NRG Energy (NRG) 10-Q 5 May 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2016	Apr. 30, 2016
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	Mar. 31, 2016
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		314,908,041
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016		Mar. 31, 2015
Operating Revenues
Total operating revenues	$ 3,229	[1]	$ 3,829	[2]
Operating Costs and Expenses
Cost of operations	2,189		3,063
Depreciation and amortization	313		395
Selling, general and administrative	255		265
Acquisition-related transaction and integration costs	2		10
Development activity expenses	26		34
Total operating costs and expenses	2,785		3,767
Gain on sale of assets and postretirement benefits curtailment	32		14
Operating Income	476		76
Other Income/(Expense)
Equity in losses of unconsolidated affiliates	(7)		(3)
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	(146)		0
Other income, net	18		19
Gain on debt extinguishment	11		0
Interest expense	(284)		(301)
Total other expense	(408)		(285)
Income/(Loss) Before Income Taxes	68		(209)
Income tax expense/(benefit)	21		(73)
Net Income/(Loss)	47		(136)
Less: Net (loss) attributable to noncontrolling interest and redeemable noncontrolling interests	(35)		(16)
Net Income/(Loss) Attributable to NRG Energy, Inc.	82		(120)
Dividends for preferred shares	5		5
Income/(Loss) Available for Common Stockholders	$ 77		$ (125)
Earnings/(Loss) per Share Attributable to NRG Energy, Inc. Common Stockholders
Weighted average number of common shares outstanding - basic	315		336
Earnings/(Loss) per Weighted Average Common Share — Basic	$ 0.24		$ (0.37)
Weighted average number of common shares outstanding — diluted	315		336
Earnings/(Loss) per Weighted Average Common Share — Diluted	$ 0.24		$ (0.37)
Dividends Per Common Share	$ 0.15		$ 0.15
[1]	(a) Operating revenues include inter-segment sales and net derivative gains and losses of:$251 $1 $5 $4 $66 $— $327(b) Includes gain on sale of assets$32 $— $— $— $— $— $32(c) Includes gain on debt extinguishment$— $— $— $— $11 $— $11(d) Includes net loss of $43 million related to residential solar
[2]	(a) Operating revenues include inter-segment sales and net derivative gains and losses of:$246 $— $— $— $34 $— $280(b) Includes gain on postretirement benefits curtailment $14 $— $— $— $— $— $14(c) Includes net loss of $45 million related to residential solar

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income/(Loss) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net Income/(Loss)	$ 47	$ (136)
Other Comprehensive Income/(Loss), net of tax
Unrealized loss on derivatives, net of income tax expense/(benefit) of $1 and ($6)	(32)	(12)
Foreign currency translation adjustments, net of income tax benefit of $0 and $(7)	6	(11)
Available-for-sale securities, net of income tax benefit of $0 and $(4)	3	(1)
Defined benefit plans, net of tax expense of $0 and $4	1	7
Other comprehensive loss	(22)	(17)
Comprehensive Income/(Loss)	25	(153)
Less: Comprehensive income/(loss) attributable to noncontrolling interest and redeemable noncontrolling interests	(52)	(29)
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.	77	(124)
Dividends for preferred shares	5	5
Comprehensive Income/(Loss) Available for Common Stockholders	$ 72	$ (129)

Condensed Consolidated Stateme4

Condensed Consolidated Statement of Comprehensive Loss Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Unrealized gain/loss on derivatives, income tax benefit	$ 1	$ (6)
Foreign currency translation adjustments, income tax benefit	0	(7)
Available-for-sale securities, income tax expense	0	(4)
Defined benefit plans, income tax expense	$ 0	$ 4

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Current Assets
Cash and cash equivalents	$ 1,659	$ 1,518
Funds deposited by counterparties	101	106
Restricted cash	387	414
Accounts receivable — trade, less allowance for doubtful accounts of $19 and $21	1,018	1,157
Inventory	1,161	1,252
Derivative instruments	2,113	1,915
Cash collateral paid in support of energy risk management activities	411	568
Renewable energy grant receivable, net	35	13
Disposal Group, Including Discontinued Operation, Other Assets, Current	0	6
Prepayments and other current assets	461	442
Total current assets	7,346	7,391
Property, plant and equipment, net of accumulated depreciation of $7,093 and $6,804	18,763	18,732
Other Assets
Equity investments in affiliates	898	1,045
Notes receivable, less current portion	40	53
Goodwill	999	999
Intangible assets, net of accumulated amortization of $1,592 and $1,525	2,256	2,310
Nuclear decommissioning trust fund	577	561
Derivative instruments	465	305
Deferred income taxes	185	167
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent	0	105
Other non-current assets	1,151	1,214
Total other assets	6,571	6,759
Total Assets	32,680	32,882
Current Liabilities
Current portion of long-term debt and capital leases	465	481
Accounts payable	845	869
Derivative instruments	1,947	1,721
Cash collateral received in support of energy risk management activities	100	106
Disposal Group, Including Discontinued Operation, Liabilities, Current	0	2
Accrued expenses and other current liabilities	981	1,196
Total current liabilities	4,338	4,375
Other Liabilities
Long-term debt and capital leases	18,677	18,983
Nuclear decommissioning reserve	330	326
Nuclear decommissioning trust liability	294	283
Deferred income taxes	37	19
Derivative instruments	627	493
Off-market Lease, Unfavorable	1,122	1,146
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent	0	4
Other non-current liabilities	1,547	1,488
Total non-current liabilities	22,634	22,742
Total Liabilities	26,972	27,117
2.822% convertible perpetual preferred stock	304	302
Redeemable noncontrolling interest in subsidiaries	23	29
Stockholders’ Equity
Common stock	4	4
Additional paid-in capital	8,299	8,296
Retained deficit	(2,977)	(3,007)
Less treasury stock, at cost — 102,450,781 and 102,749,908 shares, respectively	(2,406)	(2,413)
Accumulated other comprehensive loss	(195)	(173)
Noncontrolling interest	2,656	2,727
Total Stockholders’ Equity	5,381	5,434
Total Liabilities and Stockholders’ Equity	$ 32,680	$ 32,882

Condensed Consolidated Balance6

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Accounts receivable - trade, allowance for doubtful accounts	$ 19	$ 21
Property, plant and equipment, accumulated depreciation	7,093	6,804
Intangible assets, accumulated amortization	1,592	1,525
Accumulated Amortization of Out of Market Contracts	$ 687	$ 664
Convertible perpetual preferred stock, interest rate (as a percentage)	2.822%	2.822%
Treasury stock, shares (in shares)	102,450,781	102,749,908

Condensed Consolidated Stateme7

Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash Flows from Operating Activities
Net Income/(Loss)	$ 47	$ (136)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions and equity in earnings of unconsolidated affiliates	17	32
Depreciation and amortization	313	395
Provision for bad debts	10	15
Amortization of nuclear fuel	13	13
Amortization of financing costs and debt discount/premiums	1	(4)
Adjustment for debt extinguishment	(11)	0
Amortization of intangibles and out-of-market contracts	26	19
Amortization of unearned equity compensation	8	11
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	146	0
Changes in deferred income taxes and liability for uncertain tax benefits	(25)	(83)
Changes in nuclear decommissioning trust liability	9	(3)
Changes in derivative instruments	(50)	261
Changes in collateral deposits supporting energy risk management activities	156	(213)
Loss on sale of emission allowances	47	0
Gain on sale of assets and postretirement benefits curtailment	(32)	(14)
Cash used by changes in other working capital	(121)	(33)
Net Cash Provided/(Used) by Operating Activities	554	260
Cash Flows from Investing Activities
Acquisitions of businesses, net of cash acquired	(6)	(1)
Capital expenditures	(279)	(252)
Increase in restricted cash, net	(12)	(11)
Decrease in restricted cash to support equity requirements for U.S. DOE funded projects	39	25
Decrease in notes receivable	1	5
Purchases of emission allowances	12	0
Proceeds from sale of emission allowances	7	0
Investments in nuclear decommissioning trust fund securities	(200)	(193)
Proceeds from the sale of nuclear decommissioning trust fund securities	191	196
Proceeds from renewable energy grants and state rebates	8	2
Proceeds from sale of assets, net of cash disposed of	120	0
Investments in unconsolidated affiliates	(4)	(44)
Other	4	3
Net Cash Used by Investing Activities	(143)	(270)
Cash Flows from Financing Activities
Payment of dividends to common and preferred stockholders	(48)	(51)
Payment for treasury stock	0	(79)
Net receipts from/(payments for) settlement of acquired derivatives that include financing elements	39	40
Proceeds from issuance of long-term debt	61	248
Distributions from, net of contributions to, noncontrolling interest in subsidiaries	10	(25)
Proceeds from issuance of common stock	0	1
Payments for short and long-term debt	(316)	(94)
Other - contingent consideration	(10)	0
Net Cash (Used)/Provided by Financing Activities	(264)	40
Effect of exchange rate changes on cash and cash equivalents	(6)	18
Net Increase in Cash and Cash Equivalents	141	48
Cash and Cash Equivalents at Beginning of Period	1,518	2,116
Cash and Cash Equivalents at End of Period	$ 1,659	$ 2,164

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block]	Basis of Presentation NRG Energy, Inc., or NRG or the Company, is an integrated competitive power company, which produces, sells and delivers energy and energy products and services in major competitive power markets in the U.S. while positioning itself as a leader in the way residential, industrial and commercial consumers think about and use energy products and services. NRG has one of the nation's largest and most diverse competitive power generation portfolios balanced with the nation's largest competitive retail energy business. The Company owns and operates approximately 48,000 MWs 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 2015 Form 10-K. Interim results are not necessarily indicative of results for a full year. In the opinion of management, the accompanying unaudited interim condensed consolidated financial statements contain all material adjustments consisting of normal and recurring accruals necessary to present fairly the Company's consolidated financial position as of March 31, 2016, and the results of operations, comprehensive income/(loss) and cash flows for the three months ended March 31, 2016, and 2015. Use of Estimates The preparation of financial statements in conformity with U.S. 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	3 Months Ended
	Mar. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Other Cash Flow Information NRG’s investing activities exclude capital expenditures of $98 million which were accrued and unpaid at March 31, 2016 . Noncontrolling Interest The following table reflects the changes in NRG's noncontrolling interest balance: (In millions) Balance as of December 31, 2015 $ 2,727 Distributions to noncontrolling interest (42 ) Contributions from noncontrolling interest 12 Comprehensive loss attributable to noncontrolling interest (41 ) Balance as of March 31, 2016 $ 2,656 Redeemable Noncontrolling Interest The following table reflects the changes in the Company's redeemable noncontrolling interest balance for the three months ended March 31, 2016 : (In millions) Balance as of December 31, 2015 $ 29 Cash contributions from noncontrolling interest, net of distributions 5 Comprehensive loss attributable to noncontrolling interest (11 ) Balance as of March 31, 2016 $ 23 Recent Accounting Developments ASU 2016-09 — In March 2016, the FASB issued ASU 2016-09, Compensation - Stock Compensation (Topic 718), or ASU No. 2016-09. The amendments of ASU No. 2016-09 were issued as part of the FASB's Simplification Initiative focused on improving areas of GAAP for which cost and complexity may be reduced while maintaining or improving the usefulness of information disclosed within the financial statements. 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 guidance in ASU No. 2016-09 is effective for fiscal years beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted. The Company does not expect the standard to have a material impact on its results of operations, cash flows and financial position. ASU 2016-07 — In March 2016, the FASB issued ASU 2016-07, Investments - Equity Method and Joint Ventures (Topic 323), or ASU No. 2016-07. The amendments of ASU No. 2016-07 eliminate the requirement that when an investment qualifies for use of the equity method as a result of an increase in the level of ownership interest or degree of influence, an investor must adjust the investment, results of operations, and retained earnings retroactively on a step-by-step basis as if the equity method had been in effect during all previous periods that the investment had been held. The amendments require that the equity method investor add the cost of acquiring the additional interest in the investee to the current basis of the investor's previously held interest and adopt the equity method of accounting with no retroactive adjustment to the investment. In addition, ASU No. 2016-07 requires that an entity that has an available-for-sale equity security that becomes qualified for the equity method of accounting recognize through earnings the unrealized holding gain or loss in accumulated other comprehensive income at the date the investment becomes qualified for use of the equity method. The guidance in ASU No. 2016-07 is effective for fiscal years beginning after December 15, 2016, and interim periods within those annual periods. The adoption of ASU No. 2016-07 is required to be applied prospectively and early adoption is permitted. The Company does not expect the standard to have a material impact on its results of operations, cash flows and financial position. ASU 2016-02 — In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), or ASU No. 2016-02. The amendments of ASU 2016-02 complete the joint effort between the FASB and the International Accounting Standards Board, or IASB, to develop a common leasing standard for U.S. GAAP and International Financial Reporting Standards, or IFRS, 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. The guidance in ASU No. 2016-02 provides that a lessee that may have previously accounted for a lease as an operating lease under current U.S. GAAP should recognize the assets and liabilities that arise from a lease on the balance sheet. In addition, ASU No. 2016-02 expands the required quantitative and qualitative disclosures with regards to lease arrangements. The guidance in ASU No. 2016-02 is effective for fiscal years beginning after December 15, 2018, and interim periods within those annual periods. The adoption of ASU 2016-02 is required to be applied using a modified retrospective approach for the earliest period presented and early adoption is permitted. The Company is currently evaluating the impact of the standard on the Company's results of operations, cash flows and financial position. ASU 2016-01 — In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, or ASU No. 2016-01. The amendments of ASU No. 2016-01 eliminate available-for-sale classification of equity investments and require that equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) to be generally measured at fair value with changes in fair value recognized in net income. Further, the amendments require that financial assets and financial liabilities to be presented separately in the notes to the financial statements, grouped by measurement category and form of financial asset. The guidance in ASU No. 2016-01 is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those annual periods. The Company is currently evaluating the impact of the standard on the Company's results of operations, cash flows and financial position. ASU 2015-16 — In September 2015, the FASB issued ASU No. 2015-16, Business Combinations (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments , or ASU No. 2015-16. The amendments of ASU No. 2015-16 require that an acquirer recognize measurement period adjustments to the provisional amounts recognized in a business combination in the reporting period during which the adjustments are determined. Additionally, the amendments of ASU No. 2015-16 require the acquirer to record in the same period's financial statements the effect on earnings of changes in depreciation, amortization or other income effects, if any, as a result of the measurement period adjustment, calculated as if the accounting had been completed at the acquisition date as well as disclosing either on the face of the income statement or in the notes the portion of the amount recorded in current period earnings that would have been recorded in previous reporting periods. The guidance in ASU No. 2015-16 is effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. The amendments should be applied prospectively. The Company adopted ASU No. 2015-16 for the year ended December 31, 2016, and the adoption did not have a material impact on the Company's results of operations, cash flows and financial position. ASU 2014-09 — In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), or ASU No. 2014-09. The amendments of ASU No. 2014-09 complete the joint effort between the FASB and the IASB, to develop a common revenue standard for U.S. GAAP and IFRS, and to improve financial reporting. The guidance in ASU No. 2014-09 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 the following steps to be applied by an entity: (1) identify the contract with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when (or as) the entity satisfies the performance obligation. In August 2015, the FASB issued ASU 2015-14, which formally deferred the effective date by one year to make the guidance of ASU No. 2014-09 effective for annual reporting periods beginning after December 15, 2017, including interim periods therein. Early adoption is permitted, but not prior to the original effective date, which was for annual reporting periods beginning after December 15, 2016. In March 2016, the FASB issued ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606), or ASU No. 2016-08. The amendments of ASU No. 2016-08 clarify how to apply the implementation guidance on principal versus agent considerations related to the sale of goods or services to a customer as updated by ASU No. 2014-09. In April 2016, the FASB issued ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606), or ASU No. 2016-10. The amendments of ASU No. 2016-10 provide further clarification on contract revenue recognition as updated by ASU No. 2014-09, specifically related to the identification of separately identifiable performance obligations and the implementation of licensing contracts. The Company is currently evaluating the impact of the standard on the Company's results of operations, cash flows and financial position.

Business Acquisitions and Dispo

Business Acquisitions and Dispositions	3 Months Ended
	Mar. 31, 2016
Business Combinations [Abstract]
Mergers, Acquisitions and Dispositions Disclosures [Text Block]	Business Acquisitions and Dispositions The Company has completed the following business acquisitions and dispositions that are material to the Company's financial statements: Acquisitions 2015 Acquisition of Desert Sunlight On June 29, 2015, NRG Yield, Inc., through its subsidiary Yield Operating, acquired 25% of the membership interest in Desert Sunlight Investment Holdings, LLC, which owns two solar photovoltaic facilities that total 550 MW located in Desert Center, California from EFS Desert Sun, LLC, an affiliate of GE Energy Financial Services, for a purchase price of $285 million . The Company accounts for its 25% investment as an equity method investment. Dispositions Seward Disposition On November 24, 2015, GenOn entered into an agreement with Robindale Energy Services, Inc. to sell 100% of its interest in Seward Generation, LLC, or Seward, for cash consideration of $75 million . Seward owns a 525 MW coal-fired facility in Pennsylvania. At December 31, 2015, GenOn had $5 million of current assets, $83 million of non-current assets, $1 million of current liabilities and $4 million of non-current liabilities classified as held for sale for Seward on its balance sheet. On February 2, 2016, GenOn completed the sale of Seward and received gross cash proceeds of $75 million excluding $3 million cash on hand transferred to the buyer. GenOn will also receive $5 million in deferred cash consideration in five $1 million annual installments and up to $2.5 million in payments contingent upon future environmental testing. In addition, Robindale committed to future inventory purchases from GenOn of $13 million through 2019. Shelby Disposition On November 9, 2015, GenOn entered into an agreement with Rockland Power Partners II, LP to sell 100% of its interest in the Shelby County Energy Center, LLC, or Shelby for cash consideration of $46 million . Shelby owns a 352 MW natural gas-fired facility located in Illinois. At December 31, 2015, GenOn had $1 million of current assets, $22 million of non-current assets, and $1 million of current liabilities classified as held for sale for Shelby on its balance sheet. On March 1, 2016, GenOn completed the sale of Shelby for cash proceeds of $46 million , which resulted in a gain of $29 million recognized within GenOn's consolidated results of operations during the first quarter of 2016. In addition, GenOn retained $10 million related to future revenue rights retained as part of the agreement. Transfer of Assets under Common Control On November 3, 2015, the Company sold 75% of the Class B interests of NRG Wind TE Holdco, which owns a portfolio of 12 wind facilities totaling 814 net MW, to NRG Yield, Inc. NRG Yield, Inc. paid total cash consideration of $209 million , subject to working capital adjustments. NRG Yield, Inc. is responsible for its pro-rata share of non-recourse project debt of $193 million and noncontrolling interest associated with a tax equity structure of $159 million (as of the acquisition date). In February 2016, the company made a final working capital payment of $2 million to NRG Yield, Inc. reducing total cash consideration to $207 million . On January 2, 2015, the Company sold the following facilities to NRG Yield, Inc.: Walnut Creek, the Tapestry projects (Buffalo Bear, Pinnacle and Taloga) and Laredo Ridge. NRG Yield, Inc. paid total cash consideration of $489 million , including $9 million of working capital adjustments, plus assumed project level debt of $737 million .

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2016
Fair Value of Financial Instruments Disclosure [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 2015 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 March 31, 2016 As of December 31, 2015 Carrying Amount Fair Value Carrying Amount Fair Value (In millions) Assets: Notes receivable (a) $ 57 $ 57 $ 73 $ 73 Liabilities: Long-term debt, including current portion (b) 19,288 18,116 19,620 18,263 (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. 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 March 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 12 — — 12 Other (a) 11 — — 11 Nuclear trust fund investments: Cash and cash equivalents 17 — — 17 U.S. government and federal agency obligations 64 1 — 65 Federal agency mortgage-backed securities — 69 — 69 Commercial mortgage-backed securities — 20 — 20 Corporate debt securities — 72 — 72 Equity securities 281 — 52 333 Foreign government fixed income securities — 1 — 1 Other trust fund investments: U.S. government and federal agency obligations 1 — — 1 Derivative assets: Commodity contracts 624 1,790 164 2,578 Total assets $ 1,010 $ 1,953 $ 233 $ 3,196 Derivative liabilities: Commodity contracts 902 1,306 181 2,389 Interest rate contracts — 185 — 185 Total liabilities $ 902 $ 1,491 $ 181 $ 2,574 (a) Consists primarily of mutual funds held in a Rabbi Trust for non-qualified deferred compensation plans for certain former employees. As of December 31, 2015 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 9 — — 9 Other (a) 14 — — 14 Nuclear trust fund investments: Cash and cash equivalents 6 — — 6 U.S. government and federal agency obligations 54 1 — 55 Federal agency mortgage-backed securities — 59 — 59 Commercial mortgage-backed securities — 25 — 25 Corporate debt securities — 81 — 81 Equity securities 280 — 54 334 Foreign government fixed income securities — 1 — 1 Other trust fund investments: U.S. government and federal agency obligations 1 — — 1 Derivative assets: Commodity contracts 622 1,449 149 2,220 Total assets $ 986 $ 1,616 $ 220 $ 2,822 Derivative liabilities: Commodity contracts 868 1,036 182 2,086 Interest rate contracts — 128 — 128 Total liabilities $ 868 $ 1,164 $ 182 $ 2,214 (a) Primarily consists of mutual funds held in rabbi trusts for non-qualified deferred compensation plans for certain former employees and a total return swap that does not meet the definition of a derivative. There were no transfers during the three months ended March 31, 2016 , and 2015 between Levels 1 and 2. The following tables reconcile, for the three months ended March 31, 2016 , and 2015 , the beginning and ending balances for financial instruments that are recognized at fair value in the consolidated financial statements, at least annually, using significant unobservable inputs: Fair Value Measurement Using Significant Unobservable Inputs (Level 3) Three months ended March 31, 2016 (In millions) Debt Securities Trust Fund Investments Derivatives (a) Total Beginning balance $ 17 $ 54 $ (33 ) $ 38 Total gains/(losses) — realized/unrealized: Included in earnings — — (17 ) (17 ) Included in nuclear decommissioning obligation — (2 ) — (2 ) Purchases — — 5 5 Transfers into Level 3 (b) — — 27 27 Transfers out of Level 3 (b) — — 1 1 Ending balance as of March 31, 2016 $ 17 $ 52 $ (17 ) $ 52 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 March 31. 2016 $ — $ — $ (24 ) $ (24 ) (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 March 31, 2015 (In millions) Debt Securities Other Trust Fund Investments Derivatives (a) Total Beginning balance $ 18 $ 11 $ 52 $ 80 $ 161 Total gains/(losses) — realized/unrealized: Included in earnings — — — (55 ) (55 ) Included in nuclear decommissioning obligations — — 2 — 2 Purchases — — — (4 ) (4 ) Transfers into Level 3 (b) — — — 15 15 Transfers out of Level 3 (b) — — — (2 ) (2 ) Ending balance as of March 31, 2015 $ 18 $ 11 $ 54 $ 34 $ 117 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 March 31, 2015 $ — $ — $ — $ (20 ) $ (20 ) (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 March 31, 2016 , contracts valued with prices provided by models and other valuation techniques make up 6% of the total derivative assets and 7% of the total derivative liabilities. NRG's significant positions classified as Level 3 include physical and financial power and physical coal executed in illiquid markets as well as financial transmission rights, or FTRs. The significant unobservable inputs used in developing fair value include illiquid power and coal location pricing which is derived as a basis to liquid locations. The basis spread is based on observable market data when available or derived from historic prices and forward market prices from similar observable markets when not available. For FTRs, NRG uses the most recent auction prices to derive the fair value. The following tables quantify the significant unobservable inputs used in developing the fair value of the Company's Level 3 positions as of March 31, 2016 and December 31, 2015 : Significant Unobservable Inputs March 31, 2016 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) Power Contracts $ 120 $ 115 Discounted Cash Flow Forward Market Price (per MWh) $ 9 $ 95 $ 25 Coal Contracts — 15 Discounted Cash Flow Forward Market Price (per ton) 28 41 33 FTRs 44 51 Discounted Cash Flow Auction Prices (per MWh) (62 ) 51 — $ 164 $ 181 Significant Unobservable Inputs December 31, 2015 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) Power Contracts $ 86 $ 100 Discounted Cash Flow Forward Market Price (per MWh) $ 10 $ 92 $ 27 Coal Contracts — 12 Discounted Cash Flow Forward Market Price (per ton) 28 45 35 FTRs 63 70 Discounted Cash Flow Auction Prices (per MWh) (98 ) 87 — $ 149 $ 182 The following table provides sensitivity of fair value measurements to increases/(decreases) in significant unobservable inputs as of March 31, 2016 and December 31, 2015 : Significant Unobservable Input Position Change In Input Impact on Fair Value Measurement Forward Market Price Power/Coal Buy Increase/(Decrease) Higher/(Lower) Forward Market Price Power/Coal Sell Increase/(Decrease) Lower/(Higher) FTR Prices Buy Increase/(Decrease) Higher/(Lower) FTR Prices Sell Increase/(Decrease) Lower/(Higher) The fair value of each contract is discounted using a risk-free interest rate. In addition, the Company applies a credit reserve to reflect credit risk, which is calculated based on published default probabilities. As of March 31, 2016 , the credit reserve resulted in a $5 million increase in fair value, which is composed of a $3 million gain in OCI and a $2 million gain in operating revenue and cost of operations. As of March 31, 2015 , the credit reserve resulted in a $5 million increase in fair value, which was composed of a $3 million gain in OCI and a $2 million gain in operating revenues 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 2015 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 2015 Form 10-K. As of March 31, 2016 , counterparty credit exposure, excluding credit risk exposure under certain long term agreements, was $887 million and NRG held collateral (cash and letters of credit) against those positions of $204 million , resulting in a net exposure of $686 million . Approximately 92% of the Company's exposure before collateral is expected to roll off by the end of 2017 . 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) Category (% of Total) Financial institutions 51 % Utilities, energy merchants, marketers and other 35 ISOs 14 Total as of March 31, 2016 100 % Net Exposure (a) Category (% of Total) Investment grade 97 % Non-rated (b) 2 Non-investment grade 1 Total as of March 31, 2016 100 % (a) Counterparty credit exposure excludes uranium and coal transportation contracts because of the unavailability of market prices. (b) For non-rated counterparties, a significant portion are related to ISO and municipal public power entities, which are considered investment grade equivalent ratings based on NRG's internal credit ratings. 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 $223 million as of March 31, 2016 . 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. Counterparty credit exposure described above excludes credit risk exposure under certain long term agreements, including California tolling agreements, Gulf Coast load obligations, wind and solar PPAs, and a coal supply agreement. 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 March 31, 2016 , aggregate credit risk exposure managed by NRG to these counterparties was approximately $4.5 billion , including $2.7 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 and other technology and market factors, which NRG is unable to predict. In the case of the coal supply agreement, NRG holds a lien against the underlying asset, which significantly reduces the risk of loss. 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 March 31, 2016 , 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	3 Months Ended
	Mar. 31, 2016
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 2015 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 March 31, 2016 As of December 31, 2015 (In millions, except otherwise noted) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Cash and cash equivalents $ 17 $ — $ — — $ 6 $ — $ — — U.S. government and federal agency obligations 65 4 — 11 55 1 — 11 Federal agency mortgage-backed securities 69 2 — 23 59 1 — 25 Commercial mortgage-backed securities 20 — 1 28 25 — 2 28 Corporate debt securities 72 2 1 11 81 1 1 10 Equity securities 333 198 — — 334 199 — — Foreign government fixed income securities 1 — — 8 1 — — 9 Total $ 577 $ 206 $ 2 $ 561 $ 202 $ 3 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. Three months ended March 31, 2016 2015 (In millions) Realized gains $ 4 $ 6 Realized losses 3 2 Proceeds from sale of securities 191 196

Accounting for Derivative Instr

Accounting for Derivative Instruments and Hedging Activities	3 Months Ended
	Mar. 31, 2016
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 2015 Form 10-K. Energy-Related Commodities As of March 31, 2016 , NRG had energy-related derivative instruments extending through 2024. The Company voluntarily de-designated all remaining commodity cash flow hedges as of January 1, 2014, and prospectively marked these derivatives to market through the income statement. 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 March 31, 2016 , the Company had interest rate derivative instruments on non-recourse debt extending through 2032, 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 March 31, 2016 , and December 31, 2015 . 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 March 31, 2016 December 31, 2015 Category Units (In millions) Emissions Short Ton 1 1 Coal Short Ton 29 35 Natural Gas MMBtu 223 293 Oil Barrel 1 1 Power MWh (49 ) (74 ) Capacity MW/Day (1 ) (1 ) Interest Dollars $ 2,284 $ 2,326 Equity Shares 1 1 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 March 31, 2016 December 31, 2015 March 31, 2016 December 31, 2015 (In millions) Derivatives designated as cash flow hedges: Interest rate contracts current $ — $ — $ 41 $ 42 Interest rate contracts long-term — — 115 68 Total derivatives designated as cash flow hedges — — 156 110 Derivatives not designated as cash flow hedges : Interest rate contracts current — — 5 5 Interest rate contracts long-term — — 24 13 Commodity contracts current 2,113 1,915 1,901 1,674 Commodity contracts long-term 465 305 488 412 Total derivatives not designated as cash flow hedges 2,578 2,220 2,418 2,104 Total derivatives $ 2,578 $ 2,220 $ 2,574 $ 2,214 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 March 31, 2016 (In millions) Commodity contracts: Derivative assets $ 2,578 $ (2,000 ) $ (99 ) $ 479 Derivative liabilities (2,389 ) 2,000 186 (203 ) Total commodity contracts 189 — 87 276 Interest rate contracts: Derivative liabilities (185 ) — — (185 ) Total derivative instruments $ 4 $ — $ 87 $ 91 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, 2015 (In millions) Commodity contracts: Derivative assets $ 2,220 $ (1,616 ) $ (113 ) $ 491 Derivative liabilities (2,086 ) 1,616 271 (199 ) Total commodity contracts 134 — 158 292 Interest rate contracts: Derivative liabilities (128 ) — — (128 ) Total derivative instruments $ 6 $ — $ 158 $ 164 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: Three months ended March 31, 2016 Energy Commodities Interest Rate Total (In millions) Accumulated OCI beginning balance $ — $ (101 ) $ (101 ) Reclassified from accumulated OCI to income: Due to realization of previously deferred amounts — 3 3 Mark-to-market of cash flow hedge accounting contracts — (52 ) (52 ) Accumulated OCI ending balance, net of $24 tax $ — $ (150 ) $ (150 ) Losses expected to be realized from OCI during the next 12 months, net of $3 tax $ — $ (20 ) $ (20 ) Three months ended March 31, 2015 Energy Commodities Interest Rate Total (In millions) Accumulated OCI beginning balance $ (1 ) $ (67 ) $ (68 ) Reclassified from accumulated OCI to income: Due to realization of previously deferred amounts — 2 2 Mark-to-market of cash flow hedge accounting contracts — (18 ) (18 ) Accumulated OCI ending balance, net of $50 tax $ (1 ) $ (83 ) $ (84 ) Amounts reclassified from accumulated OCI into income and amounts recognized in income from the ineffective portion of cash flow hedges are recorded to operating revenue for commodity contracts and interest expense for interest rate contracts. There was no ineffectiveness for the three months ended March 31, 2016 , and 2015 . 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 earnings. 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 March 31, 2016 2015 Unrealized mark-to-market results (In millions) Reversal of previously recognized unrealized gains on settled positions related to economic hedges $ (86 ) $ (114 ) Reversal of acquired gain positions related to economic hedges (13 ) (26 ) Net unrealized gains/(losses) on open positions related to economic hedges 134 (138 ) Total unrealized mark-to-market gains/(losses) for economic hedging activities 35 (278 ) Reversal of previously recognized unrealized losses/(gains) on settled positions related to trading activity 8 (21 ) Reversal of acquired gain positions related to trading activity — (7 ) Net unrealized gains on open positions related to trading activity 11 6 Total unrealized mark-to-market gains/(losses) for trading activity 19 (22 ) Total unrealized gains/(losses) $ 54 $ (300 ) Three months ended March 31, 2016 2015 (In millions) Unrealized gains/(losses) included in operating revenues $ 45 $ (109 ) Unrealized gains/(losses) included in cost of operations 9 (191 ) Total impact to statement of operations — energy commodities $ 54 $ (300 ) Total impact to statement of operations — interest rate contracts $ (11 ) $ (14 ) 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 revenue or cost of operations during the same period. For the three months ended March 31, 2016 , the $134 million unrealized gain from open economic hedge positions was primarily the result of an increase in value of forward sales of power due to decreases in electricity prices partially offset by a decrease in value of forward purchases of coal due to decreases in coal prices. For the three months ended March 31, 2015 , the $138 million unrealized loss from open economic hedge positions was primarily the result of a decrease in value of forward purchases of coal due to decreases in coal 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 March 31, 2016 , was $126 million . The collateral required for contracts with credit rating contingent features as of March 31, 2016 , was $15 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 $6 million as of March 31, 2016 . See Note 4 , Fair Value of Financial Instruments , to this Form 10-Q for discussion regarding concentration of credit risk.

Impairments Impairments

Impairments Impairments	3 Months Ended
	Mar. 31, 2016
Asset Impairment Charges [Abstract]
Asset Impairment Charges [Text Block]	Impairments Petra Nova Parish Holdings — During the first quarter of 2016, management changed its decisions 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	3 Months Ended
	Mar. 31, 2016
Long Term 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 2015 Form 10-K. Long-term debt and capital leases consisted of the following: (In millions, except rates) March 31, 2016 December 31, 2015 March 31, 2016 interest rate % (a) Recourse debt: Senior notes, due 2018 $ 958 $ 1,039 7.625 Senior notes, due 2020 1,058 1,058 8.250 Senior notes, due 2021 1,128 1,128 7.875 Senior notes, due 2022 1,060 1,100 6.250 Senior notes, due 2023 910 936 6.625 Senior notes, due 2024 848 904 6.250 Term loan facility, due 2018 1,959 1,964 L+2.00 Tax-exempt bonds 455 455 4.125 - 6.00 Subtotal NRG recourse debt 8,376 8,584 Non-recourse debt: GenOn senior notes 1,945 1,956 7.875 - 9.875 GenOn Americas Generation senior notes 750 752 8.500 - 9.125 GenOn Other 55 56 Subtotal GenOn debt (non-recourse to NRG) 2,750 2,764 Yield Operating LLC Senior Notes, due 2024 500 500 5.375 Yield LLC and Yield Operating LLC Revolving Credit Facility, due 2019 316 306 L+2.75 Yield Inc. Convertible Senior Notes, due 2019 332 330 3.500 Yield Inc. Convertible Senior Notes, due 2020 267 266 3.250 El Segundo Energy Center, due 2023 457 485 L+1.625 - L+2.25 Marsh Landing, due 2017 and 2023 410 418 L+1.175 - L+1.875 Alta Wind I - V lease financing arrangements, due 2034 and 2035 1,002 1,002 5.696 - 7.015 Walnut Creek, term loans due 2023 344 351 L+1.625 Tapestry, due 2021 178 181 L+1.625 Laredo Ridge, due 2028 103 104 L+1.875 Alpine, due 2022 153 154 L+1.750 Energy Center Minneapolis, due 2017 and 2025 107 108 5.95 - 7.25 Viento, due 2023 189 189 L+2.75 NRG Yield - other 463 469 various Subtotal NRG Yield debt (non-recourse to NRG) 4,821 4,863 Ivanpah, due 2033 and 2038 1,145 1,149 2.285 - 4.256 Agua Caliente, due 2037 877 879 2.395 - 3.633 CVSR, due 2037 780 793 2.339 - 3.775 Dandan, due 2033 102 98 L+2.25 Peaker bonds, due 2019 72 72 L+1.07 Cedro Hill, due 2025 102 103 L+3.125 NRG Other 263 315 various Subtotal other NRG non-recourse debt 3,341 3,409 Subtotal all non-recourse debt 10,912 11,036 Subtotal long-term debt (including current maturities) 19,288 19,620 Capital leases: Capital leases 15 13 various Other 3 3 various Subtotal long-term debt and capital leases (including current maturities) 19,306 19,636 Less current maturities 465 481 Less debt issuance costs 164 172 Total long-term debt and capital leases $ 18,677 $ 18,983 (a) As of March 31, 2016 , L+ equals 3 month LIBOR plus x%, with the exception of the Viento Funding II term loan, which is 6 month LIBOR plus x%, and the NRG Marsh Landing term loan, Walnut Creek term loan, and NRG Yield Operating LLC revolving credit facility, which are 1 month LIBOR plus x%. NRG Recourse Debt Senior Notes 2016 Senior Notes Repurchases During the first quarter of 2016, the Company repurchased $203 million in aggregate principal of its Senior Notes in the open market for $192 million , which included accrued interest of $3 million . In connection with the repurchases, an $11 million gain on debt extinguishment was recorded. Principal Repurchased Cash Paid (a) Average Early Redemption Percentage Amount in millions, except rates 7.625% senior notes due 2018 $ 81 $ 84 103.222 % 6.625% senior notes due 2023 26 23 88.505 % 6.250% senior notes due 2022 40 36 87.000 % 6.250% senior notes due 2024 56 49 87.060 % Total $ 203 $ 192 (a) Includes accrued interest. Yield LLC and 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 or for the issuance of letters of credit. At March 31, 2016 , there was $316 million outstanding and $60 million of letters of credit issued under the revolving credit facility. Project Financings High Lonesome Mesa Facility Prior to the Company's acquisition of EME, an intercompany tax credit agreement related to the High Lonesome Mesa facility was terminated. The termination resulted in an event of default under the project financing arrangement. The Company received additional default notices for various items. The facility is secured by the assets of High Lonesome Mesa and is non-recourse to NRG. On November 3, 2015, the lender sent a notice of acceleration and indicated that it would accept the Company's interest in the assets in lieu of repayment. On January 27, 2016, High Lonesome Mesa, LLC, or HLM, filed at FERC for approval to transfer 100% of the ownership interests in HLM to subsidiaries of the lien holders (Macquarie Bank Limited and Hannon Armstrong Capital, LLC). On March 2, 2016 HLM received FERC approval and on March 31, 2016 the Company transferred 100% of its interest in HLM to the lien holders and deconsolidated HLM. Dandan Financing In December 2013, NRG, through its wholly-owned subsidiary, NRG Solar Dandan LLC, or Dandan, entered into a credit agreement with a bank, or the Dandan Financing Agreement, for an $81 million construction loan and a $23 million cash grant loan. The construction loans have interest rates of LIBOR plus an applicable margin of 2.25% or base rate plus 1.25% and the cash grant loans have an interest rate of LIBOR plus an applicable margin of 1.75% . The term loan has an interest rate of LIBOR plus an applicable margin of 2.25% , which escalates 0.25% on the fifth, tenth, and fifteenth anniversary of the term conversion. The term loan, which is secured by all the assets of Dandan, matures January 2033, and amortizes based upon a predetermined schedule. The Dandan Financing Agreement also includes a letter of credit facility on behalf of Dandan of up to $5 million . Dandan pays an availability fee of 2.25% from the closing date until the 5th anniversary of the term conversion date and 2.50% from the 5th anniversary of the term conversion date on issued letters of credit. On January 29, 2016, the construction loan converted to a $79 million term loan with $23 million outstanding under the cash grant loan. In addition, a $4 million debt service letter of credit was issued replacing the $5 million construction letter of credit that was outstanding at year end. As of March 31, 2016, $81 million was outstanding under the term loan, $23 million was outstanding under the cash grant loan and $4 million in letters of credit in support of the project were issued. Midwest Generation On April 7, 2016, Midwest Generation, LLC, or MWG, entered into an agreement to sell certain quantities of unforced capacity that has cleared various PJM Reliability Pricing Model auctions to a trading counterparty for net proceeds of $253 million . MWG will continue to operate the applicable generation facilities and remains responsible for performance penalties and eligible for performance bonus payments, if any. Accordingly, MWG will continue to account for all revenues and costs as before; however, the proceeds will be recorded as a financing obligation while capacity payments by PJM to the counterparty will be reflected as debt amortization and interest expense through the end of the 2018/19 delivery year. MWG will amortize the upfront discount to interest expense, at an effective interest rate of 4.4% , over the term of the arrangement, through June 2019.

Variable Interest Entities

Variable Interest Entities	3 Months Ended
	Mar. 31, 2016
Variable Interest Entities Disclosure [Abstract]
Variable Interest Entity	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, Yield Operating, 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 $108 million as of March 31, 2016 . Sherbino I Wind Farm LLC — NRG owns a 50% interest in Sherbino, a joint venture with BP Wind Energy North America Inc. NRG's maximum exposure to loss is limited to its equity investment, which was $77 million as of March 31, 2016 . 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 2015 Form 10-K. For one of the tax equity arrangements, the Company has a deficit restoration obligation equal to $30 million as of March 31, 2016 , 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) March 31, 2016 Current assets $ 86 Net property, plant and equipment 1,782 Other long-term assets 923 Total assets 2,791 Current liabilities 59 Long-term debt 360 Other long-term liabilities 190 Total liabilities 609 Noncontrolling interests 745 Net assets less noncontrolling interests $ 1,437

Changes in Capital Structure

Changes in Capital Structure	3 Months Ended
	Mar. 31, 2016
Changes in Capital Structure Disclosure [Abstract]
Changes in Capital Structure	Changes in Capital Structure As of March 31, 2016 , and December 31, 2015 , 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, 2015 416,939,950 (102,749,908 ) 314,190,042 Shares issued under LTIPs 417,051 — 417,051 Shares issued under ESPP — 299,127 299,127 Balance as of March 31, 2016 417,357,001 (102,450,781 ) 314,906,220 Employee Stock Purchase Plan As of March 31, 2016 , there were 977,786 shares of treasury stock available for issuance under the ESPP. NRG Common Stock Dividends The following table lists the dividends paid during the three months ended March 31, 2016 : First Quarter 2016 Dividends per Common Share $ 0.145 On April 18, 2016 , NRG declared a quarterly dividend on the Company's common stock of $0.03 per share, payable May 16, 2016 , to stockholders of record as of May 2, 2016 , 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	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Earnings 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 earnings/(loss) per share while giving effect to all potentially dilutive common shares that were outstanding during the period. The reconciliation of NRG's basic and diluted earnings/(loss) per share is shown in the following table: Three months ended March 31, (In millions, except per share data) 2016 2015 Basic earnings/(loss) per share attributable to NRG Energy, Inc. common stockholders Net income/(loss) attributable to NRG Energy, Inc. $ 82 $ (120 ) Dividends for preferred shares 5 5 Income/(loss) available for common stockholders $ 77 $ (125 ) Weighted average number of common shares outstanding - basic 315 336 Earnings/(loss) per weighted average common share — basic $ 0.24 $ (0.37 ) Diluted earnings/(loss) per share attributable to NRG Energy, Inc. common stockholders Weighted average number of common shares outstanding 315 336 Total dilutive shares 315 336 Earnings/(loss) per weighted average common share — diluted $ 0.24 $ (0.37 ) 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 March 31, (In millions of shares) 2016 2015 Equity compensation plans 4 7 Embedded derivative of 2.822% redeemable perpetual preferred stock 16 16 Total 20 23

Segment Reporting

Segment Reporting	3 Months Ended
	Mar. 31, 2016
Segment Reporting Disclosure [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/Business (previously NRG Business); Retail Mass (previously NRG Home Retail); Renewables (previously NRG Renew), which includes solar and wind assets, excluding those in the NRG Yield segment; NRG Yield; and corporate activities. The Company's corporate segment includes BETM, international businesses, residential solar and electric vehicle services. Effective January 1, 2016, the Company began reporting the results of its residential solar business in its corporate segment. The financial information for the three months ended March 31, 2015 has been recast to reflect the change. Intersegment sales are accounted for at market. On November 3, 2015, NRG Yield acquired 75% of the class B interests in NRG Wind TE Holdco, which owns a portfolio of 12 wind facilities, from the Company. The acquisition was treated as a transfer of entities under common control and accordingly the financial information for the three months ended March 31, 2015 has been recast to reflect this change. 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). (In millions) Generation/Business (a)(b) Retail Mass (a) Renewables (a) NRG Yield (a) Corporate (a)(c)(d) Eliminations Total Three months ended March 31, 2016 Operating revenues (a) $ 2,120 $ 1,048 $ 109 $ 220 $ 59 $ (327 ) $ 3,229 Depreciation and amortization 146 28 56 66 17 — 313 Impairment loss on investment (137 ) — — — (9 ) — (146 ) Equity in (losses)/earnings of unconsolidated affiliates (5 ) — (4 ) 2 1 (1 ) (7 ) Income/(Loss) before income taxes 160 146 (51 ) 2 (192 ) 3 68 Net Income/(Loss) 159 146 (45 ) 2 (218 ) 3 47 Net Income/(Loss) attributable to NRG Energy, Inc. $ 159 $ 146 $ (35 ) $ 10 $ (205 ) $ 7 $ 82 Total assets as of March 31, 2016 $ 17,124 $ 1,919 $ 5,736 $ 7,659 $ 19,184 $ (18,942 ) $ 32,680 (a) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 251 $ 1 $ 5 $ 4 $ 66 $ — $ 327 (b) Includes gain on sale of assets $ 32 $ — $ — $ — $ — $ — $ 32 (c) Includes gain on debt extinguishment $ — $ — $ — $ — $ 11 $ — $ 11 (d) Includes net loss of $43 million related to residential solar (In millions) Generation/Business (a)(b) Retail Mass Renewables NRG Yield Corporate (a)(c) Eliminations Total Three months ended March 31, 2015 Operating revenues (a) $ 2,509 $ 1,311 $ 91 $ 200 $ (2 ) $ (280 ) $ 3,829 Depreciation and amortization 233 30 52 67 13 — 395 Equity in (losses)/earnings of unconsolidated affiliates (4 ) — (1 ) 2 (1 ) 1 (3 ) Income/(Loss) before income taxes 29 104 (57 ) (24 ) (262 ) 1 (209 ) Net Income/(Loss) 29 104 (51 ) (20 ) (199 ) 1 (136 ) Net Income/(Loss) attributable to NRG Energy, Inc. $ 29 $ 104 $ (46 ) $ (15 ) $ (187 ) $ (5 ) $ (120 ) (a) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 246 $ — $ — $ — $ 34 $ — $ 280 (b) Includes gain on postretirement benefits curtailment $ 14 $ — $ — $ — $ — $ — $ 14 (c) Includes net loss of $45 million related to residential solar

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Effective Tax Rate The income tax provision consisted of the following: Three months ended March 31, (In millions except otherwise noted) 2016 2015 Income/(loss) before income taxes $ 68 $ (209 ) Income tax expense/(benefit) 21 (73 ) Effective tax rate 30.9 % 34.9 % For the three months ended March 31, 2016 , NRG's overall effective tax rate was different than the statutory rate of 35% primarily due to the change in the valuation allowance, partially offset by the recording of a deferred tax liability associated with the amortization of indefinite lived assets. For the three months ended March 31, 2015 , NRG's overall effective tax rate was different than the statutory rate of 35% primarily due to the impact of production tax credits generated from the Company's wind assets partially offset by non-taxable equity earnings and tax expense attributable to consolidated partnerships. Uncertain Tax Benefits As of March 31, 2016 , NRG has recorded a non-current tax liability of $42 million for uncertain tax benefits from positions taken on various state income tax returns, including accrued interest. For the three months ended March 31, 2016 , NRG accrued an insignificant amount of interest relating to the uncertain tax benefits. As of March 31, 2016 , NRG had cumulative interest and penalties related to these uncertain tax benefits of $3 million . The Company recognizes interest and penalties related to uncertain tax benefits in income tax expense. NRG is subject to examination by taxing authorities for income tax returns filed in the U.S. federal jurisdiction and various state and foreign jurisdictions including operations located in Australia. The Company is not subject to U.S. federal income tax examinations for years prior to 2011. With few exceptions, state and local income tax examinations are no longer open for years before 2009. The Company's primary foreign operations are also no longer subject to examination by local jurisdictions for years prior to 2010.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2016
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 2015 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 GenOn and 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 March 31, 2016 , hedges under the first liens were in-the-money for NRG on a counterparty aggregate basis. Ivanpah Energy Production Guarantee — The Company's PPAs with PG&E with respect to the Ivanpah project contain provisions for contract quantity and guaranteed energy production, which require that Ivanpah units 1 and 3 deliver to PG&E no less than the guaranteed energy production amount specified in the PPAs in any period of twenty-four consecutive months, or performance measurement period, during the term of the PPAs. If either of Ivanpah units 1 and 3 deliver less than the guaranteed energy production amount in any performance measurement period, PG&E may, at its option, declare an event of default. The two units did not meet their guaranteed energy production amount for the initial performance measurement period. On December 18, 2015, PG&E filed a request with the CPUC that it approve forbearance agreements relating to Ivanpah units 1 and 3. Under the forbearance agreements, PG&E agrees to refrain from taking certain actions (including declaring an event of default and invoking associated remedies) for an initial six-month period of time. If the units meet certain production requirements during such period, then the forbearance agreements provide for a six-month extension of such period. On March 17, 2016, the CPUC adopted a resolution approving the forbearance agreements. The CPUC’s approval became final and non-appealable on April 18, 2016, when no parties filed applications for rehearing of the CPUC’s decision. NRG has received confirmation from PG&E that the forbearance agreements are now considered final and non-appealable, and are now in full effect. 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. 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. 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. In March 2012, the Court of Appeals 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. 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 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 Court of Appeals' decision and the Supreme Court granted the petition. On April 21, 2015, the 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 Supreme Court left open whether the claims were preempted on the basis of conflict preemption. The 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. On May 20, 2016, the U.S. District Court for the District of Nevada will hear argument on the defendants' motion for summary judgment in one of the Kansas cases. 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 Supreme Court denied the petition for a writ of certiorari, thereby ending one of the five lawsuits. 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 is responding to this second subpoena. 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. Maryland Department of the Environment v. GenOn Chalk Point and GenOn Mid-Atlantic — On January 25, 2013, Food & Water Watch, the Patuxent Riverkeeper and the Potomac Riverkeeper (together, the Citizens Group) sent GenOn Mid-Atlantic a letter alleging that the Chalk Point, Dickerson and Morgantown generating facilities were violating the terms of the three National Pollution Discharge Elimination System permits by discharging nitrogen and phosphorous in excess of the limits in each permit. On March 21, 2013, the MDE sent GenOn Mid-Atlantic a similar letter with respect to the Chalk Point and Dickerson generating facilities, threatening to sue within 60 days if the generating facilities were not brought into compliance. On June 11, 2013, the Maryland Attorney General on behalf of the MDE filed a complaint in the U.S. District Court for the District of Maryland alleging violations of the CWA and Maryland environmental laws related to water. The Company is in discussions to resolve the matter and expects to pay a penalty in excess of $100,000 . 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. 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. Potomac River Environmental Investigation — In March 2013, NRG Potomac River LLC 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 is currently reviewing the information provided by DOEE. 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. The Company is vigorously defending against these lawsuits. NRG requested and was granted a stay in the California case and one of the New Jersey cases pending a decision of an unrelated case by the U.S. Supreme Court, the results of which could materially affect these lawsuits. The Company believes that it has established an adequate reserve for these cases. 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 have 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 hearing on the demurrers is scheduled for June 9, 2016. Braun v. NRG Yield, Inc. — On April 19, 2016, plaintiffs filed a purported class action lawsuit against NRG Yield, Inc. and against each current and former member of its board of directors individually 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 June 22, 2015 Class C common stock offering. Plaintiffs seek compensatory damages, rescission, attorney’s fees and costs.

Regulatory Matters

Regulatory Matters	3 Months Ended
	Mar. 31, 2016
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 2015 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 U.S. Supreme Court’s Decision Regarding Maryland's Generator Contracting Programs — On April 19, 2016, the U.S. Supreme Court issued its decision in Hughes v. Talen Energy Marketing, the case concerning Maryland’s program to provide subsidies, through state-mandate contracts, to new generation in the state. The Court held that Maryland’s program is invalid and is preempted by the Supremacy Clause of the U.S. Constitution because it sets an interstate wholesale rate for power, thereby intruding on FERC’s exclusive authority under the FPA. The Court focused on the Maryland program’s requirement that generation participating in the program clear the market in the FERC-jurisdictional auction, and also that the contracts entered into under the Maryland program did not transfer ownership of capacity from one party to another outside the auction. The Court emphasized that its holding was limited, and that it was not addressing the permissibility of many types of measures states might use to encourage new or clean generation, such as tax incentives, land grants, direct subsidies, or other types of measures. Due to the narrow holding and how the Court addressed the factors and interests at issue in this case, state programs that encourage new or clean generation and that do not condition payment of funds on capacity clearing a FERC-jurisdictional auction should not be affected by the Court’s ruling. In addition, projects already built pursuant to comparable state programs should not be affected by the Hughes decision. The Company anticipates that there will be considerable litigation in the coming years over the meaning and application of the decision. East Region Montgomery County Station Power Tax — On December 20, 2013, the Company received a letter from Montgomery County, Maryland requesting payment of an energy tax for the consumption of station power at the Dickerson Facility over the previous three years. Montgomery County seeks payment in the amount of $22 million , which includes tax, interest and penalties. The Company disputed the applicability of the tax. On December 11, 2015, the Maryland Tax Court reversed Montgomery County's assessment. Montgomery County has filed an appeal and briefing is underway.

Environmental Matters

Environmental Matters	3 Months Ended
	Mar. 31, 2016
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 2015 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. Environmental laws have become increasingly stringent and NRG expects this trend to continue. The electric generation industry is facing new requirements regarding GHGs, combustion byproducts, water discharge and use, and threatened and endangered species. In general, future laws are expected to require the addition of emissions controls or other environmental controls or to impose certain restrictions on the operations of the Company's facilities, which could have a material effect on the Company's operations. The EPA finalized CSAPR in 2011, which was intended to replace CAIR in January 2012, to address certain states' obligation 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 NO x budgets for 11 states including Maryland, New Jersey, New York, Ohio, Pennsylvania and Texas. The EPA is currently reviewing the decision. In December 2015, the EPA proposed the CSAPR Update Rule using the 2008 Ozone NAAQS, which would reduce the total amount of ozone season NO x as compared with the previously utilized 1997 Ozone NAAQS. If finalized, this proposal would reduce future NO x allocations and/or current banked allowances. While NRG cannot predict the final outcome of this rulemaking, 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 limits 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 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. 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. 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. The Company has evaluated the impact of the new rule on its results of operations, financial condition and cash flows and has accrued its environmental and asset retirement obligations under the rule based on current estimates as of March 31, 2016. East Region Maryland Environmental Regulations — In December 2014, MDE proposed a regulation regarding NO x emissions from coal-fired electric generating units, which had it been finalized would have required by 2020 the Company (at each of the three Dickerson coal-fired units and the Chalk Point coal-fired unit that does not have an SCR) to either (1) install and operate an SCR; (2) retire the unit; or (3) convert the fuel source from coal to natural gas. In early 2015, the State of Maryland decided not to finalize the regulation as proposed. In November 2015, MDE finalized revised regulations to address future NO x reductions, which although more stringent than previous regulations, will not cause the Company to spend capital to comply. As a result of the new regulations, on February 29, 2016, NRG notified PJM that it was withdrawing the standing deactivation notices for Dickerson Units 1, 2 and 3 and Chalk Point Units 1 and 2. Environmental Capital Expenditures NRG estimates that environmental capital expenditures from 2016 through 2020 required to comply with environmental laws will be approximately $339 million , which includes $66 million for GenOn and $254 million for Midwest Generation. These costs, the majority of which will be expended by the end of 2016, are primarily associated with (i) DSI/ESP upgrades at the Powerton facility and the Joliet gas conversion to satisfy the IL CPS and (ii) MATS compliance at the Avon Lake facility.

Condensed Consolidating Financi

Condensed Consolidating Financial Information	3 Months Ended
	Mar. 31, 2016
Condensed Consolidating Financial Information Disclosure [Abstract]
Condensed Consolidating Financial Information	Condensed Consolidating Financial Information As of March 31, 2016 , the Company had outstanding $6.0 billion of Senior Notes due from 2018 - 2024, 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, including GenOn and its 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 March 31, 2016 : Ace Energy, Inc. Norwalk Power LLC NRG Norwalk Harbor Operations Inc. Allied Warranty LLC NRG Advisory Services, LLC NRG Operating Services, Inc. Arthur Kill Power LLC NRG Affiliate Services Inc. NRG Oswego Harbor Power Operations Inc. Astoria Gas Turbine Power LLC NRG Artesian Energy LLC NRG PacGen Inc. Bayou Cove Peaking Power, LLC NRG Arthur Kill Operations Inc. NRG Portable Power LLC BidURenergy, Inc. NRG Astoria Gas Turbine Operations Inc. NRG Power Marketing LLC Cabrillo Power I LLC NRG Bayou Cove LLC NRG Reliability Solutions LLC Cabrillo Power II LLC NRG Business Services LLC NRG Renter's Protection LLC Carbon Management Solutions LLC NRG Business Solutions LLC NRG Retail LLC Cirro Group, Inc. NRG Cabrillo Power Operations Inc. NRG Retail Northeast LLC Cirro Energy Services, Inc. NRG California Peaker Operations LLC NRG Rockford Acquisition LLC Clean Edge Energy LLC NRG Cedar Bayou Development Company, LLC NRG Saguaro Operations Inc. Conemaugh Power LLC NRG Connected Home LLC NRG Security LLC Connecticut Jet Power LLC NRG Connecticut Affiliate Services Inc. NRG Services Corporation Cottonwood Development LLC NRG Construction LLC NRG SimplySmart Solutions LLC Cottonwood Energy Company LP NRG Curtailment Solutions Holdings LLC NRG South Central Affiliate Services Inc. Cottonwood Generating Partners I LLC NRG Curtailment Solutions Inc NRG South Central Generating LLC Cottonwood Generating Partners II LLC NRG Development Company Inc. NRG South Central Operations Inc. Cottonwood Generating Partners III LLC NRG Devon Operations Inc. NRG South Texas LP Cottonwood Technology Partners LP NRG Dispatch Services LLC NRG Texas C&I Supply LLC Devon Power LLC NRG Distributed Generation PR LLC NRG Texas Gregory LLC Dunkirk Power LLC NRG Dunkirk Operations Inc. NRG Texas Holding Inc. Eastern Sierra Energy Company LLC NRG El Segundo Operations Inc. NRG Texas LLC El Segundo Power, LLC NRG Energy Efficiency-L LLC NRG Texas Power LLC El Segundo Power II LLC NRG Energy Efficiency-P LLC NRG Warranty Services LLC Energy Alternatives Wholesale, LLC NRG Energy Labor Services LLC NRG West Coast LLC Energy Choice Solutions, LLC NRG ECOKAP Holdings LLC NRG Western Affiliate Services Inc. Energy Plus Holdings LLC NRG Energy Services Group LLC O'Brien Cogeneration, Inc. II Energy Plus Natural Gas LLC NRG Energy Services International Inc. ONSITE Energy, Inc. Energy Protection Insurance Company NRG Energy Services LLC Oswego Harbor Power LLC Everything Energy LLC NRG Generation Holdings, Inc. RE Retail Receivables, LLC Forward Home Security LLC NRG GreenCo LLC Reliant Energy Northeast LLC GCP Funding Company, LLC NRG GreenCo Holdings LLC Reliant Energy Power Supply, LLC Green Mountain Energy Company NRG Home & Business Solutions LLC Reliant Energy Retail Holdings, LLC Gregory Partners, LLC NRG Home Services LLC Reliant Energy Retail Services, LLC Gregory Power Partners LLC NRG Home Solutions LLC RERH Holdings LLC Huntley Power LLC NRG Home Solutions Product LLC Saguaro Power LLC Independence Energy Alliance LLC NRG Homer City Services LLC Somerset Operations Inc. Independence Energy Group LLC NRG Huntley Operations Inc. Somerset Power LLC Independence Energy Natural Gas LLC NRG HQ DG LLC Texas Genco Financing Corp. Indian River Operations Inc. NRG Identity Protect LLC Texas Genco GP, LLC Indian River Power LLC NRG Ilion Limited Partnership Texas Genco Holdings, Inc. Keystone Power LLC NRG Ilion LP LLC Texas Genco LP, LLC Langford Wind Power, LLC NRG International LLC Texas Genco Operating Services, LLC Louisiana Generating LLC NRG Maintenance Services LLC Texas Genco Services, LP Meriden Gas Turbines LLC NRG Mextrans Inc. US Retailers LLC Middletown Power LLC NRG MidAtlantic Affiliate Services Inc. Vienna Operations Inc. Montville Power LLC NRG Middletown Operations Inc. Vienna Power LLC NEO Corporation NRG Montville Operations Inc. WCP (Generation) Holdings LLC NEO Freehold-Gen LLC NRG New Roads Holdings LLC West Coast Power LLC NEO Power Services Inc. NRG North Central Operations Inc. New Genco GP, LLC 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 March 31, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 1,956 $ 1,299 $ — $ (26 ) $ 3,229 Operating Costs and Expenses Cost of operations 1,450 759 10 (30 ) 2,189 Depreciation and amortization 117 190 6 — 313 Selling, general and administrative 98 99 58 — 255 Acquisition-related transaction and integration costs — — 2 — 2 Development activity expenses — 19 7 — 26 Total operating costs and expenses 1,665 1,067 83 (30 ) 2,785 Gain on sale of assets — 32 — — 32 Operating Income/(Loss) 291 264 (83 ) 4 476 Other Income/(Expense) Equity in (losses)/earnings of consolidated subsidiaries (24 ) 4 213 (193 ) — Equity in losses of unconsolidated affiliates — (8 ) — 1 (7 ) Impairment loss on investment — (140 ) (6 ) — (146 ) Other income/(expense), net — 20 (2 ) — 18 Gain on debt extinguishment — — 11 — 11 Interest expense (5 ) (150 ) (129 ) — (284 ) Total other (expense)/income (29 ) (274 ) 87 (192 ) (408 ) Income/(Loss) Before Income Taxes 262 (10 ) 4 (188 ) 68 Income tax expense/(benefit) 100 (8 ) (83 ) 12 21 Net Income/(Loss) 162 (2 ) 87 (200 ) 47 Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests — (33 ) 5 (7 ) (35 ) Net Income Attributable to NRG Energy, Inc. $ 162 $ 31 $ 82 $ (193 ) $ 82 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME For the Three Months Ended March 31, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Net Income/(Loss) $ 162 $ (2 ) $ 87 $ (200 ) $ 47 Other Comprehensive Income/(Loss), net of tax Unrealized (loss)/gain on derivatives, net — (50 ) 24 (6 ) (32 ) Foreign currency translation adjustments, net 4 4 6 (8 ) 6 Available-for-sale securities, net — — 3 — 3 Defined benefit plans, net 1 — — — 1 Other comprehensive income/(loss) 5 (46 ) 33 (14 ) (22 ) Comprehensive Income/(Loss) 167 (48 ) 120 (214 ) 25 Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (50 ) 5 (7 ) (52 ) Comprehensive Income Attributable to NRG Energy, Inc. 167 2 115 (207 ) 77 Dividends for preferred shares — — 5 — 5 Comprehensive Income Available for Common Stockholders $ 167 $ 2 $ 110 $ (207 ) $ 72 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS March 31, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated ASSETS (In millions) Current Assets Cash and cash equivalents $ — $ 1,070 $ 589 $ — $ 1,659 Funds deposited by counterparties 34 66 1 — 101 Restricted cash 8 379 — — 387 Accounts receivable - trade, net 723 290 5 — 1,018 Accounts receivable - affiliate 290 318 25 (628 ) 5 Inventory 550 611 — — 1,161 Derivative instruments 1,405 946 — (238 ) 2,113 Cash collateral paid in support of energy risk management activities 324 87 — — 411 Renewable energy grant receivable, net — 35 — — 35 Prepayments and other current assets 121 248 87 — 456 Total current assets 3,455 4,050 707 (866 ) 7,346 Net property, plant and equipment 4,732 13,825 233 (27 ) 18,763 Other Assets Investment in subsidiaries 894 2,218 11,197 (14,309 ) — Equity investments in affiliates (14 ) 1,002 — (90 ) 898 Notes receivable, less current portion — 31 8 1 40 Goodwill 697 302 — — 999 Intangible assets, net 737 1,521 1 (3 ) 2,256 Nuclear decommissioning trust fund 577 — — — 577 Derivative instruments 234 281 — (50 ) 465 Deferred income tax 11 497 (323 ) — 185 Other non-current assets 53 722 376 — 1,151 Total other assets 3,189 6,574 11,259 (14,451 ) 6,571 Total Assets $ 11,376 $ 24,449 $ 12,199 $ (15,344 ) $ 32,680 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Current portion of long-term debt and capital leases $ — $ 529 $ (65 ) $ 1 $ 465 Accounts payable 498 316 31 — 845 Accounts payable — affiliate 259 300 57 (616 ) — Derivative instruments 1,335 850 — (238 ) 1,947 Cash collateral received in support of energy risk management activities 34 66 — — 100 Accrued expenses and other current liabilities 275 427 279 — 981 Total current liabilities 2,401 2,488 302 (853 ) 4,338 Other Liabilities Long-term debt and capital leases 301 10,391 7,985 — 18,677 Nuclear decommissioning reserve 330 — — — 330 Nuclear decommissioning trust liability 294 — — — 294 Deferred income taxes 809 265 (1,037 ) — 37 Derivative instruments 352 325 — (50 ) 627 Out-of-market contracts, net 92 1,030 — — 1,122 Other non-current liabilities 554 788 205 — 1,547 Total non-current liabilities 2,732 12,799 7,153 (50 ) 22,634 Total liabilities 5,133 15,287 7,455 (903 ) 26,972 2.822% convertible perpetual preferred stock — — 304 — 304 Redeemable noncontrolling interest in subsidiaries — 23 — — 23 Stockholders’ Equity 6,243 9,139 4,440 (14,441 ) 5,381 Total Liabilities and Stockholders’ Equity $ 11,376 $ 24,449 $ 12,199 $ (15,344 ) $ 32,680 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the Three Months Ended March 31, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net Income/(loss) $ 162 $ (2 ) $ 87 $ (200 ) $ 47 Adjustments to reconcile net loss to net cash provided by operating activities: Distributions from unconsolidated affiliates — 22 — (12 ) 10 Equity in losses of unconsolidated affiliates — 8 — (1 ) 7 Depreciation and amortization 117 190 6 — 313 Provision for bad debts 8 2 — — 10 Amortization of nuclear fuel 13 — — — 13 Amortization of financing costs and debt discount/premiums — 7 (6 ) — 1 Adjustment for debt extinguishment — — (11 ) — (11 ) Amortization of intangibles and out-of-market contracts 11 15 — — 26 Amortization of unearned equity compensation — — 8 — 8 Changes in deferred income taxes and liability for uncertain tax benefits (613 ) (1,696 ) 2,284 — (25 ) Changes in nuclear decommissioning trust liability 9 — — — 9 Changes in derivative instruments (28 ) (22 ) — — (50 ) Changes in collateral deposits supporting energy risk management activities 150 6 — — 156 Proceeds from sale of emission allowances 47 — — — 47 Gain on sale of assets — (32 ) — — (32 ) Impairment losses — 140 6 — 146 Cash used by changes in other working capital 338 1,728 (2,400 ) 213 (121 ) Net Cash Provided/(Used) by Operating Activities $ 214 $ 366 $ (26 ) $ — $ 554 Cash Flows from Investing Activities Payments for from intercompany loans to subsidiaries (151 ) (11 ) — 162 — Proceeds from dividends from NRG Yield, Inc. — (19 ) — 19 — Acquisition of businesses, net of cash acquired — (6 ) — — (6 ) Capital expenditures (44 ) (219 ) (16 ) — (279 ) Increase in restricted cash, net (2 ) (10 ) — — (12 ) Decrease in restricted cash — U.S. DOE funded projects — 39 — — 39 Decrease in notes receivable — 1 — — 1 Investments in nuclear decommissioning trust fund securities (200 ) — — — (200 ) Proceeds from sales of nuclear decommissioning trust fund securities 191 — — — 191 Proceeds from renewable energy grants and state rebates — 8 — — 8 Purchases of emission allowances (12 ) — — — (12 ) Proceeds from sale of emission allowances 7 — — — 7 Proceeds from sale of assets, net of cash disposed of — 120 — — 120 Investments in unconsolidated affiliates — (4 ) — — (4 ) Other — 4 — — 4 Net Cash Used by Investing Activities (211 ) (97 ) (16 ) 181 (143 ) Cash Flows from Financing Activities Proceeds from intercompany loans — — 162 (162 ) — Proceeds from dividends from NRG Yield, Inc. — — 19 (19 ) — Payment of dividends to common and preferred stockholders — — (48 ) — (48 ) Net receipts from settlement of acquired derivatives that include financing elements — 39 — — 39 Proceeds from issuance of long-term debt — 61 — — 61 Distributions from, net of contributions to, noncontrolling interest in subsidiaries — 10 — — 10 Proceeds from issuance of common stock — — — — — Payments for short and long-term debt — (121 ) (195 ) — (316 ) Other (3 ) (7 ) — — (10 ) Net Cash Used by Financing Activities (3 ) (18 ) (62 ) (181 ) (264 ) Effect of exchange rate changes on cash and cash equivalents — (6 ) — — (6 ) Net Increase/(Decrease) in Cash and Cash Equivalents — 245 (104 ) — 141 Cash and Cash Equivalents at Beginning of Period — 825 693 — 1,518 Cash and Cash Equivalents at End of Period $ — $ 1,070 $ 589 $ — $ 1,659 (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 March 31, 2015 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 2,566 $ 1,303 $ — $ (40 ) $ 3,829 Operating Costs and Expenses Cost of operations 2,104 996 12 (49 ) 3,063 Depreciation and amortization 204 186 5 — 395 Selling, general and administrative 105 100 60 — 265 Acquisition-related transaction and integration costs — 2 8 — 10 Development activity expenses — 15 19 — 34 Total operating costs and expenses 2,413 1,299 104 (49 ) 3,767 Gain on postretirement benefits curtailment — 14 — — 14 Operating Income/(Loss) 153 18 (104 ) 9 76 Other Income/(Expense) Equity in (losses)/earnings of consolidated subsidiaries (13 ) (8 ) 50 (29 ) — Equity in losses of unconsolidated affiliates — (4 ) (1 ) 2 (3 ) Other income, net 1 17 1 — 19 Interest expense (4 ) (158 ) (139 ) — (301 ) Total other expense (16 ) (153 ) (89 ) (27 ) (285 ) Income/(Loss) Before Income Taxes 137 (135 ) (193 ) (18 ) (209 ) Income tax expense/(benefit) 54 (60 ) (67 ) — (73 ) Net Income/(Loss) 83 (75 ) (126 ) (18 ) (136 ) Less: Net loss attributable to noncontrolling interest and redeemable noncontrolling interest — (21 ) (6 ) 11 (16 ) Net Income/(Loss) Attributable to NRG Energy, Inc. $ 83 $ (54 ) $ (120 ) $ (29 ) $ (120 ) (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 March 31, 2015 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Net Income/(Loss) $ 83 $ (75 ) $ (126 ) $ (18 ) $ (136 ) Other Comprehensive Income/(Loss), net of tax Unrealized (loss)/gain on derivatives, net (7 ) 11 (16 ) — (12 ) Foreign currency translation adjustments, net — (9 ) (2 ) — (11 ) Available-for-sale securities, net — (1 ) — — (1 ) Defined benefit plans, net (3 ) (1 ) 11 — 7 Other comprehensive loss (10 ) — (7 ) — (17 ) Comprehensive Income/(Loss) 73 (75 ) (133 ) (18 ) (153 ) Less: Comprehensive loss attributable to noncontrolling interest and redeemable noncontrolling interest — (34 ) (6 ) 11 (29 ) Comprehensive Income/(Loss) Attributable to NRG Energy, Inc. 73 (41 ) (127 ) (29 ) (124 ) Dividends for preferred shares — — 5 — 5 Comprehensive Income/(Loss) Available for Common Stockholders $ 73 $ (41 ) $ (132 ) $ (29 ) $ (129 ) (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2015 Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated ASSETS (In millions) Current Assets Cash and cash equivalents $ — $ 825 $ 693 $ — $ 1,518 Funds deposited by counterparties 55 51 — — 106 Restricted cash 5 409 — — 414 Accounts receivable - trade, net 851 304 2 — 1,157 Accounts receivable - affiliate 395 260 571 (1,222 ) 4 Inventory 570 682 — — 1,252 Derivative instruments 1,202 871 — (158 ) 1,915 Cash collateral paid in support of energy risk management activities 474 94 — — 568 Renewable energy grant receivable, net — 13 — — 13 Current assets held-for-sale — 6 — — 6 Prepayments and other current assets 93 274 71 — 438 Total current assets 3,645 3,789 1,337 (1,380 ) 7,391 Net Property, Plant and Equipment 4,767 13,773 219 (27 ) 18,732 Other Assets Investment in subsidiaries 842 2,244 11,039 (14,125 ) — Equity investments in affiliates (14 ) 1,160 1 (102 ) 1,045 Notes receivable, less current portion — 46 7 — 53 Goodwill 697 302 — — 999 Intangible assets, net 763 1,551 2 (6 ) 2,310 Nuclear decommissioning trust fund 561 — — — 561 Derivative instruments 153 184 — (32 ) 305 Deferred income taxes (6 ) 815 (642 ) — 167 Non-current assets held for sale — 105 — — 105 Other non-current assets 80 749 385 — 1,214 Total other assets 3,076 7,156 10,792 (14,265 ) 6,759 Total Assets $ 11,488 $ 24,718 $ 12,348 $ (15,672 ) $ 32,882 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Current portion of long-term debt and capital leases $ 2 $ 460 $ 19 $ — $ 481 Accounts payable 553 277 39 — 869 Accounts payable — affiliate 151 2,000 (929 ) (1,222 ) — Derivative instruments 1,130 749 — (158 ) 1,721 Cash collateral received in support of energy risk management activities 55 51 — — 106 Current liabilities held-for-sale — 2 — — 2 Accrued expenses and other current liabilities 319 429 449 (1 ) 1,196 Total current liabilities 2,210 3,968 (422 ) (1,381 ) 4,375 Other Liabilities Long-term debt and capital leases 302 10,496 8,185 — 18,983 Nuclear decommissioning reserve 326 — — — 326 Nuclear decommissioning trust liability 283 — — — 283 Deferred income taxes 179 (1,088 ) 928 — 19 Derivative instruments 301 224 — (32 ) 493 Out-of-market contracts, net 95 1,051 — — 1,146 Non-current liabilities held-for-sale — 4 — — 4 Other non-current liabilities 554 735 199 — 1,488 Total non-current liabilities 2,040 11,422 9,312 (32 ) 22,742 Total Liabilities 4,250 15,390 8,890 (1,413 ) 27,117 2.822% Preferred Stock — — 302 — 302 Redeemable noncontrolling interest in subsidiaries — 29 — — 29 Stockholders’ Equity 7,238 9,299 3,156 (14,259 ) 5,434 Total Liabilities and Stockholders’ Equity $ 11,488 $ 24,718 $ 12,348 $ (15,672 ) $ 32,882 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the Three Months Ended March 31, 2015 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net Income/(Loss) 83 (75 ) (126 ) (18 ) (136 ) Adjustments to reconcile net loss to net cash provided by operating activities: Distributions from unconsolidated affiliates — 40 — (11 ) 29 Equity in losses of unconsolidated affiliates — 4 1 (2 ) 3 Depreciation and amortization 204 186 5 — 395 Provision for bad debts 13 — 2 — 15 Amortization of nuclear fuel 13 — — — 13 Amortization of financing costs and debt discount/premiums — (11 ) 7 — (4 ) Amortization of intangibles and out-of-market contracts 12 7 — — 19 Amortization of unearned equity compensation — — 11 — 11 Changes in deferred income taxes and liability for uncertain tax benefits 55 (36 ) (102 ) — (83 ) Changes in nuclear decommissioning trust liability (3 ) — — — (3 ) Changes in derivative instruments 131 130 — — 261 Changes in collateral deposits supporting energy risk management activities (132 ) (81 ) — — (213 ) Gain on postretirement benefits curtailment and sale of assets — (14 ) — — (14 ) Cash provided/(used) by changes in other working capital 444 (580 ) (337 ) 440 (33 ) Net Cash Provided/(Used) by Operating Activities 820 (430 ) (539 ) 409 260 Cash Flows from Investing Activities Intercompany loans (to)/from subsidiaries (737 ) 328 409 — — Acquisition of businesses, net of cash acquired — (1 ) — — (1 ) Capital expenditures (89 ) (157 ) (6 ) — (252 ) Increase in restricted cash, net — (11 ) — — (11 ) Decrease in restricted cash — U.S. DOE projects — 24 1 — 25 Decrease in notes receivable — 5 — — 5 Investments in nuclear decommissioning trust fund securities (193 ) — — — (193 ) Proceeds from sales of nuclear decommissioning trust fund securities 196 — — — 196 Proceeds from renewable energy grants — 2 — — 2 Investments in unconsolidated affiliates (2 ) (5 ) (37 ) — (44 ) Other — 3 — — 3 Net Cash (Used)/Provided by Investing Activities (825 ) 188 367 — (270 ) Cash Flows from Financing Activities Proceeds from intercompany loans — — 409 (409 ) — Payment of dividends to common and preferred stockholders — — (51 ) — (51 ) Payment for treasury stock — — (79 ) — (79 ) Net payment for settlement of acquired derivatives that include financing elements — 40 — — 40 Proceeds from issuance of long-term debt — 221 27 — 248 Contributions to, net of distributions from, noncontrolling interest in subsidiaries — (25 ) — — (25 ) Proceeds from issuance of common stock — — 1 — 1 Payments for short and long-term debt — (89 ) (5 ) — (94 ) Net Cash Provided by Financing Activities — 147 302 (409 ) 40 Effect of exchange rate changes on cash and cash equivalents — 18 — — 18 Net (Decrease)/Increase in Cash and Cash Equivalents (5 ) (77 ) 130 — 48 Cash and Cash Equivalents at Beginning of Period 18 1,455 643 — 2,116 Cash and Cash Equivalents at End of Period $ 13 $ 1,378 $ 773 $ — $ 2,164 (a) All significant intercompany transactions have been eliminated in consolidation.

Summary of Significant Accoun25

Summary of Significant Accounting Policies (Policy)	3 Months Ended
	Mar. 31, 2016
Accounting Policies [Abstract]
Business Description and Basis of Presentation [Text Block]	NRG Energy, Inc., or NRG or the Company, is an integrated competitive power company, which produces, sells and delivers energy and energy products and services in major competitive power markets in the U.S. while positioning itself as a leader in the way residential, industrial and commercial consumers think about and use energy products and services. NRG has one of the nation's largest and most diverse competitive power generation portfolios balanced with the nation's largest competitive retail energy business. The Company owns and operates approximately 48,000 MWs 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 2015 Form 10-K. Interim results are not necessarily indicative of results for a full year. In the opinion of management, the accompanying unaudited interim condensed consolidated financial statements contain all material adjustments consisting of normal and recurring accruals necessary to present fairly the Company's consolidated financial position as of March 31, 2016, and the results of operations, comprehensive income/(loss) and cash flows for the three months ended March 31, 2016, and 2015.
Reclassification, Policy [Policy Text Block]	Reclassifications Certain prior year amounts have been reclassified for comparative purposes. The reclassifications did not affect results from operations, net assets or cash flows.
Use of Estimates (Policy)	Use of Estimates The preparation of financial statements in conformity with U.S. 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.
Cash Flow, Supplemental Disclosures [Text Block]	Other Cash Flow Information NRG’s investing activities exclude capital expenditures of $98 million which were accrued and unpaid at March 31, 2016
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Developments ASU 2016-09 — In March 2016, the FASB issued ASU 2016-09, Compensation - Stock Compensation (Topic 718), or ASU No. 2016-09. The amendments of ASU No. 2016-09 were issued as part of the FASB's Simplification Initiative focused on improving areas of GAAP for which cost and complexity may be reduced while maintaining or improving the usefulness of information disclosed within the financial statements. 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 guidance in ASU No. 2016-09 is effective for fiscal years beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted. The Company does not expect the standard to have a material impact on its results of operations, cash flows and financial position. ASU 2016-07 — In March 2016, the FASB issued ASU 2016-07, Investments - Equity Method and Joint Ventures (Topic 323), or ASU No. 2016-07. The amendments of ASU No. 2016-07 eliminate the requirement that when an investment qualifies for use of the equity method as a result of an increase in the level of ownership interest or degree of influence, an investor must adjust the investment, results of operations, and retained earnings retroactively on a step-by-step basis as if the equity method had been in effect during all previous periods that the investment had been held. The amendments require that the equity method investor add the cost of acquiring the additional interest in the investee to the current basis of the investor's previously held interest and adopt the equity method of accounting with no retroactive adjustment to the investment. In addition, ASU No. 2016-07 requires that an entity that has an available-for-sale equity security that becomes qualified for the equity method of accounting recognize through earnings the unrealized holding gain or loss in accumulated other comprehensive income at the date the investment becomes qualified for use of the equity method. The guidance in ASU No. 2016-07 is effective for fiscal years beginning after December 15, 2016, and interim periods within those annual periods. The adoption of ASU No. 2016-07 is required to be applied prospectively and early adoption is permitted. The Company does not expect the standard to have a material impact on its results of operations, cash flows and financial position. ASU 2016-02 — In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), or ASU No. 2016-02. The amendments of ASU 2016-02 complete the joint effort between the FASB and the International Accounting Standards Board, or IASB, to develop a common leasing standard for U.S. GAAP and International Financial Reporting Standards, or IFRS, 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. The guidance in ASU No. 2016-02 provides that a lessee that may have previously accounted for a lease as an operating lease under current U.S. GAAP should recognize the assets and liabilities that arise from a lease on the balance sheet. In addition, ASU No. 2016-02 expands the required quantitative and qualitative disclosures with regards to lease arrangements. The guidance in ASU No. 2016-02 is effective for fiscal years beginning after December 15, 2018, and interim periods within those annual periods. The adoption of ASU 2016-02 is required to be applied using a modified retrospective approach for the earliest period presented and early adoption is permitted. The Company is currently evaluating the impact of the standard on the Company's results of operations, cash flows and financial position. ASU 2016-01 — In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, or ASU No. 2016-01. The amendments of ASU No. 2016-01 eliminate available-for-sale classification of equity investments and require that equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) to be generally measured at fair value with changes in fair value recognized in net income. Further, the amendments require that financial assets and financial liabilities to be presented separately in the notes to the financial statements, grouped by measurement category and form of financial asset. The guidance in ASU No. 2016-01 is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those annual periods. The Company is currently evaluating the impact of the standard on the Company's results of operations, cash flows and financial position. ASU 2015-16 — In September 2015, the FASB issued ASU No. 2015-16, Business Combinations (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments , or ASU No. 2015-16. The amendments of ASU No. 2015-16 require that an acquirer recognize measurement period adjustments to the provisional amounts recognized in a business combination in the reporting period during which the adjustments are determined. Additionally, the amendments of ASU No. 2015-16 require the acquirer to record in the same period's financial statements the effect on earnings of changes in depreciation, amortization or other income effects, if any, as a result of the measurement period adjustment, calculated as if the accounting had been completed at the acquisition date as well as disclosing either on the face of the income statement or in the notes the portion of the amount recorded in current period earnings that would have been recorded in previous reporting periods. The guidance in ASU No. 2015-16 is effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. The amendments should be applied prospectively. The Company adopted ASU No. 2015-16 for the year ended December 31, 2016, and the adoption did not have a material impact on the Company's results of operations, cash flows and financial position. ASU 2014-09 — In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), or ASU No. 2014-09. The amendments of ASU No. 2014-09 complete the joint effort between the FASB and the IASB, to develop a common revenue standard for U.S. GAAP and IFRS, and to improve financial reporting. The guidance in ASU No. 2014-09 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 the following steps to be applied by an entity: (1) identify the contract with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when (or as) the entity satisfies the performance obligation. In August 2015, the FASB issued ASU 2015-14, which formally deferred the effective date by one year to make the guidance of ASU No. 2014-09 effective for annual reporting periods beginning after December 15, 2017, including interim periods therein. Early adoption is permitted, but not prior to the original effective date, which was for annual reporting periods beginning after December 15, 2016. In March 2016, the FASB issued ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606), or ASU No. 2016-08. The amendments of ASU No. 2016-08 clarify how to apply the implementation guidance on principal versus agent considerations related to the sale of goods or services to a customer as updated by ASU No. 2014-09. In April 2016, the FASB issued ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606), or ASU No. 2016-10. The amendments of ASU No. 2016-10 provide further clarification on contract revenue recognition as updated by ASU No. 2014-09, specifically related to the identification of separately identifiable performance obligations and the implementation of licensing contracts. The Company is currently evaluating the impact of the standard on the Company's results of operations, cash flows and financial position.
Nuclear Decommissioning (Policy)	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 (Policy)	The Company's segment structure reflects how management currently makes financial decisions and allocates resources. The Company's businesses are segregated as follows: Generation/Business (previously NRG Business); Retail Mass (previously NRG Home Retail); Renewables (previously NRG Renew), which includes solar and wind assets, excluding those in the NRG Yield segment; NRG Yield; and corporate activities. The Company's corporate segment includes BETM, international businesses, residential solar and electric vehicle services. Effective January 1, 2016, the Company began reporting the results of its residential solar business in its corporate segment. The financial information for the three months ended March 31, 2015 has been recast to reflect the change. Intersegment sales are accounted for at market.

Summary of Significant Accoun26

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2016
Accounting Policies [Abstract]
Schedule of Change in Noncontrolling Interest	Noncontrolling Interest The following table reflects the changes in NRG's noncontrolling interest balance: (In millions) Balance as of December 31, 2015 $ 2,727 Distributions to noncontrolling interest (42 ) Contributions from noncontrolling interest 12 Comprehensive loss attributable to noncontrolling interest (41 ) Balance as of March 31, 2016 $ 2,656
Redeemable Noncontrolling Interest [Table Text Block]	Redeemable Noncontrolling Interest The following table reflects the changes in the Company's redeemable noncontrolling interest balance for the three months ended March 31, 2016 : (In millions) Balance as of December 31, 2015 $ 29 Cash contributions from noncontrolling interest, net of distributions 5 Comprehensive loss attributable to noncontrolling interest (11 ) Balance as of March 31, 2016 $ 23

Fair Value of Financial Instr27

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2016
Fair Value of Financial Instruments Disclosure [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 March 31, 2016 As of December 31, 2015 Carrying Amount Fair Value Carrying Amount Fair Value (In millions) Assets: Notes receivable (a) $ 57 $ 57 $ 73 $ 73 Liabilities: Long-term debt, including current portion (b) 19,288 18,116 19,620 18,263 (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.
Assets and liabilities measured and recorded at fair value on the consolidated balance sheets on a recurring basis	The following tables present assets and liabilities measured and recorded at fair value on the Company's condensed consolidated balance sheets on a recurring basis and their level within the fair value hierarchy: As of March 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 12 — — 12 Other (a) 11 — — 11 Nuclear trust fund investments: Cash and cash equivalents 17 — — 17 U.S. government and federal agency obligations 64 1 — 65 Federal agency mortgage-backed securities — 69 — 69 Commercial mortgage-backed securities — 20 — 20 Corporate debt securities — 72 — 72 Equity securities 281 — 52 333 Foreign government fixed income securities — 1 — 1 Other trust fund investments: U.S. government and federal agency obligations 1 — — 1 Derivative assets: Commodity contracts 624 1,790 164 2,578 Total assets $ 1,010 $ 1,953 $ 233 $ 3,196 Derivative liabilities: Commodity contracts 902 1,306 181 2,389 Interest rate contracts — 185 — 185 Total liabilities $ 902 $ 1,491 $ 181 $ 2,574 (a) Consists primarily of mutual funds held in a Rabbi Trust for non-qualified deferred compensation plans for certain former employees. As of December 31, 2015 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 9 — — 9 Other (a) 14 — — 14 Nuclear trust fund investments: Cash and cash equivalents 6 — — 6 U.S. government and federal agency obligations 54 1 — 55 Federal agency mortgage-backed securities — 59 — 59 Commercial mortgage-backed securities — 25 — 25 Corporate debt securities — 81 — 81 Equity securities 280 — 54 334 Foreign government fixed income securities — 1 — 1 Other trust fund investments: U.S. government and federal agency obligations 1 — — 1 Derivative assets: Commodity contracts 622 1,449 149 2,220 Total assets $ 986 $ 1,616 $ 220 $ 2,822 Derivative liabilities: Commodity contracts 868 1,036 182 2,086 Interest rate contracts — 128 — 128 Total liabilities $ 868 $ 1,164 $ 182 $ 2,214 (a) Primarily consists of mutual funds held in rabbi trusts for non-qualified deferred compensation plans for certain former employees and a total return swap that does not meet the definition of a derivative.
Reconciliation of beginning and ending balances for financial instruments that are recognized at fair value in the consolidated financial statements at least annually using significant unobservable inputs	The following tables reconcile, for the three months ended March 31, 2016 , and 2015 , the beginning and ending balances for financial instruments that are recognized at fair value in the consolidated financial statements, at least annually, using significant unobservable inputs: Fair Value Measurement Using Significant Unobservable Inputs (Level 3) Three months ended March 31, 2016 (In millions) Debt Securities Trust Fund Investments Derivatives (a) Total Beginning balance $ 17 $ 54 $ (33 ) $ 38 Total gains/(losses) — realized/unrealized: Included in earnings — — (17 ) (17 ) Included in nuclear decommissioning obligation — (2 ) — (2 ) Purchases — — 5 5 Transfers into Level 3 (b) — — 27 27 Transfers out of Level 3 (b) — — 1 1 Ending balance as of March 31, 2016 $ 17 $ 52 $ (17 ) $ 52 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 March 31. 2016 $ — $ — $ (24 ) $ (24 ) (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 March 31, 2015 (In millions) Debt Securities Other Trust Fund Investments Derivatives (a) Total Beginning balance $ 18 $ 11 $ 52 $ 80 $ 161 Total gains/(losses) — realized/unrealized: Included in earnings — — — (55 ) (55 ) Included in nuclear decommissioning obligations — — 2 — 2 Purchases — — — (4 ) (4 ) Transfers into Level 3 (b) — — — 15 15 Transfers out of Level 3 (b) — — — (2 ) (2 ) Ending balance as of March 31, 2015 $ 18 $ 11 $ 54 $ 34 $ 117 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 March 31, 2015 $ — $ — $ — $ (20 ) $ (20 ) (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 Inputs, Assets, Quantitative Information [Table Text Block]	The following tables quantify the significant unobservable inputs used in developing the fair value of the Company's Level 3 positions as of March 31, 2016 and December 31, 2015 : Significant Unobservable Inputs March 31, 2016 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) Power Contracts $ 120 $ 115 Discounted Cash Flow Forward Market Price (per MWh) $ 9 $ 95 $ 25 Coal Contracts — 15 Discounted Cash Flow Forward Market Price (per ton) 28 41 33 FTRs 44 51 Discounted Cash Flow Auction Prices (per MWh) (62 ) 51 — $ 164 $ 181 Significant Unobservable Inputs December 31, 2015 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) Power Contracts $ 86 $ 100 Discounted Cash Flow Forward Market Price (per MWh) $ 10 $ 92 $ 27 Coal Contracts — 12 Discounted Cash Flow Forward Market Price (per ton) 28 45 35 FTRs 63 70 Discounted Cash Flow Auction Prices (per MWh) (98 ) 87 — $ 149 $ 182
Fair Value Inputs, Sensitivity Analysis [Table Text Block]	The following table provides sensitivity of fair value measurements to increases/(decreases) in significant unobservable inputs as of March 31, 2016 and December 31, 2015 : Significant Unobservable Input Position Change In Input Impact on Fair Value Measurement Forward Market Price Power/Coal Buy Increase/(Decrease) Higher/(Lower) Forward Market Price Power/Coal 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) Category (% of Total) Financial institutions 51 % Utilities, energy merchants, marketers and other 35 ISOs 14 Total as of March 31, 2016 100 % Net Exposure (a) Category (% of Total) Investment grade 97 % Non-rated (b) 2 Non-investment grade 1 Total as of March 31, 2016 100 % (a) Counterparty credit exposure excludes uranium and coal transportation contracts because of the unavailability of market prices. (b) For non-rated counterparties, a significant portion are related to ISO and municipal public power entities, which are considered investment grade equivalent ratings based on NRG's internal credit ratings.

Nuclear Decommissioning Trust28

Nuclear Decommissioning Trust Fund (Tables)	3 Months Ended
	Mar. 31, 2016
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 March 31, 2016 As of December 31, 2015 (In millions, except otherwise noted) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Cash and cash equivalents $ 17 $ — $ — — $ 6 $ — $ — — U.S. government and federal agency obligations 65 4 — 11 55 1 — 11 Federal agency mortgage-backed securities 69 2 — 23 59 1 — 25 Commercial mortgage-backed securities 20 — 1 28 25 — 2 28 Corporate debt securities 72 2 1 11 81 1 1 10 Equity securities 333 198 — — 334 199 — — Foreign government fixed income securities 1 — — 8 1 — — 9 Total $ 577 $ 206 $ 2 $ 561 $ 202 $ 3
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. Three months ended March 31, 2016 2015 (In millions) Realized gains $ 4 $ 6 Realized losses 3 2 Proceeds from sale of securities 191 196

Accounting for Derivative Ins29

Accounting for Derivative Instruments and Hedging Activities (Tables)	3 Months Ended
	Mar. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Net notional volume buy/(sell) of NRG's open derivative transactions broken out by commodity	The following table summarizes the net notional volume buy/(sell) of NRG's open derivative transactions broken out by category, excluding those derivatives that qualified for the NPNS exception, as of March 31, 2016 , and December 31, 2015 . 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 March 31, 2016 December 31, 2015 Category Units (In millions) Emissions Short Ton 1 1 Coal Short Ton 29 35 Natural Gas MMBtu 223 293 Oil Barrel 1 1 Power MWh (49 ) (74 ) Capacity MW/Day (1 ) (1 ) Interest Dollars $ 2,284 $ 2,326 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 March 31, 2016 December 31, 2015 March 31, 2016 December 31, 2015 (In millions) Derivatives designated as cash flow hedges: Interest rate contracts current $ — $ — $ 41 $ 42 Interest rate contracts long-term — — 115 68 Total derivatives designated as cash flow hedges — — 156 110 Derivatives not designated as cash flow hedges : Interest rate contracts current — — 5 5 Interest rate contracts long-term — — 24 13 Commodity contracts current 2,113 1,915 1,901 1,674 Commodity contracts long-term 465 305 488 412 Total derivatives not designated as cash flow hedges 2,578 2,220 2,418 2,104 Total derivatives $ 2,578 $ 2,220 $ 2,574 $ 2,214
Offsetting of derivatives by counterparty master agreement level and collateral received or paid	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 March 31, 2016 (In millions) Commodity contracts: Derivative assets $ 2,578 $ (2,000 ) $ (99 ) $ 479 Derivative liabilities (2,389 ) 2,000 186 (203 ) Total commodity contracts 189 — 87 276 Interest rate contracts: Derivative liabilities (185 ) — — (185 ) Total derivative instruments $ 4 $ — $ 87 $ 91 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, 2015 (In millions) Commodity contracts: Derivative assets $ 2,220 $ (1,616 ) $ (113 ) $ 491 Derivative liabilities (2,086 ) 1,616 271 (199 ) Total commodity contracts 134 — 158 292 Interest rate contracts: Derivative liabilities (128 ) — — (128 ) Total derivative instruments $ 6 $ — $ 158 $ 164
Effects of ASC 815 on the Company's accumulated OCI balance attributable to cash flow hedge derivatives, net of tax	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: Three months ended March 31, 2016 Energy Commodities Interest Rate Total (In millions) Accumulated OCI beginning balance $ — $ (101 ) $ (101 ) Reclassified from accumulated OCI to income: Due to realization of previously deferred amounts — 3 3 Mark-to-market of cash flow hedge accounting contracts — (52 ) (52 ) Accumulated OCI ending balance, net of $24 tax $ — $ (150 ) $ (150 ) Losses expected to be realized from OCI during the next 12 months, net of $3 tax $ — $ (20 ) $ (20 ) Three months ended March 31, 2015 Energy Commodities Interest Rate Total (In millions) Accumulated OCI beginning balance $ (1 ) $ (67 ) $ (68 ) Reclassified from accumulated OCI to income: Due to realization of previously deferred amounts — 2 2 Mark-to-market of cash flow hedge accounting contracts — (18 ) (18 ) Accumulated OCI ending balance, net of $50 tax $ (1 ) $ (83 ) $ (84 )
Pre-tax effects of economic hedges that have not been designated as cash flow hedges, ineffectiveness on cash flow hedges and trading activity on the Company's statement of operations	The following table summarizes the pre-tax effects of economic hedges that have not been designated as cash flow hedges, 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 March 31, 2016 2015 Unrealized mark-to-market results (In millions) Reversal of previously recognized unrealized gains on settled positions related to economic hedges $ (86 ) $ (114 ) Reversal of acquired gain positions related to economic hedges (13 ) (26 ) Net unrealized gains/(losses) on open positions related to economic hedges 134 (138 ) Total unrealized mark-to-market gains/(losses) for economic hedging activities 35 (278 ) Reversal of previously recognized unrealized losses/(gains) on settled positions related to trading activity 8 (21 ) Reversal of acquired gain positions related to trading activity — (7 ) Net unrealized gains on open positions related to trading activity 11 6 Total unrealized mark-to-market gains/(losses) for trading activity 19 (22 ) Total unrealized gains/(losses) $ 54 $ (300 ) Three months ended March 31, 2016 2015 (In millions) Unrealized gains/(losses) included in operating revenues $ 45 $ (109 ) Unrealized gains/(losses) included in cost of operations 9 (191 ) Total impact to statement of operations — energy commodities $ 54 $ (300 ) Total impact to statement of operations — interest rate contracts $ (11 ) $ (14 )

Debt and Capital Leases Debt an

Debt and Capital Leases Debt and Capital Leases (Tables)	3 Months Ended
	Mar. 31, 2016
Debt Instrument [Line Items]
Long-term debt and capital leases	Long-term debt and capital leases consisted of the following: (In millions, except rates) March 31, 2016 December 31, 2015 March 31, 2016 interest rate % (a) Recourse debt: Senior notes, due 2018 $ 958 $ 1,039 7.625 Senior notes, due 2020 1,058 1,058 8.250 Senior notes, due 2021 1,128 1,128 7.875 Senior notes, due 2022 1,060 1,100 6.250 Senior notes, due 2023 910 936 6.625 Senior notes, due 2024 848 904 6.250 Term loan facility, due 2018 1,959 1,964 L+2.00 Tax-exempt bonds 455 455 4.125 - 6.00 Subtotal NRG recourse debt 8,376 8,584 Non-recourse debt: GenOn senior notes 1,945 1,956 7.875 - 9.875 GenOn Americas Generation senior notes 750 752 8.500 - 9.125 GenOn Other 55 56 Subtotal GenOn debt (non-recourse to NRG) 2,750 2,764 Yield Operating LLC Senior Notes, due 2024 500 500 5.375 Yield LLC and Yield Operating LLC Revolving Credit Facility, due 2019 316 306 L+2.75 Yield Inc. Convertible Senior Notes, due 2019 332 330 3.500 Yield Inc. Convertible Senior Notes, due 2020 267 266 3.250 El Segundo Energy Center, due 2023 457 485 L+1.625 - L+2.25 Marsh Landing, due 2017 and 2023 410 418 L+1.175 - L+1.875 Alta Wind I - V lease financing arrangements, due 2034 and 2035 1,002 1,002 5.696 - 7.015 Walnut Creek, term loans due 2023 344 351 L+1.625 Tapestry, due 2021 178 181 L+1.625 Laredo Ridge, due 2028 103 104 L+1.875 Alpine, due 2022 153 154 L+1.750 Energy Center Minneapolis, due 2017 and 2025 107 108 5.95 - 7.25 Viento, due 2023 189 189 L+2.75 NRG Yield - other 463 469 various Subtotal NRG Yield debt (non-recourse to NRG) 4,821 4,863 Ivanpah, due 2033 and 2038 1,145 1,149 2.285 - 4.256 Agua Caliente, due 2037 877 879 2.395 - 3.633 CVSR, due 2037 780 793 2.339 - 3.775 Dandan, due 2033 102 98 L+2.25 Peaker bonds, due 2019 72 72 L+1.07 Cedro Hill, due 2025 102 103 L+3.125 NRG Other 263 315 various Subtotal other NRG non-recourse debt 3,341 3,409 Subtotal all non-recourse debt 10,912 11,036 Subtotal long-term debt (including current maturities) 19,288 19,620 Capital leases: Capital leases 15 13 various Other 3 3 various Subtotal long-term debt and capital leases (including current maturities) 19,306 19,636 Less current maturities 465 481 Less debt issuance costs 164 172 Total long-term debt and capital leases $ 18,677 $ 18,983 (a) As of March 31, 2016 , L+ equals 3 month LIBOR plus x%, with the exception of the Viento Funding II term loan, which is 6 month LIBOR plus x%, and the NRG Marsh Landing term loan, Walnut Creek term loan, and NRG Yield Operating LLC revolving credit facility, which are 1 month LIBOR plus x%.
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument Redemption [Table Text Block]	During the first quarter of 2016, the Company repurchased $203 million in aggregate principal of its Senior Notes in the open market for $192 million , which included accrued interest of $3 million . In connection with the repurchases, an $11 million gain on debt extinguishment was recorded. Principal Repurchased Cash Paid (a) Average Early Redemption Percentage Amount in millions, except rates 7.625% senior notes due 2018 $ 81 $ 84 103.222 % 6.625% senior notes due 2023 26 23 88.505 % 6.250% senior notes due 2022 40 36 87.000 % 6.250% senior notes due 2024 56 49 87.060 % Total $ 203 $ 192 (a) Includes accrued interest.

Variable Interest Entities Summ

Variable Interest Entities Summarized Financial Information (Tables)	3 Months Ended
	Mar. 31, 2016
Equity Method Investments and Joint Ventures [Abstract]
Additional Financial Information Disclosure [Text Block]	The summarized financial information for the Company's consolidated VIEs consisted of the following: (In millions) March 31, 2016 Current assets $ 86 Net property, plant and equipment 1,782 Other long-term assets 923 Total assets 2,791 Current liabilities 59 Long-term debt 360 Other long-term liabilities 190 Total liabilities 609 Noncontrolling interests 745 Net assets less noncontrolling interests $ 1,437

Changes in Capital Structure (T

Changes in Capital Structure (Tables)	3 Months Ended
	Mar. 31, 2016
Changes in Capital Structure Disclosure [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, 2015 416,939,950 (102,749,908 ) 314,190,042 Shares issued under LTIPs 417,051 — 417,051 Shares issued under ESPP — 299,127 299,127 Balance as of March 31, 2016 417,357,001 (102,450,781 ) 314,906,220
Schedule of dividends paid	The following table lists the dividends paid during the three months ended March 31, 2016 : First Quarter 2016 Dividends per Common Share $ 0.145

Earnings_(Loss) Per Share (Tabl

Earnings/(Loss) Per Share (Tables)	3 Months Ended
	Mar. 31, 2016
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 March 31, (In millions, except per share data) 2016 2015 Basic earnings/(loss) per share attributable to NRG Energy, Inc. common stockholders Net income/(loss) attributable to NRG Energy, Inc. $ 82 $ (120 ) Dividends for preferred shares 5 5 Income/(loss) available for common stockholders $ 77 $ (125 ) Weighted average number of common shares outstanding - basic 315 336 Earnings/(loss) per weighted average common share — basic $ 0.24 $ (0.37 ) Diluted earnings/(loss) per share attributable to NRG Energy, Inc. common stockholders Weighted average number of common shares outstanding 315 336 Total dilutive shares 315 336 Earnings/(loss) per weighted average common share — diluted $ 0.24 $ (0.37 )
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 March 31, (In millions of shares) 2016 2015 Equity compensation plans 4 7 Embedded derivative of 2.822% redeemable perpetual preferred stock 16 16 Total 20 23

Segment Reporting (Tables)

Segment Reporting (Tables)	3 Months Ended
	Mar. 31, 2016
Segment Reporting Disclosure [Abstract]
Schedule of segment reporting information, by segment	(In millions) Generation/Business (a)(b) Retail Mass (a) Renewables (a) NRG Yield (a) Corporate (a)(c)(d) Eliminations Total Three months ended March 31, 2016 Operating revenues (a) $ 2,120 $ 1,048 $ 109 $ 220 $ 59 $ (327 ) $ 3,229 Depreciation and amortization 146 28 56 66 17 — 313 Impairment loss on investment (137 ) — — — (9 ) — (146 ) Equity in (losses)/earnings of unconsolidated affiliates (5 ) — (4 ) 2 1 (1 ) (7 ) Income/(Loss) before income taxes 160 146 (51 ) 2 (192 ) 3 68 Net Income/(Loss) 159 146 (45 ) 2 (218 ) 3 47 Net Income/(Loss) attributable to NRG Energy, Inc. $ 159 $ 146 $ (35 ) $ 10 $ (205 ) $ 7 $ 82 Total assets as of March 31, 2016 $ 17,124 $ 1,919 $ 5,736 $ 7,659 $ 19,184 $ (18,942 ) $ 32,680 (a) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 251 $ 1 $ 5 $ 4 $ 66 $ — $ 327 (b) Includes gain on sale of assets $ 32 $ — $ — $ — $ — $ — $ 32 (c) Includes gain on debt extinguishment $ — $ — $ — $ — $ 11 $ — $ 11 (d) Includes net loss of $43 million related to residential solar (In millions) Generation/Business (a)(b) Retail Mass Renewables NRG Yield Corporate (a)(c) Eliminations Total Three months ended March 31, 2015 Operating revenues (a) $ 2,509 $ 1,311 $ 91 $ 200 $ (2 ) $ (280 ) $ 3,829 Depreciation and amortization 233 30 52 67 13 — 395 Equity in (losses)/earnings of unconsolidated affiliates (4 ) — (1 ) 2 (1 ) 1 (3 ) Income/(Loss) before income taxes 29 104 (57 ) (24 ) (262 ) 1 (209 ) Net Income/(Loss) 29 104 (51 ) (20 ) (199 ) 1 (136 ) Net Income/(Loss) attributable to NRG Energy, Inc. $ 29 $ 104 $ (46 ) $ (15 ) $ (187 ) $ (5 ) $ (120 ) (a) Operating revenues include inter-segment sales and net derivative gains and losses of: $ 246 $ — $ — $ — $ 34 $ — $ 280 (b) Includes gain on postretirement benefits curtailment $ 14 $ — $ — $ — $ — $ — $ 14 (c) Includes net loss of $45 million related to residential solar

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	The income tax provision consisted of the following: Three months ended March 31, (In millions except otherwise noted) 2016 2015 Income/(loss) before income taxes $ 68 $ (209 ) Income tax expense/(benefit) 21 (73 ) Effective tax rate 30.9 % 34.9 %

Condensed Consolidating Finan36

Condensed Consolidating Financial Information (Tables)	3 Months Ended
	Mar. 31, 2016
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 March 31, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 1,956 $ 1,299 $ — $ (26 ) $ 3,229 Operating Costs and Expenses Cost of operations 1,450 759 10 (30 ) 2,189 Depreciation and amortization 117 190 6 — 313 Selling, general and administrative 98 99 58 — 255 Acquisition-related transaction and integration costs — — 2 — 2 Development activity expenses — 19 7 — 26 Total operating costs and expenses 1,665 1,067 83 (30 ) 2,785 Gain on sale of assets — 32 — — 32 Operating Income/(Loss) 291 264 (83 ) 4 476 Other Income/(Expense) Equity in (losses)/earnings of consolidated subsidiaries (24 ) 4 213 (193 ) — Equity in losses of unconsolidated affiliates — (8 ) — 1 (7 ) Impairment loss on investment — (140 ) (6 ) — (146 ) Other income/(expense), net — 20 (2 ) — 18 Gain on debt extinguishment — — 11 — 11 Interest expense (5 ) (150 ) (129 ) — (284 ) Total other (expense)/income (29 ) (274 ) 87 (192 ) (408 ) Income/(Loss) Before Income Taxes 262 (10 ) 4 (188 ) 68 Income tax expense/(benefit) 100 (8 ) (83 ) 12 21 Net Income/(Loss) 162 (2 ) 87 (200 ) 47 Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests — (33 ) 5 (7 ) (35 ) Net Income Attributable to NRG Energy, Inc. $ 162 $ 31 $ 82 $ (193 ) $ 82 (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 March 31, 2015 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 2,566 $ 1,303 $ — $ (40 ) $ 3,829 Operating Costs and Expenses Cost of operations 2,104 996 12 (49 ) 3,063 Depreciation and amortization 204 186 5 — 395 Selling, general and administrative 105 100 60 — 265 Acquisition-related transaction and integration costs — 2 8 — 10 Development activity expenses — 15 19 — 34 Total operating costs and expenses 2,413 1,299 104 (49 ) 3,767 Gain on postretirement benefits curtailment — 14 — — 14 Operating Income/(Loss) 153 18 (104 ) 9 76 Other Income/(Expense) Equity in (losses)/earnings of consolidated subsidiaries (13 ) (8 ) 50 (29 ) — Equity in losses of unconsolidated affiliates — (4 ) (1 ) 2 (3 ) Other income, net 1 17 1 — 19 Interest expense (4 ) (158 ) (139 ) — (301 ) Total other expense (16 ) (153 ) (89 ) (27 ) (285 ) Income/(Loss) Before Income Taxes 137 (135 ) (193 ) (18 ) (209 ) Income tax expense/(benefit) 54 (60 ) (67 ) — (73 ) Net Income/(Loss) 83 (75 ) (126 ) (18 ) (136 ) Less: Net loss attributable to noncontrolling interest and redeemable noncontrolling interest — (21 ) (6 ) 11 (16 ) Net Income/(Loss) Attributable to NRG Energy, Inc. $ 83 $ (54 ) $ (120 ) $ (29 ) $ (120 ) (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 For the Three Months Ended March 31, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Net Income/(Loss) $ 162 $ (2 ) $ 87 $ (200 ) $ 47 Other Comprehensive Income/(Loss), net of tax Unrealized (loss)/gain on derivatives, net — (50 ) 24 (6 ) (32 ) Foreign currency translation adjustments, net 4 4 6 (8 ) 6 Available-for-sale securities, net — — 3 — 3 Defined benefit plans, net 1 — — — 1 Other comprehensive income/(loss) 5 (46 ) 33 (14 ) (22 ) Comprehensive Income/(Loss) 167 (48 ) 120 (214 ) 25 Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (50 ) 5 (7 ) (52 ) Comprehensive Income Attributable to NRG Energy, Inc. 167 2 115 (207 ) 77 Dividends for preferred shares — — 5 — 5 Comprehensive Income Available for Common Stockholders $ 167 $ 2 $ 110 $ (207 ) $ 72 (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 March 31, 2015 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Net Income/(Loss) $ 83 $ (75 ) $ (126 ) $ (18 ) $ (136 ) Other Comprehensive Income/(Loss), net of tax Unrealized (loss)/gain on derivatives, net (7 ) 11 (16 ) — (12 ) Foreign currency translation adjustments, net — (9 ) (2 ) — (11 ) Available-for-sale securities, net — (1 ) — — (1 ) Defined benefit plans, net (3 ) (1 ) 11 — 7 Other comprehensive loss (10 ) — (7 ) — (17 ) Comprehensive Income/(Loss) 73 (75 ) (133 ) (18 ) (153 ) Less: Comprehensive loss attributable to noncontrolling interest and redeemable noncontrolling interest — (34 ) (6 ) 11 (29 ) Comprehensive Income/(Loss) Attributable to NRG Energy, Inc. 73 (41 ) (127 ) (29 ) (124 ) Dividends for preferred shares — — 5 — 5 Comprehensive Income/(Loss) Available for Common Stockholders $ 73 $ (41 ) $ (132 ) $ (29 ) $ (129 ) (a) All significant intercompany transactions have been eliminated in consolidation.
Condensed Consolidating Balance Sheets	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS March 31, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated ASSETS (In millions) Current Assets Cash and cash equivalents $ — $ 1,070 $ 589 $ — $ 1,659 Funds deposited by counterparties 34 66 1 — 101 Restricted cash 8 379 — — 387 Accounts receivable - trade, net 723 290 5 — 1,018 Accounts receivable - affiliate 290 318 25 (628 ) 5 Inventory 550 611 — — 1,161 Derivative instruments 1,405 946 — (238 ) 2,113 Cash collateral paid in support of energy risk management activities 324 87 — — 411 Renewable energy grant receivable, net — 35 — — 35 Prepayments and other current assets 121 248 87 — 456 Total current assets 3,455 4,050 707 (866 ) 7,346 Net property, plant and equipment 4,732 13,825 233 (27 ) 18,763 Other Assets Investment in subsidiaries 894 2,218 11,197 (14,309 ) — Equity investments in affiliates (14 ) 1,002 — (90 ) 898 Notes receivable, less current portion — 31 8 1 40 Goodwill 697 302 — — 999 Intangible assets, net 737 1,521 1 (3 ) 2,256 Nuclear decommissioning trust fund 577 — — — 577 Derivative instruments 234 281 — (50 ) 465 Deferred income tax 11 497 (323 ) — 185 Other non-current assets 53 722 376 — 1,151 Total other assets 3,189 6,574 11,259 (14,451 ) 6,571 Total Assets $ 11,376 $ 24,449 $ 12,199 $ (15,344 ) $ 32,680 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Current portion of long-term debt and capital leases $ — $ 529 $ (65 ) $ 1 $ 465 Accounts payable 498 316 31 — 845 Accounts payable — affiliate 259 300 57 (616 ) — Derivative instruments 1,335 850 — (238 ) 1,947 Cash collateral received in support of energy risk management activities 34 66 — — 100 Accrued expenses and other current liabilities 275 427 279 — 981 Total current liabilities 2,401 2,488 302 (853 ) 4,338 Other Liabilities Long-term debt and capital leases 301 10,391 7,985 — 18,677 Nuclear decommissioning reserve 330 — — — 330 Nuclear decommissioning trust liability 294 — — — 294 Deferred income taxes 809 265 (1,037 ) — 37 Derivative instruments 352 325 — (50 ) 627 Out-of-market contracts, net 92 1,030 — — 1,122 Other non-current liabilities 554 788 205 — 1,547 Total non-current liabilities 2,732 12,799 7,153 (50 ) 22,634 Total liabilities 5,133 15,287 7,455 (903 ) 26,972 2.822% convertible perpetual preferred stock — — 304 — 304 Redeemable noncontrolling interest in subsidiaries — 23 — — 23 Stockholders’ Equity 6,243 9,139 4,440 (14,441 ) 5,381 Total Liabilities and Stockholders’ Equity $ 11,376 $ 24,449 $ 12,199 $ (15,344 ) $ 32,680 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2015 Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated ASSETS (In millions) Current Assets Cash and cash equivalents $ — $ 825 $ 693 $ — $ 1,518 Funds deposited by counterparties 55 51 — — 106 Restricted cash 5 409 — — 414 Accounts receivable - trade, net 851 304 2 — 1,157 Accounts receivable - affiliate 395 260 571 (1,222 ) 4 Inventory 570 682 — — 1,252 Derivative instruments 1,202 871 — (158 ) 1,915 Cash collateral paid in support of energy risk management activities 474 94 — — 568 Renewable energy grant receivable, net — 13 — — 13 Current assets held-for-sale — 6 — — 6 Prepayments and other current assets 93 274 71 — 438 Total current assets 3,645 3,789 1,337 (1,380 ) 7,391 Net Property, Plant and Equipment 4,767 13,773 219 (27 ) 18,732 Other Assets Investment in subsidiaries 842 2,244 11,039 (14,125 ) — Equity investments in affiliates (14 ) 1,160 1 (102 ) 1,045 Notes receivable, less current portion — 46 7 — 53 Goodwill 697 302 — — 999 Intangible assets, net 763 1,551 2 (6 ) 2,310 Nuclear decommissioning trust fund 561 — — — 561 Derivative instruments 153 184 — (32 ) 305 Deferred income taxes (6 ) 815 (642 ) — 167 Non-current assets held for sale — 105 — — 105 Other non-current assets 80 749 385 — 1,214 Total other assets 3,076 7,156 10,792 (14,265 ) 6,759 Total Assets $ 11,488 $ 24,718 $ 12,348 $ (15,672 ) $ 32,882 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Current portion of long-term debt and capital leases $ 2 $ 460 $ 19 $ — $ 481 Accounts payable 553 277 39 — 869 Accounts payable — affiliate 151 2,000 (929 ) (1,222 ) — Derivative instruments 1,130 749 — (158 ) 1,721 Cash collateral received in support of energy risk management activities 55 51 — — 106 Current liabilities held-for-sale — 2 — — 2 Accrued expenses and other current liabilities 319 429 449 (1 ) 1,196 Total current liabilities 2,210 3,968 (422 ) (1,381 ) 4,375 Other Liabilities Long-term debt and capital leases 302 10,496 8,185 — 18,983 Nuclear decommissioning reserve 326 — — — 326 Nuclear decommissioning trust liability 283 — — — 283 Deferred income taxes 179 (1,088 ) 928 — 19 Derivative instruments 301 224 — (32 ) 493 Out-of-market contracts, net 95 1,051 — — 1,146 Non-current liabilities held-for-sale — 4 — — 4 Other non-current liabilities 554 735 199 — 1,488 Total non-current liabilities 2,040 11,422 9,312 (32 ) 22,742 Total Liabilities 4,250 15,390 8,890 (1,413 ) 27,117 2.822% Preferred Stock — — 302 — 302 Redeemable noncontrolling interest in subsidiaries — 29 — — 29 Stockholders’ Equity 7,238 9,299 3,156 (14,259 ) 5,434 Total Liabilities and Stockholders’ Equity $ 11,488 $ 24,718 $ 12,348 $ (15,672 ) $ 32,882 (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 Three Months Ended March 31, 2016 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net Income/(loss) $ 162 $ (2 ) $ 87 $ (200 ) $ 47 Adjustments to reconcile net loss to net cash provided by operating activities: Distributions from unconsolidated affiliates — 22 — (12 ) 10 Equity in losses of unconsolidated affiliates — 8 — (1 ) 7 Depreciation and amortization 117 190 6 — 313 Provision for bad debts 8 2 — — 10 Amortization of nuclear fuel 13 — — — 13 Amortization of financing costs and debt discount/premiums — 7 (6 ) — 1 Adjustment for debt extinguishment — — (11 ) — (11 ) Amortization of intangibles and out-of-market contracts 11 15 — — 26 Amortization of unearned equity compensation — — 8 — 8 Changes in deferred income taxes and liability for uncertain tax benefits (613 ) (1,696 ) 2,284 — (25 ) Changes in nuclear decommissioning trust liability 9 — — — 9 Changes in derivative instruments (28 ) (22 ) — — (50 ) Changes in collateral deposits supporting energy risk management activities 150 6 — — 156 Proceeds from sale of emission allowances 47 — — — 47 Gain on sale of assets — (32 ) — — (32 ) Impairment losses — 140 6 — 146 Cash used by changes in other working capital 338 1,728 (2,400 ) 213 (121 ) Net Cash Provided/(Used) by Operating Activities $ 214 $ 366 $ (26 ) $ — $ 554 Cash Flows from Investing Activities Payments for from intercompany loans to subsidiaries (151 ) (11 ) — 162 — Proceeds from dividends from NRG Yield, Inc. — (19 ) — 19 — Acquisition of businesses, net of cash acquired — (6 ) — — (6 ) Capital expenditures (44 ) (219 ) (16 ) — (279 ) Increase in restricted cash, net (2 ) (10 ) — — (12 ) Decrease in restricted cash — U.S. DOE funded projects — 39 — — 39 Decrease in notes receivable — 1 — — 1 Investments in nuclear decommissioning trust fund securities (200 ) — — — (200 ) Proceeds from sales of nuclear decommissioning trust fund securities 191 — — — 191 Proceeds from renewable energy grants and state rebates — 8 — — 8 Purchases of emission allowances (12 ) — — — (12 ) Proceeds from sale of emission allowances 7 — — — 7 Proceeds from sale of assets, net of cash disposed of — 120 — — 120 Investments in unconsolidated affiliates — (4 ) — — (4 ) Other — 4 — — 4 Net Cash Used by Investing Activities (211 ) (97 ) (16 ) 181 (143 ) Cash Flows from Financing Activities Proceeds from intercompany loans — — 162 (162 ) — Proceeds from dividends from NRG Yield, Inc. — — 19 (19 ) — Payment of dividends to common and preferred stockholders — — (48 ) — (48 ) Net receipts from settlement of acquired derivatives that include financing elements — 39 — — 39 Proceeds from issuance of long-term debt — 61 — — 61 Distributions from, net of contributions to, noncontrolling interest in subsidiaries — 10 — — 10 Proceeds from issuance of common stock — — — — — Payments for short and long-term debt — (121 ) (195 ) — (316 ) Other (3 ) (7 ) — — (10 ) Net Cash Used by Financing Activities (3 ) (18 ) (62 ) (181 ) (264 ) Effect of exchange rate changes on cash and cash equivalents — (6 ) — — (6 ) Net Increase/(Decrease) in Cash and Cash Equivalents — 245 (104 ) — 141 Cash and Cash Equivalents at Beginning of Period — 825 693 — 1,518 Cash and Cash Equivalents at End of Period $ — $ 1,070 $ 589 $ — $ 1,659 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the Three Months Ended March 31, 2015 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net Income/(Loss) 83 (75 ) (126 ) (18 ) (136 ) Adjustments to reconcile net loss to net cash provided by operating activities: Distributions from unconsolidated affiliates — 40 — (11 ) 29 Equity in losses of unconsolidated affiliates — 4 1 (2 ) 3 Depreciation and amortization 204 186 5 — 395 Provision for bad debts 13 — 2 — 15 Amortization of nuclear fuel 13 — — — 13 Amortization of financing costs and debt discount/premiums — (11 ) 7 — (4 ) Amortization of intangibles and out-of-market contracts 12 7 — — 19 Amortization of unearned equity compensation — — 11 — 11 Changes in deferred income taxes and liability for uncertain tax benefits 55 (36 ) (102 ) — (83 ) Changes in nuclear decommissioning trust liability (3 ) — — — (3 ) Changes in derivative instruments 131 130 — — 261 Changes in collateral deposits supporting energy risk management activities (132 ) (81 ) — — (213 ) Gain on postretirement benefits curtailment and sale of assets — (14 ) — — (14 ) Cash provided/(used) by changes in other working capital 444 (580 ) (337 ) 440 (33 ) Net Cash Provided/(Used) by Operating Activities 820 (430 ) (539 ) 409 260 Cash Flows from Investing Activities Intercompany loans (to)/from subsidiaries (737 ) 328 409 — — Acquisition of businesses, net of cash acquired — (1 ) — — (1 ) Capital expenditures (89 ) (157 ) (6 ) — (252 ) Increase in restricted cash, net — (11 ) — — (11 ) Decrease in restricted cash — U.S. DOE projects — 24 1 — 25 Decrease in notes receivable — 5 — — 5 Investments in nuclear decommissioning trust fund securities (193 ) — — — (193 ) Proceeds from sales of nuclear decommissioning trust fund securities 196 — — — 196 Proceeds from renewable energy grants — 2 — — 2 Investments in unconsolidated affiliates (2 ) (5 ) (37 ) — (44 ) Other — 3 — — 3 Net Cash (Used)/Provided by Investing Activities (825 ) 188 367 — (270 ) Cash Flows from Financing Activities Proceeds from intercompany loans — — 409 (409 ) — Payment of dividends to common and preferred stockholders — — (51 ) — (51 ) Payment for treasury stock — — (79 ) — (79 ) Net payment for settlement of acquired derivatives that include financing elements — 40 — — 40 Proceeds from issuance of long-term debt — 221 27 — 248 Contributions to, net of distributions from, noncontrolling interest in subsidiaries — (25 ) — — (25 ) Proceeds from issuance of common stock — — 1 — 1 Payments for short and long-term debt — (89 ) (5 ) — (94 ) Net Cash Provided by Financing Activities — 147 302 (409 ) 40 Effect of exchange rate changes on cash and cash equivalents — 18 — — 18 Net (Decrease)/Increase in Cash and Cash Equivalents (5 ) (77 ) 130 — 48 Cash and Cash Equivalents at Beginning of Period 18 1,455 643 — 2,116 Cash and Cash Equivalents at End of Period $ 13 $ 1,378 $ 773 $ — $ 2,164 (a) All significant intercompany transactions have been eliminated in consolidation.

Basis of Presentation Basis of

Basis of Presentation Basis of Presentation (Details)	Mar. 31, 2016MW
Basis of Presentation [Abstract]
Power Generation Capacity, Megawatts	48,000

Summary of Significant Accoun38

Summary of Significant Accounting Policies (NCI - Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Noncontrolling Interest [Line Items]
Capital expenditures accrued and unpaid	$ 98
Balance as of December 31, 2015	2,656		$ 2,727
Distributions to noncontrolling interest	(42)
Contributions from noncontrolling interest	12
Less: Comprehensive loss attributable to noncontrolling interest and redeemable noncontrolling interest	(52)	$ (29)
Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Less: Comprehensive loss attributable to noncontrolling interest and redeemable noncontrolling interest	$ (41)

Summary of Significant Accoun39

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Redeemable NCI - Details 3) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Noncontrolling Interest [Line Items]
Redeemable noncontrolling interest in subsidiaries	$ 23		$ 29
Cash contributions from noncontrolling interest, net of distributions	5
Less: Comprehensive loss attributable to noncontrolling interest and redeemable noncontrolling interest	(52)	$ (29)
Redeemable noncontrolling interest [Member]
Noncontrolling Interest [Line Items]
Less: Comprehensive loss attributable to noncontrolling interest and redeemable noncontrolling interest	$ (11)

Business Acquisitions and Dis40

Business Acquisitions and Dispositions Business Acquisitions and Dispositions (Details 1 - Acquisitions) $ in Millions	3 Months Ended
	Jun. 30, 2015USD ($)MW	Mar. 31, 2016MW
Business Acquisition [Line Items]
Power Generation Capacity, Megawatts		48,000
Desert Sunlight [Member]
Business Acquisition [Line Items]
Percentage of Ownership	25.00%
Power Generation Capacity, Megawatts	550
Payments to Acquire Businesses, Gross | $	$ 285

Business Acquisitions and Dis41

Business Acquisitions and Dispositions Business Acquisitions and Dispositions (Details 2 - Dispositions) $ in Millions	Mar. 02, 2016USD ($)	Feb. 03, 2016USD ($)	Nov. 25, 2015USD ($)	Nov. 10, 2015USD ($)	Mar. 31, 2016USD ($)MW	Mar. 31, 2015USD ($)	Feb. 02, 2016USD ($)	Dec. 31, 2015USD ($)	Nov. 24, 2015MW	Nov. 09, 2015MW
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Power Generation Capacity, Megawatts | MW					48,000
Disposal Group, Including Discontinued Operation, Other Assets, Current					$ 0			$ 6
Disposal Group, Including Discontinued Operation, Liabilities, Current					0			2
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent					0			4
Gain (Loss) on Disposition of Assets						$ 14
Seward Generating Station [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of Ownership									100.00%
Proceeds from Sale of Property, Plant, and Equipment		$ 75	$ 75
Disposal Group, Including Discontinued Operation, Cash							$ 3
Amount of Continuing Cash Flow After Disposition		5
Power Generation Capacity, Megawatts | MW									525
Disposal Group, Including Discontinued Operation, Other Assets, Current								5
Disposal Group, Including Discontinued Operation, Assets, Noncurrent								83
Disposal Group, Including Discontinued Operation, Liabilities, Current								1
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent								4
Shelby County Energy Center, LLC [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of Ownership										100.00%
Proceeds from Sale of Property, Plant, and Equipment	$ 46			$ 46
Power Generation Capacity, Megawatts | MW										352
Disposal Group, Including Discontinued Operation, Other Assets, Current								1
Disposal Group, Including Discontinued Operation, Assets, Noncurrent								22
Disposal Group, Including Discontinued Operation, Liabilities, Current								$ 1
Gain (Loss) on Disposition of Assets					29
Future Revenue Rights					10
Robindale Energy Services, Inc [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Long-term Purchase Commitment, Amount					$ 13
Annual [Member] | Seward Generating Station [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Amount of Continuing Cash Flow After Disposition		1
Environmental Testing [Member] | Seward Generating Station [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Amount of Continuing Cash Flow After Disposition		$ 2.5

Business Acquisitions and Dis42

Business Acquisitions and Dispositions Business Acquisitions and Dispositions (Details 3 - Transfer of Assets) (Details)	Mar. 31, 2016USD ($)MW	Dec. 31, 2015USD ($)	Nov. 02, 2015USD ($)facilityMW	Jan. 02, 2015USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Power Generation Capacity, Megawatts | MW	48,000
Long-term Debt	$ 19,288,000,000	$ 19,620,000,000
ROFO Assets [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration Paid for Sale of Assets Under Common Control			$ 209,000,000	$ 489,000,000
Consideration Paid for Sale of Assets Under Common Control, net of Working Capital Adjustments			$ 207,000,000
Percentage of Ownership Sold of Subsidiary			75.00%
Number of Facilities			12
Power Generation Capacity, Megawatts | MW			814
Long-term Debt			$ 193,000,000	737,000,000
Financial Institutions [Member] | ROFO Assets [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value		$ 159,000,000
Working Capital Adjustment [Member] | ROFO Assets [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration Paid for Sale of Assets Under Common Control			$ 2,000,000	$ 9,000,000

Fair Value of Financial Instr43

Fair Value of Financial Instruments (Details 1 - Balance Sheet grouping) - USD ($) $ in Millions		Mar. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt, including current portion (b)		$ 19,288	$ 19,620
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Notes receivable	[1]	57	73
Long-term debt, including current portion (b)	[2]	19,288	19,620
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Notes receivable	[1]	57	73
Long-term debt, including current portion (b)	[2]	$ 18,116	$ 18,263
[1]	Includes the current portion of notes receivable which is recorded in prepayments and other current assets on the Company's consolidated balance sheets
[2]	Excludes deferred financing costs, which are recorded as a reduction to long-term debt on the Company's consolidated balance sheets.

Fair Value of Financial Instr44

Fair Value of Financial Instruments (Details 2 - Recurring FV) - USD ($) $ in Millions	Mar. 31, 2016		Dec. 31, 2015
Fair Value Assets and Liabilities, Measured on Recurring Basis
Derivative Assets	$ 2,578		$ 2,220
Derivative Liabilities	2,574		2,214
Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring Basis
Derivative Assets	2,578		2,220
Derivative Liabilities	2,389		2,086
Interest rate contracts
Fair Value Assets and Liabilities, Measured on Recurring Basis
Derivative Liabilities	185		128
Fair Value, Measurements, Recurring
Fair Value Assets and Liabilities, Measured on Recurring Basis
Debt securities	17		17
Available-for-sale securities	12		9
Other (a)	11	[1]	14	[2]
Total assets	3,196		2,822
Total liabilities	2,574		2,214
Fair Value, Measurements, Recurring | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring Basis
Derivative Assets	2,578		2,220
Derivative Liabilities	2,389		2,086
Fair Value, Measurements, Recurring | Interest rate contracts
Fair Value Assets and Liabilities, Measured on Recurring Basis
Derivative Liabilities	185		128
Fair Value, Measurements, Recurring | Cash and cash equivalents
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	17		6
Fair Value, Measurements, Recurring | U.S. government and federal agency obligations
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	65		55
U.S. government and federal agency obligations	1		1
Fair Value, Measurements, Recurring | Federal agency mortgage-backed securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	69		59
Fair Value, Measurements, Recurring | Commercial mortgage-backed securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	20		25
Fair Value, Measurements, Recurring | Corporate debt securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	72		81
Fair Value, Measurements, Recurring | Equity securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	333		334
Fair Value, Measurements, Recurring | Foreign government fixed income securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	1		1
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring
Fair Value Assets and Liabilities, Measured on Recurring Basis
Debt securities	17		17
Available-for-sale securities	0		0
Other (a)	0	[1]	0	[2]
Total assets	233		220
Total liabilities	181		182
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring Basis
Derivative Assets	164		149
Derivative Liabilities	181		182
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring | Interest rate contracts
Fair Value Assets and Liabilities, Measured on Recurring Basis
Derivative Liabilities	0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring | Cash and cash equivalents
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring | U.S. government and federal agency obligations
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	0		0
U.S. government and federal agency obligations	0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring | Federal agency mortgage-backed securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring | Commercial mortgage-backed securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring | Corporate debt securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring | Equity securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	52		54
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring | Foreign government fixed income securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	0		0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring
Fair Value Assets and Liabilities, Measured on Recurring Basis
Debt securities	0		0
Available-for-sale securities	0		0
Other (a)	0	[1]	0	[2]
Total assets	1,953		1,616
Total liabilities	1,491		1,164
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring Basis
Derivative Assets	1,790		1,449
Derivative Liabilities	1,306		1,036
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring | Interest rate contracts
Fair Value Assets and Liabilities, Measured on Recurring Basis
Derivative Liabilities	185		128
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring | Cash and cash equivalents
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	0		0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring | U.S. government and federal agency obligations
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	1		1
U.S. government and federal agency obligations	0		0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring | Federal agency mortgage-backed securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	69		59
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring | Commercial mortgage-backed securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	20		25
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring | Corporate debt securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	72		81
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring | Equity securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	0		0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring | Foreign government fixed income securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	1		1
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring
Fair Value Assets and Liabilities, Measured on Recurring Basis
Debt securities	0		0
Available-for-sale securities	12		9
Other (a)	11	[1]	14	[2]
Total assets	1,010		986
Total liabilities	902		868
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring | Commodity contracts
Fair Value Assets and Liabilities, Measured on Recurring Basis
Derivative Assets	624		622
Derivative Liabilities	902		868
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring | Interest rate contracts
Fair Value Assets and Liabilities, Measured on Recurring Basis
Derivative Liabilities	0		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring | Cash and cash equivalents
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	17		6
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring | U.S. government and federal agency obligations
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	64		54
U.S. government and federal agency obligations	1		1
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring | Federal agency mortgage-backed securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	0		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring | Commercial mortgage-backed securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	0		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring | Corporate debt securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	0		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring | Equity securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	281		280
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring | Foreign government fixed income securities
Fair Value Assets and Liabilities, Measured on Recurring Basis
Decommissioning Fund Investments	$ 0		$ 0
[1]	Consists primarily of mutual funds held in a Rabbi Trust for non-qualified deferred compensation plans for certain former employees.
[2]	Primarily consists of mutual funds held in rabbi trusts for non-qualified deferred compensation plans for certain former employees and a total return swap that does not meet the definition of a derivative.

Fair Value of Financial Instr45

Fair Value of Financial Instruments (Details 3 - Level 3 FV) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016		Mar. 31, 2015		Dec. 31, 2015		Dec. 31, 2014
Fair Value Asset and Liabilities, Measured on Recurring Basis Unobservable Input, Changes
No transfers from Level 1 to Level 2		$ 0		$ 0
No transfers from Level 2 to Level 1		0		0
Fair Value, Inputs, Level 3 [Member]
Fair Value Asset and Liabilities, Measured on Recurring Basis Unobservable Input, Changes
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs		52		117		$ 38		$ 161
Total gains/(losses) - realized/unrealized:
Included in earnings		(17)		(55)
Included in nuclear decommissioning obligation		(2)		2
Purchases		5		(4)
Transfers into Level 3 (b)		27	[1]	15	[2]
Transfers out of Level 3 (b)		1	[1]	(2)	[2]
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 March 31, 2015		(24)		(20)
Fair Value, Inputs, Level 3 [Member] | Debt Securities
Fair Value Asset and Liabilities, Measured on Recurring Basis Unobservable Input, Changes
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs		17		18		17		18
Total gains/(losses) - realized/unrealized:
Included in earnings		0		0
Included in nuclear decommissioning obligation		0		0
Purchases		0		0
Transfers into Level 3 (b)		0	[1]	0	[2]
Transfers out of Level 3 (b)		0	[1]	0	[2]
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 March 31, 2015		0		0
Fair Value, Inputs, Level 3 [Member] | Other
Fair Value Asset and Liabilities, Measured on Recurring Basis Unobservable Input, Changes
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs				11				11
Total gains/(losses) - realized/unrealized:
Included in earnings				0
Included in nuclear decommissioning obligation				0
Purchases				0
Transfers into Level 3 (b)	[2]			0
Transfers out of Level 3 (b)	[2]			0
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 March 31, 2015				0
Fair Value, Inputs, Level 3 [Member] | Trust Fund Investments
Fair Value Asset and Liabilities, Measured on Recurring Basis Unobservable Input, Changes
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs		52		54		54		52
Total gains/(losses) - realized/unrealized:
Included in earnings		0		0
Included in nuclear decommissioning obligation		(2)		2
Purchases		0		0
Transfers into Level 3 (b)		0	[1]	0	[2]
Transfers out of Level 3 (b)		0	[1]	0	[2]
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 March 31, 2015		0		0
Fair Value, Inputs, Level 3 [Member] | Derivatives(a)
Fair Value Asset and Liabilities, Measured on Recurring Basis Unobservable Input, Changes
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs		(17)	[3]	34	[4]	$ (33)	[3]	$ 80	[4]
Total gains/(losses) - realized/unrealized:
Included in earnings		(17)	[3]	(55)	[4]
Included in nuclear decommissioning obligation		0	[3]	0	[4]
Purchases		5	[3]	(4)	[4]
Transfers into Level 3 (b)		27	[1],[3]	15	[2],[4]
Transfers out of Level 3 (b)		1	[1],[3]	(2)	[2],[4]
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 March 31, 2015		$ (24)	[3]	$ (20)	[4]
[1]	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.
[2]	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.
[3]	Consists of derivative assets and liabilities, net.
[4]	Consists of derivative assets and liabilities, net.

Fair Value of Financial Instr46

Fair Value of Financial Instruments Fair Value of Financial Instruments (Details 4 - Derivative FV Measurements) $ / T in Millions, $ / MWh in Millions, $ in Millions	Mar. 31, 2016USD ($)$ / T$ / MWh	Dec. 31, 2015USD ($)$ / T$ / MWh	Mar. 31, 2015USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total derivative assets valued with prices provied by models and other valuation techniques (as a percent)	6.00%
Total derivative liabilities valued with prices provied by models and other valuation techniques (as a percent)	7.00%
Derivative Asset, Fair Value, Gross Asset	$ 2,578	$ 2,220
Derivative Liability, Fair Value, Gross Liability	2,574	2,214
Valuation Allowances and Reserves, Balance	5		$ 5
Increase in fair value as a result of the credit reserve, portion recorded in OCI	3		3
Increase in fair value as a result of the credit reserve, portion recorded in operating revenue and cost of operations	2		$ 2
Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	2,578	2,220
Derivative Liability, Fair Value, Gross Liability	2,389	2,086
Commodity contracts | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	2,578	2,220
Derivative Liability, Fair Value, Gross Liability	2,389	2,086
Commodity contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	164	149
Derivative Liability, Fair Value, Gross Liability	181	182
Power Contracts [Member] | Commodity contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	120	86
Derivative Liability, Fair Value, Gross Liability	115	100
Coal Contract [Member] | Commodity contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	15	12
Financial Transmission Rights [Member] | Commodity contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	44	63
Derivative Liability, Fair Value, Gross Liability	$ 51	$ 70
Minimum [Member] | Power Contracts [Member] | Commodity contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Forward Price | $ / MWh	9	10
Minimum [Member] | Coal Contract [Member] | Commodity contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Forward Price | $ / T	28	28
Minimum [Member] | Financial Transmission Rights [Member] | Commodity contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Auction Price | $ / MWh	(62)	(98)
Maximum [Member] | Power Contracts [Member] | Commodity contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Forward Price | $ / MWh	95	92
Maximum [Member] | Coal Contract [Member] | Commodity contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Forward Price | $ / T	41	45
Maximum [Member] | Financial Transmission Rights [Member] | Commodity contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Auction Price | $ / MWh	51	87
Weighted Average [Member] | Power Contracts [Member] | Commodity contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Forward Price | $ / MWh	25	27
Weighted Average [Member] | Coal Contract [Member] | Commodity contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Forward Price | $ / T	33	35
Weighted Average [Member] | Financial Transmission Rights [Member] | Commodity contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Auction Price | $ / MWh	0	0

Fair Value of Financial Instr47

Fair Value of Financial Instruments (Details 5 - Credit Risk) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)
Concentration of Credit Risk
Counterparty credit exposure to a portion of the Company's counterparties	$ 887
Collateral held (cash and letters of credit) against counterparty credit exposure to a portion of the Company's counterparties	204
Net counterparty credit exposure to a portion of the Company's counterparties	$ 686
Company's exposure before collateral is expected to roll off by the end of 2014 (as a percent)	92.00%
Net Exposure (as a percent)	100.00%	[1]
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	$ 223
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	$ 4,500
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)	97.00%	[1]
Non-rated (b)
Concentration of Credit Risk
Net Exposure (as a percent)	2.00%	[1],[2]
External Credit Rating, Non Investment Grade [Member]
Concentration of Credit Risk
Net Exposure (as a percent)	1.00%	[1]
Financial institutions
Concentration of Credit Risk
Net Exposure (as a percent)	51.00%	[1]
Utilities, energy merchants, marketers and other
Concentration of Credit Risk
Net Exposure (as a percent)	35.00%	[1]
ISOs
Concentration of Credit Risk
Net Exposure (as a percent)	14.00%	[1]
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	$ 2,700
[1]	Counterparty credit exposure excludes uranium and coal transportation contracts because of the unavailability of market prices.
[2]	For non-rated counterparties, a significant portion are related to ISO and municipal public power entities, which are considered investment grade equivalent ratings based on NRG's internal credit ratings.

Nuclear Decommissioning Trust48

Nuclear Decommissioning Trust Fund (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Nuclear decommissioning trust fund disclosure
Fair Value	$ 577		$ 561
Unrealized Gains	206		202
Unrealized Losses	2		3
Realized gains	4	$ 6
Realized losses	3	2
Proceeds from sale of securities	191	$ 196
Cash and Cash Equivalents [Member]
Nuclear decommissioning trust fund disclosure
Fair Value	17		6
Unrealized Gains	0		0
Unrealized Losses	$ 0		$ 0
Weighted-average Maturities (In years)	0 years		0 years
U.S. government and federal agency obligations
Nuclear decommissioning trust fund disclosure
Fair Value	$ 65		$ 55
Unrealized Gains	4		1
Unrealized Losses	$ 0		$ 0
Weighted-average Maturities (In years)	11 years		11 years
Federal agency mortgage-backed securities
Nuclear decommissioning trust fund disclosure
Fair Value	$ 69		$ 59
Unrealized Gains	2		1
Unrealized Losses	$ 0		$ 0
Weighted-average Maturities (In years)	23 years		25 years
Commercial mortgage-backed securities
Nuclear decommissioning trust fund disclosure
Fair Value	$ 20		$ 25
Unrealized Gains	0		0
Unrealized Losses	$ 1		$ 2
Weighted-average Maturities (In years)	28 years		28 years
Corporate debt securities
Nuclear decommissioning trust fund disclosure
Fair Value	$ 72		$ 81
Unrealized Gains	2		1
Unrealized Losses	$ 1		$ 1
Weighted-average Maturities (In years)	11 years		10 years
Equity securities
Nuclear decommissioning trust fund disclosure
Fair Value	$ 333		$ 334
Unrealized Gains	198		199
Unrealized Losses	$ 0		$ 0
Weighted-average Maturities (In years)	0 years		0 years
Foreign government fixed income securities
Nuclear decommissioning trust fund disclosure
Fair Value	$ 1		$ 1
Unrealized Gains	0		0
Unrealized Losses	$ 0		$ 0
Weighted-average Maturities (In years)	8 years		9 years

Accounting for Derivative Ins49

Accounting for Derivative Instruments and Hedging Activities (Details 1 - Underlying Derivatives and FV of Derivatives) shares in Millions, bbl in Millions, T in Millions, MWh in Millions, MMBTU in Millions, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016USD ($)MWhMMBTUTsharesbbl	Dec. 31, 2015USD ($)MWhMMBTUTsharesbbl
Fair Value of Derivative Instrument
Derivative Assets	$ 2,578	$ 2,220
Derivative Liabilities	2,574	2,214
Derivatives Designated as Cash Flow Hedges
Fair Value of Derivative Instrument
Derivative Assets	0	0
Derivative Liabilities	156	110
Derivatives Not Designated as Cash Flow Hedges
Fair Value of Derivative Instrument
Derivative Assets	2,578	2,220
Derivative Liabilities	2,418	2,104
Interest rate contracts current | Derivatives Designated as Cash Flow Hedges
Fair Value of Derivative Instrument
Derivative Assets	0	0
Derivative Liabilities	41	42
Interest rate contracts current | Derivatives Not Designated as Cash Flow Hedges
Fair Value of Derivative Instrument
Derivative Assets	0	0
Derivative Liabilities	5	5
Interest rate contracts long-term | Derivatives Designated as Cash Flow Hedges
Fair Value of Derivative Instrument
Derivative Assets	0	0
Derivative Liabilities	115	68
Interest rate contracts long-term | Derivatives Not Designated as Cash Flow Hedges
Fair Value of Derivative Instrument
Derivative Assets	0	0
Derivative Liabilities	24	13
Commodity contracts current | Derivatives Not Designated as Cash Flow Hedges
Fair Value of Derivative Instrument
Derivative Assets	2,113	1,915
Derivative Liabilities	1,901	1,674
Commodity contracts long-term | Derivatives Not Designated as Cash Flow Hedges
Fair Value of Derivative Instrument
Derivative Assets	465	305
Derivative Liabilities	$ 488	$ 412
Long [Member] | Emissions | Short Ton [Member]
Volumetric Underlying Derivative Transactions
Derivative, Nonmonetary Notional Amount, Mass | T	1	1
Long [Member] | Coal | Short Ton [Member]
Volumetric Underlying Derivative Transactions
Derivative, Nonmonetary Notional Amount, Mass | T	29	35
Long [Member] | Natural Gas | MMbtu [Member]
Volumetric Underlying Derivative Transactions
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	223	293
Long [Member] | Oil | Barrel [Member]
Volumetric Underlying Derivative Transactions
Derivative, Nonmonetary Notional Amount, Volume | bbl	1	1
Long [Member] | Interest | United States of America, Dollars
Volumetric Underlying Derivative Transactions
Derivative, Notional Amount	$ 2,284	$ 2,326
Long [Member] | Equity | Shares [Member]
Volumetric Underlying Derivative Transactions
Derivative, Non-monetary Notional Amount, Other | shares	1	1
Short [Member] | Power | M Wh [Member]
Volumetric Underlying Derivative Transactions
Derivative, Nonmonetary Notional Amount, Energy Measure | MWh	(49)	(74)
Short [Member] | Capacity | MW/Day [Member]
Volumetric Underlying Derivative Transactions
Derivative, Nonmonetary Notional Amount, Energy Measure | MWh	(1)	(1)

Accounting for Derivative Ins50

Accounting for Derivative Instruments and Hedging Activities (Details 2 - Offsetting Derivatives) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Derivative Assets	$ 2,578	$ 2,220
Cash Collateral (Held) / Posted	(100)	(106)
Gross Amounts of Recognized Derivative Liabilities	(2,574)	(2,214)
Cash Collateral Posted	411	568
Gross Amounts of Recognized Assets / Liabilities	4	6
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	87	158
Derivative Asset, Fair Value, Amount Offset Against Collateral Net Of Derivative Liability, Fair Value, Amount Offset Against Collateral	91	164
Commodity contracts
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Derivative Assets	2,578	2,220
Derivative Instruments	(2,000)	(1,616)
Cash Collateral (Held) / Posted	(99)	(113)
Net Amount	479	491
Gross Amounts of Recognized Derivative Liabilities	(2,389)	(2,086)
Derivative Instruments	2,000	1,616
Cash Collateral Posted	186	271
Derivative Liability, Fair Value, Amount Offset Against Collateral	(203)	(199)
Gross Amounts of Recognized Assets / Liabilities	189	134
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	87	158
Derivative Asset, Fair Value, Amount Offset Against Collateral Net Of Derivative Liability, Fair Value, Amount Offset Against Collateral	276	292
Interest rate contracts
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Gross Amounts of Recognized Derivative Liabilities	(185)	(128)
Derivative Instruments	0	0
Cash Collateral Posted	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ (185)	$ (128)

Accounting for Derivative Ins51

Accounting for Derivative Instruments and Hedging Activities (Details 3 - AOCI) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Effects of ASC 815 on NRG's Accumulated OCI Balance Attributable to Cash Flow Hedge Derivatives, net of tax
Accumulated OCI beginning balance	$ (101)	$ (68)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	3	2
Mark-to-market of cash flow hedge accounting contracts	(52)	(18)
Accumulated OCI ending balance, net of tax	(150)	(84)
Gains/(losses) expected to be realized from OCI during the next 12 months, net of tax	(20)
Accumulated OCI ending balance, tax	24	50
Gains/(losses) expected to be realized from OCI during the next 12 months, tax	3	0
Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net	0	0
Commodity contracts
Effects of ASC 815 on NRG's Accumulated OCI Balance Attributable to Cash Flow Hedge Derivatives, net of tax
Accumulated OCI beginning balance	0	(1)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	0
Mark-to-market of cash flow hedge accounting contracts	0	0
Accumulated OCI ending balance, net of tax	0	(1)
Gains/(losses) expected to be realized from OCI during the next 12 months, net of tax	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	(101)	(67)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	3	2
Mark-to-market of cash flow hedge accounting contracts	(52)	(18)
Accumulated OCI ending balance, net of tax	(150)	$ (83)
Gains/(losses) expected to be realized from OCI during the next 12 months, net of tax	$ (20)

Accounting for Derivative Ins52

Accounting for Derivative Instruments and Hedging Activities Accounting for Derivative Instruments and Hedging Activities (Details 4 - mark to market) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Unrealized mark-to-market results
Reversal of previously recognized unrealized gains on settled positions related to economic hedges	$ (86)	$ (114)
Reversal of acquired gain positions related to economic hedges	(13)	(26)
Net unrealized gains/(losses) on open positions related to economic hedges	134	(138)
Total unrealized mark-to-market gains/(losses) for economic hedging activities	35	(278)
Reversal of previously recognized unrealized losses/(gains) on settled positions related to trading activity	8	(21)
Reversal of acquired gain positions related to trading activity	0	(7)
Net unrealized gains on open positions related to trading activity	11	6
Total unrealized mark-to-market gains/(losses) for trading activity	19	(22)
Impact of derivative instruments on statement of operations
Total unrealized losses	54	(300)
Credit Risk Related Contingent Features
Derivative Liability, Fair Value of Collateral	126
Derivative, Net Liability Position, Collateral Required Contracts with Credit Rating Contingent Feature	15
Collateral due on net liability position that has not been called by a certain marginable agreement counterparty	6
Commodity contracts
Impact of derivative instruments on statement of operations
Total unrealized losses	54	(300)
Commodity contracts | Sales [Member]
Impact of derivative instruments on statement of operations
Total unrealized losses	45	(109)
Commodity contracts | Cost of Sales [Member]
Impact of derivative instruments on statement of operations
Total unrealized losses	9	(191)
Interest rate contracts
Impact of derivative instruments on statement of operations
Total unrealized losses	$ (11)	$ (14)

Impairments (Details)

Impairments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	$ 146	$ 0
Petra Nova Parish Holdings [Member]
Equity Method Investment, Ownership Percentage	50.00%
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	$ 140

Debt and Capital Leases (Detail

Debt and Capital Leases (Details 1 - Debt Table) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Dec. 31, 2015
Debt and Capital Leases
Long-term Debt		$ 19,288	$ 19,620
Capital Lease Obligations		15	13
Subtotal		19,306	19,636
Less current maturities		465	481
Deferred Finance Costs, Net		164	172
Total long-term debt and capital leases		$ 18,677	18,983
Interest rate, variable basis		3 month LIBOR
Recourse Debt
Debt and Capital Leases
Long-term Debt		$ 8,376	8,584
Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 10,912	11,036
Marsh Landing Term Loan Facility [Member]
Debt and Capital Leases
Interest rate, variable basis		1 - month LIBOR
Marsh Landing Term Loan Facility [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 410	418
Senior Notes Due In 2018 [Member] | Recourse Debt
Debt and Capital Leases
Long-term Debt		$ 958	1,039
Interest rate, stated rate	[1]	7.625%
Senior Notes Due In 2020 [Member] | Recourse Debt
Debt and Capital Leases
Long-term Debt		$ 1,058	1,058
Interest rate, stated rate	[1]	8.25%
Senior notes, due 2021 | Recourse Debt
Debt and Capital Leases
Long-term Debt		$ 1,128	1,128
Interest rate, stated rate	[1]	7.875%
Senior Notes Due In 2022 [Member] | Recourse Debt
Debt and Capital Leases
Long-term Debt		$ 1,060	1,100
Interest rate, stated rate	[1]	6.25%
Senior Notes Due in 2023 [Member] | Recourse Debt
Debt and Capital Leases
Long-term Debt		$ 910	936
Interest rate, stated rate	[1]	6.625%
Senior Notes 2024 [Member] | Recourse Debt
Debt and Capital Leases
Long-term Debt		$ 848	904
Interest rate, stated rate	[1]	6.25%
Term loan facility, due 2018 | Recourse Debt
Debt and Capital Leases
Long-term Debt		$ 1,959	1,964
Tax-exempt Bonds [Member] | Recourse Debt
Debt and Capital Leases
Long-term Debt		$ 455	455
Indian River Power LLC, tax-exempt bonds, due 2040 | Recourse Debt
Debt and Capital Leases
Interest rate, stated rate	[1]	6.00%
Indian River Power LLC, tax-exempt bonds, due 2045 | Recourse Debt
Debt and Capital Leases
Interest rate, stated rate	[1]	5.375%
Dunkirk Power LLC, tax-exempt bonds, due 2042 | Recourse Debt
Debt and Capital Leases
Interest rate, stated rate	[1]	5.875%
Fort Bend County, tax-exempt bonds, due 2038 and 2042 | Recourse Debt
Debt and Capital Leases
Interest rate, stated rate	[1]	4.125%
GenOn Senior Notes [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 1,945	1,956
GenOn Senior Notes Due in 2017 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, stated rate	[1]	7.875%
GenOn senior notes, due 2018 | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, stated rate	[1]	9.50%
GenOn senior notes, due 2020 | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, stated rate	[1]	9.875%
GenOn Americas Generation Senior Notes [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 750	752
GenOn Americas Generation Senior Notes Due in 2021 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, stated rate	[1]	8.50%
GenOn Americas Generation senior notes, due in 2031 | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, stated rate	[1]	9.125%
GenOn Other [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 55	56
Genon [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		2,750	2,764
5.375% Senior Notes due in 2024 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 500	500
Interest rate, stated rate	[1]	5.375%
NRG Yield Revolving Credit Facility [Member]
Debt and Capital Leases
Long-term Debt		$ 316	306
Interest rate, variable basis		1 - month LIBOR
3.5% Convertible Notes due 2019 [Member]
Debt and Capital Leases
Long-term Debt		$ 332	330
3.5% Convertible Notes due 2019 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, stated rate	[1]	3.50%
3.25% Convertible Notes due 2020 [Member]
Debt and Capital Leases
Long-term Debt		$ 267	266
3.25% Convertible Notes due 2020 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, stated rate	[1]	3.25%
West Holdings Credit Agreement [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 457	485
Alta Wind I - V Lease financing arrangement [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 1,002	1,002
Alta Wind I [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, stated rate	[1]	7.015%
Alta Wind II [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, stated rate	[1]	5.696%
Alta Wind III [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, stated rate	[1]	6.067%
Alta Wind IV [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, stated rate	[1]	5.938%
Alta Wind V [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, stated rate	[1]	6.071%
Walnut Creek Energy, LLC, due in 2023 [Member]
Debt and Capital Leases
Interest rate, variable basis		1 - month LIBOR
Walnut Creek Energy, LLC, due in 2023 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 344	351
Interest rate, variable basis	[1]	LIBOR
Tapestry Wind LLC due in 2021 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 178	181
Interest rate, variable basis	[1]	LIBOR
Laredo Ridge Wind, LLC, due in 2026 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 103	104
Interest rate, variable basis	[1]	LIBOR
NRG Solar Alpine LLC, due 2022 | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 153	154
NRG Energy Center Minneapolis LLC, senior secured notes, due 2013, 2017, and 2025 | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 107	108
NRG Energy Center Minneapolis LLC Senior Secured Notes, due 2017 | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, range, minimum	[1]	7.12%
Interest rate, range, maximum	[1]	7.25%
NRG Energy Center Minneapolis LLC Senior Secured Notes, due 2025 | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, stated rate	[1]	5.95%
Viento Funding II, Inc., due in 2023 [Member]
Debt and Capital Leases
Interest rate, variable basis		6 - month LIBOR
Viento Funding II, Inc., due in 2023 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 189	189
Interest rate, variable basis	[1]	LIBOR
NRG Yield - Other [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 463	469
NRG Yield, Inc. | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		4,821	4,863
Ivanpah Financing, due 2014 and 2038 | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 1,145	1,149
Interest rate, range, minimum	[1]	2.285%
Interest rate, range, maximum	[1]	4.256%
Agua Caliente Solar LLC, due 2037 | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 877	879
Interest rate, range, minimum	[1]	2.395%
Interest rate, range, maximum	[1]	3.633%
CVSR - High Plains Ranch II LLC, due 2037 | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 780	793
Interest rate, range, minimum	[1]	2.339%
Interest rate, range, maximum	[1]	3.775%
NRG Solar Dandan [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 102	98
NRG Peaker Finance Co. LLC Bonds Due 2019 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 72	72
Interest rate, variable basis	[1]	LIBOR
Cedro Hill Wind LLC, due in 2025 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 102	103
Interest rate, variable basis	[1]	LIBOR
Other (Non-recourse debt) | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		$ 263	315
NRG Energy [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Long-term Debt		3,341	3,409
Other (Capital leases)
Debt and Capital Leases
Capital Lease Obligations		$ 3	$ 3
London Interbank Offered Rate (LIBOR) [Member] | Term loan facility, due 2018 | Recourse Debt
Debt and Capital Leases
Interest rate, variable basis	[1]	LIBOR
Interest rate, basis spread on variable rate	[1]	2.00%
London Interbank Offered Rate (LIBOR) [Member] | NRG Yield Revolving Credit Facility [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, variable basis	[1]	LIBOR
Interest rate, basis spread on variable rate	[1]	2.75%
London Interbank Offered Rate (LIBOR) [Member] | West Holdings Credit Agreement [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, variable basis	[1]	LIBOR
Interest rate, range, minimum	[1]	1.625%
Interest rate, range, maximum	[1]	2.25%
London Interbank Offered Rate (LIBOR) [Member] | Marsh Landing Term Loan Due 2017 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, variable basis	[1]	LIBOR
Interest rate, basis spread on variable rate	[1]	1.75%
London Interbank Offered Rate (LIBOR) [Member] | GenOn Marsh Landing term loan, due 2023 | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, variable basis	[1]	LIBOR
Interest rate, basis spread on variable rate	[1]	1.875%
London Interbank Offered Rate (LIBOR) [Member] | Walnut Creek Energy, LLC, due in 2023 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, basis spread on variable rate	[1]	1.625%
London Interbank Offered Rate (LIBOR) [Member] | Tapestry Wind LLC due in 2021 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, basis spread on variable rate	[1]	1.625%
London Interbank Offered Rate (LIBOR) [Member] | Laredo Ridge Wind, LLC, due in 2026 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, basis spread on variable rate	[1]	1.875%
London Interbank Offered Rate (LIBOR) [Member] | NRG Solar Alpine LLC, due 2022 | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, variable basis	[1]	LIBOR
Interest rate, basis spread on variable rate	[1]	1.75%
London Interbank Offered Rate (LIBOR) [Member] | Viento Funding II, Inc., due in 2023 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, basis spread on variable rate	[1]	2.75%
London Interbank Offered Rate (LIBOR) [Member] | NRG Solar Dandan [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, variable basis	[1]	LIBOR
Interest rate, basis spread on variable rate	[1]	2.25%
London Interbank Offered Rate (LIBOR) [Member] | NRG Peaker Finance Co. LLC Bonds Due 2019 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, basis spread on variable rate	[1]	1.07%
London Interbank Offered Rate (LIBOR) [Member] | Cedro Hill Wind LLC, due in 2025 [Member] | Non Recourse Debt [Member]
Debt and Capital Leases
Interest rate, basis spread on variable rate	[1]	3.125%
[1]	As of March 31, 2016, L+ equals 3 month LIBOR plus x%, with the exception of the Viento Funding II term loan, which is 6 month LIBOR plus x%, and the NRG Marsh Landing term loan, Walnut Creek term loan, and NRG Yield Operating LLC revolving credit facility, which are 1 month LIBOR plus x%.

Debt and Capital Leases Debt 55

Debt and Capital Leases Debt and Capital Leases (Details 2 - Repurchases - Recourse Debt) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Debt and Capital Leases
Gain on debt extinguishment		$ 11	$ 0
Senior Notes [Member]
Debt and Capital Leases
Debt Instrument, Principal Amount Repurchased		203
Debt Instrument, Repurchase Amount		192
Debt Instrument Repurchase, Accrued Interest		3
Recourse Debt | Senior Notes Due In 2018 [Member]
Debt and Capital Leases
Debt Instrument, Principal Amount Repurchased		81
Debt Instrument, Repurchase Amount	[1]	$ 84
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed		(103.222%)
Recourse Debt | Senior Notes Due in 2023 [Member]
Debt and Capital Leases
Debt Instrument, Principal Amount Repurchased		$ 26
Debt Instrument, Repurchase Amount	[1]	$ 23
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed		(88.505%)
Recourse Debt | Senior Notes Due In 2022 [Member]
Debt and Capital Leases
Debt Instrument, Principal Amount Repurchased		$ 40
Debt Instrument, Repurchase Amount	[1]	$ 36
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed		(87.00%)
Recourse Debt | Senior Notes 2024 [Member]
Debt and Capital Leases
Debt Instrument, Principal Amount Repurchased		$ 56
Debt Instrument, Repurchase Amount	[1]	$ 49
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed		(87.06%)
Recourse Debt | Senior Notes [Member]
Debt and Capital Leases
Debt Instrument, Principal Amount Repurchased		$ 203
Debt Instrument, Repurchase Amount	[1]	$ 192
[1]	(a) Includes accrued interest.

Debt and Capital Leases Debt 56

Debt and Capital Leases Debt and Capital Leases (Details 3 - Non-recourse Debt - Yield) - NRG Yield Revolving Credit Facility [Member] $ in Millions	Mar. 31, 2016USD ($)
Debt and Capital Leases
Line of Credit Facility, Fair Value of Amount Outstanding	$ 316
Letter of Credit [Member]
Debt and Capital Leases
Letters of Credit Outstanding, Amount	$ 60

Debt and Capital Leases Debt 57

Debt and Capital Leases Debt and Capital Leases (Details 4 - Non Recourse Debt - Project Financings) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
		Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2013	Jan. 29, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Long-term Debt			$ 19,288			$ 19,620
High Lonesome Mesa, LLC, due in 2017 [Member]
Debt Instrument [Line Items]
Percentage of Ownership			100.00%
Construction Loans [Member] | NRG Solar Dandan [Member]
Debt Instrument [Line Items]
Long-term Debt			$ 81	$ 81
Debt Instrument, Interest Rate, Stated Percentage				1.25%
Letters of Credit, Issued Amount				$ 5
Letters of Credit Outstanding, Amount			4			5
Term Loan Facility [Member] | NRG Solar Dandan [Member]
Debt Instrument [Line Items]
Long-term Debt					$ 79
Letters of Credit, Issued Amount					4
Cash Grant Loan [Member] | NRG Solar Dandan [Member]
Debt Instrument [Line Items]
Long-term Debt			23	$ 23	$ 23
Non Recourse Debt [Member]
Debt Instrument [Line Items]
Long-term Debt			10,912			11,036
Non Recourse Debt [Member] | NRG Solar Dandan [Member]
Debt Instrument [Line Items]
Long-term Debt			$ 102			$ 98
London Interbank Offered Rate (LIBOR) [Member] | Construction Loans [Member] | NRG Solar Dandan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				2.25%
Debt Instrument, Interest Rate, Increase (Decrease)				0.25%
London Interbank Offered Rate (LIBOR) [Member] | Cash Grant Loan [Member] | NRG Solar Dandan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				1.75%
London Interbank Offered Rate (LIBOR) [Member] | Non Recourse Debt [Member] | NRG Solar Dandan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	[1]		2.25%
Until 5th anniversary of term conversion date [Member] | Construction Loans [Member] | NRG Solar Dandan [Member]
Debt Instrument [Line Items]
Letters Of Credit, Availability Fee, Percentage Of Applicable Margin				2.25%
From 5th anniversary of term conversion date [Member] | Construction Loans [Member] | NRG Solar Dandan [Member]
Debt Instrument [Line Items]
Letters Of Credit, Availability Fee, Percentage Of Applicable Margin				2.50%
Subsequent Event [Member]
Debt Instrument [Line Items]
Proceeds from Sale of Other Assets		$ 253
Midwest Generation [Member] | Non Recourse Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	[1]		4.40%
[1]	As of March 31, 2016, L+ equals 3 month LIBOR plus x%, with the exception of the Viento Funding II term loan, which is 6 month LIBOR plus x%, and the NRG Marsh Landing term loan, Walnut Creek term loan, and NRG Yield Operating LLC revolving credit facility, which are 1 month LIBOR plus x%.

Variable Interest Entities (Det

Variable Interest Entities (Details) $ in Millions	Mar. 31, 2016USD ($)facilityMW	Dec. 31, 2015USD ($)
Investments Accounted for by the Equity Method
Generation Capacity (in MW) | MW	48,000
Equity investments in affiliates	$ 898	$ 1,045
Deficit Restoration Obligation	30
Current assets	86
Net property, plant and equipment	1,782
Other long-term assets	923
Total assets	2,791
Current liabilities	59
Long-term debt	360
Other long-term liabilities	190
Total liabilities	609
Noncontrolling interests	745
Net assets less noncontrolling interests	$ 1,437
GenConn Energy LLC
Investments Accounted for by the Equity Method
Economic interest in equity method investments (as a percent)	50.00%
Power generation units | facility	2
Generation Capacity (in MW) | MW	190
Equity investments in affiliates	$ 108
Sherbino I Wind Farm LLC
Investments Accounted for by the Equity Method
Economic interest in equity method investments (as a percent)	50.00%
Equity investments in affiliates	$ 77

Changes in Capital Structure (D

Changes in Capital Structure (Details) - shares	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Common stock authorized (in shares)
Common stock, shares authorized	500,000,000	500,000,000
Shares issued, balance at the beginning of the year	416,939,950
Treasury shares, balance at the beginning of the year	(102,749,908)
Common Stock, Shares, Outstanding, beginning of year	314,190,042
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	417,051
Stock Issued During Period, Shares, Employee Stock Purchase Plans	299,127
Shares issued, balance at the end of the year	417,357,001
Treasury shares, balance at the end of the year	(102,450,781)
Common Stock, Shares, Outstanding, end of year	314,906,220
Common Stock, Capital Shares Reserved for Employee Stock Purchase Plan	977,786
Common Stock [Member]
Common stock authorized (in shares)
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	417,051
Stock Issued During Period, Shares, Employee Stock Purchase Plans	0
Treasury Stock [Member]
Common stock authorized (in shares)
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	0
Stock Issued During Period, Shares, Employee Stock Purchase Plans	299,127

Changes in Capital Structure Ch

Changes in Capital Structure Changes in Capital Structure (Details 2 - Dividends) - $ / shares	3 Months Ended		12 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016
Dividends Payable [Line Items]
Dividends per Common Share		$ 0.145
Subsequent Event [Member]
Dividends Payable [Line Items]
Dividends Payable, Date Declared	Apr. 18, 2016
Common Stock, Dividends, Per Share, Declared	$ 0.0003
Dividends Payable, Date to be Paid	May 16, 2016
Dividends Payable, Date of Record	May 2, 2016
Scenario, Plan [Member] | Subsequent Event [Member]
Dividends Payable [Line Items]
Common Stock, Dividends, Proposed Annual Amount, Per Share			$ 0.12

Earnings_(Loss) Per Share (Deta

Earnings/(Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Numerator:
Net income/(loss) attributable to NRG Energy, Inc.	$ 82	$ (120)
Dividends for preferred shares	5	5
Income/(loss) available for common stockholders	$ 77	$ (125)
Denominator:
Weighted average number of common shares outstanding - basic	315	336
Basic earnings per share:
Earnings/(loss) per weighted average common share — basic	$ 0.24	$ (0.37)
Denominator (diluted earnings per share):
Total dilutive shares	315	336
Diluted earnings per share:
Earnings/(loss) per weighted average common share — diluted	$ 0.24	$ (0.37)
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of diluted earnings per share, amount	20	23
Convertible perpetual preferred stock, interest rate (as a percentage)	2.822%	2.822%	2.822%
Equity compensation plans
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of diluted earnings per share, amount	4	7
Embedded derivative of 3.625% redeemable perpetual preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of diluted earnings per share, amount	16	16

Segment Reporting (Details)

Segment Reporting (Details)	3 Months Ended
	Mar. 31, 2016USD ($)		Mar. 31, 2015USD ($)		Dec. 31, 2015USD ($)	Nov. 02, 2015USD ($)	Nov. 02, 2015facility
Segment Reporting Information
Operating revenues	$ 3,229,000,000	[1]	$ 3,829,000,000	[2]
Depreciation and amortization	313,000,000		395,000,000
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	(146,000,000)		0
Equity in earnings/(losses) of unconsolidated affiliates	(7,000,000)		(3,000,000)
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	68,000,000		(209,000,000)
Net Income/(Loss)	47,000,000		(136,000,000)
Net income/(loss) attributable to NRG Energy, Inc.	82,000,000		(120,000,000)
Total Assets	32,680,000,000				$ 32,882,000,000
Inter-Segment Sales	327,000,000		280,000,000
Loss on debt extinguishment	(11,000,000)		0
Gain (Loss) on Disposition of Assets	32,000,000		14,000,000
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments			14,000,000
Generation/Business
Segment Reporting Information
Operating revenues	2,120,000,000	[1]	2,509,000,000	[2]
Depreciation and amortization	146,000,000		233,000,000
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	(137,000,000)
Equity in earnings/(losses) of unconsolidated affiliates	(5,000,000)		(4,000,000)
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	160,000,000		29,000,000
Net Income/(Loss)	159,000,000		29,000,000
Net income/(loss) attributable to NRG Energy, Inc.	159,000,000		29,000,000
Total Assets	17,124,000,000
Inter-Segment Sales	251,000,000		246,000,000
Loss on debt extinguishment	0
Gain (Loss) on Disposition of Assets	32,000,000
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments			14,000,000
Solar
Segment Reporting Information
Net Income/(Loss)	43,000,000		45,000,000
NRG Yield(a)
Segment Reporting Information
Operating revenues	220,000,000	[1]	200,000,000	[2]
Depreciation and amortization	66,000,000		67,000,000
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	0
Equity in earnings/(losses) of unconsolidated affiliates	2,000,000		2,000,000
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	2,000,000		(24,000,000)
Net Income/(Loss)	2,000,000		(20,000,000)
Net income/(loss) attributable to NRG Energy, Inc.	10,000,000		(15,000,000)
Total Assets	7,659,000,000
Inter-Segment Sales	4,000,000		0
Loss on debt extinguishment	0
Gain (Loss) on Disposition of Assets	0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments			0
Corporate
Segment Reporting Information
Operating revenues	59,000,000	[1]	(2,000,000)	[2]
Depreciation and amortization	17,000,000		13,000,000
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	(9,000,000)
Equity in earnings/(losses) of unconsolidated affiliates	1,000,000		(1,000,000)
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	(192,000,000)		(262,000,000)
Net Income/(Loss)	(218,000,000)		(199,000,000)
Net income/(loss) attributable to NRG Energy, Inc.	(205,000,000)		(187,000,000)
Total Assets	19,184,000,000
Inter-Segment Sales	66,000,000		34,000,000
Loss on debt extinguishment	(11,000,000)
Gain (Loss) on Disposition of Assets	0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments			0
Elimination
Segment Reporting Information
Operating revenues	(327,000,000)	[1]	(280,000,000)	[2]
Depreciation and amortization	0		0
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	0
Equity in earnings/(losses) of unconsolidated affiliates	(1,000,000)		1,000,000
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	3,000,000		1,000,000
Net Income/(Loss)	3,000,000		1,000,000
Net income/(loss) attributable to NRG Energy, Inc.	7,000,000		(5,000,000)
Total Assets	(18,942,000,000)
Inter-Segment Sales	0		0
Loss on debt extinguishment	0
Gain (Loss) on Disposition of Assets	0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments			0
Retail Mass(a)
Segment Reporting Information
Operating revenues	1,048,000,000	[1]	1,311,000,000	[2]
Depreciation and amortization	28,000,000		30,000,000
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	0
Equity in earnings/(losses) of unconsolidated affiliates	0		0
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	146,000,000		104,000,000
Net Income/(Loss)	146,000,000		104,000,000
Net income/(loss) attributable to NRG Energy, Inc.	146,000,000		104,000,000
Total Assets	1,919,000,000
Inter-Segment Sales	1,000,000		0
Loss on debt extinguishment	0
Gain (Loss) on Disposition of Assets	0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments			0
Renewables(a)
Segment Reporting Information
Operating revenues	109,000,000	[1]	91,000,000	[2]
Depreciation and amortization	56,000,000		52,000,000
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	0
Equity in earnings/(losses) of unconsolidated affiliates	(4,000,000)		(1,000,000)
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	(51,000,000)		(57,000,000)
Net Income/(Loss)	(45,000,000)		(51,000,000)
Net income/(loss) attributable to NRG Energy, Inc.	(35,000,000)		(46,000,000)
Total Assets	5,736,000,000
Inter-Segment Sales	5,000,000		0
Loss on debt extinguishment	0
Gain (Loss) on Disposition of Assets	$ 0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments			$ 0
ROFO Assets [Member]
Segment Reporting Information
Number of Facilities						12	12
[1]	(a) Operating revenues include inter-segment sales and net derivative gains and losses of:$251 $1 $5 $4 $66 $— $327(b) Includes gain on sale of assets$32 $— $— $— $— $— $32(c) Includes gain on debt extinguishment$— $— $— $— $11 $— $11(d) Includes net loss of $43 million related to residential solar
[2]	(a) Operating revenues include inter-segment sales and net derivative gains and losses of:$246 $— $— $— $34 $— $280(b) Includes gain on postretirement benefits curtailment $14 $— $— $— $— $— $14(c) Includes net loss of $45 million related to residential solar

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Effective Tax Rate
Income/(loss) before income taxes	$ 68	$ (209)
Income tax expense/(benefit)	$ 21	$ (73)
Effective tax rate	30.90%	34.90%
Statutory tax rate (as a percent)	35.00%	35.00%
Uncertain Tax Benefits
Non-current tax liability for uncertain tax benefits	$ 42
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	$ 3

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($)	1 Months Ended	3 Months Ended		12 Months Ended
	Jun. 30, 2013	Mar. 31, 2016	Sep. 30, 2010	Dec. 31, 2015
MD Department of Environment v. Chalk Point [Member]
Loss Contingencies
Civil Penalties	$ 0
Midwest Generation New Source Review [Member]
Loss Contingencies
Civil Penalties			$ 37,500
Telephone Consumer Protection Act Purported Class Actions [Member]
Loss Contingencies
Loss Contingency, Damages Sought		1,500
CDWR and SDGE v Sunrise Power [Member]
Loss Contingencies
Loss Contingency, Damages Sought				1.2
Remaining Term				70 months

Regulatory Matters (Details)

Regulatory Matters (Details) $ in Millions	Dec. 20, 2013USD ($)
Genon [Member]
Regulatory Matters [Line Items]
Regulatory payments sought	$ 22

Environmental Matters (Details)

Environmental Matters (Details) $ in Millions	Mar. 31, 2016USD ($)
Environmental capital expenditures [Line Items]
Environmental Capital Expenditures, Estimated	$ 339
Genon [Member]
Environmental capital expenditures [Line Items]
Environmental Capital Expenditures, Estimated	66
Midwest Generation [Member]
Environmental capital expenditures [Line Items]
Environmental Capital Expenditures, Estimated	$ 254

Condensed Consolidating Finan67

Condensed Consolidating Financial Information (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Debt Instrument
Long-term Debt	$ 19,288	$ 19,620
Recourse Debt
Debt Instrument
Long-term Debt	8,376	$ 8,584
Senior Notes [Member] | Recourse Debt
Debt Instrument
Long-term Debt	$ 6,000

Condensed Consolidating Finan68

Condensed Consolidating Financial Information (Details 2) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016		Mar. 31, 2015
Operating Revenues
Total operating revenues		$ 3,229	[1]	$ 3,829	[2]
Operating Costs and Expenses
Cost of operations		2,189		3,063
Depreciation and amortization		313		395
Selling, general and administrative		255		265
Acquisition-related transaction and integration costs		2		10
Development activity expenses		26		34
Total operating costs and expenses		2,785		3,767
Gain (Loss) on Disposition of Assets		32		14
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments				14
Operating Income/(Loss)		476		76
Other Income/(Expense)
Equity in (losses)/earnings of consolidated subsidiaries		0		0
Equity in losses of unconsolidated affiliates		(7)		(3)
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net		(146)		0
Other income, net		18		19
Gain on debt extinguishment		11		0
Interest expense		(284)		(301)
Total other (expense)/income		(408)		(285)
Income/(loss) before income taxes		68		(209)
Income tax expense/(benefit)		21		(73)
Net Income/(Loss)		47		(136)
Less: Net (loss) attributable to noncontrolling interest and redeemable noncontrolling interests		(35)		(16)
Net Income Attributable to NRG Energy, Inc.		82		(120)
Other Comprehensive Income/(Loss), net of tax
Unrealized (loss)/gain on derivatives, net		(32)		(12)
Foreign currency translation adjustments, net		6		(11)
Available-for-sale securities, net		3		(1)
Defined benefit plans, net		1		7
Other comprehensive income/(loss)		(22)		(17)
Comprehensive Income/(Loss)		25		(153)
Less: Comprehensive income/(loss) attributable to noncontrolling interest and redeemable noncontrolling interests		(52)		(29)
Comprehensive Income Attributable to NRG Energy, Inc.		77		(124)
Dividends for preferred shares		(5)		(5)
Comprehensive Income Available for Common Stockholders		72		(129)
Guarantor Subsidiaries
Operating Revenues
Total operating revenues		1,956		2,566
Operating Costs and Expenses
Cost of operations		1,450		2,104
Depreciation and amortization		117		204
Selling, general and administrative		98		105
Acquisition-related transaction and integration costs		0		0
Development activity expenses		0		0
Total operating costs and expenses		1,665		2,413
Gain (Loss) on Disposition of Assets		0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments				0
Operating Income/(Loss)		291		153
Other Income/(Expense)
Equity in (losses)/earnings of consolidated subsidiaries		(24)		(13)
Equity in losses of unconsolidated affiliates		0		0
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net		0
Other income, net		0		1
Gain on debt extinguishment		0
Interest expense		(5)		(4)
Total other (expense)/income		(29)		(16)
Income/(loss) before income taxes		262		137
Income tax expense/(benefit)		100		54
Net Income/(Loss)		162		83
Less: Net (loss) attributable to noncontrolling interest and redeemable noncontrolling interests		0		0
Net Income Attributable to NRG Energy, Inc.		162		83
Other Comprehensive Income/(Loss), net of tax
Unrealized (loss)/gain on derivatives, net		0		(7)
Foreign currency translation adjustments, net		4		0
Available-for-sale securities, net		0		0
Defined benefit plans, net		(1)		3
Other comprehensive income/(loss)		5		(10)
Comprehensive Income/(Loss)		167		73
Less: Comprehensive income/(loss) attributable to noncontrolling interest and redeemable noncontrolling interests		0		0
Comprehensive Income Attributable to NRG Energy, Inc.		167		73
Dividends for preferred shares		0		0
Comprehensive Income Available for Common Stockholders		167		73
Non-Guarantor Subsidiaries
Operating Revenues
Total operating revenues		1,299		1,303
Operating Costs and Expenses
Cost of operations		759		996
Depreciation and amortization		190		186
Selling, general and administrative		99		100
Acquisition-related transaction and integration costs		0		2
Development activity expenses		19		15
Total operating costs and expenses		1,067		1,299
Gain (Loss) on Disposition of Assets		32
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments				14
Operating Income/(Loss)		264		18
Other Income/(Expense)
Equity in (losses)/earnings of consolidated subsidiaries		4		(8)
Equity in losses of unconsolidated affiliates		(8)		(4)
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net		(140)
Other income, net		20		17
Gain on debt extinguishment		0
Interest expense		(150)		(158)
Total other (expense)/income		(274)		(153)
Income/(loss) before income taxes		(10)		(135)
Income tax expense/(benefit)		(8)		(60)
Net Income/(Loss)		(2)		(75)
Less: Net (loss) attributable to noncontrolling interest and redeemable noncontrolling interests		(33)		(21)
Net Income Attributable to NRG Energy, Inc.		31		(54)
Other Comprehensive Income/(Loss), net of tax
Unrealized (loss)/gain on derivatives, net		(50)		11
Foreign currency translation adjustments, net		4		(9)
Available-for-sale securities, net		0		(1)
Defined benefit plans, net		0		1
Other comprehensive income/(loss)		(46)		0
Comprehensive Income/(Loss)		(48)		(75)
Less: Comprehensive income/(loss) attributable to noncontrolling interest and redeemable noncontrolling interests		(50)		(34)
Comprehensive Income Attributable to NRG Energy, Inc.		2		(41)
Dividends for preferred shares		0		0
Comprehensive Income Available for Common Stockholders		2		(41)
NRG Energy, Inc.
Operating Revenues
Total operating revenues		0		0
Operating Costs and Expenses
Cost of operations		10		12
Depreciation and amortization		6		5
Selling, general and administrative		58		60
Acquisition-related transaction and integration costs		2		8
Development activity expenses		7		19
Total operating costs and expenses		83		104
Gain (Loss) on Disposition of Assets		0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments				0
Operating Income/(Loss)		(83)		(104)
Other Income/(Expense)
Equity in (losses)/earnings of consolidated subsidiaries		213		50
Equity in losses of unconsolidated affiliates		0		(1)
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net		(6)
Other income, net		(2)		1
Gain on debt extinguishment		11
Interest expense		(129)		(139)
Total other (expense)/income		87		(89)
Income/(loss) before income taxes		4		(193)
Income tax expense/(benefit)		(83)		(67)
Net Income/(Loss)		87		(126)
Less: Net (loss) attributable to noncontrolling interest and redeemable noncontrolling interests		5		(6)
Net Income Attributable to NRG Energy, Inc.		82		(120)
Other Comprehensive Income/(Loss), net of tax
Unrealized (loss)/gain on derivatives, net		24		(16)
Foreign currency translation adjustments, net		6		(2)
Available-for-sale securities, net		3		0
Defined benefit plans, net		0		(11)
Other comprehensive income/(loss)		33		(7)
Comprehensive Income/(Loss)		120		(133)
Less: Comprehensive income/(loss) attributable to noncontrolling interest and redeemable noncontrolling interests		5		(6)
Comprehensive Income Attributable to NRG Energy, Inc.		115		(127)
Dividends for preferred shares		(5)		(5)
Comprehensive Income Available for Common Stockholders		110		(132)
Eliminations
Operating Revenues
Total operating revenues		(26)	[3]	(40)	[4]
Operating Costs and Expenses
Cost of operations		(30)	[3]	(49)	[4]
Depreciation and amortization		0	[3],[5]	0	[4],[6]
Selling, general and administrative		0	[3]	0	[4]
Acquisition-related transaction and integration costs		0	[3]	0	[4]
Development activity expenses		0	[3]	0	[4]
Total operating costs and expenses		(30)	[3]	(49)	[4]
Gain (Loss) on Disposition of Assets	[3],[5]	0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	[4]			0
Operating Income/(Loss)		4	[3]	9	[4]
Other Income/(Expense)
Equity in (losses)/earnings of consolidated subsidiaries		(193)	[3]	(29)	[4]
Equity in losses of unconsolidated affiliates	[5]	1	[3]	2	[4]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	[3],[5]	0
Other income, net		0	[3]	0	[4]
Gain on debt extinguishment	[3]	0
Interest expense		0	[3]	0	[4]
Total other (expense)/income		(192)	[3]	(27)	[4]
Income/(loss) before income taxes		(188)	[3]	(18)	[4]
Income tax expense/(benefit)		12	[3]	0	[4]
Net Income/(Loss)		(200)	[3]	(18)	[4],[6]
Less: Net (loss) attributable to noncontrolling interest and redeemable noncontrolling interests		(7)	[3]	11	[4]
Net Income Attributable to NRG Energy, Inc.		(193)	[3]	(29)	[4]
Other Comprehensive Income/(Loss), net of tax
Unrealized (loss)/gain on derivatives, net		(6)	[7]	0	[8]
Foreign currency translation adjustments, net		(8)	[7]	0	[8]
Available-for-sale securities, net		0	[7]	0	[8]
Defined benefit plans, net		0	[7]	0	[8]
Other comprehensive income/(loss)		(14)	[7]	0	[8]
Comprehensive Income/(Loss)		(214)	[7]	(18)	[8]
Less: Comprehensive income/(loss) attributable to noncontrolling interest and redeemable noncontrolling interests		(7)	[7]	11	[8]
Comprehensive Income Attributable to NRG Energy, Inc.		(207)	[7]	(29)	[8]
Dividends for preferred shares		0	[7]	0	[8]
Comprehensive Income Available for Common Stockholders		$ (207)	[7]	$ (29)	[8]
[1]	(a) Operating revenues include inter-segment sales and net derivative gains and losses of:$251 $1 $5 $4 $66 $— $327(b) Includes gain on sale of assets$32 $— $— $— $— $— $32(c) Includes gain on debt extinguishment$— $— $— $— $11 $— $11(d) Includes net loss of $43 million related to residential solar
[2]	(a) Operating revenues include inter-segment sales and net derivative gains and losses of:$246 $— $— $— $34 $— $280(b) Includes gain on postretirement benefits curtailment $14 $— $— $— $— $— $14(c) Includes net loss of $45 million related to residential solar
[3]	All significant intercompany transactions have been eliminated in consolidation.
[4]	(a)All significant intercompany transactions have been eliminated in consolidation.
[5]	All significant intercompany transactions have been eliminated in consolidation.
[6]	All significant intercompany transactions have been eliminated in consolidation.
[7]	All significant intercompany transactions have been eliminated in consolidation.
[8]	All significant intercompany transactions have been eliminated in consolidation.

Condensed Consolidating Finan69

Condensed Consolidating Financial Information (Details 3) - USD ($) $ in Millions		Mar. 31, 2016		Dec. 31, 2015		Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014		Dec. 31, 2013
Condensed Financial Statements
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent		$ 0		$ 105
Current Assets
Cash and cash equivalents		1,659		1,518		$ 2,164	$ 2,116	$ 2,164		$ 2,116
Funds deposited by counterparties		101		106
Restricted cash		387		414
Accounts receivable - trade, net		1,018		1,157
Accounts receivable - affiliate		5		4
Inventory		1,161		1,252
Derivative instruments		2,113		1,915
Cash collateral paid in support of energy risk management activities		411		568
Renewable energy grant receivable, net		35		13
Disposal Group, Including Discontinued Operation, Other Assets, Current		0		6
Prepayments and other current assets		456		438
Total current assets		7,346		7,391
Net property, plant and equipment		18,763		18,732
Other Assets
Investment in subsidiaries		0		0
Equity investments in affiliates		898		1,045
Notes receivable, less current portion		40		53
Goodwill		999		999
Intangible assets, net		2,256		2,310
Nuclear decommissioning trust fund		577		561
Derivative instruments		465		305
Deferred income taxes		185		167
Other non-current assets		1,151		1,214
Total other assets		6,571		6,759
Total Assets		32,680		32,882
Current Liabilities
Current portion of long-term debt and capital leases		465		481
Accounts payable		845		869
Accounts payable — affiliate		0		0
Derivative instruments		1,947		1,721
Cash collateral received in support of energy risk management activities		100		106
Accrued expenses and other current liabilities		981		1,196
Disposal Group, Including Discontinued Operation, Liabilities, Current		0		2
Other Liabilities, Current				1,196
Total current liabilities		4,338		4,375
Other Liabilities
Long-term debt and capital leases		18,677		18,983
Nuclear decommissioning reserve		330		326
Nuclear decommissioning trust liability		294		283
Deferred income taxes		37		19
Derivative instruments		627		493
Out-of-market contracts, net of accumulated amortization of $639 and $562		1,122		1,146
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		0		4
Other non-current liabilities		1,547		1,488
Total non-current liabilities		22,634		22,742
Total liabilities		26,972		27,117
2.822% convertible perpetual preferred stock		304		302
Redeemable noncontrolling interest in subsidiaries		$ 23		$ 29
Convertible perpetual preferred stock, interest rate (as a percentage)		2.822%		2.822%		2.822%
Stockholders’ Equity		$ 5,381		$ 5,434
Total Liabilities and Stockholders’ Equity		32,680		32,882
Guarantor Subsidiaries
Condensed Financial Statements
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent				0
Current Assets
Cash and cash equivalents		0		0				13		18
Funds deposited by counterparties		34		55
Restricted cash		8		5
Accounts receivable - trade, net		723		851
Accounts receivable - affiliate		290		395
Inventory		550		570
Derivative instruments		1,405		1,202
Cash collateral paid in support of energy risk management activities		324		474
Renewable energy grant receivable, net		0		0
Disposal Group, Including Discontinued Operation, Other Assets, Current				0
Prepayments and other current assets		121		93
Total current assets		3,455		3,645
Net property, plant and equipment		4,732		4,767
Other Assets
Investment in subsidiaries		894		842
Equity investments in affiliates		(14)		(14)
Notes receivable, less current portion		0		0
Goodwill		697		697
Intangible assets, net		737		763
Nuclear decommissioning trust fund		577		561
Derivative instruments		234		153
Deferred income taxes		11		(6)
Other non-current assets		53		80
Total other assets		3,189		3,076
Total Assets		11,376		11,488
Current Liabilities
Current portion of long-term debt and capital leases		0		2
Accounts payable		498		553
Accounts payable — affiliate		259		151
Derivative instruments		1,335		1,130
Cash collateral received in support of energy risk management activities		34		55
Accrued expenses and other current liabilities		275
Disposal Group, Including Discontinued Operation, Liabilities, Current				0
Other Liabilities, Current				319
Total current liabilities		2,401		2,210
Other Liabilities
Long-term debt and capital leases		301		302
Nuclear decommissioning reserve		330		326
Nuclear decommissioning trust liability		294		283
Deferred income taxes		809		179
Derivative instruments		352		301
Out-of-market contracts, net of accumulated amortization of $639 and $562		92		95
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent				0
Other non-current liabilities		554		554
Total non-current liabilities		2,732		2,040
Total liabilities		5,133		4,250
2.822% convertible perpetual preferred stock		0		0
Redeemable noncontrolling interest in subsidiaries		0		0
Stockholders’ Equity		6,243		7,238
Total Liabilities and Stockholders’ Equity		11,376		11,488
Non-Guarantor Subsidiaries
Condensed Financial Statements
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent				105
Current Assets
Cash and cash equivalents		1,070		825				1,378		1,455
Funds deposited by counterparties		66		51
Restricted cash		379		409
Accounts receivable - trade, net		290		304
Accounts receivable - affiliate		318		260
Inventory		611		682
Derivative instruments		946		871
Cash collateral paid in support of energy risk management activities		87		94
Renewable energy grant receivable, net		35		13
Disposal Group, Including Discontinued Operation, Other Assets, Current				6
Prepayments and other current assets		248		274
Total current assets		4,050		3,789
Net property, plant and equipment		13,825		13,773
Other Assets
Investment in subsidiaries		2,218		2,244
Equity investments in affiliates		1,002		1,160
Notes receivable, less current portion		31		46
Goodwill		302		302
Intangible assets, net		1,521		1,551
Nuclear decommissioning trust fund		0		0
Derivative instruments		281		184
Deferred income taxes		497		815
Other non-current assets		722		749
Total other assets		6,574		7,156
Total Assets		24,449		24,718
Current Liabilities
Current portion of long-term debt and capital leases		529		460
Accounts payable		316		277
Accounts payable — affiliate		300		2,000
Derivative instruments		850		749
Cash collateral received in support of energy risk management activities		66		51
Accrued expenses and other current liabilities		427
Disposal Group, Including Discontinued Operation, Liabilities, Current				2
Other Liabilities, Current				429
Total current liabilities		2,488		3,968
Other Liabilities
Long-term debt and capital leases		10,391		10,496
Nuclear decommissioning reserve		0		0
Nuclear decommissioning trust liability		0		0
Deferred income taxes		265		(1,088)
Derivative instruments		325		224
Out-of-market contracts, net of accumulated amortization of $639 and $562		1,030		1,051
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent				4
Other non-current liabilities		788		735
Total non-current liabilities		12,799		11,422
Total liabilities		15,287		15,390
2.822% convertible perpetual preferred stock		0		0
Redeemable noncontrolling interest in subsidiaries		23		29
Stockholders’ Equity		9,139		9,299
Total Liabilities and Stockholders’ Equity		24,449		24,718
NRG Energy, Inc.
Condensed Financial Statements
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent				0
Current Assets
Cash and cash equivalents		589		693				773		643
Funds deposited by counterparties		1		0
Restricted cash		0		0
Accounts receivable - trade, net		5		2
Accounts receivable - affiliate		25		571
Inventory		0		0
Derivative instruments		0		0
Cash collateral paid in support of energy risk management activities		0		0
Renewable energy grant receivable, net		0		0
Disposal Group, Including Discontinued Operation, Other Assets, Current				0
Prepayments and other current assets		87		71
Total current assets		707		1,337
Net property, plant and equipment		233		219
Other Assets
Investment in subsidiaries		11,197		11,039
Equity investments in affiliates		0		1
Notes receivable, less current portion		8		7
Goodwill		0		0
Intangible assets, net		1		2
Nuclear decommissioning trust fund		0		0
Derivative instruments		0		0
Deferred income taxes		(323)		(642)
Other non-current assets		376		385
Total other assets		11,259		10,792
Total Assets		12,199		12,348
Current Liabilities
Current portion of long-term debt and capital leases		(65)		19
Accounts payable		31		39
Accounts payable — affiliate		57		(929)
Derivative instruments		0		0
Cash collateral received in support of energy risk management activities		0		0
Accrued expenses and other current liabilities		279
Disposal Group, Including Discontinued Operation, Liabilities, Current				0
Other Liabilities, Current				449
Total current liabilities		302		(422)
Other Liabilities
Long-term debt and capital leases		7,985		8,185
Nuclear decommissioning reserve		0		0
Nuclear decommissioning trust liability		0		0
Deferred income taxes		(1,037)		928
Derivative instruments		0		0
Out-of-market contracts, net of accumulated amortization of $639 and $562		0		0
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent				0
Other non-current liabilities		205		199
Total non-current liabilities		7,153		9,312
Total liabilities		7,455		8,890
2.822% convertible perpetual preferred stock		304		302
Redeemable noncontrolling interest in subsidiaries		$ 0		$ 0
Convertible perpetual preferred stock, interest rate (as a percentage)		2.822%		2.822%
Stockholders’ Equity		$ 4,440		$ 3,156
Total Liabilities and Stockholders’ Equity		12,199		12,348
Eliminations
Condensed Financial Statements
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent	[1]			0
Current Assets
Cash and cash equivalents		0	[2],[3]	0	[1]			$ 0	[4]	$ 0	[4]
Funds deposited by counterparties		0	[2]	0	[1]
Restricted cash		0	[2]	0	[1]
Accounts receivable - trade, net		0	[2]	0	[1]
Accounts receivable - affiliate		(628)	[2]	(1,222)	[1]
Inventory		0	[2]	0	[1]
Derivative instruments		(238)	[2]	(158)	[1]
Cash collateral paid in support of energy risk management activities		0	[2]	0	[1]
Renewable energy grant receivable, net		0	[2]	0	[1]
Disposal Group, Including Discontinued Operation, Other Assets, Current	[1]			0
Prepayments and other current assets		0	[2]	0	[1]
Total current assets		(866)	[2]	(1,380)	[1]
Net property, plant and equipment		(27)	[2]	(27)	[1]
Other Assets
Investment in subsidiaries		(14,309)	[2]	(14,125)	[1]
Equity investments in affiliates		(90)	[2]	(102)	[1]
Notes receivable, less current portion		1	[2]	0	[1]
Goodwill		0	[2]	0	[1]
Intangible assets, net		(3)	[2]	(6)	[1]
Nuclear decommissioning trust fund		0	[2]	0	[1]
Derivative instruments		(50)	[2]	(32)	[1]
Deferred income taxes		0	[2]	0	[1]
Other non-current assets		0	[2]	0	[1]
Total other assets		(14,451)	[2]	(14,265)	[1]
Total Assets		(15,344)	[2]	(15,672)	[1]
Current Liabilities
Current portion of long-term debt and capital leases		1	[2]	0	[1]
Accounts payable		0	[2]	0	[1]
Accounts payable — affiliate		(616)	[2]	(1,222)	[1]
Derivative instruments		(238)	[2]	(158)	[1]
Cash collateral received in support of energy risk management activities		0	[2]	0	[1]
Accrued expenses and other current liabilities	[2]	0
Disposal Group, Including Discontinued Operation, Liabilities, Current	[1]			0
Other Liabilities, Current	[1]			(1)
Total current liabilities		(853)	[2]	(1,381)	[1]
Other Liabilities
Long-term debt and capital leases		0	[2]	0	[1]
Nuclear decommissioning reserve		0	[2]	0	[1]
Nuclear decommissioning trust liability		0	[2]	0	[1]
Deferred income taxes		0	[2]	0	[1]
Derivative instruments		(50)	[2]	(32)	[1]
Out-of-market contracts, net of accumulated amortization of $639 and $562		0	[2]	0	[1]
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent	[1]			0
Other non-current liabilities		0	[2]	0	[1]
Total non-current liabilities		(50)	[2]	(32)	[1]
Total liabilities		(903)	[2]	(1,413)	[1]
2.822% convertible perpetual preferred stock		0	[2]	0	[1]
Redeemable noncontrolling interest in subsidiaries		0	[2]	0	[1]
Stockholders’ Equity		(14,441)	[2]	(14,259)	[1]
Total Liabilities and Stockholders’ Equity		$ (15,344)	[2]	$ (15,672)	[1]
[1]	All significant intercompany transactions have been eliminated in consolidation.
[2]	All significant intercompany transactions have been eliminated in consolidation.
[3]	All significant intercompany transactions have been eliminated in consolidation.
[4]	All significant intercompany transactions have been eliminated in consolidation.

Condensed Consolidating Finan70

Condensed Consolidating Financial Information (Details 4) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016		Mar. 31, 2015
Cash Flows from Operating Activities
Net Income/(Loss)		$ 47		$ (136)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions and equity in (earnings)/losses of unconsolidated affiliates and consolidated subsidiaries		(10)		(29)
Equity in earnings of unconsolidated affiliates		7		3
Depreciation and amortization		313		395
Provision for bad debts		10		15
Amortization of nuclear fuel		13		13
Amortization of financing costs and debt discount/premiums		1		(4)
Amortization of intangibles and out-of-market contracts		26		19
Amortization of unearned equity compensation		8		11
Changes in deferred income taxes and liability for uncertain tax benefits		(25)		(83)
Changes in nuclear decommissioning trust liability		9		(3)
Changes in derivative instruments		(50)		261
Changes in collateral deposits supporting energy risk management activities		156		(213)
Cash used by changes in other working capital		(121)		(33)
Loss on sale of emission allowances		47		0
Gain (Loss) on Disposition of Assets		32		14
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net		146		0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments				(14)
Gain on sale of assets and postretirement benefits curtailment				(14)
Adjustment for debt extinguishment		(11)		0
Net Cash Provided/(Used) by Operating Activities		554		260
Cash Flows from Investing Activities
Payments for from intercompany loans to subsidiaries		0		0
Proceeds from Dividends Received		0
Acquisitions of businesses, net of cash acquired		(6)		(1)
Capital expenditures		(279)		(252)
Increase in restricted cash, net		(12)		(11)
Decrease in restricted cash — U.S. DOE funded projects		39		25
Decrease in notes receivable		1		5
Investments in nuclear decommissioning trust fund securities		(200)		(193)
Proceeds from the sale of nuclear decommissioning trust fund securities		191		196
Proceeds from renewable energy grants and state rebates		8		2
Payments to Acquire Intangible Assets		12		0
Proceeds from Sale of Intangible Assets		7		0
Proceeds from sale of assets, net of cash disposed of		120		0
Investments in unconsolidated affiliates, excluding return of capital		4
(Investments in) Proceeds From Sales of Unconsolidated Affiliates		(4)		(44)
Other		4		3
Net Cash Used by Investing Activities		(143)		(270)
Cash Flows from Financing Activities
Proceeds from intercompany loans		0		0
Intercompany Dividend Proceeds - Financing		0
Payment of dividends to common and preferred stockholders		(48)		(51)
Payment for treasury stock		0		(79)
Net receipts from settlement of acquired derivatives that include financing elements		39		40
Proceeds from issuance of long-term debt		61		248
Distributions from, net of contributions to, noncontrolling interest in subsidiaries		(10)		25
Proceeds from issuance of common stock		0		1
Payments for short and long-term debt		(316)		(94)
Other - contingent consideration		(10)		0
Net Cash Used by Financing Activities		(264)		40
Effect of exchange rate changes on cash and cash equivalents		(6)		18
Net Increase/(Decrease) in Cash and Cash Equivalents		141		48
Cash and Cash Equivalents at Beginning of Period		1,518		2,116
Cash and Cash Equivalents at End of Period		1,659		2,164
Guarantor Subsidiaries
Cash Flows from Operating Activities
Net Income/(Loss)		162		83
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions and equity in (earnings)/losses of unconsolidated affiliates and consolidated subsidiaries		0		0
Equity in earnings of unconsolidated affiliates		0		0
Depreciation and amortization		117		204
Provision for bad debts		8		13
Amortization of nuclear fuel		13		13
Amortization of financing costs and debt discount/premiums		0		0
Amortization of intangibles and out-of-market contracts		11		12
Amortization of unearned equity compensation		0		0
Changes in deferred income taxes and liability for uncertain tax benefits		(613)		55
Changes in nuclear decommissioning trust liability		9		(3)
Changes in derivative instruments		(28)		131
Changes in collateral deposits supporting energy risk management activities		150		(132)
Cash used by changes in other working capital		338		444
Loss on sale of emission allowances		47
Gain (Loss) on Disposition of Assets		0
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net		0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments				0
Gain on sale of assets and postretirement benefits curtailment				0
Adjustment for debt extinguishment		0
Net Cash Provided/(Used) by Operating Activities		214		820
Cash Flows from Investing Activities
Payments for from intercompany loans to subsidiaries		(151)		(737)
Proceeds from Dividends Received		0
Acquisitions of businesses, net of cash acquired		0		0
Capital expenditures		(44)		(89)
Increase in restricted cash, net		(2)		0
Decrease in restricted cash — U.S. DOE funded projects		0		0
Decrease in notes receivable		0		0
Investments in nuclear decommissioning trust fund securities		(200)		(193)
Proceeds from the sale of nuclear decommissioning trust fund securities		191		196
Proceeds from renewable energy grants and state rebates		0		0
Payments to Acquire Intangible Assets		12
Proceeds from Sale of Intangible Assets		7
Proceeds from sale of assets, net of cash disposed of		0
Investments in unconsolidated affiliates, excluding return of capital		0
(Investments in) Proceeds From Sales of Unconsolidated Affiliates				(2)
Other		0		0
Net Cash Used by Investing Activities		(211)		(825)
Cash Flows from Financing Activities
Proceeds from intercompany loans		0		0
Intercompany Dividend Proceeds - Financing		0
Payment of dividends to common and preferred stockholders		0		0
Payment for treasury stock				0
Net receipts from settlement of acquired derivatives that include financing elements		0		0
Proceeds from issuance of long-term debt		0		0
Distributions from, net of contributions to, noncontrolling interest in subsidiaries		0		0
Proceeds from issuance of common stock		0		0
Payments for short and long-term debt		0		0
Other - contingent consideration		(3)
Net Cash Used by Financing Activities		(3)		0
Effect of exchange rate changes on cash and cash equivalents		0		0
Net Increase/(Decrease) in Cash and Cash Equivalents		0		(5)
Cash and Cash Equivalents at Beginning of Period		0
Cash and Cash Equivalents at End of Period		0
Non-Guarantor Subsidiaries
Cash Flows from Operating Activities
Net Income/(Loss)		(2)		(75)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions and equity in (earnings)/losses of unconsolidated affiliates and consolidated subsidiaries		(22)		(40)
Equity in earnings of unconsolidated affiliates		8		4
Depreciation and amortization		190		186
Provision for bad debts		2		0
Amortization of nuclear fuel		0		0
Amortization of financing costs and debt discount/premiums		7		(11)
Amortization of intangibles and out-of-market contracts		15		7
Amortization of unearned equity compensation		0		0
Changes in deferred income taxes and liability for uncertain tax benefits		(1,696)		(36)
Changes in nuclear decommissioning trust liability		0		0
Changes in derivative instruments		(22)		130
Changes in collateral deposits supporting energy risk management activities		6		(81)
Cash used by changes in other working capital		1,728		(580)
Loss on sale of emission allowances		0
Gain (Loss) on Disposition of Assets		32
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net		140
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments				(14)
Gain on sale of assets and postretirement benefits curtailment				(14)
Adjustment for debt extinguishment		0
Net Cash Provided/(Used) by Operating Activities		366		(430)
Cash Flows from Investing Activities
Payments for from intercompany loans to subsidiaries		(11)		328
Proceeds from Dividends Received		(19)
Acquisitions of businesses, net of cash acquired		(6)		(1)
Capital expenditures		(219)		(157)
Increase in restricted cash, net		(10)		(11)
Decrease in restricted cash — U.S. DOE funded projects		39		24
Decrease in notes receivable		1		5
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		8		2
Payments to Acquire Intangible Assets		0
Proceeds from Sale of Intangible Assets		0
Proceeds from sale of assets, net of cash disposed of		120
Investments in unconsolidated affiliates, excluding return of capital		4
(Investments in) Proceeds From Sales of Unconsolidated Affiliates				(5)
Other		4		3
Net Cash Used by Investing Activities		(97)		188
Cash Flows from Financing Activities
Proceeds from intercompany loans		0		0
Intercompany Dividend Proceeds - Financing		0
Payment of dividends to common and preferred stockholders		0		0
Payment for treasury stock				0
Net receipts from settlement of acquired derivatives that include financing elements		39		40
Proceeds from issuance of long-term debt		61		221
Distributions from, net of contributions to, noncontrolling interest in subsidiaries		(10)		25
Proceeds from issuance of common stock		0		0
Payments for short and long-term debt		(121)		(89)
Other - contingent consideration		(7)
Net Cash Used by Financing Activities		(18)		147
Effect of exchange rate changes on cash and cash equivalents		(6)		18
Net Increase/(Decrease) in Cash and Cash Equivalents		245		(77)
Cash and Cash Equivalents at Beginning of Period		825
Cash and Cash Equivalents at End of Period		1,070
NRG Energy, Inc.
Cash Flows from Operating Activities
Net Income/(Loss)		87		(126)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions and equity in (earnings)/losses of unconsolidated affiliates and consolidated subsidiaries		0		0
Equity in earnings of unconsolidated affiliates		0		1
Depreciation and amortization		6		5
Provision for bad debts		0		2
Amortization of nuclear fuel		0		0
Amortization of financing costs and debt discount/premiums		(6)		7
Amortization of intangibles and out-of-market contracts		0		0
Amortization of unearned equity compensation		8		11
Changes in deferred income taxes and liability for uncertain tax benefits		2,284		(102)
Changes in nuclear decommissioning trust liability		0		0
Changes in derivative instruments		0		0
Changes in collateral deposits supporting energy risk management activities		0		0
Cash used by changes in other working capital		(2,400)		(337)
Loss on sale of emission allowances		0
Gain (Loss) on Disposition of Assets		0
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net		6
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments				0
Gain on sale of assets and postretirement benefits curtailment				0
Adjustment for debt extinguishment		(11)
Net Cash Provided/(Used) by Operating Activities		(26)		(539)
Cash Flows from Investing Activities
Payments for from intercompany loans to subsidiaries		0		409
Proceeds from Dividends Received		0
Acquisitions of businesses, net of cash acquired		0		0
Capital expenditures		(16)		(6)
Increase in restricted cash, net		0		0
Decrease in restricted cash — U.S. DOE funded projects		0		1
Decrease in notes receivable		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
Payments to Acquire Intangible Assets		0
Proceeds from Sale of Intangible Assets		0
Proceeds from sale of assets, net of cash disposed of		0
Investments in unconsolidated affiliates, excluding return of capital		0
(Investments in) Proceeds From Sales of Unconsolidated Affiliates				(37)
Other		0		0
Net Cash Used by Investing Activities		(16)		367
Cash Flows from Financing Activities
Proceeds from intercompany loans		162		409
Intercompany Dividend Proceeds - Financing		19
Payment of dividends to common and preferred stockholders		(48)		(51)
Payment for treasury stock				(79)
Net receipts from settlement of acquired derivatives that include financing elements		0		0
Proceeds from issuance of long-term debt		0		27
Distributions from, net of contributions to, noncontrolling interest in subsidiaries		0		0
Proceeds from issuance of common stock		0		1
Payments for short and long-term debt		(195)		(5)
Other - contingent consideration		0
Net Cash Used by Financing Activities		(62)		302
Effect of exchange rate changes on cash and cash equivalents		0		0
Net Increase/(Decrease) in Cash and Cash Equivalents		(104)		130
Cash and Cash Equivalents at Beginning of Period		693
Cash and Cash Equivalents at End of Period		589
Eliminations
Cash Flows from Operating Activities
Net Income/(Loss)		(200)	[1]	(18)	[2],[3]
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Distributions and equity in (earnings)/losses of unconsolidated affiliates and consolidated subsidiaries	[4]	12		11
Equity in earnings of unconsolidated affiliates	[4]	(1)	[1]	(2)	[2]
Depreciation and amortization		0	[1],[4]	0	[2],[3]
Provision for bad debts		0	[4]	0	[3]
Amortization of nuclear fuel		0	[4]	0	[3]
Amortization of financing costs and debt discount/premiums		0	[4]	0	[3]
Amortization of intangibles and out-of-market contracts		0	[4]	0	[3]
Amortization of unearned equity compensation		0	[4]	0	[3]
Changes in deferred income taxes and liability for uncertain tax benefits		0	[4]	0	[3]
Changes in nuclear decommissioning trust liability		0	[4]	0	[3]
Changes in derivative instruments		0	[4]	0	[3]
Changes in collateral deposits supporting energy risk management activities		0	[4]	0	[3]
Cash used by changes in other working capital		213	[4]	440	[3]
Loss on sale of emission allowances	[4]	0
Gain (Loss) on Disposition of Assets	[1],[4]	0
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	[1],[4]	0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	[2]			0
Gain on sale of assets and postretirement benefits curtailment	[3]			0
Adjustment for debt extinguishment	[4]	0
Net Cash Provided/(Used) by Operating Activities	[3]	0		409
Cash Flows from Investing Activities
Payments for from intercompany loans to subsidiaries		162	[4]	0	[3]
Proceeds from Dividends Received	[4]	19
Acquisitions of businesses, net of cash acquired		0	[4]	0	[3]
Capital expenditures		0	[4]	0	[3]
Increase in restricted cash, net		0	[4]	0	[3]
Decrease in restricted cash — U.S. DOE funded projects		0	[4]	0	[3]
Decrease in notes receivable		0	[4]	0	[3]
Investments in nuclear decommissioning trust fund securities		0	[4]	0	[3]
Proceeds from the sale of nuclear decommissioning trust fund securities		0	[4]	0	[3]
Proceeds from renewable energy grants and state rebates		0	[4]	0	[3]
Payments to Acquire Intangible Assets	[4]	0
Proceeds from Sale of Intangible Assets	[4]	0
Proceeds from sale of assets, net of cash disposed of	[4]	0
Investments in unconsolidated affiliates, excluding return of capital	[4]	0
(Investments in) Proceeds From Sales of Unconsolidated Affiliates	[3]			0
Other		0	[4]	0	[3]
Net Cash Used by Investing Activities		181	[4]	0	[3]
Cash Flows from Financing Activities
Proceeds from intercompany loans		(162)	[4]	(409)	[3]
Intercompany Dividend Proceeds - Financing	[4]	(19)
Payment of dividends to common and preferred stockholders		0	[4]	0	[3]
Payment for treasury stock	[3]			0
Net receipts from settlement of acquired derivatives that include financing elements		0	[4]	0	[3]
Proceeds from issuance of long-term debt		0	[4]	0	[3]
Distributions from, net of contributions to, noncontrolling interest in subsidiaries		0	[4]	0	[3]
Proceeds from issuance of common stock		0	[4]	0	[3]
Payments for short and long-term debt		0	[4]	0	[3]
Other - contingent consideration	[4]	0
Net Cash Used by Financing Activities		(181)	[4]	(409)	[3]
Effect of exchange rate changes on cash and cash equivalents		0	[4]	0	[3]
Net Increase/(Decrease) in Cash and Cash Equivalents		0	[4]	$ 0	[3]
Cash and Cash Equivalents at Beginning of Period	[5]	0
Cash and Cash Equivalents at End of Period	[4],[6]	$ 0
[1]	All significant intercompany transactions have been eliminated in consolidation.
[2]	(a)All significant intercompany transactions have been eliminated in consolidation.
[3]	All significant intercompany transactions have been eliminated in consolidation.
[4]	All significant intercompany transactions have been eliminated in consolidation.
[5]	All significant intercompany transactions have been eliminated in consolidation.
[6]	All significant intercompany transactions have been eliminated in consolidation.