities 10 — — 10 Nuclear trust fund investments: Cash and cash equivalents 25 — — 25 U.S. government and federal agency obligations 72 1 — 73 Federal agency mortgage-backed securities — 62 — 62 Commercial mortgage-backed securities — 17 — 17 Corporate debt securities — 84 — 84 Equity securities 292 — 54 346 Foreign government fixed income securities — 3 — 3 Other trust fund investments: U.S. government and federal agency obligations 1 — — 1 Derivative assets: Commodity contracts 560 549 90 1,199 Interest rate contracts — 49 — 49 Total assets $ 960 $ 765 $ 161 $ 1,886 Derivative liabilities: Commodity contracts 494 636 158 1,288 Interest rate contracts — 88 — 88 Total liabilities $ 494 $ 724 $ 158 $ 1,376
Reconciliation of Beginning and Ending Balances for Financial Instruments Recognized at Fair Value Using Significant Unobservable Inputs	The following tables reconcile, for the three and nine months ended September 30, 2017 and 2016 , 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, 2017 Nine months ended September 30, 2017 (In millions) Debt Securities Trust Fund Investments Derivatives (a) Total Debt Securities Trust Fund Investments Derivatives (a) Total Beginning balance $ 18 $ 61 $ (11 ) $ 68 $ 17 $ 54 $ (68 ) $ 3 Total gains/(losses) — realized/unrealized: Included in earnings 1 — (28 ) (27 ) 2 — 18 20 Included in nuclear decommissioning obligation — 3 — 3 — 10 — 10 Purchases — 1 (9 ) (8 ) — 1 — 1 Transfers into Level 3 (b) — — (6 ) (6 ) — — (11 ) (11 ) Transfers out of Level 3 (b) — — 6 6 — — 13 13 Ending balance as of September 30, 2017 $ 19 $ 65 $ (48 ) $ 36 $ 19 $ 65 $ (48 ) $ 36 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, 2017 $ — $ — $ (13 ) $ (13 ) $ — $ — $ (6 ) $ (6 ) (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, 2016 Nine months ended September 30, 2016 (In millions) Debt Securities Trust Fund Investments Derivatives (a) Total Debt Securities Trust Fund Investments Derivatives (a) Total Beginning balance $ 16 $ 51 $ 18 $ 85 $ 17 $ 54 $ (22 ) $ 49 Total (losses)/gains — realized/unrealized: Included in earnings — — (5 ) (5 ) — — 4 4 Included in OCI 1 — — 1 — — — — Included in nuclear decommissioning obligations — 3 — 3 — (1 ) — (1 ) Purchases — — (25 ) (25 ) — 1 2 3 Transfers into Level 3 (b) — — (13 ) (13 ) — — (6 ) (6 ) Transfers out of Level 3 (b) — — 3 3 — — — — Ending balance as of September 30, 2016 $ 17 $ 54 $ (22 ) $ 49 $ 17 $ 54 $ (22 ) $ 49 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, 2016 $ — $ — $ (4 ) $ (4 ) $ — $ — $ (11 ) $ (11 ) (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 in Developing Fair Values	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, 2017 and December 31, 2016 : Significant Unobservable Inputs September 30, 2017 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) Power Contracts $ 47 $ 101 Discounted Cash Flow Forward Market Price (per MWh) $ 10 $ 88 $ 24 FTRs 51 45 Discounted Cash Flow Auction Prices (per MWh) (31 ) 36 — $ 98 $ 146 Significant Unobservable Inputs December 31, 2016 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) Power Contracts $ 39 $ 108 Discounted Cash Flow Forward Market Price (per MWh) $ 11 $ 104 $ 31 FTRs 51 50 Discounted Cash Flow Auction Prices (per MWh) (22 ) 17 — $ 90 $ 158
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, 2017 and December 31, 2016 : 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 91 % Financial institutions 9 Total as of September 30, 2017 100 % Net Exposure (a) (b) Category by Counterparty Credit Quality (% of Total) Investment grade 79 % Non-Investment grade/Non-Rated 21 Total as of September 30, 2017 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 Trust30

Nuclear Decommissioning Trust Fund (Tables)	9 Months Ended
	Sep. 30, 2017
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 (including other-than-temporary impairments) for the securities held in the trust funds, as well as information about the contractual maturities of those securities. As of September 30, 2017 As of December 31, 2016 (In millions, except otherwise noted) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Cash and cash equivalents $ 31 $ — $ — — $ 25 $ — $ — — U.S. government and federal agency obligations 44 2 — 10 73 1 — 11 Federal agency mortgage-backed securities 74 1 1 24 62 1 1 25 Commercial mortgage-backed securities 11 — — 23 17 — 1 26 Corporate debt securities 108 2 1 11 84 1 2 11 Equity securities 398 260 — — 346 214 — — Foreign government fixed income securities 4 — — 9 3 — — 9 Total $ 670 $ 265 $ 2 $ 610 $ 217 $ 4
Summary of Proceeds from Sales of Available-for-sale Securities and the Related Realized Gains and Losses	The following table summarizes proceeds from sales of available-for-sale securities and the related realized gains and losses from these sales. The cost of securities sold is determined on the specific identification method. Nine months ended September 30, 2017 2016 (In millions) Realized gains $ 8 $ 7 Realized losses 6 3 Proceeds from sale of securities 382 354

Accounting for Derivative Ins31

Accounting for Derivative Instruments and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2017
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, 2017 and December 31, 2016 . 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, 2017 December 31, 2016 Category Units (In millions) Emissions Short Ton (1 ) — Coal Short Ton 15 35 Natural Gas MMBtu (62 ) (53 ) Oil Barrel — 1 Power MWh 19 7 Capacity MW/Day (1 ) (1 ) Interest Dollars $ 3,806 $ 3,429 Equity Shares 1 1
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, 2017 December 31, 2016 September 30, 2017 December 31, 2016 (In millions) Derivatives designated as cash flow hedges: Interest rate contracts current $ — $ — $ 8 $ 28 Interest rate contracts long-term 10 12 15 41 Total derivatives designated as cash flow hedges 10 12 23 69 Derivatives not designated as cash flow hedges : Interest rate contracts current 5 — 19 7 Interest rate contracts long-term 27 37 36 12 Commodity contracts current 470 1,067 495 1,057 Commodity contracts long-term 169 132 256 231 Total derivatives not designated as cash flow hedges 671 1,236 806 1,307 Total derivatives $ 681 $ 1,248 $ 829 $ 1,376
Offsetting of Derivatives by Counterparty, Assets	The following table summarizes the offsetting of derivatives by counterparty master agreement level and collateral received or paid: Gross Amounts Not Offset in the Statement of Financial Position Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount As of September 30, 2017 (In millions) Commodity contracts: Derivative assets $ 639 $ (546 ) $ (5 ) $ 88 Derivative liabilities (751 ) 546 83 (122 ) Total commodity contracts (112 ) — 78 (34 ) Interest rate contracts: Derivative assets 42 (2 ) — 40 Derivative liabilities (78 ) 2 — (76 ) Total interest rate contracts (36 ) — — (36 ) Total derivative instruments $ (148 ) $ — $ 78 $ (70 ) Gross Amounts Not Offset in the Statement of Financial Position Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount As of December 31, 2016 (In millions) Commodity contracts: Derivative assets $ 1,199 $ (1,021 ) $ (13 ) $ 165 Derivative liabilities (1,288 ) 1,021 13 (254 ) Total commodity contracts (89 ) — — (89 ) Interest rate contracts: Derivative assets 49 (4 ) — 45 Derivative liabilities (88 ) 4 — (84 ) Total interest rate contracts (39 ) — — (39 ) Total derivative instruments $ (128 ) $ — $ — $ (128 )
Offsetting of Derivatives by Counterparty, Liabilities	The following table summarizes the offsetting of derivatives by counterparty master agreement level and collateral received or paid: Gross Amounts Not Offset in the Statement of Financial Position Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount As of September 30, 2017 (In millions) Commodity contracts: Derivative assets $ 639 $ (546 ) $ (5 ) $ 88 Derivative liabilities (751 ) 546 83 (122 ) Total commodity contracts (112 ) — 78 (34 ) Interest rate contracts: Derivative assets 42 (2 ) — 40 Derivative liabilities (78 ) 2 — (76 ) Total interest rate contracts (36 ) — — (36 ) Total derivative instruments $ (148 ) $ — $ 78 $ (70 ) Gross Amounts Not Offset in the Statement of Financial Position Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount As of December 31, 2016 (In millions) Commodity contracts: Derivative assets $ 1,199 $ (1,021 ) $ (13 ) $ 165 Derivative liabilities (1,288 ) 1,021 13 (254 ) Total commodity contracts (89 ) — — (89 ) Interest rate contracts: Derivative assets 49 (4 ) — 45 Derivative liabilities (88 ) 4 — (84 ) Total interest rate contracts (39 ) — — (39 ) Total derivative instruments $ (128 ) $ — $ — $ (128 )
Effects of ASC 815 on the Company's Accumulated OCI Balance Attributable to Cash Flow Hedge Derivatives, Net ofTax	The following table summarizes the effects of ASC 815 on the Company's accumulated OCI balance attributable to cash flow hedge derivatives, net of tax: Interest Rate Contracts Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In millions) Accumulated OCI beginning balance $ (67 ) $ (165 ) $ (66 ) $ (101 ) Reclassified from accumulated OCI to income: Due to realization of previously deferred amounts 4 2 10 12 Mark-to-market of cash flow hedge accounting contracts 4 32 (3 ) (42 ) Accumulated OCI ending balance, net of $15, and $28 tax $ (59 ) $ (131 ) $ (59 ) $ (131 ) Losses expected to be realized from OCI during the next 12 months, net of $4 tax $ 14 $ 14
Pre-tax Effects of Economic Hedges that Have Not Been Designated as Cash Flow Hedges, Ineffectiveness on Cash flow hedges and Trading Activity	The following table summarizes the 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 effect of energy commodity contracts is included within operating revenues and cost of operations and the effect of interest rate contracts is included in interest expense. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Unrealized mark-to-market results (In millions) Reversal of previously recognized unrealized (gains)/losses on settled positions related to economic hedges $ (6 ) $ (30 ) $ 19 $ (75 ) Reversal of acquired gain positions related to economic hedges (2 ) (7 ) (1 ) (11 ) Net unrealized (losses)/gains on open positions related to economic hedges (16 ) (50 ) (1 ) 27 Total unrealized mark-to-market (losses)/gains for economic hedging activities (24 ) (87 ) 17 (59 ) Reversal of previously recognized unrealized (gains)/losses on settled positions related to trading activity (5 ) 3 (24 ) 13 Net unrealized (losses)/gains on open positions related to trading activity — (8 ) 17 14 Total unrealized mark-to-market (losses)/gains for trading activity (5 ) (5 ) (7 ) 27 Total unrealized (losses)/gains $ (29 ) $ (92 ) $ 10 $ (32 ) Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In millions) Unrealized gains/(losses) included in operating revenues $ 21 $ 57 $ 178 $ (333 ) Unrealized (losses)/gains included in cost of operations (50 ) (149 ) (168 ) 301 Total impact to statement of operations — energy commodities $ (29 ) $ (92 ) $ 10 $ (32 ) Total impact to statement of operations — interest rate contracts $ 11 $ 9 $ (8 ) $ (9 )

Debt and Capital Leases (Tables

Debt and Capital Leases (Tables)	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Long-term Debt and Capital Leases	Long-term debt and capital leases consisted of the following: (In millions, except rates) September 30, 2017 December 31, 2016 September 30, 2017 interest rate % (a) Recourse debt: Senior notes, due 2018 $ 398 $ 398 7.625 Senior notes, due 2021 207 207 7.875 Senior notes, due 2022 992 992 6.250 Senior notes, due 2023 869 869 6.625 Senior notes, due 2024 733 733 6.250 Senior notes, due 2026 1,000 1,000 7.250 Senior notes, due 2027 1,250 1,250 6.625 Term loan facility, due 2023 1,876 1,891 L+2.25 Tax-exempt bonds 465 455 4.125 - 6.00 Subtotal NRG recourse debt 7,790 7,795 Non-recourse debt: NRG Yield Operating LLC Senior Notes, due 2024 500 500 5.375 NRG Yield Operating LLC Senior Notes, due 2026 350 350 5.000 NRG Yield, Inc. Convertible Senior Notes, due 2019 345 345 3.500 NRG Yield, Inc. Convertible Senior Notes, due 2020 288 288 3.250 El Segundo Energy Center, due 2023 400 443 L+1.75 - L+2.375 Marsh Landing, due 2017 and 2023 334 370 L+1.750 - L+1.875 Alta Wind I - V lease financing arrangements, due 2034 and 2035 940 965 5.696 - 7.015 Walnut Creek, term loans due 2023 279 310 L+1.625 Utah Portfolio, due 2022 284 287 L+2.625 Tapestry, due 2021 165 172 L+1.625 CVSR, due 2037 746 771 2.339 - 3.775 CVSR HoldCo, due 2037 194 199 4.680 Alpine, due 2022 138 145 L+1.750 Energy Center Minneapolis, due 2017 and 2025 82 96 5.95 - 7.25 Energy Center Minneapolis, due 2031 125 125 3.55 Viento, due 2023 169 178 L+3.00 NRG Yield - other 562 540 various Subtotal NRG Yield debt (non-recourse to NRG) 5,901 6,084 Ivanpah, due 2033 and 2038 1,097 1,113 2.285 - 4.256 Carlsbad Energy Project 407 — 4.120 Agua Caliente, due 2037 833 849 2.395 - 3.633 Agua Caliente Borrower 1, due 2038 89 — 5.430 Cedro Hill, due 2025 153 163 L+1.75 Midwest Generation, due 2019 173 231 4.390 NRG Other 689 468 various Subtotal other NRG non-recourse debt 3,441 2,824 Subtotal all non-recourse debt 9,342 8,908 Subtotal long-term debt (including current maturities) 17,132 16,703 Capital leases 6 6 various Subtotal long-term debt and capital leases (including current maturities) 17,138 16,709 Less current maturities (1,247 ) (516 ) Less debt issuance costs (198 ) (188 ) Discounts (35 ) (48 ) Total long-term debt and capital leases $ 15,658 $ 15,957 (a) As of September 30, 2017 , L+ equals 3 month LIBOR plus x%, with the exception of the Utah Portfolio term loans.

Variable Interest Entities, o33

Variable Interest Entities, or VIEs (Tables)	9 Months Ended
	Sep. 30, 2017
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, 2017 December 31, 2016 Current assets $ 74 $ 87 Net property, plant and equipment 1,466 1,534 Other long-term assets 1,026 954 Total assets 2,566 2,575 Current liabilities 69 59 Long-term debt 420 442 Other long-term liabilities 187 183 Total liabilities 676 684 Noncontrolling interests 578 529 Net assets less noncontrolling interests $ 1,312 $ 1,362

Changes in Capital Structure (T

Changes in Capital Structure (Tables)	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Changes in NRG's Common Shares Issued and Outstanding	The following table reflects the changes in NRG's common stock issued and outstanding: Issued Treasury Outstanding Balance as of December 31, 2016 417,583,825 (102,140,814 ) 315,443,011 Shares issued under LTIPs 634,738 — 634,738 Shares issued under ESPP — 560,769 560,769 Balance as of September 30, 2017 418,218,563 (101,580,045 ) 316,638,518
Schedule of Dividends Paid	The following table lists the dividends paid during the nine months ended September 30, 2017 : Third Quarter 2017 Second Quarter 2017 First Quarter 2017 Dividends per Common Share $ 0.03 $ 0.03 $ 0.03

Earnings_(Loss) Per Share (Tabl

Earnings/(Loss) Per Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Reconciliation of NRG's Basic and Diluted Earnings per Share	The reconciliation of NRG's basic and diluted earnings/(loss) per share is shown in the following table: Three months ended September 30, Nine months ended September 30, (In millions, except per share data) 2017 2016 2017 2016 Basic and diluted income/(loss) per share attributable to NRG Energy, Inc. common stockholders Net income/(loss) attributable to NRG Energy, Inc. $ 171 $ 402 $ (619 ) $ 213 Dividends for preferred shares — — — 5 Gain on redemption of 2.822% redeemable perpetual preferred stock — — — (78 ) Income/(loss) available for common stockholders $ 171 $ 402 $ (619 ) $ 286 Weighted average number of common shares outstanding - basic 317 316 317 315 Income/(loss) per weighted average common share — basic $ 0.54 $ 1.27 $ (1.95 ) $ 0.91 Diluted income/(loss) per share attributable to NRG Energy, Inc. common stockholders Weighted average number of common shares outstanding - diluted 317 316 317 315 Incremental shares attributable to the issuance of equity compensation (treasury stock method) 5 1 — 1 Total dilutive shares 322 317 317 316 Income/(loss) per weighted average common share — diluted $ 0.53 $ 1.27 $ (1.95 ) $ 0.91
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 earnings/(loss) per share: Three months ended September 30, Nine months ended September 30, (In millions of shares) 2017 2016 2017 2016 Equity compensation plans 1 2 6 3 Total 1 2 6 3

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Generation (a) Retail (a) Renewables (a) NRG Yield Corporate (a) Eliminations Total Three months ended September 30, 2017 (In millions) Operating revenues (a) $ 1,224 $ 1,937 $ 144 $ 265 $ 2 $ (523 ) $ 3,049 Depreciation and amortization 96 29 51 88 8 — 272 Impairment losses 1 — 13 — — — 14 Equity in (losses)/earnings of unconsolidated affiliates 12 — (3 ) 28 — (10 ) 27 Loss on debt extinguishment, net — — — — (1 ) — (1 ) Income/(loss) from continuing operations before income taxes 258 69 (7 ) 49 (161 ) (12 ) 196 Income/(loss) from continuing operations 258 69 (4 ) 41 (162 ) (12 ) 190 Loss from discontinued operations, net of tax — — — — (27 ) — (27 ) Net Income/(loss) 258 69 (4 ) 41 (189 ) (12 ) 163 Net Income/(loss) attributable to NRG Energy, Inc. $ 258 — $ 69 $ 9 $ 35 $ (220 ) $ 20 $ 171 Total assets as of September 30, 2017 $ 8,585 $ 2,445 $ 5,357 $ 8,442 $ 11,090 $ (10,449 ) $ 25,470 (a) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 491 $ (8 ) $ 19 $ — $ 21 $ — $ 523 Generation (a) Retail (a) Renewables (a) NRG Yield Corporate (a) Eliminations Total Three months ended September 30, 2016 (In millions) Operating revenues (a) $ 1,536 $ 2,012 $ 139 $ 272 $ 24 $ (562 ) $ 3,421 Depreciation and amortization 134 26 48 75 15 — 298 Impairment losses 9 — — — — — 9 Equity in earnings/(losses) of unconsolidated affiliates 6 — (10 ) 16 5 (1 ) 16 Gain on sale of assets — — — 4 — 4 Loss on debt extinguishment, net — — — — (50 ) — (50 ) Income/(loss) from continuing operations before income taxes 370 (78 ) (1 ) 63 (202 ) 4 156 Income/(loss) from continuing operations 372 (78 ) 2 50 (222 ) 4 128 Income from discontinued operations, net of tax — — — — 265 — 265 Net Income/(Loss) 372 (78 ) 2 50 43 4 393 Net Income/(Loss) attributable to NRG Energy, Inc. $ 372 $ (78 ) $ (9 ) $ 55 $ 19 $ 43 $ 402 (a) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 506 $ (2 ) $ 8 $ — $ 50 $ 52 $ — $ 562 Generation (a) Retail (a) Renewables (a) NRG Yield Corporate (a) Eliminations Total Nine months ended September 30, 2017 (In millions) Operating revenues (a) $ 3,072 $ 4,875 $ 364 $ 767 $ 13 $ (959 ) $ 8,132 Depreciation and amortization 287 87 150 241 24 — 789 Impairment losses 42 — 35 — — — 77 Equity in (losses)/earnings of unconsolidated affiliates (16 ) — (6 ) 63 7 (19 ) 29 Gain on sale of assets 4 — — — — — 4 Loss on debt extinguishment, net — — (3 ) — — — (3 ) Income/(loss) from continuing operations before income taxes 202 371 (97 ) 100 (430 ) (21 ) 125 Income/(loss) from continuing operations 200 380 (84 ) 85 (440 ) (21 ) 120 Loss from discontinued operations, net of tax — — — — (802 ) — (802 ) Net Income/(Loss) 200 380 (84 ) 85 (1,242 ) (21 ) (682 ) Net Income/(Loss) attributable to NRG Energy, Inc. $ 200 $ 380 $ (18 ) $ 87 $ (1,306 ) $ 38 $ (619 ) (a) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 897 $ 3 $ 23 $ — $ 36 $ — $ 959 Generation (a) Retail (a) Renewables (a) NRG Yield (a) Corporate (a) Eliminations Total Nine months ended September 30, 2016 (In millions) Operating revenues (a) $ 3,173 $ 4,918 $ 336 $ 789 $ 54 $ (942 ) $ 8,328 Depreciation and amortization 331 83 143 224 45 — 826 Impairment losses 26 — 27 — 12 — 65 Equity in earnings/(losses) of unconsolidated affiliates 1 — (16 ) 34 11 (17 ) 13 Loss on sale of assets — — — — (79 ) — (79 ) Impairment loss on investment (142 ) — 1 — (6 ) — (147 ) Loss on debt extinguishment, net — — — — (119 ) — (119 ) (Loss)/income from continuing operations before income taxes (51 ) 735 (121 ) 141 (706 ) (15 ) (17 ) (Loss)/income from continuing operations (49 ) 734 (107 ) 116 (771 ) (15 ) (92 ) Income from discontinued operations, net of tax — — — — 256 — 256 Net (Loss)/Income (49 ) 734 (107 ) 116 (515 ) (15 ) 164 Net (Loss)/Income attributable to NRG Energy, Inc. $ (49 ) $ 734 $ (103 ) $ 113 $ (547 ) $ 65 $ 213 (a) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 836 $ 3 $ 16 $ 6 $ 81 $ — $ 942

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2017
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 otherwise noted) 2017 2016 2017 2016 Income/(Loss) before income taxes $ 196 $ 156 $ 125 $ (17 ) Income tax expense from continuing operations 6 28 5 75 Effective tax rate 3.1 % 17.9 % 4.0 % (441.2 )%

Condensed Consolidating Finan38

Condensed Consolidating Financial Information (Tables)	9 Months Ended
	Sep. 30, 2017
Condensed Consolidating Financial Information Disclosure [Abstract]
Condensed Consolidating Statements of Operations	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the three months ended September 30, 2017 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 2,160 $ 1,021 $ — $ (132 ) $ 3,049 Operating Costs and Expenses Cost of operations 1,588 682 15 (129 ) 2,156 Depreciation and amortization 104 160 8 — 272 Impairment losses — 14 — — 14 Selling, general and administrative 97 29 88 (1 ) 213 Reorganization — — 18 — 18 Development activity expenses — 9 5 14 Total operating costs and expenses 1,789 894 134 (130 ) 2,687 Other income - affiliate — — 14 — 14 Operating Income/(Loss) 371 127 (120 ) (2 ) 376 Other Income/(Expense) Equity in losses of consolidated subsidiaries (41 ) (9 ) (134 ) 184 — Equity in (losses)/earnings of unconsolidated affiliates — (606 ) 666 (33 ) 27 Other income 7 3 5 — 15 Loss on debt extinguishment — (1 ) — — (1 ) Interest expense (4 ) (103 ) (114 ) — (221 ) Total other (expense)/income (38 ) (716 ) 423 151 (180 ) Income/(Loss) from Continuing Operations Before Income Taxes 333 (589 ) 303 149 196 Income tax expense/(benefit) 113 (209 ) 102 — 6 Income/(Loss) from Continuing Operations 220 (380 ) 201 149 190 Loss from Discontinued Operations, net of income tax — (27 ) — — (27 ) Net Income/(Loss) 220 (407 ) 201 149 163 Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests — (3 ) 30 (35 ) (8 ) Net Income/(Loss) Attributable to NRG Energy, Inc. $ 220 $ (404 ) $ 171 $ 184 $ 171 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the nine months ended September 30, 2017 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 5,517 $ 2,872 $ — $ (257 ) $ 8,132 Operating Costs and Expenses Cost of operations 4,156 1,904 46 (254 ) 5,852 Depreciation and amortization 307 458 24 — 789 Impairment losses 42 35 — — 77 Selling, general and administrative 281 115 304 (3 ) 697 Reorganization — — 18 — 18 Development activity expenses — 34 15 — 49 Total operating costs and expenses 4,786 2,546 407 (257 ) 7,482 Other income - affiliate — — 104 — 104 Gain on sale of assets 4 — — — 4 Operating Income/(Loss) 735 326 (303 ) — 758 Other Income/(Expense) Equity in losses of consolidated subsidiaries (61 ) (66 ) (182 ) 309 — Equity in earnings/(losses) of unconsolidated affiliates — 101 (3 ) (69 ) 29 Other income 8 15 10 — 33 Loss on debt extinguishment — (3 ) — — (3 ) Interest expense (11 ) (328 ) (353 ) — (692 ) Total other expense (64 ) (281 ) (528 ) 240 (633 ) Income/(Loss) from Continuing Operations Before Income Taxes 671 45 (831 ) 240 125 Income tax expense/(benefit) 244 28 (267 ) — 5 Income/(Loss) from Continuing Operations 427 17 (564 ) 240 120 Loss from Discontinued Operations, net of income tax — (802 ) — — (802 ) Net Income/(Loss) 427 (785 ) (564 ) 240 (682 ) Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests — (49 ) 55 (69 ) (63 ) Net Income/(Loss) Attributable to $ 427 $ (736 ) $ (619 ) $ 309 $ (619 ) (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the three months ended September 30, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 2,424 $ 1,090 $ — $ (93 ) $ 3,421 Operating Costs and Expenses Cost of operations 1,719 804 10 (93 ) 2,440 Depreciation and amortization 147 144 7 — 298 Impairment losses 8 1 — — 9 Selling, general and administrative 115 50 112 — 277 Development activity expenses — 10 11 — 21 Total operating costs and expenses 1,989 1,009 140 (93 ) 3,045 Other income - affiliate — — 48 — 48 Gain on sale of assets — — 4 — 4 Operating Income/(Loss) 435 81 (88 ) — 428 Other Income/(Expense) Equity in (losses)/earnings of consolidated subsidiaries (114 ) (10 ) 562 (438 ) — Equity in earnings/(losses) of unconsolidated affiliates 2 75 (12 ) (49 ) 16 Loss on investment — (8 ) — — (8 ) Other income/(loss), net 1 6 — — 7 Loss on debt extinguishment — — (50 ) — (50 ) Interest expense (4 ) (104 ) (129 ) — (237 ) Total other expense (115 ) (41 ) 371 (487 ) (272 ) Income from Continuing Operations Before Income Taxes 320 40 283 (487 ) 156 Income tax expense/(benefit) 134 45 (151 ) — 28 Income from Continuing Operations 186 (5 ) 434 (487 ) 128 Income from Discontinued Operations, net of income tax — 263 2 — 265 Net Income 186 258 436 (487 ) 393 Less: Net income/(loss) attributable to noncontrolling interest and redeemable noncontrolling interest — 6 34 (49 ) (9 ) Net Income Attributable to NRG Energy, Inc. $ 186 $ 252 $ 402 $ (438 ) $ 402 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the nine months ended September 30, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 6,079 $ 2,400 $ — $ (151 ) $ 8,328 Operating Costs and Expenses Cost of operations 4,278 1,558 29 (154 ) 5,711 Depreciation and amortization 372 435 19 — 826 Impairment losses 8 57 — — 65 Selling, general and administrative 306 144 351 — 801 Development activity expenses — 42 23 — 65 Total operating costs and expenses 4,964 2,236 422 (154 ) 7,468 Other income - affiliate — — 144 — 144 Loss on sale of assets — — (79 ) — (79 ) Operating Income/(Loss) 1,115 164 (357 ) 3 925 Other Income/(Expense) Equity in (losses)/earnings of consolidated subsidiaries (195 ) (80 ) 904 (629 ) — Equity in earnings/(losses) of unconsolidated affiliates 5 114 (2 ) (104 ) 13 Impairment loss on investment — (147 ) — — (147 ) Other income, net 3 25 2 (1 ) 29 Loss on debt extinguishment — (4 ) (115 ) — (119 ) Interest expense (11 ) (312 ) (395 ) (718 ) Total other (expense)/income (198 ) (404 ) 394 (734 ) (942 ) Income/(Loss) Before Income Taxes 917 (240 ) 37 (731 ) (17 ) Income tax expense/(benefit) 362 (49 ) (238 ) — 75 Income/(Loss) from Continuing Operations 555 (191 ) 275 (731 ) (92 ) Income from Discontinued Operations, net of income tax — 248 8 — 256 Net Income 555 57 283 (731 ) 164 Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (17 ) 70 (102 ) (49 ) Net Income Attributable to NRG Energy, Inc. $ 555 $ 74 $ 213 $ (629 ) $ 213 (a) All significant intercompany transactions have been eliminated in consolidation.
Condensed Consolidating Statements of Comprehensive Income/(Loss)	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) For the three months ended September 30, 2017 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Net Income/(Loss) $ 220 $ (407 ) $ 201 $ 149 $ 163 Other Comprehensive Income/(Loss), net of tax Unrealized gain on derivatives, net — 7 7 (7 ) 7 Foreign currency translation adjustments, net 2 2 2 (4 ) 2 Available-for-sale securities, net — — 1 — 1 Defined benefit plans, net — — (2 ) 1 (1 ) Other comprehensive income 2 9 8 (10 ) 9 Comprehensive Income/(Loss) 222 (398 ) 209 139 172 Less: Comprehensive income/(loss) attributable to noncontrolling interest and redeemable noncontrolling interest — — 30 (35 ) (5 ) Comprehensive Income/(Loss) Attributable to NRG Energy, Inc. $ 222 $ (398 ) $ 179 $ 174 $ 177 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) For the nine months ended September 30, 2017 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Net Income/(Loss) $ 427 $ (785 ) $ (564 ) $ 240 $ (682 ) Other Comprehensive Income/(Loss), net of tax Unrealized gain on derivatives, net — 6 7 (7 ) 6 Foreign currency translation adjustments, net 7 7 9 (13 ) 10 Available-for-sale securities, net — — 2 — 2 Defined benefit plans, net — 29 25 (28 ) 26 Other comprehensive income 7 42 43 (48 ) 44 Comprehensive Income/(Loss) 434 (743 ) (521 ) 192 (638 ) Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (47 ) 55 (69 ) (61 ) Comprehensive Income/(Loss) Attributable to NRG Energy, Inc. $ 434 $ (696 ) $ (576 ) $ 261 $ (577 ) (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) For the three months ended September 30, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Net Income $ 186 $ 258 $ 436 $ (487 ) $ 393 Other Comprehensive Income/(Loss), net of tax Unrealized income on derivatives, net — 40 26 (39 ) 27 Foreign currency translation adjustments, net 2 2 4 (5 ) 3 Defined benefit plans, net 54 — (43 ) 20 31 Other comprehensive loss 56 42 (13 ) (24 ) 61 Comprehensive Income 242 300 423 (511 ) 454 Less: Comprehensive income/(loss) attributable to noncontrolling interest and redeemable noncontrolling interest — 13 34 (49 ) (2 ) Comprehensive Income Attributable to NRG Energy, Inc. $ 242 $ 287 $ 389 $ (462 ) $ 456 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) For the nine months ended September 30, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Net Income $ 555 $ 57 $ 283 $ (731 ) $ 164 Other Comprehensive Income/(Loss), net of tax Unrealized (loss)/gain on derivatives, net — (15 ) 46 (39 ) (8 ) Foreign currency translation adjustments, net 4 4 6 (8 ) 6 Available-for-sale securities, net — — 1 — 1 Defined benefit plans, net 55 — (43 ) 20 32 Other comprehensive income/(loss) 59 (11 ) 10 (27 ) 31 Comprehensive Income 614 46 293 (758 ) 195 Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (38 ) 70 (102 ) (70 ) Comprehensive Income Attributable to NRG Energy, Inc. 614 84 223 (656 ) 265 Dividends for preferred shares — — 5 — 5 Gain on redemption of preferred shares — — (78 ) — (78 ) Comprehensive Income Available for Common Stockholders $ 614 $ 84 $ 296 $ (656 ) $ 338 (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, 2017 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated ASSETS (In millions) Current Assets Cash and cash equivalents $ (20 ) $ 350 $ 893 $ — $ 1,223 Funds deposited by counterparties 29 2 — — 31 Restricted cash 14 523 — — 537 Accounts receivable - trade, net 876 395 3 — 1,274 Accounts receivable - affiliate 222 191 (22 ) (337 ) 54 Inventory 406 224 — — 630 Derivative instruments 438 106 5 (74 ) 475 Cash collateral posted in support of energy risk management activities 190 13 — — 203 Prepayments and other current assets 108 147 45 — 300 Current assets - held for sale — 33 — — 33 Total current assets 2,263 1,984 924 (411 ) 4,760 Net property, plant and equipment 3,980 11,142 236 (26 ) 15,332 Other Assets Investment in subsidiaries 1,098 1,004 9,409 (11,511 ) — Equity investments in affiliates — 1,135 3 — 1,138 Notes receivable, less current portion — 5 — — 5 Goodwill 359 303 — — 662 Intangible assets, net 520 1,321 — (3 ) 1,838 Nuclear decommissioning trust fund 670 — — — 670 Derivative instruments 187 38 27 (46 ) 206 Deferred income tax (5 ) (148 ) 358 — 205 Non-current assets held-for-sale — 10 — — 10 Other non-current assets 63 520 61 — 644 Total other assets 2,892 4,188 9,858 (11,560 ) 5,378 Total Assets $ 9,135 $ 17,314 $ 11,018 $ (11,997 ) $ 25,470 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Current portion of long-term debt and capital leases $ — $ 623 $ 624 $ — $ 1,247 Accounts payable 599 285 31 — 915 Accounts payable — affiliate 528 (340 ) 146 (338 ) (4 ) Derivative instruments 418 178 — (74 ) 522 Cash collateral received in support of energy risk management activities 29 2 — — 31 Accrued expenses and other current liabilities 301 57 472 — 830 Accrued expenses and other current liabilities-affiliate — 164 — — 164 Total current liabilities 1,875 969 1,273 (412 ) 3,705 Other Liabilities Long-term debt and capital leases 244 8,644 6,770 — 15,658 Nuclear decommissioning reserve 265 — — — 265 Nuclear decommissioning trust liability 397 — — — 397 Deferred income taxes 428 — (407 ) — 21 Derivative instruments 194 159 — (46 ) 307 Out-of-market contracts, net 69 144 — — 213 Non-current liabilities held-for-sale — 13 — — 13 Other non-current liabilities 377 315 424 — 1,116 Total non-current liabilities 1,974 9,275 6,787 (46 ) 17,990 Total liabilities 3,849 10,244 8,060 (458 ) 21,695 Redeemable noncontrolling interest in subsidiaries — 85 — — 85 Stockholders’ Equity 5,286 6,985 2,958 (11,539 ) 3,690 Total Liabilities and Stockholders’ Equity $ 9,135 $ 17,314 $ 11,018 $ (11,997 ) $ 25,470 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2016 Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated ASSETS (In millions) Current Assets Cash and cash equivalents $ (9 ) $ 624 $ 323 $ — $ 938 Funds deposited by counterparties 2 — — — 2 Restricted cash 11 435 — — 446 Accounts receivable - trade, net 734 321 3 — 1,058 Accounts receivable - affiliate 307 (254 ) 200 (139 ) 114 Inventory 482 239 — — 721 Derivative instruments 962 196 1 (92 ) 1,067 Cash collateral posted in support of energy risk management activities 116 34 — — 150 Current assets held-for-sale — 9 — — 9 Prepayments and other current assets 76 152 62 — 290 Current assets - discontinued operations — 1,919 — — 1,919 Total current assets 2,681 3,675 589 (231 ) 6,714 Net Property, Plant and Equipment 4,219 10,926 251 (27 ) 15,369 Other Assets Investment in subsidiaries 1,090 1,054 10,128 (12,272 ) — Equity investments in affiliates (13 ) 1,128 5 — 1,120 Notes receivable, less current portion — 16 — — 16 Goodwill 359 303 — — 662 Intangible assets, net 592 1,384 — (3 ) 1,973 Nuclear decommissioning trust fund 610 — — — 610 Derivative instruments 144 44 36 (43 ) 181 Deferred income taxes 3 — 222 — 225 Non-current assets held for sale — 10 — — 10 Other non-current assets 67 446 328 — 841 Non-current assets - discontinued operations — 2,961 — — 2,961 Total other assets 2,852 7,346 10,719 (12,318 ) 8,599 Total Assets $ 9,752 $ 21,947 $ 11,559 $ (12,576 ) $ 30,682 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Current portion of long-term debt and capital leases $ — $ 498 $ 18 $ — $ 516 Accounts payable 501 247 34 — 782 Accounts payable — affiliate 744 (452 ) (122 ) (139 ) 31 Derivative instruments 947 237 — (92 ) 1,092 Cash collateral received in support of energy risk management activities 81 — — — 81 Accrued expenses and other current liabilities 316 209 465 — 990 Current liabilities - discontinued operations — 1,210 — — 1,210 Total current liabilities 2,589 1,949 395 (231 ) 4,702 Other Liabilities Long-term debt and capital leases 244 8,252 7,461 — 15,957 Nuclear decommissioning reserve 287 — — — 287 Nuclear decommissioning trust liability 339 — — — 339 Deferred income taxes 186 125 (291 ) — 20 Derivative instruments 157 170 — (43 ) 284 Out-of-market contracts, net 80 150 — — 230 Non-current liabilities held-for-sale — 11 — — 11 Other non-current liabilities 396 456 324 — 1,176 Non-current liabilities - discontinued operations — 3,184 — — 3,184 Total non-current liabilities 1,689 12,348 7,494 (43 ) 21,488 Total Liabilities 4,278 14,297 7,889 (274 ) 26,190 Redeemable noncontrolling interest in subsidiaries — 46 — — 46 Stockholders’ Equity 5,474 7,604 3,670 (12,302 ) 4,446 Total Liabilities and Stockholders’ Equity $ 9,752 $ 21,947 $ 11,559 $ (12,576 ) $ 30,682 (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, 2017 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net income/(loss) $ 427 $ (785 ) $ (564 ) $ 240 $ (682 ) Loss from discontinued operations — (802 ) — — (802 ) Net income/(loss) from continuing operations 427 17 (564 ) 240 120 Adjustments to reconcile net income/(loss) to net cash provided by operating activities: Distributions from unconsolidated affiliates — 60 — (7 ) 53 Equity in losses/(earnings) of unconsolidated affiliates — (101 ) 3 69 (29 ) Depreciation and amortization 307 458 24 — 789 Provision for bad debts 40 2 15 — 57 Amortization of nuclear fuel 37 — — — 37 Amortization of financing costs and debt discount/premiums — 31 13 — 44 Adjustment for debt extinguishment — 3 — — 3 Amortization of intangibles and out-of-market contracts 20 59 — — 79 Amortization of unearned equity compensation — — 27 — 27 Impairment losses 42 35 — — 77 Changes in deferred income taxes and liability for uncertain tax benefits 244 28 (246 ) — 26 Changes in nuclear decommissioning trust liability 20 — — — 20 Changes in derivative instruments (11 ) 32 12 (8 ) 25 Changes in collateral deposits supporting energy risk management activities (126 ) 23 — — (103 ) Proceeds from sale of emission allowances 21 — — — 21 Gain on sale of assets (22 ) — — — (22 ) Cash (used)/provided by changes in other working capital (958 ) (523 ) 1,395 (294 ) (380 ) Cash provided by continuing operations 41 124 679 — 844 Cash used by discontinued operations — (38 ) — — (38 ) Net Cash Provided by Operating Activities 41 86 679 — 806 Cash Flows from Investing Activities Dividends from NRG Yield, Inc. — — 69 (69 ) — Acquisition of Drop Down Assets, net of cash acquired — (176 ) — 176 — Intercompany dividends — — 129 (129 ) — Acquisition of business, net of cash acquired — (36 ) — — (36 ) Capital expenditures (135 ) (606 ) (19 ) — (760 ) Decrease in notes receivable — 11 — — 11 Purchases of emission allowances (47 ) — — — (47 ) Proceeds from sale of emission allowances 105 — — — 105 Investments in nuclear decommissioning trust fund securities (402 ) — — — (402 ) Proceeds from sales of nuclear decommissioning trust fund securities 382 — — — 382 Proceeds from renewable energy grants and state rebates 8 — — — 8 Proceeds from sale of assets, net of cash disposed of 36 — — — 36 Investments in unconsolidated affiliates — (31 ) — — (31 ) Other 22 — — — 22 Cash (used)/provided by continuing operations (31 ) (838 ) 179 (22 ) (712 ) Cash used by discontinued operations — (53 ) — — (53 ) Net Cash (Used)/Provided by Investing Activities (31 ) (891 ) 179 (22 ) (765 ) Cash Flows from Financing Activities Dividends from NRG Yield, Inc. — (69 ) — 69 — Payments from/(for) intercompany loans 9 417 (426 ) — — Acquisition of Drop Down Assets, net of cash acquired — — 176 (176 ) — Intercompany dividends — (129 ) — 129 — Payment of dividends to common and preferred stockholders — — (28 ) — (28 ) Net receipts from settlement of acquired derivatives that include financing elements — 2 — — 2 Proceeds from issuance of long-term debt — 920 214 — 1,134 Payments for short and long-term debt — (493 ) (219 ) — (712 ) Receivable from affiliate — (125 ) — — (125 ) Contributions from, net of distributions to, noncontrolling interest in subsidiaries — 65 — — 65 Payment of debt issuance costs — (38 ) (5 ) — (43 ) Other - contingent consideration — (10 ) — — (10 ) Cash provided/(used) by continuing operations 9 540 (288 ) 22 283 Cash used by discontinued operations — (224 ) — — (224 ) Net Cash Provided/(Used) by Financing Activities 9 316 (288 ) 22 59 Change in cash from discontinued operations — (315 ) — — (315 ) Effect of exchange rate changes on cash and cash equivalents — (10 ) — — (10 ) Net Increase/(Decrease) in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties 19 (184 ) 570 — 405 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at Beginning of Period 4 1,059 323 — 1,386 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at End of Period $ 23 $ 875 $ 893 $ — $ 1,791 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the nine months ended September 30, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net Income $ 555 $ 57 $ 283 $ (731 ) $ 164 Less: Income from discontinued operations — 248 8 — 256 Net income/(loss) from continuing operations 555 (191 ) 275 (731 ) (92 ) Adjustments to reconcile net income/(loss) to net cash provided by operating activities: Distributions from unconsolidated affiliates — 65 — (8 ) 57 Equity in (earnings)/losses of unconsolidated affiliates (5 ) (20 ) 2 10 (13 ) Depreciation and amortization 372 435 19 — 826 Provision for bad debts 31 5 — — 36 Amortization of nuclear fuel 39 — — — 39 Amortization of financing costs and debt discount/premiums — 25 17 — 42 Adjustment for debt extinguishment — 102 17 — 119 Amortization of intangibles and out-of-market contracts 32 99 — — 131 Amortization of unearned equity compensation — — 23 — 23 Impairment losses 8 203 — — 211 Changes in deferred income taxes and liability for uncertain tax benefits (134 ) (90 ) 253 — 29 Changes in nuclear decommissioning trust liability 24 — — — 24 Changes in derivative instruments (173 ) 206 (3 ) — 30 Changes in collateral posted supporting energy risk management activities 268 (7 ) — — 261 Proceeds from sale of emission allowances 11 — — — 11 Loss on sale of assets — — 70 — 70 Cash (used)/provided by changes in other working capital (827 ) 168 (200 ) 729 (130 ) Net cash provided by continuing operations 201 1,000 473 — 1,674 Cash provided by discontinued operations — 67 — — 67 Net Cash Provided by Operating Activities 201 1,067 473 — 1,741 Cash Flows from Investing Activities Dividends from NRG Yield, Inc. — — 59 (59 ) — Acquisition of September 2016 Drop Down assets, net of cash acquired — (77 ) — 77 — Intercompany dividends — — 12 (12 ) — Acquisition of businesses, net of cash acquired — (18 ) — — (18 ) Capital expenditures (145 ) (474 ) (40 ) — (659 ) Increase in notes receivable — 2 — — 2 Purchases of emission allowances (32 ) — — — (32 ) Proceeds from sale of emission allowances 47 — — — 47 Investments in nuclear decommissioning trust fund securities (378 ) — — — (378 ) Proceeds from sales of nuclear decommissioning trust fund securities 354 — — — 354 Proceeds from renewable energy grants and state rebates — 11 — — 11 Proceeds from sale of assets, net of cash disposed of — 67 17 — 84 Investments in unconsolidated affiliates 2 (25 ) — — (23 ) Other 27 (4 ) 8 — 31 Net cash (used)/provided by continuing operations (125 ) (518 ) 56 6 (581 ) Cash provided by discontinued operations — 326 — — 326 Net Cash (Used)/Provided by Investing Activities (125 ) (192 ) 56 6 (255 ) Cash Flows from Financing Activities Dividends from NRG Yield, Inc. — (59 ) — 59 — Payments (for)/from intercompany loans (2 ) (134 ) 136 — — Acquisition of September 2016 Drop Down assets, net of cash acquired — — 77 (77 ) — Intercompany dividends (52 ) 40 — 12 — Payment of dividends to common and preferred stockholders — — (66 ) — (66 ) Payment for preferred shares — — (226 ) — (226 ) Net receipts for settlement of acquired derivatives that include financing elements — 6 — — 6 Proceeds from issuance of long-term debt — 1,097 4,140 — 5,237 Payments for short and long-term debt (2 ) (811 ) (4,540 ) — (5,353 ) Payments for debt extinguishment costs — (98 ) — — (98 ) Distributions from, net of contributions to, noncontrolling interest in subsidiaries — (127 ) — — (127 ) Proceeds from issuance of common stock — — 1 — 1 Payment of debt issuance costs — (17 ) (53 ) — (70 ) Other (3 ) (7 ) — — (10 ) Net cash used by continuing operations (59 ) (110 ) (531 ) (6 ) (706 ) Cash provided by discontinued operations — 119 — — 119 Net Cash (Used)/Provided by Financing Activities (59 ) 9 (531 ) (6 ) (587 ) Change in cash from discontinued operations — 512 — — 512 Effect of exchange rate changes on cash and cash equivalents — (6 ) — — (6 ) Net Increase/(Decrease) in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties 17 366 (2 ) — 381 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at Beginning of Period — 629 693 — 1,322 Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties at End of Period $ 17 $ 995 $ 691 $ — $ 1,703 (a) All significant intercompany transactions have been eliminated in consolidation.

Basis of Presentation - Basis o

Basis of Presentation - Basis of Presentation (Details) MW in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2017USD ($)MW	Jun. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)MW	Sep. 30, 2016USD ($)	Jun. 14, 2017USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generation capacity (in MW) | MW	30,000			30,000
GenOn | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost method investments, fair value						$ 0
Loss on disposal of discontinued operation	$ 27,000,000	$ 208,000,000	$ 0	$ 647,000,000	$ 0

Basis of Presentation - Transfo

Basis of Presentation - Transformation Plan (Details) $ in Millions	Jul. 12, 2017USD ($)MW	Dec. 31, 2020USD ($)	Sep. 30, 2017MW
Restructuring Cost and Reserve [Line Items]
Generation capacity (in MW) | MW			30,000,000
Transformation Plan
Restructuring Cost and Reserve [Line Items]
Term of plan	3 years
Transformation Plan | Operations and cost excellence
Restructuring Cost and Reserve [Line Items]
Cost savings	$ 1,065
Transformation Plan | Operations and cost excellence | Annual cost savings
Restructuring Cost and Reserve [Line Items]
Cost savings	590
Transformation Plan | Operations and cost excellence | Net margin enhancement program
Restructuring Cost and Reserve [Line Items]
Cost savings	215
Transformation Plan | Operations and cost excellence | Annual reduction in maintenance capital expenditures
Restructuring Cost and Reserve [Line Items]
Cost savings	50
Transformation Plan | Operations and cost excellence | Permanent selling general and administrative reduction associated with asset sales
Restructuring Cost and Reserve [Line Items]
Cost savings	$ 210
Transformation Plan | Portfolio optimization
Restructuring Cost and Reserve [Line Items]
Generation capacity (in MW) | MW	6,000
Transformation Plan | Portfolio optimization | NRG Yield, Inc.
Restructuring Cost and Reserve [Line Items]
Ownership interest	100.00%
Transformation Plan | Portfolio optimization | Maximum
Restructuring Cost and Reserve [Line Items]
Effect on cash flows	$ 4,000
Transformation Plan | Capital structure and allocation enhancements
Restructuring Cost and Reserve [Line Items]
Reduction in consolidated debt, original amount	19,500
Reduction in consolidated debt	18,000
Consolidated debt original amount reduction	6,500
Consolidated debt, net amount reduction	$ 6,000
Corporate net debt (corporate debt less cash and cash equivalents) to EBITDA ratio	3
Transformation Plan | Capital structure and allocation enhancements | Minimum
Restructuring Cost and Reserve [Line Items]
Effect on cash flows	$ 4,800
Transformation Plan | Capital structure and allocation enhancements | Maximum
Restructuring Cost and Reserve [Line Items]
Effect on cash flows	$ 6,300
Scenario, Forecast | Transformation Plan
Restructuring Cost and Reserve [Line Items]
Non-recurring working capital improvements		$ 370
Costs expected to be spent		$ 290

Summary of Significant Accoun41

Summary of Significant Accounting Policies - Other Balance Sheet Information (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Accounts receivable allowance for doubtful accounts	$ 61	$ 29
Property, plant and equipment accumulated depreciation	6,437	5,711
Intangible assets accumulated amortization	1,750	1,687
Out-of-market contracts accumulated amortization	$ 352	$ 457

Summary of Significant Accoun42

Summary of Significant Accounting Policies - Restricted Cash (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Cash and cash equivalents	$ 1,223	$ 938	$ 1,217	$ 853
Funds deposited by counterparties	31	2	6	55
Restricted cash	537	446	480	414
Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows	$ 1,791	1,386	$ 1,703	$ 1,322
Collateral received from GenOn		$ 79

Summary of Significant Accoun43

Summary of Significant Accounting Policies - Noncontrolling Interest (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Noncontrolling Interest [Roll Forward]
Balance as of beginning of period			$ 2,405
Contributions from noncontrolling interest			116
Sale of assets to NRG Yield, Inc.			24
Comprehensive loss attributable to noncontrolling interest	$ (5)	$ (2)	(61)	$ (70)
Dividends paid to NRG Yield, Inc. public shareholders			(80)
Distributions to noncontrolling interest			(48)
Balance as of end of period	$ 2,507		2,507
Noncontrolling Interest
Noncontrolling Interest [Roll Forward]
Non-cash adjustments to noncontrolling interest			98
Comprehensive loss attributable to noncontrolling interest			$ (8)

Summary of Significant Accoun44

Summary of Significant Accounting Policies - Redeemable Noncontrolling Interest (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Redeemable Noncontrolling Interest [Roll Forward]
Balance as of beginning of period			$ 46
Contributions from redeemable noncontrolling interest			73
Comprehensive loss attributable to noncontrolling interest	$ (5)	$ (2)	(61)	$ (70)
Distributions to redeemable noncontrolling interest			(48)
Balance as of end of period	$ 85		85
Redeemable noncontrolling interest
Redeemable Noncontrolling Interest [Roll Forward]
Non-cash adjustments to noncontrolling interest			21
Comprehensive loss attributable to noncontrolling interest			(53)
Distributions to redeemable noncontrolling interest			$ (2)

Summary of Significant Accoun45

Summary of Significant Accounting Policies - Guidance Adopted in 2017 (Details) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
New Accounting Pronouncement, Early Adoption [Line Items]
Decrease (increase) in cash flow from operations	$ 806	$ 1,741
Increase in cash flow from investing	(765)	(255)
Decrease in cash flow from financing activities	$ (59)	587
ASU 2016-18
New Accounting Pronouncement, Early Adoption [Line Items]
Decrease (increase) in cash flow from operations		(49)
Increase in cash flow from investing		66
ASU 2016-16 | Noncurrent Assets
New Accounting Pronouncement, Early Adoption [Line Items]
Adjustments for change in accounting pronouncement			$ 267
Retained Earnings | ASU 2016-16
New Accounting Pronouncement, Early Adoption [Line Items]
Adjustments for change in accounting pronouncement			$ (267)
New Accounting Pronouncement, Early Adoption, Effect | ASU 2016-15
New Accounting Pronouncement, Early Adoption [Line Items]
Decrease (increase) in cash flow from operations		98
Decrease in cash flow from financing activities		$ 98

Discontinued Operations, Disp46

Discontinued Operations, Dispositions and Acquisitions - Discontinued Operations (Details)	Jun. 14, 2017USD ($)extension	Jun. 12, 2017USD ($)extension	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Long-term debt			$ 17,132,000,000		$ 17,132,000,000		$ 16,703,000,000
GenOn Senior Notes Due in 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Interest rate, stated percentage			7.875%		7.875%
Senior Notes Due In 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Interest rate, stated percentage			9.50%		9.50%
GenOn Senior Notes Due in 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Interest rate, stated percentage			9.875%		9.875%
GenOn Americas Generation Senior Notes Due in 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Interest rate, stated percentage			8.50%		8.50%
GenOn Americas Generation Senior Notes Due in 2031
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Interest rate, stated percentage			9.125%		9.125%
GenOn
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Pension liability			$ 106,000,000		$ 106,000,000
Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of aggregate principal amount		93.00%
Intercompany secured revolving credit facility			125,000,000		125,000,000
Payment of pension contributions			13,000,000		13,000,000
Restructuring Support Agreement | GenOn
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Settlement consideration		$ 261,300,000
Estimated accumulated pension benefit obligation			106,000,000		106,000,000
Settlement Consideration | Restructuring Support Agreement | GenOn
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accrued liabilities - affiliate			261,300,000		261,300,000
Services Agreement | GenOn
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Shared services, annualized rate		84,000,000
Credit applied		28,000,000
Services Agreement | Restructuring Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Shared services, annualized rate		$ 84,000,000
Shared services, waived period	2 months	2 months
Shared services, number of extensions | extension	2	2
Shared services, extension period	1 month	1 month
Credit applied		$ 28,000,000
Monthly shared services	$ 5,000,000
Services Agreement | Restructuring Support Agreement | GenOn
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accrued liabilities - affiliate			28,000,000		28,000,000
Discontinued Operations | GenOn
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Pension Liability Assumption			25,000,000	$ 0	144,000,000	$ 0
Long-term debt			2,500,000,000		2,500,000,000
GenOn
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost method investment			$ 0		$ 0

Discontinued Operations, Disp47

Discontinued Operations, Dispositions and Acquisitions - Summary of Results (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of assets				$ 22	$ (70)
(Loss)/Income from discontinued operations, net of tax	$ (27)		$ 265	(802)	256
Discontinued Operations | GenOn
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues	0		532	646	1,509
Operating costs and expenses	0		(468)	(700)	(1,409)
Gain on sale of assets	0		262	0	294
Other expenses	0		(43)	(98)	(127)
(Loss)/Income from operations of discontinued components, before tax	0		283	(152)	267
Income tax expense	0		21	9	20
(Loss)/Incomes from operations of discontinued components	0		262	(161)	247
Interest income - affiliate	0		3	6	9
(Loss)/Income from operations of discontinued components, net of tax	0		265	(155)	256
Pre-tax loss on deconsolidation	0		0	(208)	0
Settlement consideration and services credit	0		0	(289)	0
Pension and post-retirement liability assumption	(25)		0	(144)	0
Other	(2)		0	(6)	0
Loss on disposal of discontinued components, net of tax	(27)	$ (208)	0	(647)	0
(Loss)/Income from discontinued operations, net of tax	$ (27)		$ 265	$ (802)	$ 256

Discontinued Operations, Disp48

Discontinued Operations, Dispositions and Acquisitions - Major Classes of Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other current assets	$ 0	$ 1,919
Current assets - discontinued operations	33	9
Other non-current assets	10	10
Non-current assets - discontinued operations	0	2,961
Current liabilities - discontinued operations	0	1,210
Other non-current liabilities	0	3,184
Non-current liabilities - discontinued operations	$ 13	11
GenOn | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents		1,034
Other current assets		885
Current assets - discontinued operations		1,919
Property, plant and equipment, net		2,543
Other non-current assets		418
Non-current assets - discontinued operations		2,961
Current portion of long term debt and capital leases		704
Other current liabilities		506
Current liabilities - discontinued operations		1,210
Long-term debt and capital leases		2,050
Out-of-market contracts		811
Other non-current liabilities		323
Non-current liabilities - discontinued operations		$ 3,184

Discontinued Operations, Disp49

Discontinued Operations, Dispositions and Acquisitions - Transfer of Assets Under Common Control (Details) $ in Millions	Nov. 01, 2017USD ($)MW	Sep. 30, 2017MW	Aug. 01, 2017USD ($)wind_project	Mar. 27, 2017USD ($)utility_scale_solar_projectMW	Sep. 01, 2016USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generation capacity (in MW) | MW		30,000,000
NRG Wind TE Holdco
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration			$ 44
Working capital adjustments			$ 3
Percentage of ownership sold			25.00%
Number of wind projects | wind_project			12
Agua Caliente solar project
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration				$ 130
Working capital adjustments				1
Assumed non-recourse debt in transaction				$ 328
Agua Caliente solar project | Agua Caliente
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generation capacity (in MW) | MW				46
Percentage of ownership sold				16.00%
Utility-scale solar projects located in Utah | utility_scale_solar_project				7
Agua Caliente solar project | Utah Portfolio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generation capacity (in MW) | MW				265
CVSR
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration					$ 78.5
Percentage of ownership sold					51.05%
Assumed non-recourse debt in transaction					$ 496
Subsequent Event | SPP
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generation capacity (in MW) | MW	38
Cash consideration	$ 71
Working capital adjustments	$ 3

Discontinued Operations, Disp50

Discontinued Operations, Dispositions and Acquisitions - Acquisitions (Details) $ in Millions	Nov. 09, 2016USD ($)MW	Nov. 02, 2016USD ($)MW	Oct. 03, 2016USD ($)MW	Dec. 31, 2016USD ($)	Sep. 30, 2017USD ($)MW	Dec. 31, 2017USD ($)
Business Acquisition [Line Items]
Generation capacity (in MW) | MW					30,000,000
Sun Edison Utility-Scale Solar and Wind
Business Acquisition [Line Items]
Cash consideration			$ 2	$ 124
Payment for contingent consideration liability					$ 15
Sun Edison Utility-Scale Solar and Wind | Scenario, Forecast
Business Acquisition [Line Items]
Payment for contingent consideration liability						$ 59
Sun Edison Utility-Scale Solar and Wind | Mechanically-complete Solar Assets
Business Acquisition [Line Items]
Generation capacity (in MW) | MW		530
Net interest (in MW) | MW		265
Cash consideration		$ 111
Non-recourse debt assumed		222
Borrowings				$ 65
Purchase price		328
Purchase price allocation, current assets		$ 5
PPAs period				20 years
Sun Edison Utility-Scale Solar and Wind | Construction-ready and In-development Solar Assets
Business Acquisition [Line Items]
Generation capacity (in MW) | MW			110
Sun Edison Utility-Scale Solar and Wind | Development Solar Assets
Business Acquisition [Line Items]
Generation capacity (in MW) | MW			71
Sun Edison Utility-Scale Solar and Wind | Construction-ready Solar Project
Business Acquisition [Line Items]
Generation capacity (in MW) | MW	154
Cash consideration	$ 11
SunEdison Solar Distributed Geeration | Mechanically-complete and Construction-ready Distributed Generation Solar Assets
Business Acquisition [Line Items]
Generation capacity (in MW) | MW			29
Cash consideration			$ 67
Post-closing adjustment reduced purchase price			5
Purchase price allocation to intangible assets			15
Construction in Progress | SunEdison Solar Distributed Geeration | Mechanically-complete and Construction-ready Distributed Generation Solar Assets
Business Acquisition [Line Items]
Purchase price allocated to construction in progress			$ 47

Discontinued Operations, Disp51

Discontinued Operations, Dispositions and Acquisitions - Disposition of Majority Interest in EVgo (Details) $ in Millions	Jun. 17, 2016USD ($)charging_stationparking_space	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on sale		$ 0	$ (4)	$ (4)	$ 79
Equity method investments		1,138		$ 1,138		$ 1,120
EVgo | Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration	$ 39
Cash received	17
Working capital adjustments	2.5
Capital contributions	15
Future contributions	7
Future earnout potential	70
Original financial obligation	$ 102.5
Number of public fast charging Freedom Station sites | charging_station	200
Number of commercial and multi-family parking spaces | parking_space	10,000
Loss on sale			83
Loss on the sale of the equity interest			$ 27
Remaining obligation	$ 56
Remaining interest				35.00%
Equity method investments		$ 2		$ 2

Discontinued Operations, Disp52

Discontinued Operations, Dispositions and Acquisitions - Rockford Disposition (Details) $ in Millions	Jul. 12, 2016USD ($)	May 13, 2016USD ($)	Sep. 30, 2017USD ($)MW	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Sep. 30, 2017USD ($)MW	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)	May 12, 2016USD ($)MW
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generation capacity (in MW) | MW			30,000,000			30,000,000
Impairment losses			$ 14	$ 9		$ 77	$ 65
Current assets - discontinued operations			0			0		$ 1,919
Non-current assets - discontinued operations			$ 0			$ 0		$ 2,961
Rockford
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of ownership									100.00%
Impairment losses					$ 17
Proceeds from sale of property, plant, and equipment		$ 55
Rockford | Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of ownership									100.00%
Cash consideration									$ 55
Generation capacity (in MW) | MW									450
Impairment losses					17
Current assets - discontinued operations					2
Non-current assets - discontinued operations					$ 54
Proceeds from sale of property, plant, and equipment	$ 56
Adjustments for base residual auction results	$ 1

Fair Value of Financial Instr53

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, 2017	Dec. 31, 2016
Liabilities:
Long-term debt, including current portion	$ 17,132	$ 16,703
Carrying Amount
Assets:
Notes receivable	22	34
Liabilities:
Long-term debt, including current portion	17,097	16,655
Fair Value
Assets:
Notes receivable	21	34
Liabilities:
Long-term debt, including current portion	17,423	16,620
Fair Value | Level 2
Liabilities:
Long-term debt, including current portion	9,571	9,205
Fair Value | Level 3
Liabilities:
Long-term debt, including current portion	$ 7,852	$ 7,415

Fair Value of Financial Instr54

Fair Value of Financial Instruments - Assets and Liabilities Measured and Recorded at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 681	$ 1,248
Derivative liabilities	829	1,376
Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	639	1,199
Derivative liabilities	751	1,288
Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	42	49
Derivative liabilities	78	88
Fair value, measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities	19	17
Available-for-sale securities	5	10
U.S. government and federal agency obligations	1	1
Total assets	1,376	1,886
Derivative liabilities	829	1,376
Fair value, measurements, recurring | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	639	1,199
Derivative liabilities	751	1,288
Fair value, measurements, recurring | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	42	49
Derivative liabilities	78	88
Fair value, measurements, recurring | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	31	25
Fair value, measurements, recurring | U.S. government and federal agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	44	73
Fair value, measurements, recurring | Federal agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	74	62
Fair value, measurements, recurring | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	11	17
Fair value, measurements, recurring | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	108	84
Fair value, measurements, recurring | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	398	346
Fair value, measurements, recurring | Foreign government fixed income securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	4	3
Fair value, measurements, recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities	0	0
Available-for-sale securities	5	10
U.S. government and federal agency obligations	1	1
Total assets	545	960
Derivative liabilities	201	494
Fair value, measurements, recurring | Level 1 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	132	560
Derivative liabilities	201	494
Fair value, measurements, recurring | Level 1 | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Fair value, measurements, recurring | Level 1 | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	31	25
Fair value, measurements, recurring | 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	43	72
Fair value, measurements, recurring | 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
Fair value, measurements, recurring | 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
Fair value, measurements, recurring | Level 1 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Fair value, measurements, recurring | Level 1 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	333	292
Fair value, measurements, recurring | 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
Fair value, measurements, recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities	0	0
Available-for-sale securities	0	0
U.S. government and federal agency obligations	0	0
Total assets	649	765
Derivative liabilities	482	724
Fair value, measurements, recurring | Level 2 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	409	549
Derivative liabilities	404	636
Fair value, measurements, recurring | Level 2 | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	42	49
Derivative liabilities	78	88
Fair value, measurements, recurring | 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
Fair value, measurements, recurring | 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	1	1
Fair value, measurements, recurring | Level 2 | Federal agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	74	62
Fair value, measurements, recurring | Level 2 | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	11	17
Fair value, measurements, recurring | Level 2 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	108	84
Fair value, measurements, recurring | Level 2 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Fair value, measurements, recurring | Level 2 | Foreign government fixed income securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	4	3
Fair value, measurements, recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities	19	17
Available-for-sale securities	0	0
U.S. government and federal agency obligations	0	0
Total assets	182	161
Derivative liabilities	146	158
Fair value, measurements, recurring | Level 3 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	98	90
Derivative liabilities	146	158
Fair value, measurements, recurring | Level 3 | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Fair value, measurements, recurring | 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
Fair value, measurements, recurring | 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
Fair value, measurements, recurring | 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
Fair value, measurements, recurring | 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
Fair value, measurements, recurring | Level 3 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Fair value, measurements, recurring | Level 3 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	65	54
Fair value, measurements, recurring | 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 Instr55

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, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 68	$ 85	$ 3	$ 49
Total gains/(losses) — realized/unrealized:
Included in earnings	(27)	(5)	20	4
Included in OCI		1		0
Included in nuclear decommissioning obligation	3	3	10	(1)
Purchases	(8)	(25)	1	3
Transfers into Level 3	(6)	(13)	(11)	(6)
Transfers out of Level 3	6	3	13	0
Ending balance	36	49	36	49
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 end of period	(13)	(4)	(6)	(11)
Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	18	16	17	17
Total gains/(losses) — realized/unrealized:
Included in earnings	1	0	2	0
Included in OCI		1		0
Included in nuclear decommissioning obligation	0	0	0	0
Purchases	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending balance	19	17	19	17
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 end of period	0	0	0	0
Trust Fund Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	61	51	54	54
Total gains/(losses) — realized/unrealized:
Included in earnings	0	0	0	0
Included in OCI		0		0
Included in nuclear decommissioning obligation	3	3	10	(1)
Purchases	1	0	1	1
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending balance	65	54	65	54
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 end of period	0	0	0	0
Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	(11)	18	(68)	(22)
Total gains/(losses) — realized/unrealized:
Included in earnings	(28)	(5)	18	4
Included in OCI		0		0
Included in nuclear decommissioning obligation	0	0	0	0
Purchases	(9)	(25)	0	2
Transfers into Level 3	(6)	(13)	(11)	(6)
Transfers out of Level 3	6	3	13	0
Ending balance	(48)	(22)	(48)	(22)
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 end of period	$ (13)	$ (4)	$ (6)	$ (11)

Fair Value of Financial Instr56

Fair Value of Financial Instruments - Derivative Fair Value Measurements, Narrative (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Total derivative assets valued with prices provied by models and other valuation techniques (as a percent)	14.00%
Total derivative liabilities valued with prices provied by models and other valuation techniques (as a percent)	18.00%
Increase (decrease) in credit reserve	$ 1	$ (10)

Fair Value of Financial Instr57

Fair Value of Financial Instruments - Derivative Fair Value Measurements (Details) $ in Millions	Sep. 30, 2017USD ($)$ / MWh	Dec. 31, 2016USD ($)$ / MWh
Assets
Derivative assets	$ 681	$ 1,248
Liabilities
Derivative liabilities	829	1,376
Fair value, measurements, recurring
Liabilities
Derivative liabilities	829	1,376
Fair value, measurements, recurring | Level 3
Liabilities
Derivative liabilities	146	158
Commodity contracts
Assets
Derivative assets	639	1,199
Liabilities
Derivative liabilities	751	1,288
Commodity contracts | Fair value, measurements, recurring
Assets
Derivative assets	639	1,199
Liabilities
Derivative liabilities	751	1,288
Commodity contracts | Fair value, measurements, recurring | Level 3
Assets
Derivative assets	98	90
Liabilities
Derivative liabilities	146	158
Commodity contracts | Fair value, measurements, recurring | Level 3 | Power Contracts (usd per MWh)
Assets
Derivative assets	47	39
Liabilities
Derivative liabilities	$ 101	$ 108
Commodity contracts | Fair value, measurements, recurring | Level 3 | Power Contracts (usd per MWh) | Low
Fair Value Inputs / Range
Forward Market Price (USD per MWh) | $ / MWh	10	11
Commodity contracts | Fair value, measurements, recurring | Level 3 | Power Contracts (usd per MWh) | High
Fair Value Inputs / Range
Forward Market Price (USD per MWh) | $ / MWh	88	104
Commodity contracts | Fair value, measurements, recurring | Level 3 | Power Contracts (usd per MWh) | Weighted Average
Fair Value Inputs / Range
Forward Market Price (USD per MWh) | $ / MWh	24	31
Commodity contracts | Fair value, measurements, recurring | Level 3 | FTRs (usd per MWh)
Assets
Derivative assets	$ 51	$ 51
Liabilities
Derivative liabilities	$ 45	$ 50
Commodity contracts | Fair value, measurements, recurring | Level 3 | FTRs (usd per MWh) | Low
Fair Value Inputs / Range
Auction Prices (USD per MWh) | $ / MWh	(31)	(22)
Commodity contracts | Fair value, measurements, recurring | Level 3 | FTRs (usd per MWh) | High
Fair Value Inputs / Range
Auction Prices (USD per MWh) | $ / MWh	36	17
Commodity contracts | Fair value, measurements, recurring | Level 3 | FTRs (usd per MWh) | Weighted Average
Fair Value Inputs / Range
Auction Prices (USD per MWh) | $ / MWh	0	0

Fair Value of Financial Instr58

Fair Value of Financial Instruments - Counterparty Credit Risk (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)
Concentration of Credit Risk
Counterparty credit exposure to a portion of the Company's counterparties	$ 134
Net counterparty credit exposure to a portion of the Company's counterparties	129
Collateral held (cash and letters of credit) against counterparty credit exposure to a portion of the Company's counterparties	$ 14
Company's exposure before collateral is expected to roll off by the end of 2014 (as a percent)	74.00%
Net exposure (as a percent)	100.00%
Counterparty credit risk exposure to certain counterparties, threshold (as a percent)	10.00%
Aggregate counterparty credit risk exposure for counterparties representing exposure above threshold percentage	$ 50
Estimated counterparty credit risk exposure under certain long term agreements, including California tolling agreements, South Central load obligations and solar power purchase agreements for the next 5 years	$ 4,300
Period of estimated counterparty credit risk exposure under certain long term agreements, including California tolling agreements, South Central load obligations and solar power purchase agreements (in years)	5 years
Investment grade
Concentration of Credit Risk
Net exposure (as a percent)	79.00%
Non-Investment grade/Non-Rated
Concentration of Credit Risk
Net exposure (as a percent)	21.00%
Utilities, energy merchants, marketers and other
Concentration of Credit Risk
Net exposure (as a percent)	91.00%
Financial institutions
Concentration of Credit Risk
Net exposure (as a percent)	9.00%
NRG Yield, Inc.
Concentration of Credit Risk
Estimated counterparty credit risk exposure under certain long term agreements, including California tolling agreements, South Central load obligations and solar power purchase agreements for the next 5 years	$ 2,800

Nuclear Decommissioning Trust59

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, 2017	Dec. 31, 2016
Nuclear decommissioning trust fund
Fair Value	$ 670	$ 610
Unrealized Gains	265	217
Unrealized Losses	2	4
Cash and cash equivalents
Nuclear decommissioning trust fund
Fair Value	31	25
Unrealized Gains	0	0
Unrealized Losses	0	0
U.S. government and federal agency obligations
Nuclear decommissioning trust fund
Fair Value	44	73
Unrealized Gains	2	1
Unrealized Losses	$ 0	$ 0
Weighted-average Maturities (In years)	10 years	11 years
Federal agency mortgage-backed securities
Nuclear decommissioning trust fund
Fair Value	$ 74	$ 62
Unrealized Gains	1	1
Unrealized Losses	$ 1	$ 1
Weighted-average Maturities (In years)	24 years	25 years
Commercial mortgage-backed securities
Nuclear decommissioning trust fund
Fair Value	$ 11	$ 17
Unrealized Gains	0	0
Unrealized Losses	$ 0	$ 1
Weighted-average Maturities (In years)	23 years	26 years
Corporate debt securities
Nuclear decommissioning trust fund
Fair Value	$ 108	$ 84
Unrealized Gains	2	1
Unrealized Losses	$ 1	$ 2
Weighted-average Maturities (In years)	11 years	11 years
Equity securities
Nuclear decommissioning trust fund
Fair Value	$ 398	$ 346
Unrealized Gains	260	214
Unrealized Losses	0	0
Foreign government fixed income securities
Nuclear decommissioning trust fund
Fair Value	4	3
Unrealized Gains	0	0
Unrealized Losses	$ 0	$ 0
Weighted-average Maturities (In years)	9 years	9 years

Nuclear Decommissioning Trust60

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, 2017	Sep. 30, 2016
Nuclear Decommissioning Trust Fund Disclosure [Abstract]
Realized gains	$ 8	$ 7
Realized losses	6	3
Proceeds from sale of securities	$ 382	$ 354

Accounting for Derivative Ins61

Accounting for Derivative Instruments and Hedging Activities - Net Notional Volume Buy/Sell of Open DerivativeTransactions (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, 2017USD ($)MWhMMBTUmw_per_dayTsharesbbl	Dec. 31, 2016USD ($)MWhMMBTUmw_per_dayTsharesbbl
Short | Emissions
Derivative [Line Items]
Derivative, nonmonetary notional amount, mass (ton)	1
Short | Natural Gas
Derivative [Line Items]
Derivative, nonmonetary notional amount, energy measure in (millions of btu) and (megawatt hours) | MMBTU	(62)	(53)
Short | Capacity
Derivative [Line Items]
Derivative, nonmonetary notional amount, flow rate (in mw per day) | mw_per_day	1	1
Long | Emissions
Derivative [Line Items]
Derivative, nonmonetary notional amount, mass (ton)		0
Long | Coal
Derivative [Line Items]
Derivative, nonmonetary notional amount, mass (ton)	15	35
Long | Oil
Derivative [Line Items]
Derivative, nonmonetary notional amount, volume (in barrels) | bbl	0	1
Long | Power
Derivative [Line Items]
Derivative, nonmonetary notional amount, energy measure in (millions of btu) and (megawatt hours) | MWh	(19)	(7)
Long | Interest
Derivative [Line Items]
Derivative, notional amount (in usd) | $	$ 3,806	$ 3,429
Long | Equity
Derivative [Line Items]
Derivative, non-monetary notional amount (in shares) | shares	1	1

Accounting for Derivative Ins62

Accounting for Derivative Instruments and Hedging Activities - Fair Value Within the Derivative Instrument Valuation (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivative Assets	$ 681	$ 1,248
Derivative Liabilities	829	1,376
Designated as Hedging Instrument
Derivative [Line Items]
Derivative Assets	10	12
Derivative Liabilities	23	69
Designated as Hedging Instrument | Interest rate contracts current
Derivative [Line Items]
Derivative Assets	0	0
Derivative Liabilities	8	28
Designated as Hedging Instrument | Interest rate contracts long-term
Derivative [Line Items]
Derivative Assets	10	12
Derivative Liabilities	15	41
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Assets	671	1,236
Derivative Liabilities	806	1,307
Not Designated as Hedging Instrument | Interest rate contracts current
Derivative [Line Items]
Derivative Assets	5	0
Derivative Liabilities	19	7
Not Designated as Hedging Instrument | Interest rate contracts long-term
Derivative [Line Items]
Derivative Assets	27	37
Derivative Liabilities	36	12
Not Designated as Hedging Instrument | Commodity contracts current
Derivative [Line Items]
Derivative Assets	470	1,067
Derivative Liabilities	495	1,057
Not Designated as Hedging Instrument | Commodity contracts long-term
Derivative [Line Items]
Derivative Assets	169	132
Derivative Liabilities	$ 256	$ 231

Accounting for Derivative Ins63

Accounting for Derivative Instruments and Hedging Activities - Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Derivative assets	$ 681	$ 1,248
Cash Collateral (Held) / Posted	(31)	(81)
Gross Amounts of Recognized Derivative Liabilities	(829)	(1,376)
Cash Collateral Posted	203	150
Gross Amounts of Recognized Assets / Liabilities	(148)	(128)
Derivative Asset Fair Value Gross Liability Net Of Derivative Liability Fair Value Gross Asset	0	0
Derivative, Collateral, Obligation to Return Cash Net Of Derivative, Collateral, Right to Reclaim Cash	78	0
Derivative Asset, Fair Value, Amount Offset Against Collateral Net Of Derivative Liability, Fair Value, Amount Offset Against Collateral	(70)	(128)
Commodity contracts
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Derivative assets	639	1,199
Derivative Instruments	(546)	(1,021)
Cash Collateral (Held) / Posted	(5)	(13)
Net Amount	88	165
Gross Amounts of Recognized Derivative Liabilities	(751)	(1,288)
Derivative Instruments	546	1,021
Cash Collateral Posted	83	13
Derivative Liability, Fair Value, Amount Offset Against Collateral	(122)	(254)
Gross Amounts of Recognized Assets / Liabilities	(112)	(89)
Derivative Asset Fair Value Gross Liability Net Of Derivative Liability Fair Value Gross Asset	0	0
Derivative, Collateral, Obligation to Return Cash Net Of Derivative, Collateral, Right to Reclaim Cash	78	0
Derivative Asset, Fair Value, Amount Offset Against Collateral Net Of Derivative Liability, Fair Value, Amount Offset Against Collateral	(34)	(89)
Interest rate contracts
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Derivative assets	42	49
Derivative Instruments	(2)	(4)
Cash Collateral (Held) / Posted	0	0
Net Amount	40	45
Gross Amounts of Recognized Derivative Liabilities	(78)	(88)
Derivative Instruments	2	4
Cash Collateral Posted	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(76)	(84)
Gross Amounts of Recognized Assets / Liabilities	(36)	(39)
Derivative Asset Fair Value Gross Liability Net Of Derivative Liability Fair Value Gross Asset	0	0
Derivative, Collateral, Obligation to Return Cash Net Of Derivative, Collateral, Right to Reclaim Cash	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral Net Of Derivative Liability, Fair Value, Amount Offset Against Collateral	$ (36)	$ (39)

Accounting for Derivative Ins64

Accounting for Derivative Instruments and Hedging Activities - Effect of ASC 815 on Accumulated OCI Balance Attributable to Hedge Derivatives, Net (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2016
Reclassified from accumulated OCI to income:
Accumulated other comprehensive income (loss), tax	$ 15,000,000		$ 15,000,000		$ 28,000,000
Losses expected to be realized from OCI during the next twelve months, tax	4,000,000		4,000,000
Hedge ineffectiveness	0	$ 0	0	$ 0
Interest Rate Contracts
Effects of ASC 815 on NRG's Accumulated OCI Balance Attributable to Cash Flow Hedge Derivatives, net of tax
Accumulated OCI beginning balance	(67,000,000)	(165,000,000)	(66,000,000)	(101,000,000)
Reclassified from accumulated OCI to income:
Due to realization of previously deferred amounts	4,000,000	2,000,000	10,000,000	12,000,000
Mark-to-market of cash flow hedge accounting contracts	4,000,000	32,000,000	(3,000,000)	(42,000,000)
Accumulated OCI ending balance, net of $15, and $28 tax	(59,000,000)	$ (131,000,000)	(59,000,000)	$ (131,000,000)
Losses expected to be realized from OCI during the next 12 months, net of $4 tax	$ 14,000,000		$ 14,000,000

Accounting for Derivative Ins65

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, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Unrealized mark-to-market results
Reversal of previously recognized unrealized (gains)/losses on settled positions related to economic hedges	$ (6)	$ (30)	$ 19	$ (75)
Reversal of acquired gain positions related to economic hedges	(2)	(7)	(1)	(11)
Net unrealized (losses)/gains on open positions related to economic hedges	(16)	(50)	(1)	27
Total unrealized mark-to-market (losses)/gains for economic hedging activities	(24)	(87)	17	(59)
Reversal of previously recognized unrealized (gains)/losses on settled positions related to trading activity	(5)	3	(24)	13
Net unrealized (losses)/gains on open positions related to trading activity	0	(8)	17	14
Total unrealized mark-to-market (losses)/gains for trading activity	(5)	(5)	(7)	27
Total unrealized (losses)/gains	(29)	(92)	10	(32)
Credit Risk Related Contingent Features
Unrealized (loss) gain from open economic hedge positions			(1)	27
Collateral due on net liability position that has not been called by a certain marginable agreement counterparty	17		17
Adequate Assurance Clauses
Credit Risk Related Contingent Features
Derivative net liability position, collateral required Contracts with Credit Rating Contingent Feature	27		27
Credit Rating Contingent Features
Credit Risk Related Contingent Features
Derivative net liability position, collateral required Contracts with Credit Rating Contingent Feature	34		34
Commodity contracts
Unrealized mark-to-market results
Total unrealized (losses)/gains	(29)	(92)	10	(32)
Commodity contracts | Operating revenues
Unrealized mark-to-market results
Total unrealized (losses)/gains	21	57	178	(333)
Commodity contracts | Cost of operations
Unrealized mark-to-market results
Total unrealized (losses)/gains	(50)	(149)	(168)	301
Interest rate contracts
Unrealized mark-to-market results
Total unrealized (losses)/gains	$ 11	$ 9	$ (8)	$ (9)

Impairments (Details)

Impairments (Details) - USD ($)	May 13, 2016	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Jul. 14, 2017	May 12, 2016
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses		$ 14,000,000		$ 9,000,000			$ 77,000,000	$ 65,000,000
Construction in progress			$ 0
Other impairments				8,000,000
Impairment loss on investment								$ 147,000,000
Petra Nova Parish Holdings
Impaired Long-Lived Assets Held and Used [Line Items]
Ownership percentage						50.00%
Impairment loss on investment						$ 140,000,000
Other Intangible Assets
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses					$ 8,000,000
Deferred Marketing Expenses
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses					10,000,000
Investments
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses				$ 9,000,000
Rockford
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses					17,000,000
Percentage of ownership										100.00%
Proceeds from sale of property, plant, and equipment	$ 55,000,000
Renewables
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses		$ 14,000,000	22,000,000
Collectibility of receivables | BTEC New Albany, LLC
Impaired Long-Lived Assets Held and Used [Line Items]
Amount owed from BTEC New Albany, LLC									$ 48,000,000
Collectibility of receivables | Purchaser incurred costs | BTEC New Albany, LLC
Impaired Long-Lived Assets Held and Used [Line Items]
Amount owed from BTEC New Albany, LLC									38,000,000
Collectibility of receivables | Liquidation damages | BTEC New Albany, LLC
Impaired Long-Lived Assets Held and Used [Line Items]
Amount owed from BTEC New Albany, LLC									$ 10,000,000
Construction in Progress
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses			$ 41,000,000
Solar Panels
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses					$ 17,000,000

Debt and Capital Leases - Sched

Debt and Capital Leases - Schedule of Long-term Debt and Capital Leases (Details) - USD ($) $ in Millions	Jan. 24, 2017	Sep. 30, 2017	May 26, 2017	Feb. 17, 2017	Dec. 31, 2016	Aug. 02, 2016	May 23, 2016
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 17,132			$ 16,703
Capital leases		6			6
Subtotal long-term debt and capital leases (including current maturities)		17,138			16,709
Less current maturities		(1,247)			(516)
Less debt issuance costs		(198)			(188)
Discounts		(35)			(48)
Long-term debt and capital leases		$ 15,658			15,957
Alta Wind I - V lease financing arrangements, due 2034 and 2035 | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage		5.696%
Alta Wind I - V lease financing arrangements, due 2034 and 2035 | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage		7.015%
Recourse debt
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 7,790			7,795
Recourse debt | Senior notes, due 2018
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 398			398
Interest rate, stated percentage		7.625%
Recourse debt | Senior notes, due 2021
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 207			207
Interest rate, stated percentage		7.875%				7.875%
Recourse debt | Senior notes, due 2022
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 992			992
Interest rate, stated percentage		6.25%
Recourse debt | Senior notes, due 2023
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 869			869
Interest rate, stated percentage		6.625%
Recourse debt | Senior notes, due 2024
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 733			733
Interest rate, stated percentage		6.25%
Recourse debt | Senior notes, due 2026
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 1,000			1,000		$ 1,000
Interest rate, stated percentage		7.25%					7.25%
Recourse debt | Senior notes, due 2027
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 1,250			1,250
Interest rate, stated percentage		6.625%				6.625%
Recourse debt | Term loan facility, due 2023
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 1,876			1,891
Recourse debt | Term loan facility, due 2023 | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.25%	2.25%
Recourse debt | Tax-exempt bonds
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 465			455
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%
Non-recourse debt
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 9,342			8,908
Non-recourse debt | NRG Yield Operating LLC Senior Notes, due 2024
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 500			500
Interest rate, stated percentage		5.375%
Non-recourse debt | NRG Yield Operating LLC Senior Notes, due 2026
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 350			350
Interest rate, stated percentage		5.00%
Non-recourse debt | NRG Yield, Inc. Convertible Senior Notes, due 2019
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 345			345
Interest rate, stated percentage		3.50%
Non-recourse debt | NRG Yield, Inc. Convertible Senior Notes, due 2020
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 288			288
Interest rate, stated percentage		3.25%
Non-recourse debt | El Segundo Energy Center, due 2023
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 400			443
Non-recourse debt | El Segundo Energy Center, due 2023 | LIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate		1.75%
Non-recourse debt | El Segundo Energy Center, due 2023 | LIBOR | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate		2.375%
Non-recourse debt | Marsh Landing, due 2017 and 2023
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 334			370
Non-recourse debt | Alta Wind I - V lease financing arrangements, due 2034 and 2035
Debt Instrument [Line Items]
Long-term debt, including current portion		940			965
Non-recourse debt | Walnut Creek, term loans due 2023
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 279			310
Non-recourse debt | Walnut Creek, term loans due 2023 | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.625%
Non-recourse debt | Utah Portfolio, due 2022
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 284			287
Non-recourse debt | Utah Portfolio, due 2022 | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		2.625%
Non-recourse debt | Tapestry, due 2021
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 165			172
Non-recourse debt | Tapestry, due 2021 | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.625%
Non-recourse debt | CVSR, due 2037
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 746			771
Non-recourse debt | CVSR, due 2037 | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage		2.339%
Non-recourse debt | CVSR, due 2037 | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage		3.775%
Non-recourse debt | CVSR HoldCo, due 2037
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 194			199
Interest rate, stated percentage		4.68%
Non-recourse debt | Alpine, due 2022
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 138			145
Non-recourse debt | Alpine, due 2022 | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.75%
Non-recourse debt | Energy Center Minneapolis, due 2017 and 2025
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 82			96
Non-recourse debt | Energy Center Minneapolis, due 2017 and 2025 | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage		5.95%
Non-recourse debt | Energy Center Minneapolis, due 2017 and 2025 | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage		7.25%
Non-recourse debt | NRG Energy Center Minneapolis LLC Senior Secured Notes, due 2025
Debt Instrument [Line Items]
Interest rate, stated percentage		5.95%
Non-recourse debt | Energy Center Minneapolis, due 2031
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 125			125
Interest rate, stated percentage		3.55%
Non-recourse debt | Viento, due 2023
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 169			178
Non-recourse debt | Viento, due 2023 | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		3.00%
Non-recourse debt | NRG Yield - other
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 562			540
Non-recourse debt | Subtotal NRG Yield debt (non-recourse to NRG)
Debt Instrument [Line Items]
Long-term debt, including current portion		5,901			6,084
Non-recourse debt | Ivanpah, due 2033 and 2038
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 1,097			1,113
Non-recourse debt | Ivanpah, due 2033 and 2038 | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage		2.285%
Non-recourse debt | Ivanpah, due 2033 and 2038 | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage		4.256%
Non-recourse debt | Carlsbad Energy Project
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 407			0
Interest rate, stated percentage		4.12%	4.12%
Non-recourse debt | Agua Caliente, due 2037
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 833			849
Non-recourse debt | Agua Caliente, due 2037 | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage		2.395%
Non-recourse debt | Agua Caliente, due 2037 | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage		3.633%
Non-recourse debt | Agua Caliente Borrower 1, due 2038
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 89			0
Interest rate, stated percentage		5.43%		5.43%
Non-recourse debt | Cedro Hill, due 2025
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 153			163
Non-recourse debt | Cedro Hill, due 2025 | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.75%
Non-recourse debt | Midwest Generation, due 2019
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 173			231
Interest rate, stated percentage		4.39%
Non-recourse debt | NRG Other
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 689			468
Non-recourse debt | Subtotal other NRG non-recourse debt
Debt Instrument [Line Items]
Long-term debt, including current portion		$ 3,441			$ 2,824
Non-recourse debt | Marsh Landing Term Loan Due 2017 | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.75%
Non-recourse debt | Marsh Landing Term Loan Due 2023 | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.875%

Debt and Capital Leases - Narra

Debt and Capital Leases - Narrative (Details) - USD ($)	Oct. 16, 2017	Jun. 12, 2017	May 26, 2017	Feb. 17, 2017	Jan. 24, 2017	Aug. 02, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	May 23, 2016
Debt Instrument [Line Items]
Loss on debt extinguishment							$ 1,000,000	$ 50,000,000	$ 3,000,000	$ 119,000,000
Long-term debt							17,132,000,000		17,132,000,000		$ 16,703,000,000
Recourse Debt
Debt Instrument [Line Items]
Long-term debt							7,790,000,000		7,790,000,000		7,795,000,000
Non Recourse Debt
Debt Instrument [Line Items]
Long-term debt							9,342,000,000		9,342,000,000		8,908,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Repayment of debt		$ 125,000,000
Revolving Credit Facility | Carlsbad Financing Agreement
Debt Instrument [Line Items]
Long-term construction loan			$ 194,000,000
Revolving Credit Facility | Letter of Credit
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity			83,000,000
Revolving Credit Facility | Working Capital Facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity			$ 4,000,000
Term loan facility, due 2023 | Recourse Debt
Debt Instrument [Line Items]
Long-term debt							1,876,000,000		$ 1,876,000,000		1,891,000,000
Term loan facility, due 2023 | Recourse Debt | LIBOR
Debt Instrument [Line Items]
Change in interest rate					50.00%
Basis spread on variable rate					2.25%				2.25%
Term loan facility, due 2023 | Recourse Debt | London Interbank Offered Rate (LIBOR) floor
Debt Instrument [Line Items]
Basis spread on variable rate					0.75%
Revolving Credit Facility
Debt Instrument [Line Items]
Borrowing outstanding under revolver							$ 0		$ 0
Senior notes, due 2018 | Recourse Debt
Debt Instrument [Line Items]
Interest rate, stated percentage							7.625%		7.625%
Long-term debt							$ 398,000,000		$ 398,000,000		398,000,000
Senior notes, due 2021 | Recourse Debt
Debt Instrument [Line Items]
Interest rate, stated percentage						7.875%	7.875%		7.875%
Long-term debt							$ 207,000,000		$ 207,000,000		207,000,000
Senior Notes | Recourse Debt
Debt Instrument [Line Items]
Repurchased principal amount								2,600,000,000		2,600,000,000
Repurchase amount								$ 2,700,000,000		2,700,000,000
Accrued interest included in repurchased notes										67,000,000
Loss on debt extinguishment										94,000,000
Write-off of deferred financing costs										$ 15,000,000
Long-term debt							$ 5,400,000,000		$ 5,400,000,000
Senior notes, due 2026 | Recourse Debt
Debt Instrument [Line Items]
Interest rate, stated percentage							7.25%		7.25%			7.25%
Long-term debt							$ 1,000,000,000		$ 1,000,000,000		1,000,000,000	$ 1,000,000,000
Senior notes, due 2027 | Recourse Debt
Debt Instrument [Line Items]
Interest rate, stated percentage						6.625%	6.625%		6.625%
Long-term debt							$ 1,250,000,000		$ 1,250,000,000		1,250,000,000
Proceeds from issuance of debt						$ 1,250,000,000
Senior Notes Due In 2020 | Recourse Debt
Debt Instrument [Line Items]
Interest rate, stated percentage						8.25%
NRG Yield Revolving Credit Facility
Debt Instrument [Line Items]
Borrowing outstanding under revolver							0		0
NRG Yield Revolving Credit Facility | Letter of Credit
Debt Instrument [Line Items]
Letters of credit outstanding under revolver							$ 68,000,000		$ 68,000,000
Agua Caliente Borrower 1, due 2038 | Non Recourse Debt
Debt Instrument [Line Items]
Interest rate, stated percentage				5.43%			5.43%		5.43%
Long-term debt							$ 89,000,000		$ 89,000,000		0
Percentage of ownership				51.00%
Proceeds from issuance of senior secured debt				$ 130,000,000
Carlsbad Energy Project | Non Recourse Debt
Debt Instrument [Line Items]
Interest rate, stated percentage			4.12%				4.12%		4.12%
Long-term debt							$ 407,000,000		$ 407,000,000		$ 0
Proceeds from issuance of debt			$ 407,000,000
Subsequent Event | Senior notes, due 2018 | Recourse Debt
Debt Instrument [Line Items]
Repurchased principal amount	$ 398,000,000
Interest rate, stated percentage	7.625%
Subsequent Event | Senior notes, due 2021 | Recourse Debt
Debt Instrument [Line Items]
Repurchased principal amount	$ 206,000,000
Interest rate, stated percentage	7.875%
Repurchase amount	$ 630,000,000
Accrued interest included in repurchased notes	$ 14,000,000

Variable Interest Entities, o69

Variable Interest Entities, or VIEs (Details) $ in Millions	Sep. 30, 2017USD ($)facilityMW	Dec. 31, 2016USD ($)
Investments Accounted for by the Equity Method
Generation capacity (in MW) | MW	30,000,000
Equity investments in affiliates	$ 1,138	$ 1,120
Deficit restoration obligation	100
Current assets	74	87
Net property, plant and equipment	1,466	1,534
Other long-term assets	1,026	954
Total assets	2,566	2,575
Current liabilities	69	59
Long-term debt	420	442
Other long-term liabilities	187	183
Total liabilities	676	684
Noncontrolling interests	578	529
Net assets less noncontrolling interests	$ 1,312	$ 1,362
GenConn Energy LLC
Investments Accounted for by the Equity Method
Economic interest in equity method investments (as a percent)	50.00%
Power generation facilities | facility	2
Generation capacity (in MW) | MW	190
Equity investments in affiliates	$ 102

Changes in Capital Structure -

Changes in Capital Structure - Narrative (Details) - USD ($) $ in Millions	Jun. 13, 2016	May 24, 2016	Jun. 30, 2016	Sep. 30, 2017	Apr. 27, 2017	Dec. 31, 2016
Capital Structure
Common stock, shares authorized (in shares)				500,000,000		500,000,000
Redemption of shares (as percent)			100.00%
Increase in shares available for issuance under the ESPP					3,000,000
Shares of treasury stock available for issuance under the ESPP				3,107,050
Increase in shares available for Issuance,under Amended and Restated Long-term Incentive Plan					3,000,000
Convertible Preferred Stock
Capital Structure
Redemption of shares (as percent)	100.00%	100.00%
Preferred shares repurchased (in shares)		$ 344.5
Preferred stock, dividend rate amended (as percent)		2.822%	2.822%
Repurchase of outstanding shares	$ 226
Gain on redemption	78
Carrying value of preferred stock at time of redemption	$ 304

Changes in Capital Structure 71

Changes in Capital Structure - Changes in NRG's Common Shares Outstanding and Issued (Details)	9 Months Ended
	Sep. 30, 2017shares
Schedule of Stock by Class, Equity [Roll Forward]
Balance as of beginning of period	417,583,825
Treasury shares, balance as of beginning of period	(102,140,814)
Outstanding, as of beginning of period	315,443,011
Shares issued under LTIPs	634,738
Shares issued under ESPP	560,769
Balance as of end of period	418,218,563
Treasury shares, balance as of end of the period	(101,580,045)
Outstanding, as of end of period	316,638,518
Issued
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs	634,738
Shares issued under ESPP	0
Treasury
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs	0
Shares issued under ESPP	560,769

Changes in Capital Structure 72

Changes in Capital Structure - Schedule of Dividends Paid (Details) - $ / shares	Oct. 18, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Dividends Payable [Line Items]
Dividends per Common Share (in usd per share)		$ 0.03	$ 0.03	$ 0.03	$ 0.03	$ 0.09	$ 0.21
Subsequent Event
Dividends Payable [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_(Loss) Per Share - Rec

Earnings/(Loss) Per Share - Reconciliation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	May 24, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 13, 2016
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Repurchase of shares (as percent)				100.00%
Basic and diluted income/(loss) per share attributable to NRG Energy, Inc. common stockholders
Net income/(loss) attributable to NRG Energy, Inc.		$ 171	$ 402		$ (619)	$ 213
Dividends for preferred shares		0	0		0	5
Gain on redemption of 2.822% redeemable perpetual preferred stock		0	0		0	(78)
Net Income/(Loss) Available for Common Stockholders		$ 171	$ 402		$ (619)	$ 286
Weighted average number of common shares outstanding - basic (in shares)		317	316		317	315
Income/(loss) per weighted average common share — basic (in dollars per share)		$ 0.54	$ 1.27		$ (1.95)	$ 0.91
Diluted income/(loss) per share attributable to NRG Energy, Inc. common stockholders
Weighted average number of common shares outstanding - diluted (in shares)		317	316		317	315
Incremental shares attributable to the issuance of equity compensation (treasury stock method) (in shares)		5	1		0	1
Total dilutive shares (in shares)		322	317		317	316
Income/(loss) per weighted average common share — diluted (dollars per share)		$ 0.53	$ 1.27		$ (1.95)	$ 0.91
Convertible Preferred Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Repurchase of shares (as percent)	100.00%						100.00%
Preferred stock, dividend rate amended (as percent)	2.822%			2.822%

Earnings_(Loss) Per Share - Ant

Earnings/(Loss) Per Share - Anti-dilutive Securities (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1	2	6	3
Equity compensation plans
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1	2	6	3

Segment Reporting (Details)

Segment Reporting (Details) $ in Millions	3 Months Ended			9 Months Ended		11 Months Ended
	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Aug. 01, 2017acquisition	Mar. 27, 2017utility_scale_solar_project	Dec. 31, 2016USD ($)	Sep. 01, 2016
Segment Reporting Information
Number of acquisitions | acquisition						3
Operating revenues	$ 3,049		$ 3,421	$ 8,132	$ 8,328
Depreciation and amortization	272		298	789	826
Impairment losses	14		9	77	65
Equity in (losses)/earnings of unconsolidated affiliates	27		16	29	13
Gain/(loss) on sale of assets	0		4	4	(79)
Impairment loss on investment					(147)
Loss on debt extinguishment, net	(1)		(50)	(3)	(119)
Income/(loss) from continuing operations before income taxes	196		156	125	(17)
Income/(loss) from continuing operations	190		128	120	(92)
(Loss)/Income from discontinued operations, net of income tax	(27)		265	(802)	256
Net income/(loss)	163		393	(682)	164
Net Income/(loss) attributable to NRG Energy, Inc.	171		402	(619)	213
Total assets	25,470			25,470				$ 30,682
Renewables
Segment Reporting Information
Impairment losses	14	$ 22
Operating Segments | Generation
Segment Reporting Information
Operating revenues	1,224		1,536	3,072	3,173
Depreciation and amortization	96		134	287	331
Impairment losses	1		9	42	26
Equity in (losses)/earnings of unconsolidated affiliates	12		6	(16)	1
Gain/(loss) on sale of assets				4	0
Impairment loss on investment					(142)
Loss on debt extinguishment, net	0		0	0	0
Income/(loss) from continuing operations before income taxes	258		370	202	(51)
Income/(loss) from continuing operations	258		372	200	(49)
(Loss)/Income from discontinued operations, net of income tax	0		0	0	0
Net income/(loss)	258		372	200	(49)
Net Income/(loss) attributable to NRG Energy, Inc.	258		372	200	(49)
Total assets	8,585			8,585
Operating Segments | Retail
Segment Reporting Information
Operating revenues	1,937		2,012	4,875	4,918
Depreciation and amortization	29		26	87	83
Impairment losses	0		0	0	0
Equity in (losses)/earnings of unconsolidated affiliates	0		0	0	0
Gain/(loss) on sale of assets			0	0	0
Impairment loss on investment					0
Loss on debt extinguishment, net	0		0	0	0
Income/(loss) from continuing operations before income taxes	69		(78)	371	735
Income/(loss) from continuing operations	69		(78)	380	734
(Loss)/Income from discontinued operations, net of income tax	0		0	0	0
Net income/(loss)	69		(78)	380	734
Net Income/(loss) attributable to NRG Energy, Inc.	69		(78)	380	734
Total assets	2,445			2,445
Operating Segments | Renewables
Segment Reporting Information
Operating revenues	144		139	364	336
Depreciation and amortization	51		48	150	143
Impairment losses	13		0	35	27
Equity in (losses)/earnings of unconsolidated affiliates	(3)		(10)	(6)	(16)
Gain/(loss) on sale of assets			0	0	0
Impairment loss on investment					1
Loss on debt extinguishment, net	0		0	(3)	0
Income/(loss) from continuing operations before income taxes	(7)		(1)	(97)	(121)
Income/(loss) from continuing operations	(4)		2	(84)	(107)
(Loss)/Income from discontinued operations, net of income tax	0		0	0	0
Net income/(loss)	(4)		2	(84)	(107)
Net Income/(loss) attributable to NRG Energy, Inc.	9		(9)	(18)	(103)
Total assets	5,357			5,357
Operating Segments | NRG Yield
Segment Reporting Information
Operating revenues	265		272	767	789
Depreciation and amortization	88		75	241	224
Impairment losses	0		0	0	0
Equity in (losses)/earnings of unconsolidated affiliates	28		16	63	34
Gain/(loss) on sale of assets			0	0	0
Impairment loss on investment					0
Loss on debt extinguishment, net	0		0	0	0
Income/(loss) from continuing operations before income taxes	49		63	100	141
Income/(loss) from continuing operations	41		50	85	116
(Loss)/Income from discontinued operations, net of income tax	0		0	0	0
Net income/(loss)	41		50	85	116
Net Income/(loss) attributable to NRG Energy, Inc.	35		55	87	113
Total assets	8,442			8,442
Operating Segments | Corporate
Segment Reporting Information
Operating revenues	2		24	13	54
Depreciation and amortization	8		15	24	45
Impairment losses	0		0	0	12
Equity in (losses)/earnings of unconsolidated affiliates	0		5	7	11
Gain/(loss) on sale of assets			4	0	(79)
Impairment loss on investment					(6)
Loss on debt extinguishment, net	(1)		(50)	0	(119)
Income/(loss) from continuing operations before income taxes	(161)		(202)	(430)	(706)
Income/(loss) from continuing operations	(162)		(222)	(440)	(771)
(Loss)/Income from discontinued operations, net of income tax	(27)		265	(802)	256
Net income/(loss)	(189)		43	(1,242)	(515)
Net Income/(loss) attributable to NRG Energy, Inc.	(220)		19	(1,306)	(547)
Total assets	11,090			11,090
Eliminations
Segment Reporting Information
Operating revenues	(523)		(562)	(959)	(942)
Depreciation and amortization	0		0	0	0
Impairment losses	0		0	0	0
Equity in (losses)/earnings of unconsolidated affiliates	(10)		(1)	(19)	(17)
Gain/(loss) on sale of assets			0	0	0
Impairment loss on investment					0
Loss on debt extinguishment, net	0		0	0	0
Income/(loss) from continuing operations before income taxes	(12)		4	(21)	(15)
Income/(loss) from continuing operations	(12)		4	(21)	(15)
(Loss)/Income from discontinued operations, net of income tax	0		0	0	0
Net income/(loss)	(12)		4	(21)	(15)
Net Income/(loss) attributable to NRG Energy, Inc.	20		43	38	65
Total assets	(10,449)			(10,449)
Eliminations | Generation
Segment Reporting Information
Operating revenues	(491)		(506)	(897)	(836)
Eliminations | Retail
Segment Reporting Information
Operating revenues	8		2	(3)	(3)
Eliminations | Renewables
Segment Reporting Information
Operating revenues	(19)		(8)	(23)	(16)
Eliminations | NRG Yield
Segment Reporting Information
Operating revenues	0		0	0	(6)
Eliminations | Corporate
Segment Reporting Information
Operating revenues	$ (21)		$ (50)	$ (36)	$ (81)
CVSR
Segment Reporting Information
Percentage of ownership sold of subsidiary									51.05%
Agua Caliente
Segment Reporting Information
Percentage of ownership sold of subsidiary							16.00%
NRG Wind TE Holdco
Segment Reporting Information
Percentage of ownership sold of subsidiary						25.00%
Agua Caliente | Agua Caliente solar project
Segment Reporting Information
Percentage of ownership sold of subsidiary							16.00%
Utility-scale solar projects located in Utah | utility_scale_solar_project							7

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Effective Tax Rate
Income/(Loss) before income taxes	$ 196	$ 156	$ 125	$ (17)
Income tax expense from continuing operations	$ 6	$ 28	$ 5	$ 75
Effective tax rate	3.10%	17.90%	4.00%	(441.20%)
Statutory tax rate (as a percent)	35.00%	35.00%	35.00%	35.00%
Uncertain Tax Benefits
Non-current tax liability for uncertain tax benefits	$ 40		$ 40
Unrecognized tax benefits, penalties and interest accrued	$ 4		$ 4

Related Party Transactions - Se

Related Party Transactions - Service Agreement with GenOn (Details) $ in Millions	Jun. 14, 2017USD ($)extension	Jun. 12, 2017USD ($)extension	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)
Related Party Transaction [Line Items]
Other income - affiliate			$ 14	$ 48	$ 104	$ 144
GenOn | Services Agreement
Related Party Transaction [Line Items]
Service fees					193
Shared services, annualized rate		$ 84
Reserve against affiliate receivable			$ 15		$ 15
Credit applied		28
Restructuring Support Agreement | Services Agreement
Related Party Transaction [Line Items]
Shared services, annualized rate		$ 84
Monthly shared services	$ 5
Shared services, waived period	2 months	2 months
Shared services, number of extensions | extension	2	2
Shared services, extension period	1 month	1 month
Credit applied		$ 28

Related Party Transactions - Cr

Related Party Transactions - Credit Agreement with GenOn (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Long-term debt	$ 17,132,000,000	$ 16,703,000,000
GenOn | Revolving Credit Facility | Intercompany Credit Agreement
Related Party Transaction [Line Items]
Credit facility maximum borrowing capacity	500,000,000
Letters of credit outstanding under revolver	103,000,000	272,000,000
Long-term debt	125,000,000	$ 0
GenOn | Revolving Credit Facility | Restructuring Support Agreement, Letter of Credit Credit Facility
Related Party Transaction [Line Items]
Credit facility maximum borrowing capacity	$ 330,000,000
Line of credit facility cash collateralized percentage required	103.00%

Commitments and Contingencies (

Commitments and Contingencies (Details)

Sep. 07, 2017USD ($)

Jun. 01, 2001

May 31, 2016case

Sep. 30, 2012Claimcase

Jun. 30, 2010ClaimPlaintiff

Aug. 31, 2009USD ($)generatingunit

Mar. 10, 2010Claim

Sep. 30, 2017USD ($)lawsuit

Jul. 31, 2013Claim

Sep. 30, 2017USD ($)Plaintiff

Dec. 13, 2016

Dec. 31, 2012Claim

Senior Notes | Senior Unsecured Notes 2017 | GenOn Energy

Loss Contingencies

Interest rate, stated percentage

7.875%

Senior Notes | Senior Unsecured Notes 2018 | GenOn Energy

Loss Contingencies

Interest rate, stated percentage

9.50%

Senior Notes | Senior Unsecured Notes 2020 | GenOn Energy

Loss Contingencies

Interest rate, stated percentage

9.875%

Senior Notes | Senior Unsecured Notes 2021 | GenOn Americas Generation, LLC

Loss Contingencies

Interest rate, stated percentage

8.50%

Senior Notes | Senior Unsecured Notes 2031 | GenOn Americas Generation, LLC

Loss Contingencies

Interest rate, stated percentage

9.125%

Telephone Consumer Protection Act Purported Class Actions

Loss Contingencies

Damages sought, amount

$ 1,500

Class action lawsuits | lawsuit

3

CDWR and SDGE v Sunrise Power

Loss Contingencies

Damages sought, amount

$ 1,200,000

PPAs period

10 years

Remaining term

70 months

BTEC New Albany v. NRG Texas Power LLC

Loss Contingencies

Damages sought, amount

$ 48,000,000

Natural Gas Litigation

Loss Contingencies

Claims dismissed | case

1

Pending claims | Claim

5

Class action lawsuits | case

1

Midwest Generation New Source Review

Loss Contingencies

Number of coal-fired electric generating stations | generatingunit

6

Damages sought, amount

$ 37,500

Claims dismissed | Claim

9

9

Pending claims | Claim

10

10

1

Number of plaintiffs | Plaintiff

1

1

Lignite Contract with Texas Westmoreland Coal Co. | Texas Westmoreland Coal Co.

Loss Contingencies

Bond obligation

$ 95,500,000

$ 95,500,000

California | Telephone Consumer Protection Act Purported Class Actions

Loss Contingencies

Class action lawsuits | lawsuit

1

New Jersey | Telephone Consumer Protection Act Purported Class Actions

Loss Contingencies

Class action lawsuits | lawsuit

2

Minimum | Midwest Generation New Source Review

Loss Contingencies

Pending claims | Plaintiff

1

Maximum | Midwest Generation New Source Review

Loss Contingencies

Pending claims | Claim

10

Condensed Consolidating Finan80

Condensed Consolidating Financial Information - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term debt	$ 17,132	$ 16,703
Recourse Debt
Debt Instrument [Line Items]
Long-term debt	7,790	$ 7,795
Senior Notes | Recourse Debt
Debt Instrument [Line Items]
Long-term debt	$ 5,400

Condensed Consolidating Finan81

Condensed Consolidating Financial Information - STATEMENTS OF OPERATIONS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating Revenues
Total operating revenues	$ 3,049	$ 3,421	$ 8,132	$ 8,328
Operating Costs and Expenses
Cost of operations	2,156	2,440	5,852	5,711
Depreciation and amortization	272	298	789	826
Impairment losses	14	9	77	65
Selling, general and administrative	213	277	697	801
Reorganization	18	0	18	0
Development activity expenses	14	21	49	65
Total operating costs and expenses	2,687	3,045	7,482	7,468
Other income - affiliate	14	48	104	144
Gain/(loss) on sale of assets	0	4	4	(79)
Operating Income/(Loss)	376	428	758	925
Other Income/(Expense)
Equity in (losses)/earnings of consolidated subsidiaries	0	0	0	0
Equity in (losses)/earnings of unconsolidated affiliates	27	16	29	13
Impairment loss on investment	0	(8)	0	(147)
Other income/(loss), net	15	7	33	29
Loss on debt extinguishment	(1)	(50)	(3)	(119)
Interest expense	(221)	(237)	(692)	(718)
Total other (expense)/income	(180)	(272)	(633)	(942)
Income/(Loss) from Continuing Operations Before Income Taxes	196	156	125	(17)
Income tax expense/(benefit)	6	28	5	75
Income/(Loss) from Continuing Operations	190	128	120	(92)
(Loss)/Income from discontinued operations, net of income tax	(27)	265	(802)	256
Net Income/(Loss)	163	393	(682)	164
Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests	(8)	(9)	(63)	(49)
Net Income/(Loss) Attributable to NRG Energy, Inc.	171	402	(619)	213
Eliminations
Operating Revenues
Total operating revenues	(132)	(93)	(257)	(151)
Operating Costs and Expenses
Cost of operations	(129)	(93)	(254)	(154)
Depreciation and amortization	0	0	0	0
Impairment losses	0	0	0	0
Selling, general and administrative	(1)	0	(3)	0
Reorganization	0		0
Development activity expenses		0	0	0
Total operating costs and expenses	(130)	(93)	(257)	(154)
Other income - affiliate	0	0	0	0
Gain/(loss) on sale of assets		0	0	0
Operating Income/(Loss)	(2)	0	0	3
Other Income/(Expense)
Equity in (losses)/earnings of consolidated subsidiaries	184	(438)	309	(629)
Equity in (losses)/earnings of unconsolidated affiliates	(33)	(49)	(69)	(104)
Impairment loss on investment		0		0
Other income/(loss), net	0	0	0	(1)
Loss on debt extinguishment	0	0	0	0
Interest expense	0	0	0
Total other (expense)/income	151	(487)	240	(734)
Income/(Loss) from Continuing Operations Before Income Taxes	149	(487)	240	(731)
Income tax expense/(benefit)	0	0	0	0
Income/(Loss) from Continuing Operations	149	(487)	240	(731)
(Loss)/Income from discontinued operations, net of income tax	0	0	0	0
Net Income/(Loss)	149	(487)	240	(731)
Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests	(35)	(49)	(69)	(102)
Net Income/(Loss) Attributable to NRG Energy, Inc.	184	(438)	309	(629)
Guarantor Subsidiaries
Operating Revenues
Total operating revenues	2,160	2,424	5,517	6,079
Operating Costs and Expenses
Cost of operations	1,588	1,719	4,156	4,278
Depreciation and amortization	104	147	307	372
Impairment losses	0	8	42	8
Selling, general and administrative	97	115	281	306
Reorganization	0		0
Development activity expenses	0	0	0	0
Total operating costs and expenses	1,789	1,989	4,786	4,964
Other income - affiliate	0	0	0	0
Gain/(loss) on sale of assets		0	4	0
Operating Income/(Loss)	371	435	735	1,115
Other Income/(Expense)
Equity in (losses)/earnings of consolidated subsidiaries	(41)	(114)	(61)	(195)
Equity in (losses)/earnings of unconsolidated affiliates	0	2	0	5
Impairment loss on investment		0		0
Other income/(loss), net	7	1	8	3
Loss on debt extinguishment	0	0	0	0
Interest expense	(4)	(4)	(11)	(11)
Total other (expense)/income	(38)	(115)	(64)	(198)
Income/(Loss) from Continuing Operations Before Income Taxes	333	320	671	917
Income tax expense/(benefit)	113	134	244	362
Income/(Loss) from Continuing Operations	220	186	427	555
(Loss)/Income from discontinued operations, net of income tax	0	0	0	0
Net Income/(Loss)	220	186	427	555
Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests	0	0	0	0
Net Income/(Loss) Attributable to NRG Energy, Inc.	220	186	427	555
Non-Guarantor Subsidiaries
Operating Revenues
Total operating revenues	1,021	1,090	2,872	2,400
Operating Costs and Expenses
Cost of operations	682	804	1,904	1,558
Depreciation and amortization	160	144	458	435
Impairment losses	14	1	35	57
Selling, general and administrative	29	50	115	144
Reorganization	0		0
Development activity expenses	9	10	34	42
Total operating costs and expenses	894	1,009	2,546	2,236
Other income - affiliate	0	0	0	0
Gain/(loss) on sale of assets		0	0	0
Operating Income/(Loss)	127	81	326	164
Other Income/(Expense)
Equity in (losses)/earnings of consolidated subsidiaries	(9)	(10)	(66)	(80)
Equity in (losses)/earnings of unconsolidated affiliates	(606)	75	101	114
Impairment loss on investment		(8)		(147)
Other income/(loss), net	3	6	15	25
Loss on debt extinguishment	(1)	0	(3)	(4)
Interest expense	(103)	(104)	(328)	(312)
Total other (expense)/income	(716)	(41)	(281)	(404)
Income/(Loss) from Continuing Operations Before Income Taxes	(589)	40	45	(240)
Income tax expense/(benefit)	(209)	45	28	(49)
Income/(Loss) from Continuing Operations	(380)	(5)	17	(191)
(Loss)/Income from discontinued operations, net of income tax	(27)	263	(802)	248
Net Income/(Loss)	(407)	258	(785)	57
Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests	(3)	6	(49)	(17)
Net Income/(Loss) Attributable to NRG Energy, Inc.	(404)	252	(736)	74
NRG Energy, Inc. (Note Issuer)
Operating Revenues
Total operating revenues	0	0	0	0
Operating Costs and Expenses
Cost of operations	15	10	46	29
Depreciation and amortization	8	7	24	19
Impairment losses	0	0	0	0
Selling, general and administrative	88	112	304	351
Reorganization	18		18
Development activity expenses	5	11	15	23
Total operating costs and expenses	134	140	407	422
Other income - affiliate	14	48	104	144
Gain/(loss) on sale of assets		4	0	(79)
Operating Income/(Loss)	(120)	(88)	(303)	(357)
Other Income/(Expense)
Equity in (losses)/earnings of consolidated subsidiaries	(134)	562	(182)	904
Equity in (losses)/earnings of unconsolidated affiliates	666	(12)	(3)	(2)
Impairment loss on investment		0		0
Other income/(loss), net	5	0	10	2
Loss on debt extinguishment	0	(50)	0	(115)
Interest expense	(114)	(129)	(353)	(395)
Total other (expense)/income	423	371	(528)	394
Income/(Loss) from Continuing Operations Before Income Taxes	303	283	(831)	37
Income tax expense/(benefit)	102	(151)	(267)	(238)
Income/(Loss) from Continuing Operations	201	434	(564)	275
(Loss)/Income from discontinued operations, net of income tax	0	2	0	8
Net Income/(Loss)	201	436	(564)	283
Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests	30	34	55	70
Net Income/(Loss) Attributable to NRG Energy, Inc.	$ 171	$ 402	$ (619)	$ 213

Condensed Consolidating Finan82

Condensed Consolidating Financial Information - COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Condensed Financial Statements, Captions [Line Items]
Net income/(loss)	$ 163	$ 393	$ (682)	$ 164
Other Comprehensive Income/(Loss), net of tax
Unrealized (loss)/gain on derivatives, net	7	27	6	(8)
Foreign currency translation adjustments, net	2	3	10	6
Available-for-sale securities, net	1	0	2	1
Defined benefit plans, net	(1)	31	26	32
Other comprehensive income	9	61	44	31
Comprehensive income/(loss)	172	454	(638)	195
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest	(5)	(2)	(61)	(70)
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.	177	456	(577)	265
Dividends for preferred shares	0	0	0	5
Gain on redemption of preferred shares	0	0	0	78
Comprehensive income/(loss) available for common stockholders	177	456	(577)	338
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income/(loss)	149	(487)	240	(731)
Other Comprehensive Income/(Loss), net of tax
Unrealized (loss)/gain on derivatives, net	(7)	(39)	(7)	(39)
Foreign currency translation adjustments, net	(4)	(5)	(13)	(8)
Available-for-sale securities, net	0		0	0
Defined benefit plans, net	1	20	(28)	20
Other comprehensive income	(10)	(24)	(48)	(27)
Comprehensive income/(loss)	139	(511)	192	(758)
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest	(35)	(49)	(69)	(102)
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.	174	(462)	261	(656)
Dividends for preferred shares				0
Gain on redemption of preferred shares				0
Comprehensive income/(loss) available for common stockholders				(656)
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income/(loss)	220	186	427	555
Other Comprehensive Income/(Loss), net of tax
Unrealized (loss)/gain on derivatives, net	0	0	0	0
Foreign currency translation adjustments, net	2	2	7	4
Available-for-sale securities, net	0		0	0
Defined benefit plans, net	0	54	0	55
Other comprehensive income	2	56	7	59
Comprehensive income/(loss)	222	242	434	614
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest	0	0	0	0
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.	222	242	434	614
Dividends for preferred shares				0
Gain on redemption of preferred shares				0
Comprehensive income/(loss) available for common stockholders				614
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income/(loss)	(407)	258	(785)	57
Other Comprehensive Income/(Loss), net of tax
Unrealized (loss)/gain on derivatives, net	7	40	6	(15)
Foreign currency translation adjustments, net	2	2	7	4
Available-for-sale securities, net	0		0	0
Defined benefit plans, net	0	0	29	0
Other comprehensive income	9	42	42	(11)
Comprehensive income/(loss)	(398)	300	(743)	46
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest	0	13	(47)	(38)
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.	(398)	287	(696)	84
Dividends for preferred shares				0
Gain on redemption of preferred shares				0
Comprehensive income/(loss) available for common stockholders				84
NRG Energy, Inc. (Note Issuer)
Condensed Financial Statements, Captions [Line Items]
Net income/(loss)	201	436	(564)	283
Other Comprehensive Income/(Loss), net of tax
Unrealized (loss)/gain on derivatives, net	7	26	7	46
Foreign currency translation adjustments, net	2	4	9	6
Available-for-sale securities, net	1		2	1
Defined benefit plans, net	(2)	(43)	25	(43)
Other comprehensive income	8	(13)	43	10
Comprehensive income/(loss)	209	423	(521)	293
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest	30	34	55	70
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.	$ 179	$ 389	$ (576)	223
Dividends for preferred shares				5
Gain on redemption of preferred shares				78
Comprehensive income/(loss) available for common stockholders				$ 296

Condensed Consolidating Finan83

Condensed Consolidating Financial Information - BALANCE SHEETS (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Current Assets
Cash and cash equivalents	$ 1,223	$ 938	$ 1,217	$ 853
Funds deposited by counterparties	31	2	6	55
Restricted cash	537	446	$ 480	$ 414
Accounts receivable - trade, net	1,274	1,058
Accounts receivable - affiliate	54	114
Inventory	630	721
Derivative instruments	475	1,067
Cash collateral posted in support of energy risk management activities	203	150
Prepayments and other current assets	300	290
Current assets held-for-sale	33	9
Current assets - discontinued operations	0	1,919
Total current assets	4,760	6,714
Net property, plant and equipment	15,332	15,369
Other Assets
Investment in subsidiaries	0	0
Equity investments in affiliates	1,138	1,120
Notes receivable, less current portion	5	16
Goodwill	662	662
Intangible assets, net	1,838	1,973
Nuclear decommissioning trust fund	670	610
Derivative instruments	206	181
Deferred income taxes	205	225
Non-current assets held-for-sale	10	10
Other non-current assets	644	841
Non-current assets - discontinued operations	0	2,961
Total other assets	5,378	8,599
Total Assets	25,470	30,682
Current Liabilities
Current portion of long-term debt and capital leases	1,247	516
Accounts payable	915	782
Accounts payable — affiliate	(4)	31
Derivative instruments	522	1,092
Cash collateral received in support of energy risk management activities	31	81
Accrued expenses and other current liabilities	830	990
Accrued expenses and other current liabilities-affiliate	164	0
Current liabilities - discontinued operations	0	1,210
Total current liabilities	3,705	4,702
Other Liabilities
Long-term debt and capital leases	15,658	15,957
Nuclear decommissioning reserve	265	287
Nuclear decommissioning trust liability	397	339
Deferred income taxes	21	20
Derivative instruments	307	284
Out-of-market contracts, net	213	230
Non-current liabilities held-for-sale	13	11
Other non-current liabilities	1,116	1,176
Non-current liabilities - discontinued operations	0	3,184
Total non-current liabilities	17,990	21,488
Total Liabilities	21,695	26,190
Redeemable noncontrolling interest in subsidiaries	85	46
Stockholders’ Equity	3,690	4,446
Total Liabilities and Stockholders’ Equity	25,470	30,682
Eliminations
Current Assets
Cash and cash equivalents	0	0
Funds deposited by counterparties	0	0
Restricted cash	0	0
Accounts receivable - trade, net	0	0
Accounts receivable - affiliate	(337)	(139)
Inventory	0	0
Derivative instruments	(74)	(92)
Cash collateral posted in support of energy risk management activities	0	0
Prepayments and other current assets	0	0
Current assets held-for-sale	0	0
Current assets - discontinued operations		0
Total current assets	(411)	(231)
Net property, plant and equipment	(26)	(27)
Other Assets
Investment in subsidiaries	(11,511)	(12,272)
Equity investments in affiliates	0	0
Notes receivable, less current portion	0	0
Goodwill	0	0
Intangible assets, net	(3)	(3)
Nuclear decommissioning trust fund	0	0
Derivative instruments	(46)	(43)
Deferred income taxes	0	0
Non-current assets held-for-sale	0	0
Other non-current assets	0	0
Non-current assets - discontinued operations		0
Total other assets	(11,560)	(12,318)
Total Assets	(11,997)	(12,576)
Current Liabilities
Current portion of long-term debt and capital leases	0	0
Accounts payable	0	0
Accounts payable — affiliate	(338)	(139)
Derivative instruments	(74)	(92)
Cash collateral received in support of energy risk management activities	0	0
Accrued expenses and other current liabilities	0	0
Accrued expenses and other current liabilities-affiliate	0
Current liabilities - discontinued operations		0
Total current liabilities	(412)	(231)
Other Liabilities
Long-term debt and capital leases	0	0
Nuclear decommissioning reserve	0	0
Nuclear decommissioning trust liability	0	0
Deferred income taxes	0	0
Derivative instruments	(46)	(43)
Out-of-market contracts, net	0	0
Non-current liabilities held-for-sale	0	0
Other non-current liabilities	0	0
Non-current liabilities - discontinued operations		0
Total non-current liabilities	(46)	(43)
Total Liabilities	(458)	(274)
Redeemable noncontrolling interest in subsidiaries	0	0
Stockholders’ Equity	(11,539)	(12,302)
Total Liabilities and Stockholders’ Equity	(11,997)	(12,576)
Guarantor Subsidiaries
Current Assets
Cash and cash equivalents	(20)	(9)
Funds deposited by counterparties	29	2
Restricted cash	14	11
Accounts receivable - trade, net	876	734
Accounts receivable - affiliate	222	307
Inventory	406	482
Derivative instruments	438	962
Cash collateral posted in support of energy risk management activities	190	116
Prepayments and other current assets	108	76
Current assets held-for-sale	0	0
Current assets - discontinued operations		0
Total current assets	2,263	2,681
Net property, plant and equipment	3,980	4,219
Other Assets
Investment in subsidiaries	1,098	1,090
Equity investments in affiliates	0	(13)
Notes receivable, less current portion	0	0
Goodwill	359	359
Intangible assets, net	520	592
Nuclear decommissioning trust fund	670	610
Derivative instruments	187	144
Deferred income taxes	(5)	3
Non-current assets held-for-sale	0	0
Other non-current assets	63	67
Non-current assets - discontinued operations		0
Total other assets	2,892	2,852
Total Assets	9,135	9,752
Current Liabilities
Current portion of long-term debt and capital leases	0	0
Accounts payable	599	501
Accounts payable — affiliate	528	744
Derivative instruments	418	947
Cash collateral received in support of energy risk management activities	29	81
Accrued expenses and other current liabilities	301	316
Accrued expenses and other current liabilities-affiliate	0
Current liabilities - discontinued operations		0
Total current liabilities	1,875	2,589
Other Liabilities
Long-term debt and capital leases	244	244
Nuclear decommissioning reserve	265	287
Nuclear decommissioning trust liability	397	339
Deferred income taxes	428	186
Derivative instruments	194	157
Out-of-market contracts, net	69	80
Non-current liabilities held-for-sale	0	0
Other non-current liabilities	377	396
Non-current liabilities - discontinued operations		0
Total non-current liabilities	1,974	1,689
Total Liabilities	3,849	4,278
Redeemable noncontrolling interest in subsidiaries	0	0
Stockholders’ Equity	5,286	5,474
Total Liabilities and Stockholders’ Equity	9,135	9,752
Non-Guarantor Subsidiaries
Current Assets
Cash and cash equivalents	350	624
Funds deposited by counterparties	2	0
Restricted cash	523	435
Accounts receivable - trade, net	395	321
Accounts receivable - affiliate	191	(254)
Inventory	224	239
Derivative instruments	106	196
Cash collateral posted in support of energy risk management activities	13	34
Prepayments and other current assets	147	152
Current assets held-for-sale	33	9
Current assets - discontinued operations		1,919
Total current assets	1,984	3,675
Net property, plant and equipment	11,142	10,926
Other Assets
Investment in subsidiaries	1,004	1,054
Equity investments in affiliates	1,135	1,128
Notes receivable, less current portion	5	16
Goodwill	303	303
Intangible assets, net	1,321	1,384
Nuclear decommissioning trust fund	0	0
Derivative instruments	38	44
Deferred income taxes	(148)	0
Non-current assets held-for-sale	10	10
Other non-current assets	520	446
Non-current assets - discontinued operations		2,961
Total other assets	4,188	7,346
Total Assets	17,314	21,947
Current Liabilities
Current portion of long-term debt and capital leases	623	498
Accounts payable	285	247
Accounts payable — affiliate	(340)	(452)
Derivative instruments	178	237
Cash collateral received in support of energy risk management activities	2	0
Accrued expenses and other current liabilities	57	209
Accrued expenses and other current liabilities-affiliate	164
Current liabilities - discontinued operations		1,210
Total current liabilities	969	1,949
Other Liabilities
Long-term debt and capital leases	8,644	8,252
Nuclear decommissioning reserve	0	0
Nuclear decommissioning trust liability	0	0
Deferred income taxes	0	125
Derivative instruments	159	170
Out-of-market contracts, net	144	150
Non-current liabilities held-for-sale	13	11
Other non-current liabilities	315	456
Non-current liabilities - discontinued operations		3,184
Total non-current liabilities	9,275	12,348
Total Liabilities	10,244	14,297
Redeemable noncontrolling interest in subsidiaries	85	46
Stockholders’ Equity	6,985	7,604
Total Liabilities and Stockholders’ Equity	17,314	21,947
NRG Energy, Inc. (Note Issuer)
Current Assets
Cash and cash equivalents	893	323
Funds deposited by counterparties	0	0
Restricted cash	0	0
Accounts receivable - trade, net	3	3
Accounts receivable - affiliate	(22)	200
Inventory	0	0
Derivative instruments	5	1
Cash collateral posted in support of energy risk management activities	0	0
Prepayments and other current assets	45	62
Current assets held-for-sale	0	0
Current assets - discontinued operations		0
Total current assets	924	589
Net property, plant and equipment	236	251
Other Assets
Investment in subsidiaries	9,409	10,128
Equity investments in affiliates	3	5
Notes receivable, less current portion	0	0
Goodwill	0	0
Intangible assets, net	0	0
Nuclear decommissioning trust fund	0	0
Derivative instruments	27	36
Deferred income taxes	358	222
Non-current assets held-for-sale	0	0
Other non-current assets	61	328
Non-current assets - discontinued operations		0
Total other assets	9,858	10,719
Total Assets	11,018	11,559
Current Liabilities
Current portion of long-term debt and capital leases	624	18
Accounts payable	31	34
Accounts payable — affiliate	146	(122)
Derivative instruments	0	0
Cash collateral received in support of energy risk management activities	0	0
Accrued expenses and other current liabilities	472	465
Accrued expenses and other current liabilities-affiliate	0
Current liabilities - discontinued operations		0
Total current liabilities	1,273	395
Other Liabilities
Long-term debt and capital leases	6,770	7,461
Nuclear decommissioning reserve	0	0
Nuclear decommissioning trust liability	0	0
Deferred income taxes	(407)	(291)
Derivative instruments	0	0
Out-of-market contracts, net	0	0
Non-current liabilities held-for-sale	0	0
Other non-current liabilities	424	324
Non-current liabilities - discontinued operations		0
Total non-current liabilities	6,787	7,494
Total Liabilities	8,060	7,889
Redeemable noncontrolling interest in subsidiaries	0	0
Stockholders’ Equity	2,958	3,670
Total Liabilities and Stockholders’ Equity	$ 11,018	$ 11,559

Condensed Consolidating Finan84

Condensed Consolidating Financial Information - CASH FLOWS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Cash Flows from Operating Activities
Net Income/(Loss)	$ 163	$ 393	$ (682)	$ 164
(Loss)/Income from discontinued operations, net of income tax	(27)	265	(802)	256
Net income/(loss) from continuing operations	190	128	120	(92)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions from unconsolidated affiliates			53	57
Equity in losses/(earnings) of unconsolidated affiliates			(29)	(13)
Depreciation and amortization	272	298	789	826
Provision for bad debts			57	36
Amortization of nuclear fuel			37	39
Amortization of financing costs and debt discount/premiums			44	42
Adjustment for debt extinguishment			3	119
Amortization of intangibles and out-of-market contracts			79	131
Amortization of unearned equity compensation			27	23
Impairment losses			77	211
Changes in deferred income taxes and liability for uncertain tax benefits			26	29
Changes in nuclear decommissioning trust liability			20	24
Changes in derivative instruments			25	30
Changes in collateral posted in support of risk management activities			(103)	261
Proceeds from sale of emission allowances			21	11
Gain (loss) on sale of assets			(22)	70
Cash (used)/provided by changes in other working capital			(380)	(130)
Cash provided by continuing operations			844	1,674
Cash (used)/provided by discontinued operations			(38)	67
Net Cash Provided by Operating Activities			806	1,741
Cash Flows from Investing Activities
Dividends from NRG Yield, Inc.			0	0
Acquisition of Drop Down Assets, net of cash acquired			0	0
Intercompany dividends			0	0
Acquisitions of businesses, net of cash acquired			(36)	(18)
Capital expenditures			(760)	(659)
Increase (decrease) in notes receivable			11	2
Purchases of emission allowances			(47)	(32)
Proceeds from sale of emission allowances			105	47
Investments in nuclear decommissioning trust fund securities			(402)	(378)
Proceeds from the sale of nuclear decommissioning trust fund securities			382	354
Proceeds from renewable energy grants and state rebates			8	11
Proceeds from sale of assets, net of cash disposed of			36	84
Investments in unconsolidated affiliates			(31)	(23)
Other			22	31
Cash (used)/provided by continuing operations			(712)	(581)
Cash (used)/provided by discontinued operations			(53)	326
Net Cash (Used)/Provided by Investing Activities			(765)	(255)
Cash Flows from Financing Activities
Dividends from NRG Yield, Inc.			0	0
Payments from/(for) intercompany loans			0	0
Acquisition of assets, net of cash acquired			0	0
Intercompany dividends			0	0
Payment of dividends to common and preferred stockholders			(28)	(66)
Payment for preferred shares			0	(226)
Net receipts from settlement of acquired derivatives that include financing elements			2	6
Proceeds from issuance of long-term debt			1,134	5,237
Payments for short and long-term debt			(712)	(5,353)
Payments for debt extinguishment costs			0	(98)
Receivable from affiliate			(125)	0
Contributions from, net of distributions to, noncontrolling interest in subsidiaries			65	(127)
Proceeds from issuance of common stock			0	1
Payment of debt issuance costs			(43)	(70)
Other			(10)	(10)
Cash provided/(used) by continuing operations			283	(706)
Cash (used)/provided by discontinued operations			(224)	119
Net Cash provided/(used) by Financing Activities			59	(587)
Change in Cash from discontinued operations			(315)	512
Effect of exchange rate changes on cash and cash equivalents			(10)	(6)
Net Increase/(Decrease) in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties			405	381
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period			1,386	1,322
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	1,791	1,703	1,791	1,703
Eliminations
Cash Flows from Operating Activities
Net Income/(Loss)	149	(487)	240	(731)
(Loss)/Income from discontinued operations, net of income tax	0	0	0	0
Net income/(loss) from continuing operations	149	(487)	240	(731)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions from unconsolidated affiliates			(7)	(8)
Equity in losses/(earnings) of unconsolidated affiliates			69	10
Depreciation and amortization	0	0	0	0
Provision for bad debts			0	0
Amortization of nuclear fuel			0	0
Amortization of financing costs and debt discount/premiums			0	0
Adjustment for debt extinguishment			0	0
Amortization of intangibles and out-of-market contracts			0	0
Amortization of unearned equity compensation			0	0
Impairment losses			0	0
Changes in deferred income taxes and liability for uncertain tax benefits			0	0
Changes in nuclear decommissioning trust liability			0	0
Changes in derivative instruments			(8)	0
Changes in collateral posted in support of risk management activities			0	0
Proceeds from sale of emission allowances			0	0
Gain (loss) on sale of assets			0	0
Cash (used)/provided by changes in other working capital			(294)	729
Cash provided by continuing operations			0	0
Cash (used)/provided by discontinued operations			0	0
Net Cash Provided by Operating Activities			0	0
Cash Flows from Investing Activities
Dividends from NRG Yield, Inc.			(69)	(59)
Acquisition of Drop Down Assets, net of cash acquired			176	77
Intercompany dividends			(129)	(12)
Acquisitions of businesses, net of cash acquired			0	0
Capital expenditures			0	0
Increase (decrease) in notes receivable			0	0
Purchases of emission allowances			0	0
Proceeds from sale of 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 renewable energy grants and state rebates			0	0
Proceeds from sale of assets, net of cash disposed of			0	0
Investments in unconsolidated affiliates			0	0
Other			0	0
Cash (used)/provided by continuing operations			(22)	6
Cash (used)/provided by discontinued operations			0	0
Net Cash (Used)/Provided by Investing Activities			(22)	6
Cash Flows from Financing Activities
Dividends from NRG Yield, Inc.			69	59
Payments from/(for) intercompany loans			0	0
Acquisition of assets, net of cash acquired			(176)	(77)
Intercompany dividends			129	12
Payment of dividends to common and preferred stockholders			0	0
Payment for preferred shares				0
Net receipts from settlement of acquired derivatives that include financing elements			0	0
Proceeds from issuance of long-term debt			0	0
Payments for short and long-term debt			0	0
Payments for debt extinguishment costs				0
Receivable from affiliate			0
Contributions from, net of distributions to, noncontrolling interest in subsidiaries			0	0
Proceeds from issuance of common stock				0
Payment of debt issuance costs			0	0
Other			0	0
Cash provided/(used) by continuing operations			22	(6)
Cash (used)/provided by discontinued operations			0	0
Net Cash provided/(used) by Financing Activities			22	(6)
Change in Cash from discontinued operations			0	0
Effect of exchange rate changes on cash and cash equivalents			0	0
Net Increase/(Decrease) in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties			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)	220	186	427	555
(Loss)/Income from discontinued operations, net of income tax	0	0	0	0
Net income/(loss) from continuing operations	220	186	427	555
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions from unconsolidated affiliates			0	0
Equity in losses/(earnings) of unconsolidated affiliates			0	(5)
Depreciation and amortization	104	147	307	372
Provision for bad debts			40	31
Amortization of nuclear fuel			37	39
Amortization of financing costs and debt discount/premiums			0	0
Adjustment for debt extinguishment			0	0
Amortization of intangibles and out-of-market contracts			20	32
Amortization of unearned equity compensation			0	0
Impairment losses			42	8
Changes in deferred income taxes and liability for uncertain tax benefits			244	(134)
Changes in nuclear decommissioning trust liability			20	24
Changes in derivative instruments			(11)	(173)
Changes in collateral posted in support of risk management activities			(126)	268
Proceeds from sale of emission allowances			21	11
Gain (loss) on sale of assets			(22)	0
Cash (used)/provided by changes in other working capital			(958)	(827)
Cash provided by continuing operations			41	201
Cash (used)/provided by discontinued operations			0	0
Net Cash Provided by Operating Activities			41	201
Cash Flows from Investing Activities
Dividends from NRG Yield, Inc.			0	0
Acquisition of Drop Down Assets, net of cash acquired			0	0
Intercompany dividends			0	0
Acquisitions of businesses, net of cash acquired			0	0
Capital expenditures			(135)	(145)
Increase (decrease) in notes receivable			0	0
Purchases of emission allowances			(47)	(32)
Proceeds from sale of emission allowances			105	47
Investments in nuclear decommissioning trust fund securities			(402)	(378)
Proceeds from the sale of nuclear decommissioning trust fund securities			382	354
Proceeds from renewable energy grants and state rebates			8	0
Proceeds from sale of assets, net of cash disposed of			36	0
Investments in unconsolidated affiliates			0	2
Other			22	27
Cash (used)/provided by continuing operations			(31)	(125)
Cash (used)/provided by discontinued operations			0	0
Net Cash (Used)/Provided by Investing Activities			(31)	(125)
Cash Flows from Financing Activities
Dividends from NRG Yield, Inc.			0	0
Payments from/(for) intercompany loans			9	(2)
Acquisition of assets, net of cash acquired			0	0
Intercompany dividends			0	(52)
Payment of dividends to common and preferred stockholders			0	0
Payment for preferred shares				0
Net receipts from settlement of acquired derivatives that include financing elements			0	0
Proceeds from issuance of long-term debt			0	0
Payments for short and long-term debt			0	(2)
Payments for debt extinguishment costs				0
Receivable from affiliate			0
Contributions from, net of distributions to, noncontrolling interest in subsidiaries			0	0
Proceeds from issuance of common stock				0
Payment of debt issuance costs			0	0
Other			0	(3)
Cash provided/(used) by continuing operations			9	(59)
Cash (used)/provided by discontinued operations			0	0
Net Cash provided/(used) by Financing Activities			9	(59)
Change in Cash from discontinued operations			0	0
Effect of exchange rate changes on cash and cash equivalents			0	0
Net Increase/(Decrease) in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties			19	17
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period			4	0
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	23	17	23	17
Non-Guarantor Subsidiaries
Cash Flows from Operating Activities
Net Income/(Loss)	(407)	258	(785)	57
(Loss)/Income from discontinued operations, net of income tax	(27)	263	(802)	248
Net income/(loss) from continuing operations	(380)	(5)	17	(191)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions from unconsolidated affiliates			60	65
Equity in losses/(earnings) of unconsolidated affiliates			(101)	(20)
Depreciation and amortization	160	144	458	435
Provision for bad debts			2	5
Amortization of nuclear fuel			0	0
Amortization of financing costs and debt discount/premiums			31	25
Adjustment for debt extinguishment			3	102
Amortization of intangibles and out-of-market contracts			59	99
Amortization of unearned equity compensation			0	0
Impairment losses			35	203
Changes in deferred income taxes and liability for uncertain tax benefits			28	(90)
Changes in nuclear decommissioning trust liability			0	0
Changes in derivative instruments			32	206
Changes in collateral posted in support of risk management activities			23	(7)
Proceeds from sale of emission allowances			0	0
Gain (loss) on sale of assets			0	0
Cash (used)/provided by changes in other working capital			(523)	168
Cash provided by continuing operations			124	1,000
Cash (used)/provided by discontinued operations			(38)	67
Net Cash Provided by Operating Activities			86	1,067
Cash Flows from Investing Activities
Dividends from NRG Yield, Inc.			0	0
Acquisition of Drop Down Assets, net of cash acquired			(176)	(77)
Intercompany dividends			0	0
Acquisitions of businesses, net of cash acquired			(36)	(18)
Capital expenditures			(606)	(474)
Increase (decrease) in notes receivable			11	2
Purchases of emission allowances			0	0
Proceeds from sale of 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 renewable energy grants and state rebates			0	11
Proceeds from sale of assets, net of cash disposed of			0	67
Investments in unconsolidated affiliates			(31)	(25)
Other			0	(4)
Cash (used)/provided by continuing operations			(838)	(518)
Cash (used)/provided by discontinued operations			(53)	326
Net Cash (Used)/Provided by Investing Activities			(891)	(192)
Cash Flows from Financing Activities
Dividends from NRG Yield, Inc.			(69)	(59)
Payments from/(for) intercompany loans			417	(134)
Acquisition of assets, net of cash acquired			0	0
Intercompany dividends			(129)	40
Payment of dividends to common and preferred stockholders			0	0
Payment for preferred shares				0
Net receipts from settlement of acquired derivatives that include financing elements			2	6
Proceeds from issuance of long-term debt			920	1,097
Payments for short and long-term debt			(493)	(811)
Payments for debt extinguishment costs				(98)
Receivable from affiliate			(125)
Contributions from, net of distributions to, noncontrolling interest in subsidiaries			65	(127)
Proceeds from issuance of common stock				0
Payment of debt issuance costs			(38)	(17)
Other			(10)	(7)
Cash provided/(used) by continuing operations			540	(110)
Cash (used)/provided by discontinued operations			(224)	119
Net Cash provided/(used) by Financing Activities			316	9
Change in Cash from discontinued operations			(315)	512
Effect of exchange rate changes on cash and cash equivalents			(10)	(6)
Net Increase/(Decrease) in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties			(184)	366
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period			1,059	629
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	875	995	875	995
NRG Energy, Inc. (Note Issuer)
Cash Flows from Operating Activities
Net Income/(Loss)	201	436	(564)	283
(Loss)/Income from discontinued operations, net of income tax	0	2	0	8
Net income/(loss) from continuing operations	201	434	(564)	275
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions from unconsolidated affiliates			0	0
Equity in losses/(earnings) of unconsolidated affiliates			3	2
Depreciation and amortization	8	7	24	19
Provision for bad debts			15	0
Amortization of nuclear fuel			0	0
Amortization of financing costs and debt discount/premiums			13	17
Adjustment for debt extinguishment			0	17
Amortization of intangibles and out-of-market contracts			0	0
Amortization of unearned equity compensation			27	23
Impairment losses			0	0
Changes in deferred income taxes and liability for uncertain tax benefits			(246)	253
Changes in nuclear decommissioning trust liability			0	0
Changes in derivative instruments			12	(3)
Changes in collateral posted in support of risk management activities			0	0
Proceeds from sale of emission allowances			0	0
Gain (loss) on sale of assets			0	70
Cash (used)/provided by changes in other working capital			1,395	(200)
Cash provided by continuing operations			679	473
Cash (used)/provided by discontinued operations			0	0
Net Cash Provided by Operating Activities			679	473
Cash Flows from Investing Activities
Dividends from NRG Yield, Inc.			69	59
Acquisition of Drop Down Assets, net of cash acquired			0	0
Intercompany dividends			129	12
Acquisitions of businesses, net of cash acquired			0	0
Capital expenditures			(19)	(40)
Increase (decrease) in notes receivable			0	0
Purchases of emission allowances			0	0
Proceeds from sale of 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 renewable energy grants and state rebates			0	0
Proceeds from sale of assets, net of cash disposed of			0	17
Investments in unconsolidated affiliates			0	0
Other			0	8
Cash (used)/provided by continuing operations			179	56
Cash (used)/provided by discontinued operations			0	0
Net Cash (Used)/Provided by Investing Activities			179	56
Cash Flows from Financing Activities
Dividends from NRG Yield, Inc.			0	0
Payments from/(for) intercompany loans			(426)	136
Acquisition of assets, net of cash acquired			176	77
Intercompany dividends			0	0
Payment of dividends to common and preferred stockholders			(28)	(66)
Payment for preferred shares				(226)
Net receipts from settlement of acquired derivatives that include financing elements			0	0
Proceeds from issuance of long-term debt			214	4,140
Payments for short and long-term debt			(219)	(4,540)
Payments for debt extinguishment costs				0
Receivable from affiliate			0
Contributions from, net of distributions to, noncontrolling interest in subsidiaries			0	0
Proceeds from issuance of common stock				1
Payment of debt issuance costs			(5)	(53)
Other			0	0
Cash provided/(used) by continuing operations			(288)	(531)
Cash (used)/provided by discontinued operations			0	0
Net Cash provided/(used) by Financing Activities			(288)	(531)
Change in Cash from discontinued operations			0	0
Effect of exchange rate changes on cash and cash equivalents			0	0
Net Increase/(Decrease) in Cash and Cash Equivalents, Restricted Cash, and Funds Deposited by Counterparties			570	(2)
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period			323	693
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	$ 893	$ 691	$ 893	$ 691