NRG Energy (NRG) 10-Q 2 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 30, 2019
Document And Entity Information [Abstract]
Entity Registrant Name	NRG ENERGY, INC.
Entity Central Index Key	0001013871
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		267,153,283
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating Revenues
Total operating revenues	$ 2,165	$ 2,065
Operating Costs and Expenses
Cost of operations	1,651	1,385
Depreciation and amortization	85	120
Selling, general and administrative	194	176
Reorganization costs	13	20
Development costs	2	5
Total operating costs and expenses	1,945	1,706
Gain on sale of assets	1	2
Operating Income/(Loss)	221	361
Other Income/(Expense)
Equity in (losses)/earnings of unconsolidated affiliates	(21)	1
Other income, net	12	0
Loss on debt extinguishment, net	0	(2)
Interest expense	(114)	(116)
Total other income/(expense)	(123)	(117)
Income from Continuing Operations Before Income Taxes	98	244
Income tax expense/(benefit)	4	6
Income from Continuing Operations	94	238
Income/(loss) from discontinued operations	388	(5)
Net Income	482	233
Less: Net loss attributable to noncontrolling interest and redeemable noncontrolling interests	0	(46)
Net income attributable to NRG Energy, Inc.	$ 482	$ 279
Earnings per Share Attributable to NRG Energy, Inc.
Weighted average number of common shares outstanding — basic (in shares)	278	318
Income from continuing operations per weighted average common share — basic (in usd per share)	$ 0.34	$ 0.90
Income/(loss) from discontinued operations per weighted average common share — basic (in usd per share))	1.39	(0.02)
Earnings per Weighted Average Common Share — Basic (in usd per share)	$ 1.73	$ 0.88
Weighted average number of common shares outstanding — diluted (in shares)	280	322
Income from continuing operations per weighted average common share — diluted (in usd per share)	$ 0.34	$ 0.89
income/(loss) from discontinued operations per weighted average common share — diluted (in usd per share)	1.38	(0.02)
Earnings per Weighted Average Common Share — Diluted (in usd per share)	1.72	0.87
Dividends Per Common Share (in usd per share)	$ 0.03	$ 0.03

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net Income	$ 482	$ 233
Other Comprehensive (Loss)/Income
Unrealized gain on derivatives	0	14
Foreign currency translation adjustments	1	(2)
Defined benefit plans	(3)	(1)
Other comprehensive (loss)/income	(2)	11
Comprehensive Income/(Loss)	480	244
Less: Comprehensive loss attributable to noncontrolling interest and redeemable noncontrolling interest	0	(38)
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.	$ 480	$ 282

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Current Assets
Cash and cash equivalents	$ 859	$ 563
Funds deposited by counterparties	11	33
Restricted cash	15	17
Accounts receivable, net	898	1,024
Inventory	391	412
Derivative instruments	611	764
Cash collateral paid in support of energy risk management activities	388	287
Prepayments and other current assets	285	302
Current assets - held for sale	0	1
Current assets - discontinued operations	0	197
Total current assets	3,458	3,600
Property, plant and equipment, net	2,650	3,048
Other Assets
Equity investments in affiliates	387	412
Operating lease right-of-use assets, net	517	0
Goodwill	573	573
Intangible assets, net	580	591
Nuclear decommissioning trust fund	718	663
Derivative instruments	347	317
Deferred income taxes	45	46
Other non-current assets	255	289
Non-current assets - held-for-sale	0	77
Non-current assets - discontinued operations	0	1,012
Total other assets	3,422	3,980
Total Assets	9,530	10,628
Current Liabilities
Current portion of long-term debt and capital leases	124	72
Current portion of operating lease liabilities	74	0
Accounts payable	697	863
Derivative instruments	489	673
Cash collateral received in support of energy risk management activities	11	33
Accrued expenses and other current liabilities	550	680
Current liabilities - held-for-sale	0	5
Current liabilities - discontinued operations	0	72
Total current liabilities	1,945	2,398
Other Liabilities
Long-term debt and capital leases	6,366	6,449
Non-current operating lease liabilities	529	0
Nuclear decommissioning reserve	286	282
Nuclear decommissioning trust liability	423	371
Derivative instruments	350	304
Deferred income taxes	62	65
Other non-current liabilities	1,089	1,274
Non-current liabilities - held-for-sale	0	65
Non-current liabilities - discontinued operations	0	635
Total other liabilities	9,105	9,445
Total Liabilities	11,050	11,843
Redeemable noncontrolling interest in subsidiaries	18	19
Commitments and Contingencies
Stockholders’ Equity
Common stock; $0.01 par value; 500,000,000 shares authorized; 421,786,061 and 420,288,886 shares issued and 267,538,257 and 283,650,039 shares outstanding at March 31, 2019 and December 31, 2018, respectively	4	4
Additional paid-in capital	8,473	8,510
Accumulated deficit	(5,548)	(6,022)
Less treasury stock, at cost - 154,247,804 and 136,638,847 shares at March 31, 2019 and December 31, 2018, respectively	(4,371)	(3,632)
Accumulated other comprehensive loss	(96)	(94)
Total Stockholders’ Equity	(1,538)	(1,234)
Total Liabilities and Stockholders’ Equity	$ 9,530	$ 10,628

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par or value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	421,786,061	420,288,886
Common stock, shares outstanding (in shares)	267,538,257	283,650,039
Treasury stock, shares (in shares)	154,247,804	136,638,847

Condensed Consolidated Statem_3

Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash Flows from Operating Activities
Net Income	$ 482	$ 233
Income/(loss) from discontinued operations, net of income tax	388	(5)
Income from Continuing Operations	94	238
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in losses/(earnings) of unconsolidated affiliates	21	(1)
Depreciation, amortization and accretion	92	131
Provision for bad debts	26	15
Amortization of nuclear fuel	13	13
Amortization of financing costs and debt discount/premiums	7	6
Adjustment for debt extinguishment	0	2
Amortization of intangibles and out-of-market contracts	6	9
Amortization of unearned equity compensation	4	6
Loss/(gain) on sale and disposal of assets	3	(10)
Changes in derivative instruments	(15)	(203)
Changes in deferred income taxes and liability for uncertain tax benefits	(2)	(1)
Changes in collateral deposits in support of energy risk management activities	(123)	163
Changes in nuclear decommissioning trust liability	9	34
Changes in other working capital	(270)	(156)
Cash used by continuing operations	(135)	246
Cash provided by discontinued operations	8	104
Net Cash Provided/(Used) by Operating Activities	(127)	350
Cash Flows from Investing Activities
Payments for acquisitions of businesses	(16)	(2)
Capital expenditures	(49)	(155)
Net proceeds from sale of emission allowances	0	6
Investments in nuclear decommissioning trust fund securities	(122)	(216)
Proceeds from the sale of nuclear decommissioning trust fund securities	113	182
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees	1,313	53
Changes in investments in unconsolidated affiliates	4	(8)
Contributions to discontinued operations	(44)	(29)
Other	(1)	0
Cash (used)/provided by continuing operations	1,198	(169)
Cash used by discontinued operations	(2)	(291)
Net Cash (Used)/Provided by Investing Activities	1,196	(460)
Cash Flows from Financing Activities
Payments of dividends to common stockholders	(8)	(10)
Payments for treasury stock	(747)	(93)
Distributions to noncontrolling interests from subsidiaries	(1)	(10)
Proceeds from issuance of common stock	2	7
Payment of debt issuance costs	0	(2)
Payments for long-term debt	(37)	(39)
Cash used by continuing operations	(791)	(147)
Cash provided by discontinued operations	43	133
Net Cash Used by Financing Activities	(748)	(14)
Change in Cash from discontinued operations	49	(54)
Net Increase/(Decrease) in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash	272	(70)
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period	613	1,086
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	$ 885	$ 1,016

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	NRG Yield, Inc.	Common Stock	Additional Paid-In Capital	Additional Paid-In CapitalNRG Yield, Inc.	Accumulated Deficit	Treasury Stock	Accumulated Other Comprehensive Loss	Noncontrolling Interest	Noncontrolling InterestNRG Yield, Inc.
Balance at Dec. 31, 2017	$ 1,968		$ 4	$ 8,376		$ (6,268)	$ (2,386)	$ (72)	$ 2,314
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	249					279			(30)
Other comprehensive loss	11							11
Sale of assets to NRG Yield, Inc.		$ 12			$ 8					$ 4
ESPP share purchases	3			(2)			5
Share repurchases	(93)						(93)
Equity-based compensation	(10)			(10)
Issuance of common stock	7			7
Common stock dividends	(10)					(10)
Distributions to noncontrolling interest and dividends paid	(19)	$ (30)							(19)	$ (30)
Contributions from noncontrolling interests	153								153
Adoption of new accounting standards	17					17
Balance at Mar. 31, 2018	2,258		4	8,379		(5,982)	(2,474)	(61)	$ 2,392
Balance at Dec. 31, 2018	(1,234)		4	8,510		(6,022)	(3,632)	(94)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	482					482
Other comprehensive loss	(2)							(2)
Share repurchases	(749)			(10)			(739)
Equity-based compensation	(32)			(32)
Issuance of common stock	5			5
Common stock dividends	(8)					(8)
Balance at Mar. 31, 2019	$ (1,538)		$ 4	$ 8,473		$ (5,548)	$ (4,371)	$ (96)

Nature of Business and Basis of

Nature of Business and Basis of Presentation	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business and Basis of Presentation	Nature of Business and Basis of Presentation General NRG Energy, Inc., or NRG or the Company, is an energy company built on dynamic retail brands with diverse generation assets. NRG brings the power of energy to consumers by producing, selling and delivering electricity and related products and services in major competitive power markets in the U.S. in a manner that delivers value to all of NRG's stakeholders. NRG is perfecting the integrated model by balancing retail load with generation supply within its deregulated markets, while evolving to a customer-driven business. The Company sells energy, services, and innovative, sustainable products and services directly to retail customers under the names "NRG", "Reliant" and other brand names owned by NRG, supported by approximately 23,000 MW of generation as of March 31, 2019 . The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with the SEC's regulations for interim financial information and with the instructions to Form 10-Q. Accordingly, they do not include all of the information and notes required by generally accepted accounting principles for complete financial statements. The following notes should be read in conjunction with the accounting policies and other disclosures as set forth in the notes to the consolidated financial statements in the Company's 2018 Form 10-K. Interim results are not necessarily indicative of results for a full year. In the opinion of management, the accompanying unaudited interim condensed consolidated financial statements contain all material adjustments consisting of normal and recurring accruals necessary to present fairly the Company's consolidated financial position as of March 31, 2019 , and the results of operations, comprehensive income, cash flows and statements of stockholders' equity for the three months ended March 31, 2019 and 2018 . Discontinued Operations During the fourth quarter of 2018, as described in Note 4 , Discontinued Operations and Dispositions , the Company concluded that the sale of its South Central Portfolio to Cleco, excluding the Cottonwood facility, met held-for-sale criteria and should be presented as discontinued operations, as the sale, which closed on February 4, 2019, represented a strategic shift in the business in which NRG operates. The financial information for all historical periods has been recast to reflect the presentation of these entities as discontinued operations. On August 31, 2018, as described in Note 4 , Discontinued Operations and Dispositions , NRG deconsolidated NRG Yield, Inc. and its Renewables Platform for financial reporting purposes. The financial information for all historical periods has been recast to reflect the presentation of these entities, as well as the Carlsbad project, as discontinued operations. As a result of the sale of NRG Yield, the Company no longer controls the Agua Caliente project. Due to this change in control, the Company also deconsolidated the Agua Caliente project from its financial results and began accounting for the project as an equity method investment. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates. Reclassifications Certain prior year amounts have been reclassified for comparative purposes.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Net Income attributable to NRG Energy, Inc. The following table reflects the net income attributable to NRG Energy, Inc. after removing the net loss attributable to the noncontrolling interest and redeemable noncontrolling interest: Three months ended March 31, 2019 2018 (In millions) Income from continuing operations, net of income tax $ 94 $ 245 Income from discontinued operations, net of income tax 388 34 Net income attributable to NRG Energy, Inc. $ 482 $ 279 Other Balance Sheet Information The following table presents the allowance for doubtful accounts included in accounts receivable, net; accumulated depreciation included in property, plant and equipment, net; accumulated amortization included in intangible assets, net and accumulated amortization included in out-of-market contracts, net: March 31, 2019 December 31, 2018 (In millions) Accounts receivable allowance for doubtful accounts $ 32 $ 32 Property, plant and equipment accumulated depreciation 1,610 1,811 Intangible assets accumulated amortization 1,171 1,149 Out-of-market contracts accumulated amortization — 37 Restricted Cash The following table provides a reconciliation of cash and cash equivalents, restricted cash and funds deposited by counterparties reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the statements of cash flows. March 31, 2019 December 31, 2018 March 31, 2018 December 31, 2017 (In millions) Cash and cash equivalents $ 859 $ 563 $ 514 $ 770 Funds deposited by counterparties 11 33 241 37 Restricted cash 15 17 261 279 Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows $ 885 $ 613 $ 1,016 $ 1,086 Funds deposited by counterparties consist of cash held by the Company as a result of collateral posting obligations from its counterparties. Some amounts are segregated into separate accounts that are not contractually restricted but, based on the Company's intention, are not available for the payment of general corporate obligations. Depending on market fluctuations and the settlement of the underlying contracts, the Company will refund this collateral to the hedge counterparties pursuant to the terms and conditions of the underlying trades. Since collateral requirements fluctuate daily and the Company cannot predict if any collateral will be held for more than twelve months, the funds deposited by counterparties are classified as a current asset on the Company's balance sheet, with an offsetting liability for this cash collateral received within current liabilities. Restricted cash consists primarily of funds held to satisfy the requirements of certain debt agreements and funds held within the Company's projects that are restricted in their use. Recent Accounting Developments - Guidance Adopted in 2019 ASU 2016-02 - In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) , or Topic 842, which was further amended through various updates issued by the FASB thereafter, with the objective to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and to improve financial reporting by expanding the related disclosures. The guidance in Topic 842 provides that a lessee that may have previously accounted for a lease as an operating lease under current GAAP should recognize the assets and liabilities that arise from a lease on the balance sheet. In addition, Topic 842 expands the required quantitative and qualitative disclosures with regards to lease arrangements. The Company adopted the standard and its subsequent corresponding updates effective January 1, 2019 under the modified retrospective approach by applying the provisions of the new leases guidance at the effective date without adjusting the comparative periods presented. The Company assessed its leasing arrangements, evaluated the impact of applying practical expedients and accounting policy elections, and implemented lease accounting software to meet the reporting requirements of the standard. The Company established operating lease liabilities of $ 404 million and right-of-use assets of $ 321 million upon adoption, before considering deferred taxes. The adoption of Topic 842 did not have a material impact on the statements of operations or cash flows. See Note 8 , Leases , for further discussion. Recent Accounting Developments - Guidance Not Yet Adopted ASU 2018-17 - In October 2018, the FASB issued ASU No. 2018-17, Consolidations (Topic 810): Targeted Improvements to Related Party Guidance for Variable Interest Entities , in response to stakeholders’ observations that Topic 810, Consolidations , could be improved thereby improving general purpose financial reporting. Specifically, ASC 2018-17 requires application of the variable interest entity (VIE) guidance to private companies under common control and consideration of indirect interest held through related parties under common control for determining whether fees paid to decision makers and service providers are variable interests. The amendments are effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. All entities are required to apply the amendments retrospectively with a cumulative-effect adjustment to retained earnings at the beginning of the earliest period presented. The Company is evaluating the impact of adopting this guidance on the consolidated financial statements and disclosures. ASU 2018-13 - In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirement for Fair value Measurement) , or ASU No. 2018-13. The guidance in ASU No. 2018-13 eliminates such disclosures as the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy. The amendments in ASU No. 2018-13 add new disclosure requirements for Level 3 measurements. ASU No. 2018-13 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted for any eliminated or modified disclosures. Certain disclosures in ASU No. 2018-13 are required to be applied on a retrospective basis and others on a prospective basis. As the amendment contemplates changes in disclosures only, it will have no material impact on the Company's results of operations, cash flows, or statement of financial position.

Revenue Recognition

Revenue Recognition	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition Performance Obligations As of March 31, 2019 , estimated future fixed fee performance obligations are $500 million , $500 million , $535 million , $284 million and $29 million for fiscal years 2019 , 2020 , 2021 , 2022 and 2023 , respectively. These performance obligations are for cleared auction MWs in the PJM, ISO-NE, NYISO and MISO capacity auctions and are subject to penalties for non performance. Disaggregated Revenues The following table represents the Company’s disaggregation of revenue from contracts with customers for the three months ended March 31, 2019 and March 31, 2018, along with the reportable segment for each category: Three months ended March 31, 2019 Generation (In millions) Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue (a)(b) $ — $ 358 $ 224 $ 582 $ (276 ) $ 306 Capacity revenue (a) — — 155 155 (1 ) 154 Retail revenue Mass customers 1,321 — — — (1 ) 1,320 Business Solutions customers 286 — — — — 286 Total retail revenue 1,607 — — — (1 ) 1,606 Mark-to-market for economic hedging activities (b)(c) — 13 (8 ) 5 15 20 Other revenues (a) — 29 52 81 (2 ) 79 Total operating revenue 1,607 400 423 823 (265 ) 2,165 Less: Lease revenue 3 — 2 2 — 5 Less: Realized and unrealized ASC 815 revenue (b) — 546 97 643 (262 ) 381 Total revenue from contracts with customers $ 1,604 $ (146 ) $ 324 $ 178 $ (3 ) $ 1,779 (a) The following amounts of energy and capacity revenue primarily relate to derivative instruments and are accounted for under ASC 815 Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue $ — $ 525 $ 88 $ 613 $ (277 ) $ 336 Capacity revenue — — 18 18 — 18 Other revenue — 8 (1 ) 7 — 7 (b) Generation includes higher revenues due to the Company's large internal transfer of power based on average annualized market prices, which are offset by higher cost of operations within Retail (c) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 Three months ended March 31, 2018 Generation (In millions) Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue (a)(b) $ — $ 265 $ 339 $ 604 $ (161 ) $ 443 Capacity revenue (a) — — 142 142 — 142 Retail revenue Mass customers 1,176 — — — (1 ) 1,175 Business Solutions customers 310 — — — — 310 Total retail revenue 1,486 — — — (1 ) 1,485 Mark-to-market for economic hedging activities (b)(c) (6 ) (569 ) (5 ) (574 ) 484 (96 ) Other revenues (a) — 53 45 98 (7 ) 91 Total operating revenue 1,480 (251 ) 521 270 315 2,065 Less: Lease revenue 3 — 2 2 — 5 Less: Realized and unrealized ASC 815 revenue (b) (6 ) (150 ) 85 (65 ) 327 256 Total revenue from contracts with customers $ 1,483 $ (101 ) $ 434 $ 333 $ (12 ) $ 1,804 (a) The following amounts of energy and capacity revenue relate to derivative instruments and are accounted for under ASC 815 Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue $ — $ 413 $ 60 $ 473 $ (157 ) $ 316 Capacity revenue — — 26 26 — 26 Other revenue — 5 3 8 — 8 (b) Generation includes higher revenues due to the Company's large internal transfer of power based on average annualized market prices, which are offset by higher cost of operations within Retail (c) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 Contract Balances The following table reflects the contract assets and liabilities included in the Company’s balance sheet as of March 31, 2019 and December 31, 2018: (In millions) March 31, 2019 December 31, 2018 Deferred customer acquisition costs $ 117 $ 111 Accounts receivable, net - Contracts with customers 870 999 Accounts receivable, net - Derivative instruments 22 20 Accounts receivable, net - Affiliate 6 5 Total accounts receivable, net $ 898 $ 1,024 Unbilled revenues (included within Accounts receivable, net - Contracts with customers) $ 305 $ 392 Deferred revenues 80 67

Discontinued Operations and Dis

Discontinued Operations and Dispositions	3 Months Ended
	Mar. 31, 2019
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations and Dispositions	Discontinued Operations and Dispositions Discontinued Operations Sale of South Central Portfolio On February 4, 2019, the Company completed the sale of the South Central Portfolio to Cleco for cash consideration of $1 billion excluding working capital and other adjustments. The Company concluded that the divested business met the criteria for discontinued operations as of December 31, 2018, as the disposition represented a strategic shift in the business in which NRG operates and the criteria for held-for-sale were met. As such, all current and prior period results for the operations of the South Central Portfolio, except for the Cottonwood facility as discussed below, have been reclassified as discontinued operations. In connection with the transaction, NRG also entered into a transition services agreement to provide certain corporate services to the divested business. The South Central Portfolio includes the 1,153 MW Cottonwood natural gas generating facility. Upon the closing of the sale of the South Central Portfolio, NRG entered into an agreement with Cleco to leaseback the Cottonwood facility through May 2025. Due to its continuing involvement with the Cottonwood facility, NRG did not use discontinued operations treatment in accounting for historical and ongoing activity with Cottonwood. Summarized results of the South Central Portfolio discontinued operations were as follows: Three months ended (In millions) March 31, 2019 March 31, 2018 Operating revenues $ 31 $ 102 Operating costs and expenses (23 ) (86 ) Gain from discontinued operations, net of tax 8 16 Gain on disposal of discontinued operations, net of tax 27 — Gain from discontinued operations, including disposal, net of tax $ 35 $ 16 The following table summarizes the major classes of assets and liabilities classified as discontinued operations of the South Central Portfolio: (In millions) December 31, 2018 Cash and cash equivalents $ 89 Accounts receivable, net - trade 49 Inventory 35 Other current assets 5 Current assets - discontinued operations 178 Property, plant and equipment, net 408 Other non-current assets 1 Non-current assets - discontinued operations 409 Accounts payable 19 Other current liabilities 5 Current liabilities - discontinued operations 24 Out-of-market contracts, net 50 Other non-current liabilities 11 Non-current liabilities - discontinued operations $ 61 Sale of Ownership in NRG Yield, Inc. and the Renewables Platform On August 31, 2018, the Company completed the sale of its ownership interests in NRG Yield, Inc. and the Renewables Platform to GIP for total cash consideration of $1.348 billion . The Company concluded that the divested businesses met the criteria for discontinued operations, as the dispositions represent a strategic shift in the markets in which NRG operates. As such, all prior period results for NRG Yield, Inc. and the Renewables Platform have been reclassified as discontinued operations. In connection with the transaction, NRG entered into a transition services agreement to provide certain corporate services to the divested businesses. Carlsbad On February 6, 2018, NRG entered into an agreement with NRG Yield and GIP to sell 100% of its membership interests in Carlsbad Energy Holdings LLC, which owns the Carlsbad project, for $385 million of cash consideration, excluding working capital adjustments. The primary condition to close the Carlsbad transaction was the completion of the sale of NRG Yield and the Renewables Platform. At the time of the sale of NRG Yield and the Renewables Platform in August 2018, the Company concluded that the Carlsbad project met the criteria for discontinued operations and accordingly, all current and prior period results for Carlsbad have been reclassified as discontinued operations. The Company continued to consolidate Carlsbad for financial reporting purposes until the transaction closed on February 27, 2019. Carlsbad continues to have a ground lease and easement agreement with NRG with an initial term ending in 2039 and two ten year extensions. As a result of the transaction, additional commitments related to the project totaled approximately $23 million as of December 31, 2018 and March 31, 2019. Summarized results of NRG Yield, Inc. and the Renewables Platform and Carlsbad discontinued operations were as follows: Three months ended (In millions) March 31, 2019 March 31, 2018 Operating revenues $ 19 $ 260 Operating costs and expenses (9 ) (230 ) Other expenses (5 ) (58 ) Gain/(loss) from operations of discontinued components, before tax 5 (28 ) Income tax benefit — (7 ) Gain/(loss) from discontinued operations, net of tax 5 (21 ) Gain on disposal of discontinued operations, net of tax 348 — Gain/(loss) from discontinued operations, including disposal, net of tax $ 353 $ (21 ) The following table summarizes the major classes of assets and liabilities classified as discontinued operations of Carlsbad: (In millions) December 31, 2018 Restricted cash $ 4 Accounts receivable, net - trade 10 Other current assets 5 Current assets - discontinued operations 19 Property, plant and equipment, net 590 Intangible assets, net 9 Other non-current assets 4 Non-current assets - discontinued operations 603 Current portion of long-term debt and capital leases 20 Accounts payable 27 Other current liabilities 1 Current liabilities - discontinued operations 48 Long-term debt and capital leases 572 Other non-current liabilities 2 Non-current liabilities - discontinued operations $ 574 Sale of Assets to NRG Yield, Inc. Prior to Discontinued Operations On March 30, 2018, the Company sold to NRG Yield, Inc. 100 % of NRG's interests in Buckthorn Renewables, LLC, which owns a 154 MW construction-stage utility-scale solar generation project, located in Texas. NRG Yield, Inc. paid cash consideration of approximately $42 million, excluding working capital adjustments, and assumed non-recourse debt of approximately $183 million. GenOn On June 14, 2017, the GenOn Entities filed voluntary petitions for relief under Chapter 11 of the Bankruptcy Code in the Bankruptcy Court. As a result of the bankruptcy filings, NRG concluded that it no longer controlled GenOn as it was subject to the control of the Bankruptcy Court; and, accordingly, NRG deconsolidated GenOn for financial reporting purposes as of June 14, 2017. By eliminating a large portion of its operations in the PJM market with the deconsolidation of GenOn, NRG concluded that GenOn met the criteria for discontinued operations, as this represented a strategic shift in the business in which NRG operates. As such, all prior period results for GenOn have been reclassified as discontinued operations. GenOn's plan of reorganization was confirmed on December 14, 2018. Income from discontinued operations for the three months ended March 31, 2018 was immaterial. Dispositions The Company completed other asset sales for $10 million and $11 million of cash proceeds during the three months ended March 31, 2019 and 2018, respectively.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments For cash and cash equivalents, funds deposited by counterparties, accounts and other receivables, accounts payable, restricted cash, and cash collateral paid and received in support of energy risk management activities, the carrying amounts approximate fair values because of the short-term maturity of those instruments and are classified as Level 1 within the fair value hierarchy. The estimated carrying amounts and fair values of NRG's recorded financial instruments not carried at fair market value are as follows: As of March 31, 2019 As of December 31, 2018 Carrying Amount Fair Value Carrying Amount Fair Value (In millions) Assets: Notes receivable $ 17 $ 14 $ 17 $ 14 Liabilities: Long-term debt, including current portion (a) 6,558 6,971 6,591 6,697 (a) Excludes deferred financing costs, which are recorded as a reduction to long-term debt on the Company's consolidated balance sheets The fair value of the Company's publicly-traded long-term debt is based on quoted market prices and is classified as Level 2 within the fair value hierarchy. The fair value of debt securities, non-publicly traded long-term debt and certain notes receivable of the Company are based on expected future cash flows discounted at market interest rates or current interest rates for similar instruments with equivalent credit quality and are classified as Level 3 within the fair value hierarchy. The following table presents the level within the fair value hierarchy for long-term debt, including current portion, as of March 31, 2019 and December 31, 2018 : As of March 31, 2019 As of December 31, 2018 Level 2 Level 3 Level 2 Level 3 (In millions) Long-term debt, including current portion $ 6,834 $ 137 $ 6,528 $ 169 Recurring Fair Value Measurements Debt securities, equity securities, and trust fund investments, which are comprised of various U.S. debt and equity securities, and derivative assets and liabilities, are carried at fair market value. The following tables present assets and liabilities measured and recorded at fair value on the Company's condensed consolidated balance sheets on a recurring basis and their level within the fair value hierarchy: As of March 31, 2019 (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and non-current assets) $ 37 $ 1 $ 18 $ 18 Nuclear trust fund investments: Cash and cash equivalents 15 15 — — U.S. government and federal agency obligations 50 50 — — Federal agency mortgage-backed securities 96 — 96 — Commercial mortgage-backed securities 29 — 29 — Corporate debt securities 100 — 100 — Equity securities 354 354 — — Foreign government fixed income securities 4 — 4 — Other trust fund investments: U.S. government and federal agency obligations 1 1 — — Derivative assets: Commodity contracts 929 45 769 115 Interest rate contracts 29 — 29 — Measured using net asset value practical expedient: Equity securities — nuclear trust fund investments 70 Equity securities 9 Total assets $ 1,723 $ 466 $ 1,045 $ 133 Derivative liabilities: Commodity contracts $ 839 $ 107 $ 615 $ 117 Total liabilities $ 839 $ 107 $ 615 $ 117 As of December 31, 2018 (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and non-current assets) $ 39 $ 2 $ 18 $ 19 Nuclear trust fund investments: Cash and cash equivalents 19 19 — — U.S. government and federal agency obligations 46 46 — — Federal agency mortgage-backed securities 100 — 100 — Commercial mortgage-backed securities 22 — 22 — Corporate debt securities 96 — 96 — Equity securities 312 312 — — Foreign government fixed income securities 4 — 4 — Other trust fund investments: U.S. government and federal agency obligations 1 1 — — Derivative assets: Commodity contracts 1,042 137 796 109 Interest rate contracts 39 — 39 — Measured using net asset value practical expedient: Equity securities — nuclear trust fund investments 64 Equity securities 8 Total assets $ 1,792 $ 517 $ 1,075 $ 128 Derivative liabilities: Commodity contracts $ 977 $ 224 $ 664 $ 89 Total liabilities $ 977 $ 224 $ 664 $ 89 There were no transfers during the three months ended March 31, 2019 and 2018 between Levels 1 and 2. The following tables reconcile, for the three months ended March 31, 2019 and 2018 , the beginning and ending balances for financial instruments that are recognized at fair value in the condensed consolidated financial statements, at least annually, using significant unobservable inputs: Fair Value Measurement Using Significant Unobservable Inputs (Level 3) Three months ended March 31, 2019 (In millions) Debt Securities Derivatives (a) Total Beginning balance as of January 1, 2019 $ 19 $ 20 $ 39 Total losses — realized/unrealized — (10 ) (10 ) Cash received (1 ) — (1 ) Purchases — (2 ) (2 ) Transfers into Level 3 (b) — 17 17 Transfers out of Level 3 (b) — (27 ) (27 ) Ending balance as of March 31, 2019 $ 18 $ (2 ) $ 16 (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, 2019 $ — $ (12 ) $ (12 ) (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, 2018 (In millions) Debt Securities Derivatives (a) Total Beginning balance as of January 1, 2018 $ 19 $ (15 ) $ 4 Total gains — realized/unrealized included in earnings — 11 11 Purchases — 1 1 Transfers into Level 3 (b) — 4 4 Transfers out of Level 3 (b) — 4 4 Ending balance as of March 31, 2018 $ 19 $ 5 $ 24 Gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of March 31, 2018 $ — $ 12 $ 12 (a) Consists of derivative assets and liabilities, net (b) Transfers into/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. All transfers in/out are with Level 2 Derivative Fair Value Measurements A portion of NRG's contracts are exchange-traded contracts with readily available quoted market prices. A majority of NRG's contracts are non-exchange-traded contracts valued using prices provided by external sources, primarily price quotations available through brokers or over-the-counter and on-line exchanges. The remainder of the assets and liabilities represent contracts for which external sources or observable market quotes are not available. These contracts are valued based on various valuation techniques including, but not limited to, internal models based on a fundamental analysis of the market and extrapolation of the observable market data with similar characteristics. As of March 31, 2019 , contracts valued with prices provided by models and other valuation techniques make up 12% of derivative assets and 14% of derivative liabilities. NRG's significant positions classified as Level 3 include physical and financial power executed in illiquid markets as well as financial transmission rights, or FTRs. The significant unobservable inputs used in developing fair value include illiquid power location pricing which is derived as a basis to liquid locations. The basis spread is based on observable market data when available or derived from historic prices and forward market prices from similar observable markets when not available. For FTRs, NRG uses the most recent auction prices to derive the fair value. The following tables quantify the significant unobservable inputs used in developing the fair value of the Company's Level 3 positions as of March 31, 2019 and December 31, 2018 : March 31, 2019 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) Power Contracts $ 89 $ 104 Discounted Cash Flow Forward Market Price (per MWh) 0 $ 253 $ 28 FTRs 26 13 Discounted Cash Flow Auction Prices (per MWh) (42 ) 38 0 $ 115 $ 117 December 31, 2018 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) Power Contracts $ 89 $ 75 Discounted Cash Flow Forward Market Price (per MWh) $ 1 $ 214 $ 31 FTRs 20 14 Discounted Cash Flow Auction Prices (per MWh) (90 ) 34 0 $ 109 $ 89 The following table provides sensitivity of fair value measurements to increases/(decreases) in significant unobservable inputs as of March 31, 2019 and December 31, 2018 : Significant Unobservable Input Position Change In Input Impact on Fair Value Measurement Forward Market Price Power Buy Increase/(Decrease) Higher/(Lower) Forward Market Price Power Sell Increase/(Decrease) Lower/(Higher) FTR Prices Buy Increase/(Decrease) Higher/(Lower) FTR Prices Sell Increase/(Decrease) Lower/(Higher) The fair value of each contract is discounted using a risk-free interest rate. In addition, the Company applies a credit reserve to reflect credit risk, which is calculated based on published default probabilities. As of March 31, 2019 and December 31, 2018 , the credit reserve did not result in a significant change in fair value in operating revenue and cost of operations. Concentration of Credit Risk In addition to the credit risk discussion as disclosed in Note 2 , Summary of Significant Accounting Policies , to the Company's 2018 Form 10-K, the following is a discussion of the concentration of credit risk for the Company's contractual obligations. Credit risk relates to the risk of loss resulting from non-performance or non-payment by counterparties pursuant to the terms of their contractual obligations. NRG is exposed to counterparty credit risk through various activities including wholesale sales, fuel purchases and retail supply arrangements, and retail customer credit risk through its retail load activities. Counterparty Credit Risk The Company's counterparty credit risk policies are disclosed in its 2018 Form 10-K. As of March 31, 2019 , counterparty credit exposure, excluding credit exposure from RTOs, ISOs, registered commodity exchanges and certain long-term agreements, was $259 million and NRG held collateral (cash and letters of credit) against those positions of $102 million , resulting in a net exposure of $162 million . Approximately 50% of the Company's exposure before collateral is expected to roll off by the end of 2020 . Counterparty credit exposure is valued through observable market quotes and discounted at a risk free interest rate. The following tables highlight net counterparty credit exposure by industry sector and by counterparty credit quality. Net counterparty credit exposure is defined as the aggregate net asset position for NRG with counterparties where netting is permitted under the enabling agreement and includes all cash flow, mark-to-market and NPNS, and non-derivative transactions. The exposure is shown net of collateral held and includes amounts net of receivables or payables. Net Exposure (a)(b) Category by Industry Sector (% of Total) Utilities, energy merchants, marketers and other 78 % Financial institutions 22 Total as of March 31, 2019 100 % Net Exposure (a) (b) Category by Counterparty Credit Quality (% of Total) Investment grade 52 % Non-Investment grade/Non-Rated 48 Total as of March 31, 2019 100 % (a) Counterparty credit exposure excludes uranium and coal transportation contracts because of the unavailability of market prices (b) The figures in the tables above exclude potential counterparty credit exposure related to RTOs, ISOs, registered commodity exchanges and certain long-term contracts The Company currently has no exposure to any individual wholesale counterparties in excess of 10% of total net exposure discussed above as of March 31, 2019 . Changes in hedge positions and market prices will affect credit exposure and counterparty concentration. Given the credit quality, diversification and term of the exposure in the portfolio, NRG does not anticipate a material impact on its financial position or results of operations from nonperformance by any of NRG's counterparties. RTOs and ISOs The Company participates in the organized markets of CAISO, ERCOT, ISO-NE, MISO, NYISO and PJM, known as RTOs or ISOs. Trading in these markets is approved by FERC, or in the case of ERCOT, approved by the PUCT, and includes credit policies that, under certain circumstances, require that losses arising from the default of one member on spot market transactions be shared by the remaining participants. As a result, the counterparty credit risk to these markets is limited to NRG’s share of the overall market and are excluded from the above exposures. Exchange Traded Transactions The Company enters into commodity transactions on registered exchanges, notably ICE, NYMEX and Nodal. These clearinghouses act as the counterparty and transactions are subject to extensive collateral and margining requirements. As a result, these commodity transactions have limited counterparty credit risk. Long-Term Contracts Counterparty credit exposure described above excludes credit risk exposure under certain long-term contracts, primarily solar PPAs. As external sources or observable market quotes are not available to estimate such exposure, the Company values these contracts based on various techniques including, but not limited to, internal models based on a fundamental analysis of the market and extrapolation of observable market data with similar characteristics. Based on these valuation techniques, as of March 31, 2019 , aggregate credit risk exposure managed by NRG to these counterparties was approximately $596 million for the next five years, including exposure to PG&E as described below. This amount excludes potential credit exposures for projects with long-term PPAs that have not reached commercial operations. NRG, through its unconsolidated affiliates Ivanpah and Agua Caliente, has exposure to PG&E of approximately $326 million for the next five years. As a result of the bankruptcy filing by PG&E on January 29, 2019, it is uncertain whether and to what extent the bankruptcy may have an effect on these contracts. For further discussion see Note 10 , Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs . Retail Customer Credit Risk The Company is exposed to retail credit risk through the Company's retail electricity providers, which serve C&I customers and the Mass market. Retail credit risk results in losses when a customer fails to pay for services rendered. The losses may result from both nonpayment of customer accounts receivable and the loss of in-the-money forward value. The Company manages retail credit risk through the use of established credit policies that include monitoring of the portfolio and the use of credit mitigation measures such as deposits or prepayment arrangements. As of March 31, 2019 , the Company's retail customer credit exposure to C&I and Mass customers was diversified across many customers and various industries, as well as government entities.

Nuclear Decommissioning Trust F

Nuclear Decommissioning Trust Fund	3 Months Ended
	Mar. 31, 2019
Nuclear Decommissioning Trust Fund Disclosure [Abstract]
Nuclear Decommissioning Trust Fund	Nuclear Decommissioning Trust Fund 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 the Nuclear Decommissioning Trust liability and are not included in net income or accumulated OCI, consistent with regulatory treatment. The following table summarizes the aggregate fair values and unrealized gains and losses for the securities held in the trust funds, as well as information about the contractual maturities of those securities. As of March 31, 2019 As of December 31, 2018 (In millions, except maturities) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Cash and cash equivalents $ 15 $ — $ — — $ 19 $ — $ — — U.S. government and federal agency obligations 50 2 — 13 46 1 — 12 Federal agency mortgage-backed securities 96 1 1 25 100 1 2 23 Commercial mortgage-backed securities 29 1 — 23 22 — 1 22 Corporate debt securities 100 3 1 11 96 1 2 11 Equity securities 424 276 — — 376 231 1 — Foreign government fixed income securities 4 — — 10 4 — — 9 Total $ 718 $ 283 $ 2 $ 663 $ 234 $ 6 The following table summarizes proceeds from sales of available-for-sale securities and the related realized gains and losses from these sales. The cost of securities sold is determined on the specific identification method. Three months ended March 31, 2019 2018 (In millions) Realized gains $ 3 $ 3 Realized losses (2 ) (3 ) Proceeds from sale of securities 113 182

Accounting for Derivative Instr

Accounting for Derivative Instruments and Hedging Activities	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Accounting for Derivative Instruments and Hedging Activities	Accounting for Derivative Instruments and Hedging Activities Energy-Related Commodities As of March 31, 2019 , NRG had energy-related derivative instruments extending through 2034 . The Company marks these derivatives to market through the statement of operations. NRG has executed power purchase agreements extending through 2033 that qualified for the NPNS exception and were therefore exempt from fair value accounting treatment. Interest Rate Swaps NRG 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, 2019 , NRG had interest rate derivative instruments on recourse debt extending through 2021 . 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, 2019 and December 31, 2018 . Option contracts are reflected using delta volume. Delta volume equals the notional volume of an option adjusted for the probability that the option will be in-the-money at its expiration date. Total Volume March 31, 2019 December 31, 2018 Category Units (In millions) Emissions Short Ton 1 (2 ) Renewable Energy Certificates Certificates 1 1 Coal Short Ton 9 13 Natural Gas MMBtu (236 ) (330 ) Oil Barrels — 1 Power MWh 8 1 Capacity MW/Day (1 ) (1 ) Interest Dollars $ 1,000 $ 1,000 The decrease in the natural gas position was primarily the result of additional retail hedge positions and settlement of generation hedges. 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, 2019 December 31, 2018 March 31, 2019 December 31, 2018 (In millions) Derivatives Not Designated as Cash Flow or Fair Value Hedges: Interest rate contracts current $ 15 $ 17 $ — $ — Interest rate contracts long-term 14 22 — — Commodity contracts current 596 747 489 673 Commodity contracts long-term 333 295 350 304 Total Derivatives Not Designated as Cash Flow or Fair Value Hedges $ 958 $ 1,081 $ 839 $ 977 The Company has elected to present derivative assets and liabilities on the balance sheet on a trade-by-trade basis and does not offset amounts at the counterparty master agreement level. In addition, collateral received or paid on the Company's derivative assets or liabilities are recorded on a separate line item on the balance sheet. The following table summarizes the offsetting of derivatives by counterparty master agreement level and collateral received or paid: Gross Amounts Not Offset in the March 31, 2019 Balance Sheet Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount (In millions) Commodity contracts: Derivative assets $ 929 $ (689 ) $ (5 ) $ 235 Derivative liabilities (839 ) 689 92 (58 ) Total commodity contracts 90 — 87 177 Interest rate contracts: Derivative assets 29 — — 29 Total interest rate contracts 29 — — 29 Total derivative instruments $ 119 $ — $ 87 $ 206 Gross Amounts Not Offset in the December 31, 2018 Balance Sheet Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount (In millions) Commodity contracts: Derivative assets $ 1,042 $ (778 ) $ (31 ) $ 233 Derivative liabilities (977 ) 778 114 (85 ) Total commodity contracts 65 — 83 148 Interest rate contracts: Derivative assets 39 — — 39 Total interest rate contracts 39 — — 39 Total derivative instruments $ 104 $ — $ 83 $ 187 Accumulated Other Comprehensive Loss The following table summarizes the effects on the Company's accumulated OCL balance attributable to cash flow hedge derivatives, net of tax: Interest Rate Contracts Three months ended March 31, 2019 2018 (In millions) Accumulated OCL beginning balance $ — $ (54 ) Reclassified from accumulated OCL to income: Due to realization of previously deferred amounts — 4 Mark-to-market of cash flow hedge accounting contracts — 19 Accumulated OCL ending balance, net of $0, and $6 tax $ — $ (31 ) Amounts reclassified from accumulated OCL into income are recorded in discontinued operations. Impact of Derivative Instruments on the Statements of Operations Unrealized gains and losses associated with changes in the fair value of derivative instruments not accounted for as cash flow hedges are reflected in current period results of operations. The following table summarizes the pre-tax effects of economic hedges that have not been designated as cash flow hedges and trading activity on the Company's statement of operations. The effect of commodity hedges is included within operating revenues and cost of operations and the effect of interest rate hedges is included in interest expense. Three months ended March 31, 2019 2018 Unrealized mark-to-market results (In millions) Reversal of previously recognized unrealized losses on settled positions related to economic hedges $ 19 $ 1 Reversal of acquired gain positions related to economic hedges (2 ) — Net unrealized gains on open positions related to economic hedges 3 205 Total unrealized mark-to-market gains for economic hedging activities 20 206 Reversal of previously recognized unrealized gains on settled positions related to trading activity (6 ) (3 ) Net unrealized gains on open positions related to trading activity 13 11 Total unrealized mark-to-market gains for trading activity 7 8 Total unrealized gains $ 27 $ 214 Three months ended March 31, 2019 2018 (In millions) Unrealized gains/(losses) included in operating revenues $ 27 $ (88 ) Unrealized gains included in cost of operations — 302 Total impact to statement of operations — energy commodities $ 27 $ 214 Total impact to statement of operations — interest rate contracts $ (9 ) $ 12 The reversals of acquired gain or loss positions were valued based upon the forward prices on the acquisition date. The roll-off amounts were offset by realized gains or losses at the settled prices and are reflected in operating revenue or cost of operations during the same period. For the three months ended March 31, 2019 , the $ 3 million unrealized gain from economic hedge positions was primarily the result of an increase in value of forward power positions due to a decrease in power prices. For the three months ended March 31, 2018 , the $205 million unrealized gains from economic hedge positions was primarily the result of an increase in value of forward purchases of ERCOT heat rate contracts due to ERCOT heat rate expansion. Credit Risk Related Contingent Features Certain of the Company's hedging agreements contain provisions that require the Company to post additional collateral if the counterparty determines that there has been deterioration in credit quality, generally termed “adequate assurance” under the agreements, or require the Company to post additional collateral if there were a one notch downgrade in the Company's credit rating. The collateral required for contracts with adequate assurance clauses that are in a net liability position as of March 31, 2019 was $17 million . The collateral required for contracts with credit rating contingent features that are in a net liability position as of March 31, 2019 was $23 million . The Company is also a party to certain marginable agreements under which it has a net liability position, but the counterparty has not called for the collateral due, which was $3 million as of March 31, 2019 . See Note 5 , Fair Value of Financial Instruments , to this Form 10-Q for discussion regarding concentration of credit risk.

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	Leases The Company leases generating facilities, land, office and equipment, railcars, and storefront space at retail stores. Operating leases with an initial term greater than twelve months are recognized as right-of-use assets and lease liabilities in the consolidated balance sheets. The Company recognizes lease expense for all operating leases on a straight-line basis over the lease term. In the future, should another systematic basis become more representative of the pattern in which the lessee expects to consume the remaining economic benefit of the right-of-use asset, the Company will use that basis for lease expense. The Company considers a contract to be or to contain a lease when both of the following conditions apply: 1) an asset is either explicitly or implicitly identified in the contract and 2) the contract conveys to the Company the right to control the use of the identified asset for a period of time. The Company has the right to control the use of the identified asset when the Company has both the right to obtain substantially all the economic benefits from the use of the identified asset and the right to direct how and for what purpose the identified asset is used throughout the period of use. Lease payments are typically fixed and payable on a monthly, quarterly, semi-annual or annual basis. Lease payments under certain agreements may escalate over the lease term either by a fixed percentage or a fixed dollar amount. Certain leases may provide for variable lease payments in the form of payments based on usage, a percentage of sales from the location under lease, or index-based (e.g., the U.S. Consumer Price Index) adjustments to lease payments. The Company has no leases which contain residual value guarantees provided by the Company as a lessee. The Company’s leases may grant the Company an option to renew a lease for an additional term(s) or to terminate the lease after a certain period. As part of its transition from the guidance contained in Topic 840 to the updated guidance in Topic 842, the Company elected not to use the practical expedient of using hindsight to determine the lease term and in assessing impairment of the right-of-use assets. As permitted by Topic 842, the Company made an accounting policy election for all asset classes not to recognize right-of-assets and lease liabilities in the consolidated balance sheets for its short-term leases, which are leases that have a lease term of twelve months or less. For the initial measurement of lease liabilities, the Company uses as the discount rate either the rate implicit in the lease, if known, or its incremental borrowing rate, which is the rate of interest that the Company would have to pay to borrow, on a collateralized basis, over a similar term an amount equal to the payments for the lease. In transition to Topic 842, the Company elected to apply the effective date transition method as of the January 1, 2019 adoption date. In accordance with this method, the Company’s reporting for comparative periods prior to January 1, 2019 presented in the financial statements continues to be in conformity with the guidance in Topic 840. The Company elected the following practical expedients, which allow entities to: 1. not reassess whether any contracts that existed prior to the January 1, 2019 implementation date are or contain leases; 2. not reassess the lease classification for any leases that commenced prior to the January 1, 2019 implementation date, meaning that all commenced capital leases under Topic 840 will be classified as finance leases under Topic 842 and all commenced operating leases under Topic 840 will be classified as operating leases under Topic 842; 3. not reassess initial direct costs for any leases; 4. not reassess whether existing land easements, which were not previously accounted as leases under Topic 840, are or contain leases; and 5. not separate lease and non-lease components for all asset classes, except office space leases and generation facilities leases. As described in Note 3, Discontinued Operations and Dispositions , upon the close of the South Central Portfolio sale, the Company entered into an agreement to leaseback the Cottonwood facility through May 2025. The lease was accounted for in accordance with ASC 842-40, Sale and Leaseback Transactions , as an operating lease and accordingly, a right-of-use asset and lease liability were established on the lease commencement date and will be amortized through the end of the lease. Lease Cost: (In millions) Three months ended March 31, 2019 Operating lease cost $ 23 Variable lease cost 1 Sublease income (4 ) Total lease cost $ 20 Other information: (In millions) Three months ended March 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 21 Right-of-use assets obtained in exchange for new operating lease liabilities 214 Lease Term and Discount Rate: Weighted-average remaining lease term In Years Finance leases 2.8 Operating leases 8.2 Weighted-average discount rate % Finance leases 6.5 Operating leases 5.7 As of March 31, 2019 , annual payments based on the maturities of NRG's leases are expected to be as follows: (In millions) Remainder of 2019 $ 76 2020 96 2021 86 2022 85 2023 86 Thereafter 370 Total undiscounted lease payments $ 799 Less: present value adjustment (196 ) Total discounted lease payments $ 603

Debt and Capital Leases

Debt and Capital Leases	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Debt and Capital Leases	Debt and Capital Leases Long-term debt and capital leases consisted of the following: (In millions, except rates) March 31, 2019 December 31, 2018 March 31, 2019 interest rate % (a) Recourse debt: Senior Notes, due 2024 $ 733 $ 733 6.250 Senior Notes, due 2026 1,000 1,000 7.250 Senior Notes, due 2027 1,230 1,230 6.625 Senior Notes, due 2028 821 821 5.750 Convertible Senior Notes, due 2048 575 575 2.750 Term loan facility, due 2023 1,694 1,698 L+1.75 Tax-exempt bonds 466 466 4.125 - 6.00 Subtotal recourse debt 6,519 6,523 Non-recourse debt: Agua Caliente Borrower 1, due 2038 83 86 5.430 Midwest Generation, due 2019 20 48 4.390 Other 34 34 various Subtotal all non-recourse debt 137 168 Subtotal long-term debt (including current maturities) 6,656 6,691 Capital leases 1 1 various Subtotal long-term debt and capital leases (including current maturities) 6,657 6,692 Less current maturities (124 ) (72 ) Less debt issuance costs (69 ) (70 ) Discounts (98 ) (101 ) Total long-term debt and capital leases $ 6,366 $ 6,449 (a) As of March 31, 2019 , L+ equals 1-month LIBOR plus 1.75% Agua Caliente Borrower 1 On January 22, 2019, the lenders of the Agua Caliente Borrower 1 debt notified Agua Caliente Borrower 1, a subsidiary of the Company, of certain defaults under the financing agreement as it relates to the bankruptcy filing made by PG&E on January 29, 2019. PG&E is the offtaker of the underlying contracts, which are material to the project. The financing was entered into along with Agua Caliente Borrower 2, LLC, a subsidiary of Clearway Energy Inc., which is joint and several to the parties. The Company is working with the lenders to determine a path forward. Cottonwood - Letters of Credit On January 4, 2019, the Company entered into an $80 million credit agreement to issue letters of credit, which is currently supporting the Cottonwood facility lease. Annual fees of 1.33% on the facility are paid quarterly in advance. As of March 31, 2019, the full $80 million is issued.

Investments Accounted for Using

Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs	3 Months Ended
	Mar. 31, 2019
Variable Interest Entities Disclosure [Abstract]
Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs	Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs Entities that are not Consolidated NRG accounts for the Company's significant investments using the equity method of accounting. NRG's carrying value of equity investments can be impacted by a number of elements including impairments, unrealized gains and losses on derivatives and movements in foreign currency exchange rates. PG&E Bankruptcy - The Agua Caliente project and two of the three Ivanpah units are party to PPAs with PG&E. Both projects have project financing with the U.S. DOE. On January 29, 2019, PG&E Corp. and subsidiary utility PG&E filed for Chapter 11 bankruptcy protection. As part of their filing, PG&E asked the Bankruptcy Court to confirm exclusive jurisdiction over their "rights to reject" PPAs or other contracts regulated by FERC . As a result of the bankruptcy filing, the Agua Caliente and Ivanpah projects have issued notices of events of default under their respective loan agreements. The Company's subsidiaries are working with its partners on the projects and the loan counterparties, however, given the uncertainty involved in bankruptcy proceedings, it is uncertain whether, and to what extent, PG&E's bankruptcy may in the future impact the PPAs and have any resulting impact on the Agua Caliente and Ivanpah projects. NRG's maximum exposure to loss is limited to its equity investment, which was $201 million for Agua Caliente and $20 million for Ivanpah as of March 31, 2019. See Note 9 , Debt and Capital Leases for further discussion on Agua Caliente. Variable Interest Entities NRG accounts for its interests in certain entities that are considered VIEs under ASC 810, Consolidation , for which NRG is not the primary beneficiary, under the equity method. Through its consolidated subsidiary, NRG Solar Ivanpah LLC, NRG owns a 54.5% interest in Ivanpah Master Holdings LLC, or Ivanpah, the owner of three solar electric generating projects located in the Mojave Desert with a total capacity of 393 MW. NRG considers this investment a VIE under ASC 810 and NRG is not considered the primary beneficiary. The Company accounts for its interest under the equity method of accounting. The Ivanpah solar electric generating projects were funded in large part by loans guaranteed by the U.S. DOE and equity from the projects' partners. During the first quarter of 2018, all interested parties sought a restructuring of Ivanpah's debt in order to avoid a potential event of default with respect to the loans and entered into a settlement during the second quarter of 2018. The settlement resulted in certain transactions, including the release of reserves totaling $95 million to fund equity distributions to the partners, which reduced the equity at risk, and the prepayment of certain of the debt balance outstanding, and the amendment of certain of Ivanpah's governing documents. The equity distributions and prepayment of debt were funded by the agreed upon release of reserve funds. These events were considered to be a reconsideration event in accordance with ASC 810. As a result, NRG determined that it is not the primary beneficiary and deconsolidated Ivanpah. Entities that are Consolidated The Company has a controlling financial interest in certain entities that have been identified as VIEs under ASC 810. These arrangements are primarily related to tax equity arrangements entered into with third-parties in order to finance the cost of solar energy systems under operating leases eligible for certain tax credits as further described in Note 2 , Summary of Significant Accounting Policies to the Company's 2018 Form 10-K. The summarized financial information for the Company's consolidated VIEs consisted of the following: (In millions) March 31, 2019 December 31, 2018 Current assets $ 3 $ 3 Net property, plant and equipment 75 76 Other long-term assets 27 28 Total assets 105 107 Current liabilities 1 2 Long-term debt 29 29 Other long-term liabilities 8 7 Total liabilities 38 38 Redeemable noncontrolling interest 18 19 Net assets less noncontrolling interests $ 49 $ 50

Changes in Capital Structure

Changes in Capital Structure	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Changes in Capital Structure	Changes in Capital Structure As of March 31, 2019 and December 31, 2018 , the Company had 500,000,000 shares of common stock authorized. The following table reflects the changes in NRG's common stock issued and outstanding: Issued Treasury Outstanding Balance as of December 31, 2018 420,288,886 (136,638,847 ) 283,650,039 Shares issued under LTIPs 1,497,175 — 1,497,175 Shares repurchased — (17,608,957 ) (17,608,957 ) Balance as of March 31, 2019 421,786,061 (154,247,804 ) 267,538,257 Employee Stock Purchase Plan In March 2019, the Company reopened participation in the ESPP, which allows eligible employees to elect to withhold between 1% and 10% of their eligible compensation to purchase shares of NRG common stock at the lesser of 95% of its market value on the offering date or 95% of the fair market value on the exercise date. An offering date will occur each April 1 and October 1. An exercise date will occur each September 30 and March 31. Share Repurchases During the three months ended March 31, 2019 , the Company completed $250 million share repurchases in connection with the 2018 share repurchase program. In addition, in February 2019, the Company's board of directors authorized an additional $1.0 billion share repurchase program to be executed in 2019. The Company completed $500 million of share repurchases at an average price of $42.21 per share under the 2019 program through May 2, 2019. On February 28, 2019, the Company executed an accelerated share repurchase agreement, or ASR Agreement, with a financial institution to repurchase a total of $400 million of outstanding common stock based on a volume weighted average price. The Company received initial shares of 9,086,903 , which were recorded in treasury stock at fair value based on the closing price on March 12, 2019, of $390 million , with the remaining $10 million recorded in additional paid in capital, representing the value of the forward contract to purchase additional shares. In April 2019, the financial institution delivered the remaining shares pursuant to the ASR agreement and the Company received 351,768 additional shares. The average price paid for all the shares delivered under the ASR Agreement was $42.38 per share. Upon receipt of the additional shares in April 2019, the Company transferred the $10 million from additional paid in capital to treasury stock. The following repurchases have been made during the three months ended March 31, 2019 and through May 2, 2019: Total number of shares purchased Amounts paid for shares purchased (in millions) Board Authorized Share Repurchases 2018 program: Repurchases made during January-February to complete the 2018 program 6,153,415 $ 250 2019 program: Shares repurchased under February 28, 2019 Accelerated Share Repurchase Agreement 9,086,903 400 March repurchases 2,368,639 99 Total Share Repurchases during the three months ended March 31, 2019 17,608,957 $ 749 Additional shares delivered upon ASR settlement in April 351,768 — April repurchases 39,140 1 Total Share Repurchases during the period ended May 2, 2019 17,999,865 $ 750 NRG Common Stock Dividends A quarterly dividend of $0.03 per share was paid on the Company's common stock during the three months ended March 31, 2019 . On April 8, 2019 , NRG declared a quarterly dividend on the Company's common stock of $0.03 per share, payable May 15, 2019 , to stockholders of record as of May 1, 2019 , representing $0.12 per share on an annualized basis. The Company's common stock dividends are subject to available capital, market conditions, and compliance with associated laws, regulations and other contractual obligations.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Basic earnings per common share is computed by dividing net income by the weighted average number of common shares outstanding. Shares issued and treasury shares repurchased during the year are weighted for the portion of the year that they were outstanding. Diluted earnings per share is computed in a manner consistent with that of basic income per share while giving effect to all potentially dilutive common shares that were outstanding during the period. The outstanding non-qualified stock options, non-vested restricted stock units, and market stock units are not considered outstanding for purposes of computing basic income per share. However, these instruments are included in the denominator for purposes of computing diluted income per share under the treasury stock method. The 2048 Convertible Senior Notes are convertible, under certain circumstances, into the Company’s common stock, cash or combination thereof (at NRG's option). There is no dilutive effect for the 2048 Convertible Senior Notes due to the Company’s expectation to settle the liability in cash. The reconciliation of NRG's basic and diluted income per share is shown in the following table: Three months ended March 31, In millions, except per share data 2019 2018 Basic income per share attributable to NRG Energy, Inc; Net income attributable to NRG Energy, Inc. common stockholders $ 482 $ 279 Weighted average number of common shares outstanding - basic 278 318 Income per weighted average common share — basic $ 1.73 $ 0.88 Diluted income per share attributable to NRG Energy, Inc; Net income attributable to NRG Energy, Inc. available to common shareholders $ 482 $ 279 Weighted average number of common shares outstanding - basic 278 318 Incremental shares attributable to the issuance of equity compensation (treasury stock method) 2 4 Weighted average number of common shares outstanding - dilutive 280 322 Income per weighted average common share — diluted $ 1.72 $ 0.87 The following table summarizes NRG’s outstanding equity instruments that are anti-dilutive and were not included in the computation of the Company’s diluted income per share: Three months ended March 31, In millions of shares 2019 2018 Equity compensation plans — 1

Segment Reporting

Segment Reporting	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company's segment structure reflects how management currently makes financial decisions and allocates resources. The Company's businesses are segregated into the Generation, Retail and corporate segments. Generation includes all power plant activities, domestic and international, as well as renewables. Retail includes Mass customers and Business Solutions, which includes C&I customers and other distributed and reliability products. Intersegment sales are accounted for at market. The financial information for the three months ended March 31, 2018 has been recast to reflect the current segment structure. On February 4, 2019, as described in Note 4 , Discontinued Operations and Dispositions , the Company completed the sale of and deconsolidated the South Central Portfolio. On August 31, 2018, as described in Note 4 , Discontinued Operations and Dispositions , NRG deconsolidated NRG Yield, Inc., its Renewables Platform and Carlsbad for financial reporting purposes. The financial information for the three months ended March 31, 2018 has been recast to reflect the presentation of these entities as discontinued operations within the corporate segment. NRG’s chief operating decision maker, its chief executive officer, evaluates the performance of its segments based on operational measures including adjusted earnings before interest, taxes, depreciation and amortization, or Adjusted EBITDA, free cash flow and capital for allocation, as well as net income/(loss)and net income/(loss) attributable to NRG Energy, Inc. Three months ended March 31, 2019 (a) Retail Generation Corporate Eliminations Total (In millions) Operating revenues (b) $ 1,607 $ 823 $ 1 $ (266 ) $ 2,165 Depreciation and amortization 31 46 8 — 85 Reorganization costs 1 1 11 — 13 Equity in losses of unconsolidated affiliates — (20 ) 27 (28 ) (21 ) Income/(loss) from continuing operations before income taxes 111 114 (100 ) (27 ) 98 Income/(loss) from continuing operations 111 114 (104 ) (27 ) 94 Income from discontinued operations, net of tax — — 388 — 388 Net Income attributable to NRG Energy, Inc. $ 111 $ 114 $ 284 $ (27 ) $ 482 Total assets as of March 31, 2019 $ 3,309 $ 5,489 $ 5,680 $ (4,948 ) $ 9,530 (a) Includes intersegment revenues and costs associated with the internal transfer of power, which is based on average annualized market prices and results in higher revenues in Generation and higher cost of operations in Retail that are eliminated in consolidation (b) Operating revenues include intersegment sales and net derivative gains and losses of: $ 3 $ 235 $ 28 $ — $ 266 Three months ended March 31, 2018 (a) Retail Generation Corporate Eliminations Total (In millions) Operating revenues (b) $ 1,480 $ 270 $ 1 $ 314 $ 2,065 Depreciation and amortization 26 86 9 (1 ) 120 Reorganization costs 3 4 13 — 20 Equity in earnings/(losses) of unconsolidated affiliates — 2 (1 ) — 1 Income/(loss) from continuing operations before income taxes 944 (573 ) (128 ) 1 244 Income/(loss) from continuing operations 944 (573 ) (134 ) 1 238 Loss from discontinued operations, net of tax — — (5 ) — (5 ) Net Income/(Loss) 944 (573 ) (139 ) 1 233 Net Income/(Loss) attributable to NRG Energy, Inc. $ 943 $ (565 ) $ (100 ) $ 1 $ 279 (a) Includes intersegment revenues and costs associated with our internal transfer of power, which is based on average annualized market prices and results in higher revenues in Generation and higher cost of operations in Retail that are eliminated in consolidation (b) Operating revenues include intersegment sales and net derivative gains and losses of: $ 1 $ (309 ) $ (6 ) $ — $ (314 )

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Effective Income Tax Rate The income tax provision consisted of the following: Three months ended March 31, In millions, except rates 2019 2018 Income before income taxes $ 98 $ 244 Income tax expense from continuing operations 4 6 Effective income tax rate 4.1 % 2.5 % For the three months ended March 31, 2019 and 2018 , NRG's overall effective tax rate was lower than the statutory rate of 21% , primarily due to the tax benefit for the change in valuation allowance, partially offset by current state tax expense. Uncertain Tax Benefits As of March 31, 2019 , NRG has recorded a non-current tax liability of $31 million for uncertain tax benefits from positions taken on various state income tax returns, including accrued interest. For the three months ended March 31, 2019 , NRG accrued an immaterial amount of interest relating to the uncertain tax benefits. As of March 31, 2019 , NRG had cumulative interest and penalties related to these uncertain tax benefits of $5 million . The Company recognizes interest and penalties related to uncertain tax benefits in income tax expense. NRG is subject to examination by taxing authorities for income tax returns filed in the U.S. federal jurisdiction and various state and foreign jurisdictions including operations located in Australia. The Company is no longer subject to U.S. federal income tax examinations for years prior to 2015. With few exceptions, state and local income tax examinations are no longer open for years before 2010.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2019
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The following table summarizes NRG's material related party transactions with third party affiliates: Three months ended March 31, 2019 2018 (In millions) Revenues from Related Parties Included in Operating Revenues Gladstone $ 1 $ 1 GenConn — 1 Ivanpah 10 — Midway-Sunset 1 — Revenues from Related Parties recorded against selling, general and administrative expenses GenOn — 21 Total $ 12 $ 23 Gladstone — NRG provides services to Gladstone, an equity method investment, under an operations and maintenance agreement. Fees for services under this contract primarily include recovery of NRG's costs of operating the plant, as approved in the annual budget, as well as a base monthly fee. GenConn — NRG provides services to GenConn under operations and maintenance agreements with GenConn Devon and GenConn Middletown that began in June 2010 and June 2011, respectively. NRG no longer has an ownership interest in GenConn as a result of the sale of its ownership interests in NRG Yield, Inc. and its Renewables Platform. Ivanpah — NRG provides services to Ivanpah, an equity method investment, under an operations and maintenance agreement and a project management agreement with each project company. Fees for the services under these contracts primarily include recovery of NRG's costs of operating the plant and providing administrative services, plus a profit margin. Ivanpah became a related party to NRG upon deconsolidation in the second quarter of 2018. Midway-Sunset — NRG provides services to Midway-Sunset, an equity method investment, under an operations and maintenance agreement. Fees for the services under this contract primarily include recovery of NRG's costs of operating the plant, as approved in the annual budget, as well as a base monthly fee and an annual incentive bonus. GenOn — NRG provided various management, personnel and other services to GenOn under the transition services agreement in conjunction with the confirmation of the GenOn Entities' plan of reorganization. GenOn provided notice to NRG of its intent to terminate the transition services agreement effective August 15, 2018 and all amounts owed and payable to NRG were settled.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments First Lien Structure NRG has granted first liens to certain counterparties on a substantial portion of the Company's assets, excluding NRG's assets that have project-level financing and the assets of certain non-guarantor subsidiaries, to reduce the amount of cash collateral and letters of credit that it would otherwise be required to post from time to time to support its obligations under out-of-the-money hedge agreements for forward sales of power or MWh equivalents. The Company's lien counterparties may have a claim on NRG's assets to the extent market prices exceed the hedged price. As of March 31, 2019, all hedges under the first lien were out-of-the-money for NRG on a counterparty aggregate basis. Jewett Mine Lignite Contract The Company's Limestone facility historically blended lignite obtained from the Jewett mine, which was operated by Texas Westmoreland Coal Co, or TWCC, and coal sourced from the Powder River Basin in Wyoming. On August 18, 2016, NRG gave notice to TWCC terminating the active mining of lignite under the contract, effective on December 31, 2016. Under the contract, TWCC remained responsible for reclamation activities. NRG is responsible for reclamation costs and has recorded an adequate ARO liability. The Railroad Commission of Texas has imposed a bond obligation of approximately $99 million for the reclamation of the mine. Pursuant to the contract, NRG supports this obligation through surety bonds. Additionally, under the terms of the contract, NRG is obligated to provide additional performance assurance if required by the Railroad Commission of Texas. On October 9, 2018, TWCC and certain of its affiliates filed for protection under Chapter 11 of the U.S. Bankruptcy Code before the United States Bankruptcy Court for the Southern District of Texas. TWCC obtained authorization from the bankruptcy court to continue to perform its obligations under its contract with the Company and to maintain surety bonds programs throughout its operations. In addition, NRG has not received any indication from the Railroad Commission of Texas of an intent to draw on the surety bonds. TWCC and its debtor affiliates filed a plan of reorganization that the Bankruptcy Court confirmed on March 2, 2019. Pursuant to the plan, TWCC and its assets, including the Jewett mine and related agreements with NRG, were purchased by Westmoreland Mining LLC, an entity owned by Westmoreland Mining Holdings LLC, a new entity that is ultimately owned and controlled by certain holders of the pre-bankruptcy funded indebtedness of TWCC and certain of its affilates. Contingencies The Company's material legal proceedings are described below. The Company believes that it has valid defenses to these legal proceedings and intends to defend them vigorously. NRG records reserves for estimated losses from contingencies when information available indicates that a loss is probable and the amount of the loss, or range of loss, can be reasonably estimated. As applicable, the Company has established an adequate reserve for the matters discussed below. In addition, legal costs are expensed as incurred. Management has assessed each of the following matters based on current information and made a judgment concerning its potential outcome, considering the nature of the claim, the amount and nature of damages sought, and the probability of success. Unless specified below, the Company is unable to predict the outcome of these legal proceedings or reasonably estimate the scope or amount of any associated costs and potential liabilities. As additional information becomes available, management adjusts its assessment and estimates of such contingencies accordingly. Because litigation is subject to inherent uncertainties and unfavorable rulings or developments, it is possible that the ultimate resolution of the Company's liabilities and contingencies could be at amounts that are different from its currently recorded reserves and that such difference could be material. In addition to the legal proceedings noted below, NRG and its subsidiaries are party to other litigation or legal proceedings arising in the ordinary course of business. In management's opinion, the disposition of these ordinary course matters will not materially adversely affect NRG's consolidated financial position, results of operations, or cash flows. Midwest Generation Asbestos Liabilities — The Company, through its subsidiary, has been defending an asbestos-related indemnification claim brought by ComEd as a result of the Company's acquisition of EME. The parties have agreed to the terms of a settlement that will resolve all of ComEd's outstanding claims in the matter. California Department of Water Resources and San Diego Gas & Electric Company v. Sunrise Power Company LLC - On January 29, 2016, CDWR and SDG&E (plaintiffs) filed a lawsuit against Sunrise Power Company, along with NRG and Chevron Power Corporation (defendants). In June 2001, CDWR and Sunrise entered into a 10 -year PPA under which Sunrise would construct and operate a generating facility and provide power to CDWR. At the time the PPA was entered into, Sunrise had a transportation services agreement, or TSA, to purchase natural gas from Kern River through April 30, 2018. In August 2003, CDWR entered into an agreement with Sunrise and Kern River in which CDWR accepted assignment of the TSA through the term of the PPA. After the PPA expired, Kern River demanded that any reassignment be to a party which met certain creditworthiness standards which Sunrise did not. As such, the plaintiffs brought this lawsuit against the defendants alleging breach of contract, breach of covenant of good faith and fair dealing and improper distributions. Plaintiffs generally claim damages of $1.2 million per month for the remaining 70 months of the TSA. On April 20, 2016, the defendants filed objections in response to the plaintiffs' complaint. The objections were granted on June 14, 2016; however, the plaintiffs were allowed to file amended complaints on July 1, 2016. On July 27, 2016, defendants filed objections to the amended complaints. On November 18, 2016, the court sustained the objections and allowed plaintiffs another opportunity to file a second amended lawsuit which they did on January 13, 2017. On April 21, 2017, the court issued an order sustaining the objections without leave to amend. On July 14, 2017, plaintiffs filed a notice of appeal. On January 10, 2018, plaintiffs filed their opening appellate brief. Defendants filed their opposition brief on April 10, 2018. On May 30, 2018, plaintiffs filed their reply brief. The case is now waiting for the court of appeal to schedule oral argument. Griffoul v. NRG Residential Solar Solutions - On February 28, 2017, plaintiffs, consisting of New Jersey residential solar customers, filed a purported class action lawsuit in New Jersey state court. Plaintiffs allege violations of the New Jersey Consumer Fraud Action and Truth-in-Consumer Contracts, Warranty and Notice Act with regard to certain provisions of their residential solar contracts. The plaintiffs seek damages and injunctive relief as to the proper allocation of the solar renewable energy credits. On June 6, 2017, the defendants filed a motion to compel arbitration or dismiss the lawsuit. Plaintiffs filed their opposition on June 29, 2017. On July 14, 2017, the court denied NRG's motion to compel arbitration or dismiss the case. On July 25, 2017, NRG filed a motion for reconsideration of the appeal, which the court denied. On August 22, 2017, NRG filed a notice of appeal. After oral argument on April 24, 2018, the Appellate Division reversed the lower court on May 4, 2018, and ordered that the plaintiff must arbitrate their claims against NRG. On May 23, 2018, the plaintiff filed a petition for certification with the Supreme Court of New Jersey seeking to overturn the Appellate Division ruling. On January 25, 2019, the Supreme Court denied plaintiff’s petition for certification. Washington-St. Tammany and Claiborne Electric Cooperative v. LaGen - On June 28, 2017, plaintiffs Washington-St. Tammany Electric Cooperative, Inc. and Claiborne Electric Cooperative, Inc. filed a lawsuit against Louisiana Generating, L.L.C., or LaGen, in the United States District Court for the Middle District of Louisiana. The plaintiffs claim breach of contract against LaGen for allegedly improperly charging the plaintiffs for costs related to the installation and maintenance of certain pollution control technology. Plaintiffs seek damages for the alleged improper charges and a declaration as to which charges are proper under the contract. On September 14, 2017, the court issued a scheduling order setting this case for trial on October 21, 2019. LaGen filed its answer and affirmative defenses on November 17, 2017. On February 4, 2019, NRG sold the South Central Portfolio, including the entities subject to this litigation. However, NRG has agreed to indemnify the purchaser for certain losses suffered in connection therewith.

Regulatory Matters

Regulatory Matters	3 Months Ended
	Mar. 31, 2019
Regulatory Matters Disclosure [Abstract]
Regulatory Matters	Regulatory Matters Environmental regulatory matters are discussed within Note 18 , Environmental Matters , to this Form 10-Q . NRG operates in a highly regulated industry and is subject to regulation by various federal and state agencies. As such, NRG is affected by regulatory developments at both the federal and state levels and in the regions in which NRG operates. In addition, NRG is subject to the market rules, procedures, and protocols of the various ISO and RTO markets in which NRG participates. These power markets are subject to ongoing legislative and regulatory changes that may impact NRG's wholesale and retail businesses. In addition to the regulatory proceedings noted below, NRG and its subsidiaries are parties to other regulatory proceedings arising in the ordinary course of business or have other regulatory exposure. In management's opinion, the disposition of these ordinary course matters will not materially adversely affect NRG's consolidated financial position, results of operations, or cash flows. Zero-Emission Credits for Nuclear Plants in Illinois and New York - In 2016, Illinois enacted a Zero Emission Credit, or ZEC, program for selected nuclear units in Illinois. In total, the program directs over $2.5 billion over ten years to two Exelon-owned nuclear power plants in Illinois. That same year, the NYSPSC issued its Clean Energy Standard, or CES, which provides for ZECs which would provide more than $7.6 billion over 12 years in out-of-market subsidy payments to certain selected nuclear generating units in New York. These ZECs are out-of-market subsidies that threaten to artificially suppress market prices and interfere with the wholesale power market. NRG, along with other companies, filed complaints in the federal courts of Illinois and New York alleging that these state programs are preempted by federal law and in violation of the dormant commerce clause. These cases have proceeded through the federal district court as well as the federal appellate court in Illinois and New York, respectively. Petitions for Writ of Certiorari were filed and were subsequently denied on April 15, 2019. South Central - On August 4, 2016, NRG received a document hold notice from FERC regarding conduct in the MISO and PJM markets. It required NRG to retain communications related to multiple generating units in the South Central region. Since sending the notice, FERC has been investigating potential violations of MISO rules involving bidding for the Big Cajun 2 facility, as well as other aspects of NRG’s operations in MISO. FERC has the authority to require disgorgement of profits and to impose penalties and NRG retains any liability following the sale of the South Central Portfolio. We expect a preliminary finding from FERC by the second quarter of 2019. ISO-NE - On February 5, 2019, FERC has informed the Company that it has made a preliminary finding that the Company violated FERC's market behavior rules in connection with offers made into the ISO-NE Forward Capacity Auction in 2016. The Company understands that FERC is concerned that the Company was inaccurate in its communications with the Market Monitor regarding the costs and risks associated with operating certain units in the forward timeframe. NRG withdrew the bids prior to the 2016 auction in the normal course of our commercial business decision making. The Company will be engaging in discussions with FERC regarding this matter.

Environmental Matters

Environmental Matters	3 Months Ended
	Mar. 31, 2019
Environmental Matters Disclosure [Abstract]
Environmental Matters	Environmental Matters NRG is subject to a wide range of environmental laws in the development, construction, ownership and operation of projects. These laws generally require that governmental permits and approvals be obtained before construction and during operation of power plants. NRG is also subject to laws regarding the protection of wildlife, including migratory birds, eagles and threatened and endangered species. The electric generation industry has been facing requirements regarding GHGs, combustion byproducts, water discharge and use, and threatened and endangered species that have been put in place in recent years. However, under the current U.S. presidential administration, some of these rules are being reconsidered and reviewed. In general, future laws are expected to require the addition of emissions controls or other environmental controls or to impose certain restrictions on the operations of the Company's facilities, which could have a material effect on the Company's consolidated financial position, results of operations, or cash flows. Federal and state environmental laws generally have become more stringent over time, although this trend could slow or pause in the near term with respect to federal laws under the current U.S. presidential administration. Air On August 31, 2018, EPA proposed replacing the Clean Power Plan (CPP) rule, which sought to broadly regulate CO 2 emissions from the power sector, with the Affordable Clean Energy (ACE) rule, which if finalized, would require states to develop plans to seek heat rate improvements from coal-fired EGUs. The Company believes that the ACE rule replacing the CPP rule would on balance be positive for its generation fleet. In February 2012, the EPA promulgated standards (the MATS rule) to control emissions of HAPs from coal and oil-fired electric generating units. The rule established limits for mercury, non-mercury metals, certain organics and acid gases, which had to be met beginning in April 2015. In December 2018, the EPA proposed a finding that regulating HAPs was not "appropriate and necessary" because the costs far exceed the benefits. Nonetheless, the EPA proposed keeping the substantive requirements of the MATS rule. While NRG cannot predict the final outcome of this rulemaking, NRG believes that because it has already invested in pollution controls and cleaner technologies, the fleet is well-positioned to comply with the MATS rule. Water Once Through Cooling Regulation — In August 2014, the EPA finalized the regulation regarding the use of water for once through cooling at existing facilities to address impingement and entrainment concerns. NRG anticipates that more stringent requirements will be incorporated into some of its water discharge permits over the next several years as NPDES permits are renewed. The Company anticipates the cost of complying with these requirements to be immaterial. Effluent Limitations Guidelines — In November 2015, the EPA revised the Effluent Limitations Guidelines for Steam Electric Generating Facilities, which would have imposed more stringent requirements (as individual permits were renewed) for wastewater streams from flue gas desulfurization, fly ash, bottom ash, and flue gas mercury control. On September 18, 2017, the EPA promulgated a final rule that, among other things, postpones the compliance dates to preserve the status quo for FGD wastewater and bottom ash transport water by two years to November 2020 until the EPA completes its next rulemaking. On April 12, 2019, the United States Court of Appeals for the Fifth Circuit released its opinion remanding portions of the rule to the EPA. Accordingly, the Company has eliminated its estimate of the environmental capital expenditures that would have been required to comply with permits incorporating the revised guidelines. The Company will revisit these estimates after the rule is revised. Byproducts, Wastes, Hazardous Materials and Contamination In April 2015, the EPA finalized the rule regulating byproducts of coal combustion (e.g., ash and gypsum) as solid wastes under the RCRA. In 2017, the EPA agreed to reconsider the rule. On July 30, 2018, the EPA promulgated a rule that amends the existing ash rule by extending some of the deadlines and providing more flexibility for compliance. On August 21, 2018, the D.C. Circuit found, among other things, that the EPA had not adequately regulated unlined ponds and legacy ponds. Accordingly, we anticipate that the EPA will promulgate new regulations to address these issues (including compliance deadlines) as it reconsiders other aspects of the existing rule. The EPA has stated that it intends to further revise the rule. The Company will determine estimates of the cost of compliance after the rule is revised.

Condensed Consolidating Financi

Condensed Consolidating Financial Information	3 Months Ended
	Mar. 31, 2019
Condensed Consolidating Financial Information Disclosure [Abstract]
Condensed Financial Information of Parent Company Only Disclosure [Text Block]	Condensed Consolidating Financial Information As of March 31, 2019 , the Company had outstanding $4.4 billion of Senior Notes due from 2024 to 2048, as shown in Note 9 , 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. Unless otherwise noted below, each of the following guarantor subsidiaries fully and unconditionally guaranteed the Senior Notes as of March 31, 2019 : Ace Energy, Inc. NRG Business Services LLC NRG PacGen Inc. Allied Home Warranty GP LLC NRG Cabrillo Power Operations Inc. NRG Portable Power LLC Allied Warranty LLC NRG California Peaker Operations LLC NRG Power Marketing LLC Arthur Kill Power LLC NRG Cedar Bayou Development Company, LLC NRG Reliability Solutions LLC Astoria Gas Turbine Power LLC NRG Connected Home LLC NRG Renter's Protection LLC BidURenergy, Inc. NRG Connecticut Affiliate Services Inc. NRG Retail LLC Cabrillo Power I LLC NRG Construction LLC NRG Retail Northeast LLC Cabrillo Power II LLC NRG Curtailment Solutions, Inc NRG Rockford Acquisition LLC Carbon Management Solutions LLC NRG Development Company Inc. NRG Saguaro Operations Inc. Cirro Group, Inc. NRG Devon Operations Inc. NRG Security LLC Cirro Energy Services, Inc. NRG Dispatch Services LLC NRG Services Corporation Connecticut Jet Power LLC NRG Distributed Energy Resources Holdings LLC NRG SimplySmart Solutions LLC Devon Power LLC NRG Distributed Generation PR LLC NRG South Central Affiliate Services Inc. Dunkirk Power LLC NRG Dunkirk Operations Inc. NRG South Central Operations Inc. Eastern Sierra Energy Company LLC NRG ECOKAP Holdings LLC NRG South Texas LP El Segundo Power, LLC NRG El Segundo Operations Inc. NRG Texas C&I Supply LLC El Segundo Power II LLC NRG Energy Labor Services LLC NRG Texas Gregory LLC Energy Alternatives Wholesale, LLC NRG Energy Services Group LLC NRG Texas Holding Inc. Energy Choice Solutions LLC NRG Energy Services International Inc. NRG Texas LLC Energy Plus Holdings LLC NRG Energy Services LLC NRG Texas Power LLC Energy Plus Natural Gas LLC NRG Generation Holdings, Inc. NRG Warranty Services LLC Energy Protection Insurance Company NRG Greenco LLC NRG West Coast LLC Everything Energy LLC NRG Home & Business Solutions LLC NRG Western Affiliate Services Inc. Forward Home Security, LLC NRG Home Services LLC O'Brien Cogeneration, Inc. II GCP Funding Company, LLC NRG Home Solutions LLC ONSITE Energy, Inc. Green Mountain Energy Company NRG Home Solutions Product LLC Oswego Harbor Power LLC Gregory Partners, LLC NRG Homer City Services LLC Reliant Energy Northeast LLC Gregory Power Partners LLC NRG Huntley Operations Inc. Reliant Energy Power Supply, LLC Huntley Power LLC NRG HQ DG LLC Reliant Energy Retail Holdings, LLC Independence Energy Alliance LLC NRG Identity Protect LLC Reliant Energy Retail Services, LLC Independence Energy Group LLC NRG Ilion Limited Partnership RERH Holdings, LLC Independence Energy Natural Gas LLC NRG Ilion LP LLC Saguaro Power LLC Indian River Operations Inc. NRG International LLC Somerset Operations Inc. Indian River Power LLC NRG Maintenance Services LLC Somerset Power LLC Meriden Gas Turbines LLC NRG Mextrans Inc. Texas Genco GP, LLC Middletown Power LLC NRG MidAtlantic Affiliate Services Inc. Texas Genco Holdings, Inc. Montville Power LLC NRG Middletown Operations Inc. Texas Genco LP, LLC NEO Corporation NRG Montville Operations Inc. Texas Genco Services, LP New Genco GP, LLC NRG North Central Operations Inc. US Retailers LLC Norwalk Power LLC NRG Northeast Affiliate Services Inc. Vienna Operations Inc. NRG Advisory Services LLC NRG Norwalk Harbor Operations Inc. Vienna Power LLC NRG Affiliate Services Inc. NRG Operating Services, Inc. WCP (Generation) Holdings LLC NRG Arthur Kill Operations Inc. NRG Oswego Harbor Power Operations Inc. West Coast Power LLC NRG Astoria Gas Turbine Operations Inc. NRG conducts much of its business through and derives much of its income from its subsidiaries. Therefore, the Company's ability to make required payments with respect to its indebtedness and other obligations depends on the financial results and condition of its subsidiaries and NRG's ability to receive funds from its subsidiaries. There are no restrictions on the ability of any of the guarantor subsidiaries to transfer funds to NRG. However, there may be restrictions for certain non-guarantor subsidiaries. The following condensed consolidating financial information presents the financial information of NRG Energy, Inc., the guarantor subsidiaries and the non-guarantor subsidiaries in accordance with Rule 3-10 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, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 1,769 $ 395 $ — $ 1 $ 2,165 Operating Costs and Expenses Cost of operations 1,358 283 9 1 1,651 Depreciation and amortization 54 23 8 — 85 Selling, general and administrative 122 16 56 — 194 Reorganization costs — — 13 — 13 Development costs — — 2 — 2 Total operating costs and expenses 1,534 322 88 1 1,945 Gain on sale of assets 1 — — — 1 Operating Income/(Loss) 236 73 (88 ) — 221 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 10 — 299 (309 ) — Equity in losses of unconsolidated affiliates — (21 ) — — (21 ) Other income, net 4 1 7 — 12 Interest expense (4 ) (4 ) (106 ) — (114 ) Total other income/(expense) 10 (24 ) 200 (309 ) (123 ) Income from Continuing Operations Before Income Taxes 246 49 112 (309 ) 98 Income tax expense — — 4 — 4 Income from Continuing Operations 246 49 108 (309 ) 94 Income from discontinued operations, net of income tax 9 5 374 — 388 Net Income Attributable to NRG Energy, Inc. $ 255 $ 54 $ 482 $ (309 ) $ 482 (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, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Net Income $ 255 $ 54 $ 482 $ (309 ) $ 482 Other Comprehensive Income/(Loss) Foreign currency translation adjustments, net 1 1 1 (2 ) 1 Defined benefit plans, net — — (3 ) — (3 ) Other comprehensive income/(loss) 1 1 (2 ) (2 ) (2 ) Comprehensive Income Attributable to NRG Energy, Inc. $ 256 $ 55 $ 480 $ (311 ) $ 480 (a) All significant intercompany transactions have been eliminated in consolidation. NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS March 31, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated ASSETS (In millions) Current Assets Cash and cash equivalents $ — $ 27 $ 832 $ — $ 859 Funds deposited by counterparties 11 — — — 11 Restricted cash 12 3 — — 15 Accounts receivable, net 1,228 199 159 (688 ) 898 Inventory 277 114 — — 391 Derivative instruments 610 21 15 (35 ) 611 Cash collateral paid in support of energy risk management activities 367 21 — — 388 Prepayments and other current assets 192 11 82 — 285 Total current assets 2,697 396 1,088 (723 ) 3,458 Property, plant and equipment, net 1,512 987 151 — 2,650 Other Assets Investment in subsidiaries 477 — 3,765 (4,242 ) — Equity investments in affiliates — 387 — — 387 Operating lease right-of-use assets, net 95 289 133 — 517 Goodwill 360 213 — — 573 Intangible assets, net 414 166 — — 580 Nuclear decommissioning trust fund 718 — — — 718 Derivative instruments 334 8 14 (9 ) 347 Deferred income tax 6 (145 ) 184 — 45 Other non-current assets 143 30 94 (12 ) 255 Total other assets 2,547 948 4,190 (4,263 ) 3,422 Total Assets $ 6,756 $ 2,331 $ 5,429 $ (4,986 ) $ 9,530 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Current portion of long-term debt and capital leases $ — $ 108 $ 16 $ — $ 124 Current portion of operating lease liabilities 23 30 21 — 74 Accounts payable 1,515 (218 ) 88 (688 ) 697 Derivative instruments 505 19 — (35 ) 489 Cash collateral received in support of energy risk management activities 11 — — — 11 Accrued expenses and other current liabilities 244 57 249 — 550 Total current liabilities 2,298 (4 ) 374 (723 ) 1,945 Other Liabilities Long-term debt and capital leases 245 112 6,021 (12 ) 6,366 Non-current operating lease liabilities 77 320 132 — 529 Nuclear decommissioning reserve 286 — — — 286 Nuclear decommissioning trust liability 423 — — — 423 Derivative instruments 354 5 — (9 ) 350 Deferred income taxes 112 60 (110 ) — 62 Other non-current liabilities 408 149 532 — 1,089 Total other liabilities 1,905 646 6,575 (21 ) 9,105 Total Liabilities 4,203 642 6,949 (744 ) 11,050 Redeemable noncontrolling interest in subsidiaries — 18 — — 18 Stockholders’ Equity 2,553 1,671 (1,520 ) (4,242 ) (1,538 ) Total Liabilities and Stockholders’ Equity $ 6,756 $ 2,331 $ 5,429 $ (4,986 ) $ 9,530 (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, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net income $ 255 $ 54 $ 482 $ (309 ) $ 482 Income from discontinued operations 9 5 374 — 388 Net income from continuing operations 246 49 108 (309 ) 94 Adjustments to reconcile net income to net cash provided/(used) by operating activities: Equity in losses of unconsolidated affiliates — 21 — — 21 Depreciation, amortization and accretion 59 25 8 — 92 Provision for bad debts 23 3 — — 26 Amortization of nuclear fuel 13 — — — 13 Amortization of financing costs and debt discount/premiums — — 7 — 7 Amortization of intangibles 6 — — — 6 Amortization of unearned equity compensation — — 4 — 4 Loss on sale of assets — — 3 — 3 Changes in derivative instruments (29 ) 5 9 — (15 ) Changes in deferred income taxes and liability for uncertain tax benefits — 1 (3 ) — (2 ) Changes in collateral deposits in support of energy risk management activities (114 ) (9 ) — — (123 ) Changes in nuclear decommissioning trust liability 9 — — — 9 Changes in other working capital (221 ) (137 ) (221 ) 309 (270 ) Cash used by continuing operations (8 ) (42 ) (85 ) — (135 ) Cash provided/(used) by discontinued operations 17 (9 ) — — 8 Net Cash Provided/(Used) by Operating Activities 9 (51 ) (85 ) — (127 ) Cash Flows from Investing Activities Payments for acquisitions of businesses (16 ) — — — (16 ) Capital expenditures (36 ) (6 ) (7 ) — (49 ) Investments in nuclear decommissioning trust fund securities (122 ) — — — (122 ) Proceeds from the sale of nuclear decommissioning trust fund securities 113 — — — 113 Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees 1 404 908 — 1,313 Changes in investments in unconsolidated affiliates — 4 — — 4 Contributions to discontinued operations — (44 ) — — (44 ) Other — — (1 ) — (1 ) Cash (used)/provided by continuing operations (60 ) 358 900 — 1,198 Cash used by discontinued operations — (2 ) — — (2 ) Net Cash (Used)/Provided by Investing Activities (60 ) 356 900 — 1,196 Cash Flows from Financing Activities Payments (for)/from intercompany loans (4 ) (290 ) 294 — — Payments of dividends to common stockholders — — (8 ) — (8 ) Payments for treasury stock — — (747 ) — (747 ) Distributions to noncontrolling interests from subsidiaries — (1 ) — — (1 ) Proceeds from issuance of common stock — — 2 — 2 Payments for long-term debt — (33 ) (4 ) — (37 ) Cash used by continuing operations (4 ) (324 ) (463 ) — (791 ) Cash provided by discontinued operations — 43 — — 43 Net Cash Used by Financing Activities (4 ) (281 ) (463 ) — (748 ) Change in cash from discontinued operations 17 32 — — 49 Net (Decrease)/Increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash (72 ) (8 ) 352 — 272 Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period 95 38 480 — 613 Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period $ 23 $ 30 $ 832 $ — $ 885 (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, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 1,744 $ 329 $ — $ (8 ) $ 2,065 Operating Costs and Expenses Cost of operations 1,155 224 14 (8 ) 1,385 Depreciation and amortization 60 52 8 — 120 Selling, general and administrative 104 11 61 — 176 Reorganization costs 2 — 18 — 20 Development costs — 1 4 — 5 Total operating costs and expenses 1,321 288 105 (8 ) 1,706 Gain/(loss) on sale of assets 3 (1 ) — — 2 Operating Income/(Loss) 426 40 (105 ) — 361 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 1 — 332 (333 ) — Equity in earnings/(losses) of unconsolidated affiliates — 2 (1 ) — 1 Other income/(loss), net 5 (7 ) 2 — — Loss on debt extinguishment, net — — (2 ) — (2 ) Interest expense (3 ) (21 ) (92 ) — (116 ) Total other income/(expense) 3 (26 ) 239 (333 ) (117 ) Income from Continuing Operations Before Income Taxes 429 14 134 (333 ) 244 Income tax expense/(benefit) 113 55 (162 ) — 6 Income/(Loss) from Continuing Operations 316 (41 ) 296 (333 ) 238 Income/(loss) from discontinued operations, net of income tax 15 (20 ) — — (5 ) Net Income/(Loss) 331 (61 ) 296 (333 ) 233 Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (63 ) 17 — (46 ) Net Income Attributable to NRG Energy, Inc. $ 331 $ 2 $ 279 $ (333 ) $ 279 (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, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Net Income/(Loss) $ 331 $ (61 ) $ 296 $ (333 ) $ 233 Other Comprehensive (Loss)/Income Unrealized gain on derivatives, net — 16 15 (17 ) 14 Foreign currency translation adjustments, net (2 ) (2 ) (3 ) 5 (2 ) Defined benefit plans, net — — (1 ) — (1 ) Other comprehensive (loss)/income (2 ) 14 11 (12 ) 11 Comprehensive Income/(Loss) 329 (47 ) 307 (345 ) 244 Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (46 ) 24 (16 ) (38 ) Comprehensive Income/(Loss) Attributable to NRG Energy, Inc. $ 329 $ (1 ) $ 283 $ (329 ) $ 282 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2018 Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated ASSETS (In millions) Current Assets Cash and cash equivalents $ 55 $ 28 $ 480 $ — $ 563 Funds deposited by counterparties 33 — — — 33 Restricted cash 7 10 — — 17 Accounts receivable, net 1,354 115 309 (754 ) 1,024 Inventory 278 134 — — 412 Derivative instruments 779 50 16 (81 ) 764 Cash collateral paid in support of energy risk management activities 275 12 — — 287 Prepayments and other current assets 180 32 90 — 302 Current assets - held-for-sale — 1 — — 1 Current assets - discontinued operations 177 20 — — 197 Total current assets 3,138 402 895 (835 ) 3,600 Property, plant and equipment, net 1,938 957 153 — 3,048 Other Assets Investment in subsidiaries 446 — 4,707 (5,153 ) — Equity investments in affiliates — 412 — — 412 Goodwill 359 214 — — 573 Intangible assets, net 422 169 — — 591 Nuclear decommissioning trust fund 663 — — — 663 Derivative instruments 296 4 22 (5 ) 317 Deferred income taxes 6 (143 ) 183 — 46 Other non-current assets 133 71 97 (12 ) 289 Non-current assets - held for sale — 77 — — 77 Non-current assets - discontinued operations 405 607 — — 1,012 Total other assets 2,730 1,411 5,009 (5,170 ) 3,980 Total Assets $ 7,806 $ 2,770 $ 6,057 $ (6,005 ) $ 10,628 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Current portion of long-term debt and capital leases $ — $ 55 $ 17 $ — $ 72 Accounts payable 1,368 (185 ) 434 (754 ) 863 Derivative instruments 713 41 — (81 ) 673 Cash collateral received in support of energy risk management activities 33 — — — 33 Accrued expenses and other current liabilities 291 36 353 — 680 Current liabilities - held-for-sale — 5 — — 5 Current liabilities - discontinued operations 24 48 — — 72 Total current liabilities 2,429 — 804 (835 ) 2,398 Other Liabilities Long-term debt and capital leases 244 192 6,025 (12 ) 6,449 Nuclear decommissioning reserve 282 — — — 282 Nuclear decommissioning trust liability 371 — — — 371 Derivative instruments 306 3 — (5 ) 304 Deferred income taxes 112 61 (108 ) — 65 Other non-current liabilities 402 320 552 — 1,274 Non-current liabilities - held-for-sale — 65 — — 65 Non-current liabilities - discontinued operations 58 577 — — 635 Total other liabilities 1,775 1,218 6,469 (17 ) 9,445 Total Liabilities 4,204 1,218 7,273 (852 ) 11,843 Redeemable noncontrolling interest in subsidiaries — 19 — — 19 Stockholders’ Equity 3,602 1,533 (1,216 ) (5,153 ) (1,234 ) Total Liabilities and Stockholders’ Equity $ 7,806 $ 2,770 $ 6,057 $ (6,005 ) $ 10,628 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the three months ended March 31, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net income/(loss) $ 331 $ (61 ) $ 296 $ (333 ) $ 233 Income/(loss) from discontinued operations 15 (20 ) — — (5 ) Net income/(loss) from continuing operations 316 (41 ) 296 (333 ) 238 Adjustments to reconcile net income to net cash provided/(used) by operating activities: Distributions and equity in earnings of unconsolidated affiliates — (2 ) 1 — (1 ) Depreciation, amortization and accretion 67 56 8 — 131 Provision for bad debts 15 — — — 15 Amortization of nuclear fuel 13 — — — 13 Amortization of financing costs and debt discount/premiums — — 6 — 6 Adjustment for debt extinguishment — — 2 — 2 Amortization of intangibles and out-of-market contracts 7 2 — — 9 Amortization of unearned equity compensation — — 6 — 6 (Gain)/loss on sale of assets (11 ) 1 — — (10 ) Changes in derivative instruments (203 ) 2 15 (17 ) (203 ) Changes in deferred income taxes and liability for uncertain tax benefits 113 29 (143 ) — (1 ) Changes in collateral deposits in support of energy risk management activities 162 1 — — 163 Changes in nuclear decommissioning trust liability 34 — — — 34 Changes in other working capital 277 (339 ) (444 ) 350 (156 ) Cash provided/(used) by continuing operations 790 (291 ) (253 ) — 246 Cash provided by discontinued operations 32 72 — — 104 Net Cash Provided/(Used) by Operating Activities 822 (219 ) (253 ) — 350 Cash Flows from Investing Activities Payments for acquisitions of businesses (2 ) — — — (2 ) Capital expenditures (60 ) (74 ) (21 ) — (155 ) Proceeds from sale of emission allowances, net of purchases 6 — — — 6 Investments in nuclear decommissioning trust fund securities (216 ) — — — (216 ) Proceeds from the sale of nuclear decommissioning trust fund securities 182 — — — 182 Proceeds from sale of assets, net of cash disposed of 11 — 42 — 53 Change in investments in unconsolidated affiliates — (8 ) — — (8 ) Distributions to discontinued operations — (29 ) — — (29 ) Cash (used)/provided by continuing operations (79 ) (111 ) 21 — (169 ) Cash used by discontinued operations (1 ) (290 ) — — (291 ) Net Cash (Used)/Provided by Investing Activities (80 ) (401 ) 21 — (460 ) Cash Flows from Financing Activities Payments (for)/from intercompany loans (481 ) 417 64 — — Payment of dividends to common stockholders — — (10 ) — (10 ) Payments for treasury stock — — (93 ) — (93 ) Distributions to noncontrolling interests from subsidiaries — (10 ) — — (10 ) Proceeds from issuance of common stock — — 7 — 7 Payment of debt issuance costs — — (2 ) — (2 ) Payments for long-term debt — (34 ) (5 ) — (39 ) Cash (used)/provided by continuing operations (481 ) 373 (39 ) — (147 ) Cash provided by discontinued operations — 133 — — 133 Net Cash (Used)/Provided by Financing Activities (481 ) 506 (39 ) — (14 ) Change in cash from discontinued operations 31 (85 ) — — (54 ) Net Increase/(Decrease) in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash 230 (29 ) (271 ) — (70 ) Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period 41 425 620 — 1,086 Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period $ 271 $ 396 $ 349 $ — $ 1,016 (a) All significant intercompany transactions have been eliminated in consolidation

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates.
Reclassifications	Reclassifications Certain prior year amounts have been reclassified for comparative purposes.
Recent Accounting Developments	Recent Accounting Developments - Guidance Adopted in 2019 ASU 2016-02 - In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) , or Topic 842, which was further amended through various updates issued by the FASB thereafter, with the objective to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and to improve financial reporting by expanding the related disclosures. The guidance in Topic 842 provides that a lessee that may have previously accounted for a lease as an operating lease under current GAAP should recognize the assets and liabilities that arise from a lease on the balance sheet. In addition, Topic 842 expands the required quantitative and qualitative disclosures with regards to lease arrangements. The Company adopted the standard and its subsequent corresponding updates effective January 1, 2019 under the modified retrospective approach by applying the provisions of the new leases guidance at the effective date without adjusting the comparative periods presented. The Company assessed its leasing arrangements, evaluated the impact of applying practical expedients and accounting policy elections, and implemented lease accounting software to meet the reporting requirements of the standard. The Company established operating lease liabilities of $ 404 million and right-of-use assets of $ 321 million upon adoption, before considering deferred taxes. The adoption of Topic 842 did not have a material impact on the statements of operations or cash flows. See Note 8 , Leases , for further discussion. Recent Accounting Developments - Guidance Not Yet Adopted ASU 2018-17 - In October 2018, the FASB issued ASU No. 2018-17, Consolidations (Topic 810): Targeted Improvements to Related Party Guidance for Variable Interest Entities , in response to stakeholders’ observations that Topic 810, Consolidations , could be improved thereby improving general purpose financial reporting. Specifically, ASC 2018-17 requires application of the variable interest entity (VIE) guidance to private companies under common control and consideration of indirect interest held through related parties under common control for determining whether fees paid to decision makers and service providers are variable interests. The amendments are effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. All entities are required to apply the amendments retrospectively with a cumulative-effect adjustment to retained earnings at the beginning of the earliest period presented. The Company is evaluating the impact of adopting this guidance on the consolidated financial statements and disclosures. ASU 2018-13 - In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirement for Fair value Measurement) , or ASU No. 2018-13. The guidance in ASU No. 2018-13 eliminates such disclosures as the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy. The amendments in ASU No. 2018-13 add new disclosure requirements for Level 3 measurements. ASU No. 2018-13 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted for any eliminated or modified disclosures. Certain disclosures in ASU No. 2018-13 are required to be applied on a retrospective basis and others on a prospective basis. As the amendment contemplates changes in disclosures only, it will have no material impact on the Company's results of operations, cash flows, or statement of financial position.
Nuclear Decommissioning	NRG's Nuclear Decommissioning Trust Fund assets are comprised of securities classified as available-for-sale and recorded at fair value based on actively quoted market prices. NRG accounts for the Nuclear Decommissioning Trust Fund in accordance with ASC 980, Regulated Operations , because the Company's nuclear decommissioning activities are subject to approval by the PUCT with regulated rates that are designed to recover all decommissioning costs and that can be charged to and collected from the ratepayers per PUCT mandate. Since the Company is in compliance with PUCT rules and regulations regarding decommissioning trusts and the cost of decommissioning is the responsibility of the Texas ratepayers, not NRG, all realized and unrealized gains or losses (including other-than-temporary impairments) related to the Nuclear Decommissioning Trust Fund are recorded to the Nuclear Decommissioning Trust liability and are not included in net income or accumulated OCI, consistent with regulatory treatment.
Segment Reporting	The Company's segment structure reflects how management currently makes financial decisions and allocates resources. The Company's businesses are segregated into the Generation, Retail and corporate segments. Generation includes all power plant activities, domestic and international, as well as renewables. Retail includes Mass customers and Business Solutions, which includes C&I customers and other distributed and reliability products. Intersegment sales are accounted for at market. The financial information for the three months ended March 31, 2018 has been recast to reflect the current segment structure. On February 4, 2019, as described in Note 4 , Discontinued Operations and Dispositions , the Company completed the sale of and deconsolidated the South Central Portfolio. On August 31, 2018, as described in Note 4 , Discontinued Operations and Dispositions , NRG deconsolidated NRG Yield, Inc., its Renewables Platform and Carlsbad for financial reporting purposes. The financial information for the three months ended March 31, 2018 has been recast to reflect the presentation of these entities as discontinued operations within the corporate segment. NRG’s chief operating decision maker, its chief executive officer, evaluates the performance of its segments based on operational measures including adjusted earnings before interest, taxes, depreciation and amortization, or Adjusted EBITDA, free cash flow and capital for allocation, as well as net income/(loss)and net income/(loss) attributable to NRG Energy, Inc.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Net Income Attributable to NRG Energy, Inc. After Removing Net Loss from Noncontrolling Interest	The following table reflects the net income attributable to NRG Energy, Inc. after removing the net loss attributable to the noncontrolling interest and redeemable noncontrolling interest: Three months ended March 31, 2019 2018 (In millions) Income from continuing operations, net of income tax $ 94 $ 245 Income from discontinued operations, net of income tax 388 34 Net income attributable to NRG Energy, Inc. $ 482 $ 279
Other Balance Sheet Information	The following table presents the allowance for doubtful accounts included in accounts receivable, net; accumulated depreciation included in property, plant and equipment, net; accumulated amortization included in intangible assets, net and accumulated amortization included in out-of-market contracts, net: March 31, 2019 December 31, 2018 (In millions) Accounts receivable allowance for doubtful accounts $ 32 $ 32 Property, plant and equipment accumulated depreciation 1,610 1,811 Intangible assets accumulated amortization 1,171 1,149 Out-of-market contracts accumulated amortization — 37
Reconciliation of Cash and Cash Equivalents, Restricted Cash and Funds Deposited by Counterparties	The following table provides a reconciliation of cash and cash equivalents, restricted cash and funds deposited by counterparties reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the statements of cash flows. March 31, 2019 December 31, 2018 March 31, 2018 December 31, 2017 (In millions) Cash and cash equivalents $ 859 $ 563 $ 514 $ 770 Funds deposited by counterparties 11 33 241 37 Restricted cash 15 17 261 279 Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows $ 885 $ 613 $ 1,016 $ 1,086

Revenue Recognition (Tables)

Revenue Recognition (Tables)	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue from Contracts with Customer	Disaggregated Revenues The following table represents the Company’s disaggregation of revenue from contracts with customers for the three months ended March 31, 2019 and March 31, 2018, along with the reportable segment for each category: Three months ended March 31, 2019 Generation (In millions) Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue (a)(b) $ — $ 358 $ 224 $ 582 $ (276 ) $ 306 Capacity revenue (a) — — 155 155 (1 ) 154 Retail revenue Mass customers 1,321 — — — (1 ) 1,320 Business Solutions customers 286 — — — — 286 Total retail revenue 1,607 — — — (1 ) 1,606 Mark-to-market for economic hedging activities (b)(c) — 13 (8 ) 5 15 20 Other revenues (a) — 29 52 81 (2 ) 79 Total operating revenue 1,607 400 423 823 (265 ) 2,165 Less: Lease revenue 3 — 2 2 — 5 Less: Realized and unrealized ASC 815 revenue (b) — 546 97 643 (262 ) 381 Total revenue from contracts with customers $ 1,604 $ (146 ) $ 324 $ 178 $ (3 ) $ 1,779 (a) The following amounts of energy and capacity revenue primarily relate to derivative instruments and are accounted for under ASC 815 Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue $ — $ 525 $ 88 $ 613 $ (277 ) $ 336 Capacity revenue — — 18 18 — 18 Other revenue — 8 (1 ) 7 — 7 (b) Generation includes higher revenues due to the Company's large internal transfer of power based on average annualized market prices, which are offset by higher cost of operations within Retail (c) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815 Three months ended March 31, 2018 Generation (In millions) Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue (a)(b) $ — $ 265 $ 339 $ 604 $ (161 ) $ 443 Capacity revenue (a) — — 142 142 — 142 Retail revenue Mass customers 1,176 — — — (1 ) 1,175 Business Solutions customers 310 — — — — 310 Total retail revenue 1,486 — — — (1 ) 1,485 Mark-to-market for economic hedging activities (b)(c) (6 ) (569 ) (5 ) (574 ) 484 (96 ) Other revenues (a) — 53 45 98 (7 ) 91 Total operating revenue 1,480 (251 ) 521 270 315 2,065 Less: Lease revenue 3 — 2 2 — 5 Less: Realized and unrealized ASC 815 revenue (b) (6 ) (150 ) 85 (65 ) 327 256 Total revenue from contracts with customers $ 1,483 $ (101 ) $ 434 $ 333 $ (12 ) $ 1,804 (a) The following amounts of energy and capacity revenue relate to derivative instruments and are accounted for under ASC 815 Retail Texas East/West/Other Subtotal Corporate/Eliminations Total Energy revenue $ — $ 413 $ 60 $ 473 $ (157 ) $ 316 Capacity revenue — — 26 26 — 26 Other revenue — 5 3 8 — 8 (b) Generation includes higher revenues due to the Company's large internal transfer of power based on average annualized market prices, which are offset by higher cost of operations within Retail (c) Revenue relates entirely to unrealized gains and losses on derivative instruments accounted for under ASC 815
Contract Asset and Liabilities	The following table reflects the contract assets and liabilities included in the Company’s balance sheet as of March 31, 2019 and December 31, 2018: (In millions) March 31, 2019 December 31, 2018 Deferred customer acquisition costs $ 117 $ 111 Accounts receivable, net - Contracts with customers 870 999 Accounts receivable, net - Derivative instruments 22 20 Accounts receivable, net - Affiliate 6 5 Total accounts receivable, net $ 898 $ 1,024 Unbilled revenues (included within Accounts receivable, net - Contracts with customers) $ 305 $ 392 Deferred revenues 80 67

Discontinued Operations and D_2

Discontinued Operations and Dispositions (Tables)	3 Months Ended
	Mar. 31, 2019
Discontinued Operations and Disposal Groups [Abstract]
Summary of Results of Discontinued Operations and Major Classes of Assets and Liabilities	Summarized results of the South Central Portfolio discontinued operations were as follows: Three months ended (In millions) March 31, 2019 March 31, 2018 Operating revenues $ 31 $ 102 Operating costs and expenses (23 ) (86 ) Gain from discontinued operations, net of tax 8 16 Gain on disposal of discontinued operations, net of tax 27 — Gain from discontinued operations, including disposal, net of tax $ 35 $ 16 The following table summarizes the major classes of assets and liabilities classified as discontinued operations of the South Central Portfolio: (In millions) December 31, 2018 Cash and cash equivalents $ 89 Accounts receivable, net - trade 49 Inventory 35 Other current assets 5 Current assets - discontinued operations 178 Property, plant and equipment, net 408 Other non-current assets 1 Non-current assets - discontinued operations 409 Accounts payable 19 Other current liabilities 5 Current liabilities - discontinued operations 24 Out-of-market contracts, net 50 Other non-current liabilities 11 Non-current liabilities - discontinued operations $ 61 Summarized results of NRG Yield, Inc. and the Renewables Platform and Carlsbad discontinued operations were as follows: Three months ended (In millions) March 31, 2019 March 31, 2018 Operating revenues $ 19 $ 260 Operating costs and expenses (9 ) (230 ) Other expenses (5 ) (58 ) Gain/(loss) from operations of discontinued components, before tax 5 (28 ) Income tax benefit — (7 ) Gain/(loss) from discontinued operations, net of tax 5 (21 ) Gain on disposal of discontinued operations, net of tax 348 — Gain/(loss) from discontinued operations, including disposal, net of tax $ 353 $ (21 ) The following table summarizes the major classes of assets and liabilities classified as discontinued operations of Carlsbad: (In millions) December 31, 2018 Restricted cash $ 4 Accounts receivable, net - trade 10 Other current assets 5 Current assets - discontinued operations 19 Property, plant and equipment, net 590 Intangible assets, net 9 Other non-current assets 4 Non-current assets - discontinued operations 603 Current portion of long-term debt and capital leases 20 Accounts payable 27 Other current liabilities 1 Current liabilities - discontinued operations 48 Long-term debt and capital leases 572 Other non-current liabilities 2 Non-current liabilities - discontinued operations $ 574

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Estimated carrying amounts and fair values of NRG's recorded financial instruments not carried at fair market value	The estimated carrying amounts and fair values of NRG's recorded financial instruments not carried at fair market value are as follows: As of March 31, 2019 As of December 31, 2018 Carrying Amount Fair Value Carrying Amount Fair Value (In millions) Assets: Notes receivable $ 17 $ 14 $ 17 $ 14 Liabilities: Long-term debt, including current portion (a) 6,558 6,971 6,591 6,697 (a) Excludes deferred financing costs, which are recorded as a reduction to long-term debt on the Company's consolidated balance sheets The following table presents the level within the fair value hierarchy for long-term debt, including current portion, as of March 31, 2019 and December 31, 2018 : As of March 31, 2019 As of December 31, 2018 Level 2 Level 3 Level 2 Level 3 (In millions) Long-term debt, including current portion $ 6,834 $ 137 $ 6,528 $ 169
Assets and liabilities measured and recorded at fair value on the consolidated balance sheets on a recurring basis	The following tables present assets and liabilities measured and recorded at fair value on the Company's condensed consolidated balance sheets on a recurring basis and their level within the fair value hierarchy: As of March 31, 2019 (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and non-current assets) $ 37 $ 1 $ 18 $ 18 Nuclear trust fund investments: Cash and cash equivalents 15 15 — — U.S. government and federal agency obligations 50 50 — — Federal agency mortgage-backed securities 96 — 96 — Commercial mortgage-backed securities 29 — 29 — Corporate debt securities 100 — 100 — Equity securities 354 354 — — Foreign government fixed income securities 4 — 4 — Other trust fund investments: U.S. government and federal agency obligations 1 1 — — Derivative assets: Commodity contracts 929 45 769 115 Interest rate contracts 29 — 29 — Measured using net asset value practical expedient: Equity securities — nuclear trust fund investments 70 Equity securities 9 Total assets $ 1,723 $ 466 $ 1,045 $ 133 Derivative liabilities: Commodity contracts $ 839 $ 107 $ 615 $ 117 Total liabilities $ 839 $ 107 $ 615 $ 117 As of December 31, 2018 (In millions) Total Level 1 Level 2 Level 3 Investments in securities (classified within other current and non-current assets) $ 39 $ 2 $ 18 $ 19 Nuclear trust fund investments: Cash and cash equivalents 19 19 — — U.S. government and federal agency obligations 46 46 — — Federal agency mortgage-backed securities 100 — 100 — Commercial mortgage-backed securities 22 — 22 — Corporate debt securities 96 — 96 — Equity securities 312 312 — — Foreign government fixed income securities 4 — 4 — Other trust fund investments: U.S. government and federal agency obligations 1 1 — — Derivative assets: Commodity contracts 1,042 137 796 109 Interest rate contracts 39 — 39 — Measured using net asset value practical expedient: Equity securities — nuclear trust fund investments 64 Equity securities 8 Total assets $ 1,792 $ 517 $ 1,075 $ 128 Derivative liabilities: Commodity contracts $ 977 $ 224 $ 664 $ 89 Total liabilities $ 977 $ 224 $ 664 $ 89
Reconciliation of beginning and ending balances for financial instruments that are recognized at fair value in the consolidated financial statements at least annually using significant unobservable inputs	There were no transfers during the three months ended March 31, 2019 and 2018 between Levels 1 and 2. The following tables reconcile, for the three months ended March 31, 2019 and 2018 , the beginning and ending balances for financial instruments that are recognized at fair value in the condensed consolidated financial statements, at least annually, using significant unobservable inputs: Fair Value Measurement Using Significant Unobservable Inputs (Level 3) Three months ended March 31, 2019 (In millions) Debt Securities Derivatives (a) Total Beginning balance as of January 1, 2019 $ 19 $ 20 $ 39 Total losses — realized/unrealized — (10 ) (10 ) Cash received (1 ) — (1 ) Purchases — (2 ) (2 ) Transfers into Level 3 (b) — 17 17 Transfers out of Level 3 (b) — (27 ) (27 ) Ending balance as of March 31, 2019 $ 18 $ (2 ) $ 16 (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, 2019 $ — $ (12 ) $ (12 ) (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, 2018 (In millions) Debt Securities Derivatives (a) Total Beginning balance as of January 1, 2018 $ 19 $ (15 ) $ 4 Total gains — realized/unrealized included in earnings — 11 11 Purchases — 1 1 Transfers into Level 3 (b) — 4 4 Transfers out of Level 3 (b) — 4 4 Ending balance as of March 31, 2018 $ 19 $ 5 $ 24 Gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held as of March 31, 2018 $ — $ 12 $ 12 (a) Consists of derivative assets and liabilities, net (b) Transfers into/out of Level 3 are related to the availability of external broker quotes and are valued as of the end of the reporting period. All transfers in/out are with Level 2
Significant unobservable inputs used developing fair values, Quantitative Information	The following tables quantify the significant unobservable inputs used in developing the fair value of the Company's Level 3 positions as of March 31, 2019 and December 31, 2018 : March 31, 2019 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) Power Contracts $ 89 $ 104 Discounted Cash Flow Forward Market Price (per MWh) 0 $ 253 $ 28 FTRs 26 13 Discounted Cash Flow Auction Prices (per MWh) (42 ) 38 0 $ 115 $ 117 December 31, 2018 Fair Value Input/Range Assets Liabilities Valuation Technique Significant Unobservable Input Low High Weighted Average (In millions) Power Contracts $ 89 $ 75 Discounted Cash Flow Forward Market Price (per MWh) $ 1 $ 214 $ 31 FTRs 20 14 Discounted Cash Flow Auction Prices (per MWh) (90 ) 34 0 $ 109 $ 89
Fair value inputs, sensitivity analysis	The following table provides sensitivity of fair value measurements to increases/(decreases) in significant unobservable inputs as of March 31, 2019 and December 31, 2018 : Significant Unobservable Input Position Change In Input Impact on Fair Value Measurement Forward Market Price Power Buy Increase/(Decrease) Higher/(Lower) Forward Market Price Power Sell Increase/(Decrease) Lower/(Higher) FTR Prices Buy Increase/(Decrease) Higher/(Lower) FTR Prices Sell Increase/(Decrease) Lower/(Higher)
Net counterparty credit exposure by industry sector and by counterparty credit quality	The following tables highlight net counterparty credit exposure by industry sector and by counterparty credit quality. Net counterparty credit exposure is defined as the aggregate net asset position for NRG with counterparties where netting is permitted under the enabling agreement and includes all cash flow, mark-to-market and NPNS, and non-derivative transactions. The exposure is shown net of collateral held and includes amounts net of receivables or payables. Net Exposure (a)(b) Category by Industry Sector (% of Total) Utilities, energy merchants, marketers and other 78 % Financial institutions 22 Total as of March 31, 2019 100 % Net Exposure (a) (b) Category by Counterparty Credit Quality (% of Total) Investment grade 52 % Non-Investment grade/Non-Rated 48 Total as of March 31, 2019 100 % (a) Counterparty credit exposure excludes uranium and coal transportation contracts because of the unavailability of market prices (b) The figures in the tables above exclude potential counterparty credit exposure related to RTOs, ISOs, registered commodity exchanges and certain long-term contracts

Nuclear Decommissioning Trust_2

Nuclear Decommissioning Trust Fund (Tables)	3 Months Ended
	Mar. 31, 2019
Nuclear Decommissioning Trust Fund Disclosure [Abstract]
Summary of aggregate fair values and unrealized gains and losses (including other-than-temporary impairments) for the securities held in the nuclear decommissioning trust fund	The following table summarizes the aggregate fair values and unrealized gains and losses for the securities held in the trust funds, as well as information about the contractual maturities of those securities. As of March 31, 2019 As of December 31, 2018 (In millions, except maturities) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Fair Value Unrealized Gains Unrealized Losses Weighted-average Maturities (In years) Cash and cash equivalents $ 15 $ — $ — — $ 19 $ — $ — — U.S. government and federal agency obligations 50 2 — 13 46 1 — 12 Federal agency mortgage-backed securities 96 1 1 25 100 1 2 23 Commercial mortgage-backed securities 29 1 — 23 22 — 1 22 Corporate debt securities 100 3 1 11 96 1 2 11 Equity securities 424 276 — — 376 231 1 — Foreign government fixed income securities 4 — — 10 4 — — 9 Total $ 718 $ 283 $ 2 $ 663 $ 234 $ 6
Summary of proceeds from sales of available-for-sale securities and the related realized gains and losses	The following table summarizes proceeds from sales of available-for-sale securities and the related realized gains and losses from these sales. The cost of securities sold is determined on the specific identification method. Three months ended March 31, 2019 2018 (In millions) Realized gains $ 3 $ 3 Realized losses (2 ) (3 ) Proceeds from sale of securities 113 182

Accounting for Derivative Ins_2

Accounting for Derivative Instruments and Hedging Activities (Tables)	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Net notional volume buy/(sell) of NRG's open derivative transactions broken out by commodity	The following table summarizes the net notional volume buy/(sell) of NRG's open derivative transactions broken out by category, excluding those derivatives that qualified for the NPNS exception, as of March 31, 2019 and December 31, 2018 . Option contracts are reflected using delta volume. Delta volume equals the notional volume of an option adjusted for the probability that the option will be in-the-money at its expiration date. Total Volume March 31, 2019 December 31, 2018 Category Units (In millions) Emissions Short Ton 1 (2 ) Renewable Energy Certificates Certificates 1 1 Coal Short Ton 9 13 Natural Gas MMBtu (236 ) (330 ) Oil Barrels — 1 Power MWh 8 1 Capacity MW/Day (1 ) (1 ) Interest Dollars $ 1,000 $ 1,000
Fair value within the derivative instrument valuation on the balance sheets	The following table summarizes the fair value within the derivative instrument valuation on the balance sheets: Fair Value Derivative Assets Derivative Liabilities March 31, 2019 December 31, 2018 March 31, 2019 December 31, 2018 (In millions) Derivatives Not Designated as Cash Flow or Fair Value Hedges: Interest rate contracts current $ 15 $ 17 $ — $ — Interest rate contracts long-term 14 22 — — Commodity contracts current 596 747 489 673 Commodity contracts long-term 333 295 350 304 Total Derivatives Not Designated as Cash Flow or Fair Value Hedges $ 958 $ 1,081 $ 839 $ 977
Offsetting of derivatives by counterparty assets	The following table summarizes the offsetting of derivatives by counterparty master agreement level and collateral received or paid: Gross Amounts Not Offset in the March 31, 2019 Balance Sheet Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount (In millions) Commodity contracts: Derivative assets $ 929 $ (689 ) $ (5 ) $ 235 Derivative liabilities (839 ) 689 92 (58 ) Total commodity contracts 90 — 87 177 Interest rate contracts: Derivative assets 29 — — 29 Total interest rate contracts 29 — — 29 Total derivative instruments $ 119 $ — $ 87 $ 206 Gross Amounts Not Offset in the December 31, 2018 Balance Sheet Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount (In millions) Commodity contracts: Derivative assets $ 1,042 $ (778 ) $ (31 ) $ 233 Derivative liabilities (977 ) 778 114 (85 ) Total commodity contracts 65 — 83 148 Interest rate contracts: Derivative assets 39 — — 39 Total interest rate contracts 39 — — 39 Total derivative instruments $ 104 $ — $ 83 $ 187
Offsetting of derivatives by counterparty, liabilities	The following table summarizes the offsetting of derivatives by counterparty master agreement level and collateral received or paid: Gross Amounts Not Offset in the March 31, 2019 Balance Sheet Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount (In millions) Commodity contracts: Derivative assets $ 929 $ (689 ) $ (5 ) $ 235 Derivative liabilities (839 ) 689 92 (58 ) Total commodity contracts 90 — 87 177 Interest rate contracts: Derivative assets 29 — — 29 Total interest rate contracts 29 — — 29 Total derivative instruments $ 119 $ — $ 87 $ 206 Gross Amounts Not Offset in the December 31, 2018 Balance Sheet Gross Amounts of Recognized Assets / Liabilities Derivative Instruments Cash Collateral (Held) / Posted Net Amount (In millions) Commodity contracts: Derivative assets $ 1,042 $ (778 ) $ (31 ) $ 233 Derivative liabilities (977 ) 778 114 (85 ) Total commodity contracts 65 — 83 148 Interest rate contracts: Derivative assets 39 — — 39 Total interest rate contracts 39 — — 39 Total derivative instruments $ 104 $ — $ 83 $ 187
Effects of ASC 815 on the Company's accumulated OCI balance attributable to cash flow hedge derivatives, net of tax	The following table summarizes the effects on the Company's accumulated OCL balance attributable to cash flow hedge derivatives, net of tax: Interest Rate Contracts Three months ended March 31, 2019 2018 (In millions) Accumulated OCL beginning balance $ — $ (54 ) Reclassified from accumulated OCL to income: Due to realization of previously deferred amounts — 4 Mark-to-market of cash flow hedge accounting contracts — 19 Accumulated OCL ending balance, net of $0, and $6 tax $ — $ (31 )
Pre-tax effects of economic hedges that have not been designated as cash flow hedges, ineffectiveness on cash flow hedges and trading activity on the Company's statement of operations	The following table summarizes the pre-tax effects of economic hedges that have not been designated as cash flow hedges and trading activity on the Company's statement of operations. The effect of commodity hedges is included within operating revenues and cost of operations and the effect of interest rate hedges is included in interest expense. Three months ended March 31, 2019 2018 Unrealized mark-to-market results (In millions) Reversal of previously recognized unrealized losses on settled positions related to economic hedges $ 19 $ 1 Reversal of acquired gain positions related to economic hedges (2 ) — Net unrealized gains on open positions related to economic hedges 3 205 Total unrealized mark-to-market gains for economic hedging activities 20 206 Reversal of previously recognized unrealized gains on settled positions related to trading activity (6 ) (3 ) Net unrealized gains on open positions related to trading activity 13 11 Total unrealized mark-to-market gains for trading activity 7 8 Total unrealized gains $ 27 $ 214 Three months ended March 31, 2019 2018 (In millions) Unrealized gains/(losses) included in operating revenues $ 27 $ (88 ) Unrealized gains included in cost of operations — 302 Total impact to statement of operations — energy commodities $ 27 $ 214 Total impact to statement of operations — interest rate contracts $ (9 ) $ 12

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Lease, Cost and Other Information	Lease Cost: (In millions) Three months ended March 31, 2019 Operating lease cost $ 23 Variable lease cost 1 Sublease income (4 ) Total lease cost $ 20 Other information: (In millions) Three months ended March 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 21 Right-of-use assets obtained in exchange for new operating lease liabilities 214 Lease Term and Discount Rate: Weighted-average remaining lease term In Years Finance leases 2.8 Operating leases 8.2 Weighted-average discount rate % Finance leases 6.5 Operating leases 5.7
Schedule of Annual Payments Based on Maturities of Leases	As of March 31, 2019 , annual payments based on the maturities of NRG's leases are expected to be as follows: (In millions) Remainder of 2019 $ 76 2020 96 2021 86 2022 85 2023 86 Thereafter 370 Total undiscounted lease payments $ 799 Less: present value adjustment (196 ) Total discounted lease payments $ 603

Debt and Capital Leases (Tables

Debt and Capital Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Long-term debt and capital leases	Long-term debt and capital leases consisted of the following: (In millions, except rates) March 31, 2019 December 31, 2018 March 31, 2019 interest rate % (a) Recourse debt: Senior Notes, due 2024 $ 733 $ 733 6.250 Senior Notes, due 2026 1,000 1,000 7.250 Senior Notes, due 2027 1,230 1,230 6.625 Senior Notes, due 2028 821 821 5.750 Convertible Senior Notes, due 2048 575 575 2.750 Term loan facility, due 2023 1,694 1,698 L+1.75 Tax-exempt bonds 466 466 4.125 - 6.00 Subtotal recourse debt 6,519 6,523 Non-recourse debt: Agua Caliente Borrower 1, due 2038 83 86 5.430 Midwest Generation, due 2019 20 48 4.390 Other 34 34 various Subtotal all non-recourse debt 137 168 Subtotal long-term debt (including current maturities) 6,656 6,691 Capital leases 1 1 various Subtotal long-term debt and capital leases (including current maturities) 6,657 6,692 Less current maturities (124 ) (72 ) Less debt issuance costs (69 ) (70 ) Discounts (98 ) (101 ) Total long-term debt and capital leases $ 6,366 $ 6,449 (a) As of March 31, 2019 , L+ equals 1-month LIBOR plus 1.75%

Investments Accounted for Usi_2

Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs (Tables)	3 Months Ended
	Mar. 31, 2019
Variable Interest Entities Disclosure [Abstract]
Financial Information for Consolidated VIEs	The summarized financial information for the Company's consolidated VIEs consisted of the following: (In millions) March 31, 2019 December 31, 2018 Current assets $ 3 $ 3 Net property, plant and equipment 75 76 Other long-term assets 27 28 Total assets 105 107 Current liabilities 1 2 Long-term debt 29 29 Other long-term liabilities 8 7 Total liabilities 38 38 Redeemable noncontrolling interest 18 19 Net assets less noncontrolling interests $ 49 $ 50

Changes in Capital Structure (T

Changes in Capital Structure (Tables)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Changes in NRG's common shares issued and outstanding	The following table reflects the changes in NRG's common stock issued and outstanding: Issued Treasury Outstanding Balance as of December 31, 2018 420,288,886 (136,638,847 ) 283,650,039 Shares issued under LTIPs 1,497,175 — 1,497,175 Shares repurchased — (17,608,957 ) (17,608,957 ) Balance as of March 31, 2019 421,786,061 (154,247,804 ) 267,538,257
Shares Repurchased	The following repurchases have been made during the three months ended March 31, 2019 and through May 2, 2019: Total number of shares purchased Amounts paid for shares purchased (in millions) Board Authorized Share Repurchases 2018 program: Repurchases made during January-February to complete the 2018 program 6,153,415 $ 250 2019 program: Shares repurchased under February 28, 2019 Accelerated Share Repurchase Agreement 9,086,903 400 March repurchases 2,368,639 99 Total Share Repurchases during the three months ended March 31, 2019 17,608,957 $ 749 Additional shares delivered upon ASR settlement in April 351,768 — April repurchases 39,140 1 Total Share Repurchases during the period ended May 2, 2019 17,999,865 $ 750

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Reconciliation of NRG's basic and diluted earnings per share	The reconciliation of NRG's basic and diluted income per share is shown in the following table: Three months ended March 31, In millions, except per share data 2019 2018 Basic income per share attributable to NRG Energy, Inc; Net income attributable to NRG Energy, Inc. common stockholders $ 482 $ 279 Weighted average number of common shares outstanding - basic 278 318 Income per weighted average common share — basic $ 1.73 $ 0.88 Diluted income per share attributable to NRG Energy, Inc; Net income attributable to NRG Energy, Inc. available to common shareholders $ 482 $ 279 Weighted average number of common shares outstanding - basic 278 318 Incremental shares attributable to the issuance of equity compensation (treasury stock method) 2 4 Weighted average number of common shares outstanding - dilutive 280 322 Income per weighted average common share — diluted $ 1.72 $ 0.87
Summary of NRG's outstanding equity instruments that are anti-dilutive and were not included in the computation of the Company's diluted earnings per share	The following table summarizes NRG’s outstanding equity instruments that are anti-dilutive and were not included in the computation of the Company’s diluted income per share: Three months ended March 31, In millions of shares 2019 2018 Equity compensation plans — 1

Segment Reporting (Tables)

Segment Reporting (Tables)	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Schedule of segment reporting information, by segment	Three months ended March 31, 2019 (a) Retail Generation Corporate Eliminations Total (In millions) Operating revenues (b) $ 1,607 $ 823 $ 1 $ (266 ) $ 2,165 Depreciation and amortization 31 46 8 — 85 Reorganization costs 1 1 11 — 13 Equity in losses of unconsolidated affiliates — (20 ) 27 (28 ) (21 ) Income/(loss) from continuing operations before income taxes 111 114 (100 ) (27 ) 98 Income/(loss) from continuing operations 111 114 (104 ) (27 ) 94 Income from discontinued operations, net of tax — — 388 — 388 Net Income attributable to NRG Energy, Inc. $ 111 $ 114 $ 284 $ (27 ) $ 482 Total assets as of March 31, 2019 $ 3,309 $ 5,489 $ 5,680 $ (4,948 ) $ 9,530 (a) Includes intersegment revenues and costs associated with the internal transfer of power, which is based on average annualized market prices and results in higher revenues in Generation and higher cost of operations in Retail that are eliminated in consolidation (b) Operating revenues include intersegment sales and net derivative gains and losses of: $ 3 $ 235 $ 28 $ — $ 266 Three months ended March 31, 2018 (a) Retail Generation Corporate Eliminations Total (In millions) Operating revenues (b) $ 1,480 $ 270 $ 1 $ 314 $ 2,065 Depreciation and amortization 26 86 9 (1 ) 120 Reorganization costs 3 4 13 — 20 Equity in earnings/(losses) of unconsolidated affiliates — 2 (1 ) — 1 Income/(loss) from continuing operations before income taxes 944 (573 ) (128 ) 1 244 Income/(loss) from continuing operations 944 (573 ) (134 ) 1 238 Loss from discontinued operations, net of tax — — (5 ) — (5 ) Net Income/(Loss) 944 (573 ) (139 ) 1 233 Net Income/(Loss) attributable to NRG Energy, Inc. $ 943 $ (565 ) $ (100 ) $ 1 $ 279 (a) Includes intersegment revenues and costs associated with our internal transfer of power, which is based on average annualized market prices and results in higher revenues in Generation and higher cost of operations in Retail that are eliminated in consolidation (b) Operating revenues include intersegment sales and net derivative gains and losses of: $ 1 $ (309 ) $ (6 ) $ — $ (314 )

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2019
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 rates 2019 2018 Income before income taxes $ 98 $ 244 Income tax expense from continuing operations 4 6 Effective income tax rate 4.1 % 2.5 %

Related Party Transactions (Tab

Related Party Transactions (Tables)	3 Months Ended
	Mar. 31, 2019
Related Party Transactions [Abstract]
Schedule of NRG's Material Related Party Transactions	The following table summarizes NRG's material related party transactions with third party affiliates: Three months ended March 31, 2019 2018 (In millions) Revenues from Related Parties Included in Operating Revenues Gladstone $ 1 $ 1 GenConn — 1 Ivanpah 10 — Midway-Sunset 1 — Revenues from Related Parties recorded against selling, general and administrative expenses GenOn — 21 Total $ 12 $ 23

Condensed Consolidating Finan_2

Condensed Consolidating Financial Information (Tables)	3 Months Ended
	Mar. 31, 2019
Condensed Consolidating Financial Information Disclosure [Abstract]
Schedule of Guarantor Subsidiaries	Unless otherwise noted below, each of the following guarantor subsidiaries fully and unconditionally guaranteed the Senior Notes as of March 31, 2019 : Ace Energy, Inc. NRG Business Services LLC NRG PacGen Inc. Allied Home Warranty GP LLC NRG Cabrillo Power Operations Inc. NRG Portable Power LLC Allied Warranty LLC NRG California Peaker Operations LLC NRG Power Marketing LLC Arthur Kill Power LLC NRG Cedar Bayou Development Company, LLC NRG Reliability Solutions LLC Astoria Gas Turbine Power LLC NRG Connected Home LLC NRG Renter's Protection LLC BidURenergy, Inc. NRG Connecticut Affiliate Services Inc. NRG Retail LLC Cabrillo Power I LLC NRG Construction LLC NRG Retail Northeast LLC Cabrillo Power II LLC NRG Curtailment Solutions, Inc NRG Rockford Acquisition LLC Carbon Management Solutions LLC NRG Development Company Inc. NRG Saguaro Operations Inc. Cirro Group, Inc. NRG Devon Operations Inc. NRG Security LLC Cirro Energy Services, Inc. NRG Dispatch Services LLC NRG Services Corporation Connecticut Jet Power LLC NRG Distributed Energy Resources Holdings LLC NRG SimplySmart Solutions LLC Devon Power LLC NRG Distributed Generation PR LLC NRG South Central Affiliate Services Inc. Dunkirk Power LLC NRG Dunkirk Operations Inc. NRG South Central Operations Inc. Eastern Sierra Energy Company LLC NRG ECOKAP Holdings LLC NRG South Texas LP El Segundo Power, LLC NRG El Segundo Operations Inc. NRG Texas C&I Supply LLC El Segundo Power II LLC NRG Energy Labor Services LLC NRG Texas Gregory LLC Energy Alternatives Wholesale, LLC NRG Energy Services Group LLC NRG Texas Holding Inc. Energy Choice Solutions LLC NRG Energy Services International Inc. NRG Texas LLC Energy Plus Holdings LLC NRG Energy Services LLC NRG Texas Power LLC Energy Plus Natural Gas LLC NRG Generation Holdings, Inc. NRG Warranty Services LLC Energy Protection Insurance Company NRG Greenco LLC NRG West Coast LLC Everything Energy LLC NRG Home & Business Solutions LLC NRG Western Affiliate Services Inc. Forward Home Security, LLC NRG Home Services LLC O'Brien Cogeneration, Inc. II GCP Funding Company, LLC NRG Home Solutions LLC ONSITE Energy, Inc. Green Mountain Energy Company NRG Home Solutions Product LLC Oswego Harbor Power LLC Gregory Partners, LLC NRG Homer City Services LLC Reliant Energy Northeast LLC Gregory Power Partners LLC NRG Huntley Operations Inc. Reliant Energy Power Supply, LLC Huntley Power LLC NRG HQ DG LLC Reliant Energy Retail Holdings, LLC Independence Energy Alliance LLC NRG Identity Protect LLC Reliant Energy Retail Services, LLC Independence Energy Group LLC NRG Ilion Limited Partnership RERH Holdings, LLC Independence Energy Natural Gas LLC NRG Ilion LP LLC Saguaro Power LLC Indian River Operations Inc. NRG International LLC Somerset Operations Inc. Indian River Power LLC NRG Maintenance Services LLC Somerset Power LLC Meriden Gas Turbines LLC NRG Mextrans Inc. Texas Genco GP, LLC Middletown Power LLC NRG MidAtlantic Affiliate Services Inc. Texas Genco Holdings, Inc. Montville Power LLC NRG Middletown Operations Inc. Texas Genco LP, LLC NEO Corporation NRG Montville Operations Inc. Texas Genco Services, LP New Genco GP, LLC NRG North Central Operations Inc. US Retailers LLC Norwalk Power LLC NRG Northeast Affiliate Services Inc. Vienna Operations Inc. NRG Advisory Services LLC NRG Norwalk Harbor Operations Inc. Vienna Power LLC NRG Affiliate Services Inc. NRG Operating Services, Inc. WCP (Generation) Holdings LLC NRG Arthur Kill Operations Inc. NRG Oswego Harbor Power Operations Inc. West Coast Power LLC NRG Astoria Gas Turbine Operations Inc.
Condensed Consolidating Statements Of Operations	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS For the three months ended March 31, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 1,769 $ 395 $ — $ 1 $ 2,165 Operating Costs and Expenses Cost of operations 1,358 283 9 1 1,651 Depreciation and amortization 54 23 8 — 85 Selling, general and administrative 122 16 56 — 194 Reorganization costs — — 13 — 13 Development costs — — 2 — 2 Total operating costs and expenses 1,534 322 88 1 1,945 Gain on sale of assets 1 — — — 1 Operating Income/(Loss) 236 73 (88 ) — 221 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 10 — 299 (309 ) — Equity in losses of unconsolidated affiliates — (21 ) — — (21 ) Other income, net 4 1 7 — 12 Interest expense (4 ) (4 ) (106 ) — (114 ) Total other income/(expense) 10 (24 ) 200 (309 ) (123 ) Income from Continuing Operations Before Income Taxes 246 49 112 (309 ) 98 Income tax expense — — 4 — 4 Income from Continuing Operations 246 49 108 (309 ) 94 Income from discontinued operations, net of income tax 9 5 374 — 388 Net Income Attributable to NRG Energy, Inc. $ 255 $ 54 $ 482 $ (309 ) $ 482 (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, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Operating Revenues Total operating revenues $ 1,744 $ 329 $ — $ (8 ) $ 2,065 Operating Costs and Expenses Cost of operations 1,155 224 14 (8 ) 1,385 Depreciation and amortization 60 52 8 — 120 Selling, general and administrative 104 11 61 — 176 Reorganization costs 2 — 18 — 20 Development costs — 1 4 — 5 Total operating costs and expenses 1,321 288 105 (8 ) 1,706 Gain/(loss) on sale of assets 3 (1 ) — — 2 Operating Income/(Loss) 426 40 (105 ) — 361 Other Income/(Expense) Equity in earnings of consolidated subsidiaries 1 — 332 (333 ) — Equity in earnings/(losses) of unconsolidated affiliates — 2 (1 ) — 1 Other income/(loss), net 5 (7 ) 2 — — Loss on debt extinguishment, net — — (2 ) — (2 ) Interest expense (3 ) (21 ) (92 ) — (116 ) Total other income/(expense) 3 (26 ) 239 (333 ) (117 ) Income from Continuing Operations Before Income Taxes 429 14 134 (333 ) 244 Income tax expense/(benefit) 113 55 (162 ) — 6 Income/(Loss) from Continuing Operations 316 (41 ) 296 (333 ) 238 Income/(loss) from discontinued operations, net of income tax 15 (20 ) — — (5 ) Net Income/(Loss) 331 (61 ) 296 (333 ) 233 Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (63 ) 17 — (46 ) Net Income Attributable to NRG Energy, Inc. $ 331 $ 2 $ 279 $ (333 ) $ 279 (a) All significant intercompany transactions have been eliminated in consolidation
Condensed Consolidating Statements Of Comprehensive Income	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME For the three months ended March 31, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Net Income $ 255 $ 54 $ 482 $ (309 ) $ 482 Other Comprehensive Income/(Loss) Foreign currency translation adjustments, net 1 1 1 (2 ) 1 Defined benefit plans, net — — (3 ) — (3 ) Other comprehensive income/(loss) 1 1 (2 ) (2 ) (2 ) Comprehensive Income Attributable to NRG Energy, Inc. $ 256 $ 55 $ 480 $ (311 ) $ 480 (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, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. Eliminations (a) Consolidated (In millions) Net Income/(Loss) $ 331 $ (61 ) $ 296 $ (333 ) $ 233 Other Comprehensive (Loss)/Income Unrealized gain on derivatives, net — 16 15 (17 ) 14 Foreign currency translation adjustments, net (2 ) (2 ) (3 ) 5 (2 ) Defined benefit plans, net — — (1 ) — (1 ) Other comprehensive (loss)/income (2 ) 14 11 (12 ) 11 Comprehensive Income/(Loss) 329 (47 ) 307 (345 ) 244 Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest — (46 ) 24 (16 ) (38 ) Comprehensive Income/(Loss) Attributable to NRG Energy, Inc. $ 329 $ (1 ) $ 283 $ (329 ) $ 282 (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, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated ASSETS (In millions) Current Assets Cash and cash equivalents $ — $ 27 $ 832 $ — $ 859 Funds deposited by counterparties 11 — — — 11 Restricted cash 12 3 — — 15 Accounts receivable, net 1,228 199 159 (688 ) 898 Inventory 277 114 — — 391 Derivative instruments 610 21 15 (35 ) 611 Cash collateral paid in support of energy risk management activities 367 21 — — 388 Prepayments and other current assets 192 11 82 — 285 Total current assets 2,697 396 1,088 (723 ) 3,458 Property, plant and equipment, net 1,512 987 151 — 2,650 Other Assets Investment in subsidiaries 477 — 3,765 (4,242 ) — Equity investments in affiliates — 387 — — 387 Operating lease right-of-use assets, net 95 289 133 — 517 Goodwill 360 213 — — 573 Intangible assets, net 414 166 — — 580 Nuclear decommissioning trust fund 718 — — — 718 Derivative instruments 334 8 14 (9 ) 347 Deferred income tax 6 (145 ) 184 — 45 Other non-current assets 143 30 94 (12 ) 255 Total other assets 2,547 948 4,190 (4,263 ) 3,422 Total Assets $ 6,756 $ 2,331 $ 5,429 $ (4,986 ) $ 9,530 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Current portion of long-term debt and capital leases $ — $ 108 $ 16 $ — $ 124 Current portion of operating lease liabilities 23 30 21 — 74 Accounts payable 1,515 (218 ) 88 (688 ) 697 Derivative instruments 505 19 — (35 ) 489 Cash collateral received in support of energy risk management activities 11 — — — 11 Accrued expenses and other current liabilities 244 57 249 — 550 Total current liabilities 2,298 (4 ) 374 (723 ) 1,945 Other Liabilities Long-term debt and capital leases 245 112 6,021 (12 ) 6,366 Non-current operating lease liabilities 77 320 132 — 529 Nuclear decommissioning reserve 286 — — — 286 Nuclear decommissioning trust liability 423 — — — 423 Derivative instruments 354 5 — (9 ) 350 Deferred income taxes 112 60 (110 ) — 62 Other non-current liabilities 408 149 532 — 1,089 Total other liabilities 1,905 646 6,575 (21 ) 9,105 Total Liabilities 4,203 642 6,949 (744 ) 11,050 Redeemable noncontrolling interest in subsidiaries — 18 — — 18 Stockholders’ Equity 2,553 1,671 (1,520 ) (4,242 ) (1,538 ) Total Liabilities and Stockholders’ Equity $ 6,756 $ 2,331 $ 5,429 $ (4,986 ) $ 9,530 (a) All significant intercompany transactions have been eliminated in consolidation NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2018 Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated ASSETS (In millions) Current Assets Cash and cash equivalents $ 55 $ 28 $ 480 $ — $ 563 Funds deposited by counterparties 33 — — — 33 Restricted cash 7 10 — — 17 Accounts receivable, net 1,354 115 309 (754 ) 1,024 Inventory 278 134 — — 412 Derivative instruments 779 50 16 (81 ) 764 Cash collateral paid in support of energy risk management activities 275 12 — — 287 Prepayments and other current assets 180 32 90 — 302 Current assets - held-for-sale — 1 — — 1 Current assets - discontinued operations 177 20 — — 197 Total current assets 3,138 402 895 (835 ) 3,600 Property, plant and equipment, net 1,938 957 153 — 3,048 Other Assets Investment in subsidiaries 446 — 4,707 (5,153 ) — Equity investments in affiliates — 412 — — 412 Goodwill 359 214 — — 573 Intangible assets, net 422 169 — — 591 Nuclear decommissioning trust fund 663 — — — 663 Derivative instruments 296 4 22 (5 ) 317 Deferred income taxes 6 (143 ) 183 — 46 Other non-current assets 133 71 97 (12 ) 289 Non-current assets - held for sale — 77 — — 77 Non-current assets - discontinued operations 405 607 — — 1,012 Total other assets 2,730 1,411 5,009 (5,170 ) 3,980 Total Assets $ 7,806 $ 2,770 $ 6,057 $ (6,005 ) $ 10,628 LIABILITIES AND STOCKHOLDERS’ EQUITY Current Liabilities Current portion of long-term debt and capital leases $ — $ 55 $ 17 $ — $ 72 Accounts payable 1,368 (185 ) 434 (754 ) 863 Derivative instruments 713 41 — (81 ) 673 Cash collateral received in support of energy risk management activities 33 — — — 33 Accrued expenses and other current liabilities 291 36 353 — 680 Current liabilities - held-for-sale — 5 — — 5 Current liabilities - discontinued operations 24 48 — — 72 Total current liabilities 2,429 — 804 (835 ) 2,398 Other Liabilities Long-term debt and capital leases 244 192 6,025 (12 ) 6,449 Nuclear decommissioning reserve 282 — — — 282 Nuclear decommissioning trust liability 371 — — — 371 Derivative instruments 306 3 — (5 ) 304 Deferred income taxes 112 61 (108 ) — 65 Other non-current liabilities 402 320 552 — 1,274 Non-current liabilities - held-for-sale — 65 — — 65 Non-current liabilities - discontinued operations 58 577 — — 635 Total other liabilities 1,775 1,218 6,469 (17 ) 9,445 Total Liabilities 4,204 1,218 7,273 (852 ) 11,843 Redeemable noncontrolling interest in subsidiaries — 19 — — 19 Stockholders’ Equity 3,602 1,533 (1,216 ) (5,153 ) (1,234 ) Total Liabilities and Stockholders’ Equity $ 7,806 $ 2,770 $ 6,057 $ (6,005 ) $ 10,628 (a) All significant intercompany transactions have been eliminated in consolidation
Condensed Consolidating Statements Of Cash Flows	NRG ENERGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS For the three months ended March 31, 2019 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net income $ 255 $ 54 $ 482 $ (309 ) $ 482 Income from discontinued operations 9 5 374 — 388 Net income from continuing operations 246 49 108 (309 ) 94 Adjustments to reconcile net income to net cash provided/(used) by operating activities: Equity in losses of unconsolidated affiliates — 21 — — 21 Depreciation, amortization and accretion 59 25 8 — 92 Provision for bad debts 23 3 — — 26 Amortization of nuclear fuel 13 — — — 13 Amortization of financing costs and debt discount/premiums — — 7 — 7 Amortization of intangibles 6 — — — 6 Amortization of unearned equity compensation — — 4 — 4 Loss on sale of assets — — 3 — 3 Changes in derivative instruments (29 ) 5 9 — (15 ) Changes in deferred income taxes and liability for uncertain tax benefits — 1 (3 ) — (2 ) Changes in collateral deposits in support of energy risk management activities (114 ) (9 ) — — (123 ) Changes in nuclear decommissioning trust liability 9 — — — 9 Changes in other working capital (221 ) (137 ) (221 ) 309 (270 ) Cash used by continuing operations (8 ) (42 ) (85 ) — (135 ) Cash provided/(used) by discontinued operations 17 (9 ) — — 8 Net Cash Provided/(Used) by Operating Activities 9 (51 ) (85 ) — (127 ) Cash Flows from Investing Activities Payments for acquisitions of businesses (16 ) — — — (16 ) Capital expenditures (36 ) (6 ) (7 ) — (49 ) Investments in nuclear decommissioning trust fund securities (122 ) — — — (122 ) Proceeds from the sale of nuclear decommissioning trust fund securities 113 — — — 113 Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees 1 404 908 — 1,313 Changes in investments in unconsolidated affiliates — 4 — — 4 Contributions to discontinued operations — (44 ) — — (44 ) Other — — (1 ) — (1 ) Cash (used)/provided by continuing operations (60 ) 358 900 — 1,198 Cash used by discontinued operations — (2 ) — — (2 ) Net Cash (Used)/Provided by Investing Activities (60 ) 356 900 — 1,196 Cash Flows from Financing Activities Payments (for)/from intercompany loans (4 ) (290 ) 294 — — Payments of dividends to common stockholders — — (8 ) — (8 ) Payments for treasury stock — — (747 ) — (747 ) Distributions to noncontrolling interests from subsidiaries — (1 ) — — (1 ) Proceeds from issuance of common stock — — 2 — 2 Payments for long-term debt — (33 ) (4 ) — (37 ) Cash used by continuing operations (4 ) (324 ) (463 ) — (791 ) Cash provided by discontinued operations — 43 — — 43 Net Cash Used by Financing Activities (4 ) (281 ) (463 ) — (748 ) Change in cash from discontinued operations 17 32 — — 49 Net (Decrease)/Increase in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash (72 ) (8 ) 352 — 272 Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period 95 38 480 — 613 Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period $ 23 $ 30 $ 832 $ — $ 885 (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, 2018 (Unaudited) Guarantor Subsidiaries Non-Guarantor Subsidiaries NRG Energy, Inc. (Note Issuer) Eliminations (a) Consolidated (In millions) Cash Flows from Operating Activities Net income/(loss) $ 331 $ (61 ) $ 296 $ (333 ) $ 233 Income/(loss) from discontinued operations 15 (20 ) — — (5 ) Net income/(loss) from continuing operations 316 (41 ) 296 (333 ) 238 Adjustments to reconcile net income to net cash provided/(used) by operating activities: Distributions and equity in earnings of unconsolidated affiliates — (2 ) 1 — (1 ) Depreciation, amortization and accretion 67 56 8 — 131 Provision for bad debts 15 — — — 15 Amortization of nuclear fuel 13 — — — 13 Amortization of financing costs and debt discount/premiums — — 6 — 6 Adjustment for debt extinguishment — — 2 — 2 Amortization of intangibles and out-of-market contracts 7 2 — — 9 Amortization of unearned equity compensation — — 6 — 6 (Gain)/loss on sale of assets (11 ) 1 — — (10 ) Changes in derivative instruments (203 ) 2 15 (17 ) (203 ) Changes in deferred income taxes and liability for uncertain tax benefits 113 29 (143 ) — (1 ) Changes in collateral deposits in support of energy risk management activities 162 1 — — 163 Changes in nuclear decommissioning trust liability 34 — — — 34 Changes in other working capital 277 (339 ) (444 ) 350 (156 ) Cash provided/(used) by continuing operations 790 (291 ) (253 ) — 246 Cash provided by discontinued operations 32 72 — — 104 Net Cash Provided/(Used) by Operating Activities 822 (219 ) (253 ) — 350 Cash Flows from Investing Activities Payments for acquisitions of businesses (2 ) — — — (2 ) Capital expenditures (60 ) (74 ) (21 ) — (155 ) Proceeds from sale of emission allowances, net of purchases 6 — — — 6 Investments in nuclear decommissioning trust fund securities (216 ) — — — (216 ) Proceeds from the sale of nuclear decommissioning trust fund securities 182 — — — 182 Proceeds from sale of assets, net of cash disposed of 11 — 42 — 53 Change in investments in unconsolidated affiliates — (8 ) — — (8 ) Distributions to discontinued operations — (29 ) — — (29 ) Cash (used)/provided by continuing operations (79 ) (111 ) 21 — (169 ) Cash used by discontinued operations (1 ) (290 ) — — (291 ) Net Cash (Used)/Provided by Investing Activities (80 ) (401 ) 21 — (460 ) Cash Flows from Financing Activities Payments (for)/from intercompany loans (481 ) 417 64 — — Payment of dividends to common stockholders — — (10 ) — (10 ) Payments for treasury stock — — (93 ) — (93 ) Distributions to noncontrolling interests from subsidiaries — (10 ) — — (10 ) Proceeds from issuance of common stock — — 7 — 7 Payment of debt issuance costs — — (2 ) — (2 ) Payments for long-term debt — (34 ) (5 ) — (39 ) Cash (used)/provided by continuing operations (481 ) 373 (39 ) — (147 ) Cash provided by discontinued operations — 133 — — 133 Net Cash (Used)/Provided by Financing Activities (481 ) 506 (39 ) — (14 ) Change in cash from discontinued operations 31 (85 ) — — (54 ) Net Increase/(Decrease) in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash 230 (29 ) (271 ) — (70 ) Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period 41 425 620 — 1,086 Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period $ 271 $ 396 $ 349 $ — $ 1,016 (a) All significant intercompany transactions have been eliminated in consolidation

Nature of Business and Basis _2

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

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Net (Loss)/Income Attributable to NRG Energy, Inc. After Removing Net Loss Attributable to Noncontrolling Interest (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accounting Policies [Abstract]
Income from continuing operations, net of income tax	$ 94	$ 245
Income from discontinued operations, net of income tax	388	34
Net income attributable to NRG Energy, Inc.	$ 482	$ 279

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Other Balance Sheet Information (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Accounts receivable allowance for doubtful accounts	$ 32	$ 32
Property, plant and equipment accumulated depreciation	1,610	1,811
Intangible assets accumulated amortization	1,171	1,149
Out-of-market contracts accumulated amortization	$ 0	$ 37

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Restricted Cash (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Cash and cash equivalents	$ 859	$ 563	$ 514	$ 770
Funds deposited by counterparties	11	33	241	37
Restricted cash	15	17	261	279
Cash and cash equivalents, funds deposited by counterparties and restricted cash shown in the statement of cash flows	$ 885	$ 613	$ 1,016	$ 1,086

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Recent Accounting Developments (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities	$ 603
Operating lease right-of-use assets	$ 517		$ 0
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities		$ 404
Operating lease right-of-use assets		$ 321

Revenue Recognition - Performan

Revenue Recognition - Performance Obligations (Details) $ in Millions	Mar. 31, 2019USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01
Revenue from Contract with Customer [Abstract]
Estimated future fixed fee performance obligations	$ 500
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue remaining performance obligation period	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue from Contract with Customer [Abstract]
Estimated future fixed fee performance obligations	$ 500
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue remaining performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue from Contract with Customer [Abstract]
Estimated future fixed fee performance obligations	$ 535
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue remaining performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue from Contract with Customer [Abstract]
Estimated future fixed fee performance obligations	$ 284
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue remaining performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue from Contract with Customer [Abstract]
Estimated future fixed fee performance obligations	$ 29
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue remaining performance obligation period	1 year

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1,779	$ 1,804
Mark-to-market for economic hedging activities	20	206
Operating revenues	2,165	2,065
Lease revenue	5	5
Derivative revenue	27	214
Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	306	443
Derivative revenue	336	316
Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	154	142
Derivative revenue	18	26
Retail revenue | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,320	1,175
Retail revenue | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	286	310
Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,606	1,485
Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	20	(96)
Derivative revenue	381	256
Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	79	91
Total operating revenue
Disaggregation of Revenue [Line Items]
Operating revenues	2,165	2,065
Other revenue, derivative
Disaggregation of Revenue [Line Items]
Derivative revenue	7	8
Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(3)	(12)
Operating revenues	(266)	314
Lease revenue	0	0
Corporate/Eliminations | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(276)	(161)
Derivative revenue	(277)	(157)
Corporate/Eliminations | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(1)	0
Derivative revenue	0	0
Corporate/Eliminations | Retail revenue | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(1)	(1)
Corporate/Eliminations | Retail revenue | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Corporate/Eliminations | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(1)	(1)
Corporate/Eliminations | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	15	484
Derivative revenue	(262)	327
Corporate/Eliminations | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(2)	(7)
Corporate/Eliminations | Total operating revenue
Disaggregation of Revenue [Line Items]
Operating revenues	(265)	315
Corporate/Eliminations | Other revenue, derivative
Disaggregation of Revenue [Line Items]
Derivative revenue	0	0
Retail | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,604	1,483
Operating revenues	1,607	1,480
Lease revenue	3	3
Retail | Operating Segments | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Derivative revenue	0	0
Retail | Operating Segments | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Derivative revenue	0	0
Retail | Operating Segments | Retail revenue | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,321	1,176
Retail | Operating Segments | Retail revenue | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	286	310
Retail | Operating Segments | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,607	1,486
Retail | Operating Segments | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	0	(6)
Derivative revenue	0	(6)
Retail | Operating Segments | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Retail | Operating Segments | Total operating revenue
Disaggregation of Revenue [Line Items]
Operating revenues	1,607	1,480
Retail | Operating Segments | Other revenue, derivative
Disaggregation of Revenue [Line Items]
Derivative revenue	0	0
Retail | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Operating revenues	(3)	(1)
Generation | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	178	333
Operating revenues	823	270
Lease revenue	2	2
Generation | Operating Segments | Texas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(146)	(101)
Lease revenue	0	0
Generation | Operating Segments | East/West/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	324	434
Lease revenue	2	2
Generation | Operating Segments | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	582	604
Derivative revenue	613	473
Generation | Operating Segments | Energy revenue | Texas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	358	265
Derivative revenue	525	413
Generation | Operating Segments | Energy revenue | East/West/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	224	339
Derivative revenue	88	60
Generation | Operating Segments | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	155	142
Derivative revenue	18	26
Generation | Operating Segments | Capacity revenue | Texas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Derivative revenue	0	0
Generation | Operating Segments | Capacity revenue | East/West/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	155	142
Derivative revenue	18	26
Generation | Operating Segments | Retail revenue | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Generation | Operating Segments | Retail revenue | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Generation | Operating Segments | Retail revenue | Texas | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Generation | Operating Segments | Retail revenue | Texas | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Generation | Operating Segments | Retail revenue | East/West/Other | Mass customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Generation | Operating Segments | Retail revenue | East/West/Other | Business Solutions customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Generation | Operating Segments | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Generation | Operating Segments | Total retail revenue | Texas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Generation | Operating Segments | Total retail revenue | East/West/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Generation | Operating Segments | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	5	(574)
Derivative revenue	643	(65)
Generation | Operating Segments | Derivative revenue | Texas
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	13	(569)
Derivative revenue	546	(150)
Generation | Operating Segments | Derivative revenue | East/West/Other
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(8)	(5)
Derivative revenue	97	85
Generation | Operating Segments | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	81	98
Generation | Operating Segments | Other revenue | Texas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	29	53
Generation | Operating Segments | Other revenue | East/West/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	52	45
Generation | Operating Segments | Total operating revenue
Disaggregation of Revenue [Line Items]
Operating revenues	823	270
Generation | Operating Segments | Total operating revenue | Texas
Disaggregation of Revenue [Line Items]
Operating revenues	400	(251)
Generation | Operating Segments | Total operating revenue | East/West/Other
Disaggregation of Revenue [Line Items]
Operating revenues	423	521
Generation | Operating Segments | Other revenue, derivative
Disaggregation of Revenue [Line Items]
Derivative revenue	7	8
Generation | Operating Segments | Other revenue, derivative | Texas
Disaggregation of Revenue [Line Items]
Derivative revenue	8	5
Generation | Operating Segments | Other revenue, derivative | East/West/Other
Disaggregation of Revenue [Line Items]
Derivative revenue	(1)	3
Generation | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Operating revenues	$ (235)	$ 309

Revenue Recognition - Contract

Revenue Recognition - Contract Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Schedule Of Contract Assets And Liabilities [Line Items]
Deferred customer acquisition costs	$ 117	$ 111
Total accounts receivable, net	898	1,024
Unbilled revenues (included within Accounts receivable, net - Contracts with customers)	305	392
Deferred revenues	80	67
Accounts receivable, net - Contracts with customers
Schedule Of Contract Assets And Liabilities [Line Items]
Total accounts receivable, net	870	999
Accounts receivable, net - Derivative instruments
Schedule Of Contract Assets And Liabilities [Line Items]
Total accounts receivable, net	22	20
Accounts receivable, net - Affiliate
Schedule Of Contract Assets And Liabilities [Line Items]
Total accounts receivable, net	$ 6	$ 5

Discontinued Operations and D_3

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

Discontinued Operations and D_4

Discontinued Operations and Dispositions - Summarized of Results of Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) from discontinued operations, net of tax	$ 388	$ (5)
Discontinued Operations | South Central Portfolio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues	31	102
Operating costs and expenses	(23)	(86)
Loss from discontinued operations, net of tax	8	16
Gain on disposal of discontinued operations, net of tax	27	0
Gain/(Loss) from discontinued operations, net of tax	35	16
Discontinued Operations | Carlsbad Energy Holdings LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues	19	260
Operating costs and expenses	(9)	(230)
Other expenses	(5)	(58)
Gain/(loss) from operations of discontinued components, before tax	5	(28)
Income tax expense	0	(7)
Loss from discontinued operations, net of tax	5	(21)
Gain on disposal of discontinued operations, net of tax	348	0
Gain/(Loss) from discontinued operations, net of tax	$ 353	$ (21)

Discontinued Operations and D_5

Discontinued Operations and Dispositions - Major Classes of Assets and Liabilities Classified as Discontinued Operations (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other current assets	$ 0	$ 1
Current assets - discontinued operations	0	197
Other non-current assets	0	77
Non-current assets - discontinued operations	0	1,012
Current liabilities - discontinued operations	0	72
Other non-current liabilities	0	65
Non-current liabilities - discontinued operations	$ 0	635
South Central Portfolio | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents		89
Accounts receivable, net		49
Inventory		35
Other current assets		5
Current assets - discontinued operations		178
Property, plant and equipment, net		408
Other non-current assets		1
Non-current assets - discontinued operations		409
Accounts payable		19
Other current liabilities		5
Current liabilities - discontinued operations		24
Out-of-market contracts, net		50
Other non-current liabilities		11
Non-current liabilities - discontinued operations		61
Renewables And Carlsbad Project | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restricted Cash		4
Accounts receivable, net		10
Other current assets		5
Current assets - discontinued operations		19
Property, plant and equipment, net		590
Intangible assets, net		9
Other non-current assets		4
Non-current assets - discontinued operations		603
Current portion of long term debt and capital leases		20
Accounts payable		27
Other current liabilities		1
Current liabilities - discontinued operations		48
Long-term debt and capital leases		572
Other non-current liabilities		2
Non-current liabilities - discontinued operations		$ 574

Discontinued Operations and D_6

Discontinued Operations and Dispositions - Sale of Ownership in NRG Yield, Inc. and the Renewables Platform (Details) MW in Thousands, $ in Millions	Feb. 06, 2018USD ($)extension	Mar. 31, 2019USD ($)MW	Dec. 31, 2018USD ($)	Aug. 31, 2018USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generation capacity (in MW) | MW		23
Discontinued Operations | NRG Yield and Renewables
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration				$ 1,348
Discontinued Operations | Carlsbad Project
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration	$ 385
Ownership percentage	100.00%
Lease and easement agreement, number of extensions | extension	2
Lease renewal term	10 years
Additional commitments related to project		$ 23	$ 23

Discontinued Operations and D_7

Discontinued Operations and Dispositions - Sale of Assets to NRG Yield, Inc. Prior to Discontinued Operations (Details) $ in Millions	Mar. 31, 2019MW	Mar. 30, 2018USD ($)MW
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Generation capacity (in MW) | MW	23,000
Buckthorn Renewables, LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of ownership sold		100.00%
Generation capacity (in MW) | MW		154
Cash consideration | $		$ 42
Debt assumed | $		$ 183

Discontinued Operations and D_8

Discontinued Operations and Dispositions - Dispositions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Other | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from other asset sales	$ 10	$ 11

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Estimated Carrying Amounts and Fair Value of Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt, including current portion	$ 6,656	$ 6,691
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Notes receivable	17	17
Long-term debt, including current portion	6,558	6,591
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Notes receivable	14	14
Long-term debt, including current portion	6,971	6,697
Fair Value | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt, including current portion	6,834	6,528
Fair Value | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Long-term debt, including current portion	$ 137	$ 169

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Assets and Liabilities Measured and Recorded at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in securities (classified within other current and non-current assets)	$ 37	$ 39
U.S. government and federal agency obligations	1	1
Total assets	1,723	1,792
Derivative liabilities	839	977
Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	929	1,042
Derivative liabilities	839	977
Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	29	39
Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	15	19
U.S. government and federal agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	50	46
Federal agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	96	100
Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	29	22
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	100	96
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	354	312
Equity contracts	9	8
Foreign government fixed income securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	4	4
Equity securities — nuclear trust fund investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity contracts	70	64
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in securities (classified within other current and non-current assets)	1	2
U.S. government and federal agency obligations	1	1
Total assets	466	517
Derivative liabilities	107	224
Level 1 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	45	137
Derivative liabilities	107	224
Level 1 | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Level 1 | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	15	19
Level 1 | U.S. government and federal agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	50	46
Level 1 | Federal agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 1 | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 1 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 1 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	354	312
Level 1 | Foreign government fixed income securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in securities (classified within other current and non-current assets)	18	18
U.S. government and federal agency obligations	0	0
Total assets	1,045	1,075
Derivative liabilities	615	664
Level 2 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	769	796
Derivative liabilities	615	664
Level 2 | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	29	39
Level 2 | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 2 | U.S. government and federal agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 2 | Federal agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	96	100
Level 2 | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	29	22
Level 2 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	100	96
Level 2 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 2 | Foreign government fixed income securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	4	4
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in securities (classified within other current and non-current assets)	18	19
U.S. government and federal agency obligations	0	0
Total assets	133	128
Derivative liabilities	117	89
Level 3 | Commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	115	109
Derivative liabilities	117	89
Level 3 | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Level 3 | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 3 | U.S. government and federal agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 3 | Federal agency mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 3 | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 3 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 3 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	0	0
Level 3 | Foreign government fixed income securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nuclear trust fund investments	$ 0	$ 0

Fair Value of Financial Instr_5

Fair Value of Financial Instruments - Reconciliation of Level 3 Financial Instruments (Details) - Level 3 - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 39	$ 4
Total (losses) gains— realized/unrealized included in earnings	(10)	11
Cash received	(1)
Purchases	(2)	1
Transfers into Level 3	17	4
Transfers out of Level 3	(27)	4
Ending balance	16	24
(Losses) Gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held	(12)	12
Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	19	19
Total (losses) gains— realized/unrealized included in earnings	0	0
Cash received	(1)
Purchases	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance	18	19
(Losses) Gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held	0	0
Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	20	(15)
Total (losses) gains— realized/unrealized included in earnings	(10)	11
Cash received	0
Purchases	(2)	1
Transfers into Level 3	17	4
Transfers out of Level 3	(27)	4
Ending balance	(2)	5
(Losses) Gains for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held	$ (12)	$ 12

Fair Value of Financial Instr_6

Fair Value of Financial Instruments - Derivative Fair Value Measurements, Narrative (Details)	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Total derivative assets valued with prices provided by models and other valuation techniques (as a percent)	12.00%
Total derivative liabilities valued with prices provided by models and other valuation techniques (as a percent)	14.00%

Fair Value of Financial Instr_7

Fair Value of Financial Instruments - Derivative Fair Value Measurements (Details) $ in Millions	Mar. 31, 2019USD ($)$ / MWh	Dec. 31, 2018USD ($)$ / MWh
Liabilities
Derivative liabilities	$ 839	$ 977
Level 3
Liabilities
Derivative liabilities	117	89
Commodity contracts
Assets
Derivative assets	929	1,042
Liabilities
Derivative liabilities	839	977
Commodity contracts | Level 3
Assets
Derivative assets	115	109
Liabilities
Derivative liabilities	117	89
Commodity contracts | Level 3 | Power Contracts
Assets
Derivative assets	89	89
Liabilities
Derivative liabilities	$ 104	$ 75
Commodity contracts | Level 3 | Power Contracts | Low
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	0	1
Commodity contracts | Level 3 | Power Contracts | High
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	253	214
Commodity contracts | Level 3 | Power Contracts | Weighted Average
Fair Value Inputs / Range
Forward Market Price (per MWh) | $ / MWh	28	31
Commodity contracts | Level 3 | FTRs
Assets
Derivative assets	$ 26	$ 20
Liabilities
Derivative liabilities	$ 13	$ 14
Commodity contracts | Level 3 | FTRs | Low
Fair Value Inputs / Range
Auction Prices (per MWh) | $ / MWh	(42)	(90)
Commodity contracts | Level 3 | FTRs | High
Fair Value Inputs / Range
Auction Prices (per MWh) | $ / MWh	38	34
Commodity contracts | Level 3 | FTRs | Weighted Average
Fair Value Inputs / Range
Auction Prices (per MWh) | $ / MWh	0	0

Fair Value of Financial Instr_8

Fair Value of Financial Instruments - Counterparty Credit Risk (Details)	3 Months Ended
	Mar. 31, 2019USD ($)
Concentration of Credit Risk
Counterparty credit exposure to a portion of the Company's counterparties	$ 259,000,000
Collateral held (cash and letters of credit) against counterparty credit exposure to a portion of the Company's counterparties	102,000,000
Net counterparty credit exposure to a portion of the Company's counterparties	$ 162,000,000
Company's exposure before collateral is expected to roll off by the end of 2019 (as a percent)	50.00%
Net exposure (as a percent)	100.00%
Aggregate counterparty credit risk exposure for counterparties representing exposure above threshold percentage	$ 0
Counterparty credit risk exposure to certain counterparties, threshold (as a percent)	10.00%
Estimated counterparty credit risk exposure to certain couterparties	$ 596,000,000
Period of estimated counterparty credit risk exposure, years	5 years
Investment grade
Concentration of Credit Risk
Net exposure (as a percent)	52.00%
Non-Investment grade/Non-Rated
Concentration of Credit Risk
Net exposure (as a percent)	48.00%
Utilities, energy merchants, marketers and other
Concentration of Credit Risk
Net exposure (as a percent)	78.00%
Financial institutions
Concentration of Credit Risk
Net exposure (as a percent)	22.00%
Ivanpau And Agua Caliente [Member]
Concentration of Credit Risk
Estimated counterparty credit risk exposure to certain couterparties	$ 326,000,000
Period of estimated counterparty credit risk exposure, years	5 years

Nuclear Decommissioning Trust_3

Nuclear Decommissioning Trust Fund - Summary of aggregate fair values and realized gains and losses (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Nuclear decommissioning trust fund
Fair Value	$ 718	$ 663
Unrealized Gains	283	234
Unrealized Losses	2	6
Cash and cash equivalents
Nuclear decommissioning trust fund
Fair Value	15	19
Unrealized Gains	0	0
Unrealized Losses	0	0
U.S. government and federal agency obligations
Nuclear decommissioning trust fund
Fair Value	50	46
Unrealized Gains	2	1
Unrealized Losses	$ 0	$ 0
Weighted-average Maturities (In years)	13 years	12 years
Federal agency mortgage-backed securities
Nuclear decommissioning trust fund
Fair Value	$ 96	$ 100
Unrealized Gains	1	1
Unrealized Losses	$ 1	$ 2
Weighted-average Maturities (In years)	25 years	23 years
Commercial mortgage-backed securities
Nuclear decommissioning trust fund
Fair Value	$ 29	$ 22
Unrealized Gains	1	0
Unrealized Losses	$ 0	$ 1
Weighted-average Maturities (In years)	23 years	22 years
Corporate debt securities
Nuclear decommissioning trust fund
Fair Value	$ 100	$ 96
Unrealized Gains	3	1
Unrealized Losses	$ 1	$ 2
Weighted-average Maturities (In years)	11 years	11 years
Equity securities
Nuclear decommissioning trust fund
Fair Value	$ 424	$ 376
Unrealized Gains	276	231
Unrealized Losses	0	1
Foreign government fixed income securities
Nuclear decommissioning trust fund
Fair Value	4	4
Unrealized Gains	0	0
Unrealized Losses	$ 0	$ 0
Weighted-average Maturities (In years)	10 years	9 years

Nuclear Decommissioning Trust_4

Nuclear Decommissioning Trust Fund - Summary of proceeds from sales of available-for-sale securities and related gains and losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Nuclear Decommissioning Trust Fund Disclosure [Abstract]
Realized gains	$ 3	$ 3
Realized losses	(2)	(3)
Proceeds from sale of securities	$ 113	$ 182

Accounting for Derivative Ins_3

Accounting for Derivative Instruments and Hedging Activities - Net notional volume buy/sell of open derivative transactions (Details) shares in Millions, mw_per_day in Millions, bbl in Millions, T in Millions, MWh in Millions, MMBTU in Millions, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019USD ($)MWhMMBTUmw_per_dayTsharesbbl	Dec. 31, 2018USD ($)MWhMMBTUmw_per_dayTsharesbbl
Long | Emissions
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, mass (ton)	1	2
Long | Renewable Energy Certificates
Volumetric Underlying Derivative Transactions
Derivative, non-monetary notional amount (in shares) | shares	1	1
Long | Coal
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, mass (ton)	9	13
Long | Oil
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount (in barrels)) | bbl	0	1
Long | Power
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, energy (in MMBtu and MWh) | MWh	8	1
Long | Interest
Volumetric Underlying Derivative Transactions
Derivative, notional amount (in usd) | $	$ 1,000	$ 1,000
Short | Natural Gas
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, energy (in MMBtu and MWh) | MMBTU	236	330
Short | Capacity
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, flow rate (in MW/Day) | mw_per_day	(1)	(1)

Accounting for Derivative Ins_4

Accounting for Derivative Instruments and Hedging Activities - Fair value within the derivative instrument valuation (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative Liabilities	$ 839	$ 977
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Assets	958	1,081
Derivative Liabilities	839	977
Not Designated as Hedging Instrument | Interest rate contracts current
Derivative [Line Items]
Derivative Assets	15	17
Derivative Liabilities	0	0
Not Designated as Hedging Instrument | Interest rate contracts long-term
Derivative [Line Items]
Derivative Assets	14	22
Derivative Liabilities	0	0
Not Designated as Hedging Instrument | Commodity contracts current
Derivative [Line Items]
Derivative Assets	596	747
Derivative Liabilities	489	673
Not Designated as Hedging Instrument | Commodity contracts long-term
Derivative [Line Items]
Derivative Assets	333	295
Derivative Liabilities	$ 350	$ 304

Accounting for Derivative Ins_5

Accounting for Derivative Instruments and Hedging Activities - Offsetting of derivatives by counterparty master agreement level and collateral received (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Cash Collateral (Held) / Posted	$ (11)	$ (33)
Derivative liabilities	(839)	(977)
Cash Collateral Posted	388	287
Gross Amounts of Recognized Assets / Liabilities	119	104
Derivative Instruments	0	0
Cash Collateral (Held) / Posted	87	83
Net Amount	206	187
Commodity contracts
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Derivative assets	929	1,042
Derivative Instruments	(689)	(778)
Cash Collateral (Held) / Posted	(5)	(31)
Net Amount	235	233
Derivative liabilities	(839)	(977)
Derivative Instruments	689	778
Cash Collateral Posted	92	114
Net Amount	(58)	(85)
Gross Amounts of Recognized Assets / Liabilities	90	65
Derivative Instruments	0	0
Cash Collateral (Held) / Posted	87	83
Net Amount	177	148
Interest rate contracts
Offsetting of Derivatives by Counterparty Master Agreement Level and Collateral Received or Paid
Derivative assets	29	39
Derivative Instruments	0	0
Cash Collateral (Held) / Posted	0	0
Net Amount	29	39
Gross Amounts of Recognized Assets / Liabilities	29	39
Derivative Instruments	0	0
Cash Collateral (Held) / Posted	0	0
Net Amount	$ 29	$ 39

Accounting for Derivative Ins_6

Accounting for Derivative Instruments and Hedging Activities - Effects on accumulated OCL balance attributable to hedge derivatives, net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Reclassified from accumulated OCL to income:
Accumulated OCL, tax	$ 0	$ 6
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	0	(54)
Reclassified from accumulated OCL to income:
Due to realization of previously deferred amounts	0	4
Mark-to-market of cash flow hedge accounting contracts	0	19
Accumulated OCL ending balance, net of $0, and $6 tax	$ 0	$ (31)

Accounting for Derivative Ins_7

Accounting for Derivative Instruments and Hedging Activities - Pre-tax effects of economic hedges not designated a cash flow hedges (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Unrealized mark-to-market results
Reversal of previously recognized unrealized losses on settled positions related to economic hedges	$ 19	$ 1
Reversal of acquired gain positions related to economic hedges	(2)	0
Net unrealized gains on open positions related to economic hedges	3	205
Total unrealized mark-to-market gains for economic hedging activities	20	206
Reversal of previously recognized unrealized gains on settled positions related to trading activity	(6)	(3)
Net unrealized gains on open positions related to trading activity	13	11
Total unrealized mark-to-market gains for trading activity	7	8
Total unrealized gains	27	214
Credit Risk Related Contingent Features
Unrealized gain (loss) from open economic hedge positions	3	205
Collateral due on net liability position that has not been called by a certain marginable agreement counterparty	3
Adequate Assurance Clauses
Credit Risk Related Contingent Features
Derivative net liability position, collateral required Contracts with Credit Rating Contingent Feature	17
Credit Rating Contingent Features
Credit Risk Related Contingent Features
Derivative net liability position, collateral required Contracts with Credit Rating Contingent Feature	23
Commodity contracts
Unrealized mark-to-market results
Total unrealized gains	27	214
Commodity contracts | Operating revenues
Unrealized mark-to-market results
Total unrealized gains	27	(88)
Commodity contracts | Cost of operations
Unrealized mark-to-market results
Total unrealized gains	0	302
Interest rate contracts
Unrealized mark-to-market results
Total unrealized gains	$ (9)	$ 12

Leases - Lease Cost and Other I

Leases - Lease Cost and Other Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Lease, Cost [Abstract]
Operating lease cost	$ 23
Variable lease cost	1
Sublease income	(4)
Total lease cost	20
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	21
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 214
Weighted-average remaining lease term
Finance leases	2 years 9 months 18 days
Operating leases	8 years 2 months 12 days
Weighted-average discount rate
Finance leases	6.50%
Operating leases	5.70%

Leases - Schedule of Annual Pay

Leases - Schedule of Annual Payments Based on Maturities of Lease (Details) $ in Millions	Mar. 31, 2019USD ($)
Leases [Abstract]
Remainder of 2019	$ 76
2020	96
2021	86
2022	85
2023	86
Thereafter	370
Total undiscounted lease payments	799
Less: present value adjustment	(196)
Total discounted lease payments	$ 603

Debt and Capital Leases - Sched

Debt and Capital Leases - Schedule of Long-term Debt and Capital Leases (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt amount	$ 6,656	$ 6,691
Capital leases	1	1
Subtotal long-term debt and capital leases (including current maturities)	6,657	6,692
Less current maturities	(124)	(72)
Less debt issuance costs	(69)	(70)
Discounts	(98)	(101)
Total long-term debt and capital leases	6,366	6,449
Recourse Debt
Debt Instrument [Line Items]
Debt amount	6,519	6,523
Recourse Debt | Senior Notes, due 2024
Debt Instrument [Line Items]
Debt amount	$ 733	733
Interest rate, stated percentage	6.25%
Recourse Debt | Senior Notes, due 2026
Debt Instrument [Line Items]
Debt amount	$ 1,000	1,000
Interest rate, stated percentage	7.25%
Recourse Debt | Senior Notes, due 2027
Debt Instrument [Line Items]
Debt amount	$ 1,230	1,230
Interest rate, stated percentage	6.625%
Recourse Debt | Senior Notes, due 2028
Debt Instrument [Line Items]
Debt amount	$ 821	821
Interest rate, stated percentage	5.75%
Recourse Debt | Convertible Senior Notes, due 2048
Debt Instrument [Line Items]
Debt amount	$ 575	575
Interest rate, stated percentage	2.75%
Recourse Debt | Term loan facility, due 2023
Debt Instrument [Line Items]
Debt amount	$ 1,694	1,698
Recourse Debt | Term loan facility, due 2023 | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%
Recourse Debt | Tax-exempt bonds
Debt Instrument [Line Items]
Debt amount	$ 466	466
Recourse Debt | Tax-exempt bonds | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage	4.125%
Recourse Debt | Tax-exempt bonds | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage	6.00%
Non Recourse Debt
Debt Instrument [Line Items]
Debt amount	$ 137	168
Non Recourse Debt | Agua Caliente Borrower 1, due 2038
Debt Instrument [Line Items]
Debt amount	$ 83	86
Interest rate, stated percentage	5.43%
Non Recourse Debt | Midwest Generation, due 2019
Debt Instrument [Line Items]
Debt amount	$ 20	48
Interest rate, stated percentage	4.39%
Non Recourse Debt | Other
Debt Instrument [Line Items]
Debt amount	$ 34	$ 34

Debt and Capital Leases - Narra

Debt and Capital Leases - Narrative (Details) - Credit Agreement - Letter of Credit - USD ($)	Jan. 04, 2019	Mar. 31, 2019
Debt Instrument [Line Items]
Credit agreement	$ 80,000,000
Facility fees	1.33%
Letters of credit issued		$ 80,000,000

Investments Accounted for Usi_3

Investments Accounted for Using the Equity Method and Variable Interest Entities, or VIEs (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)projectMW	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Investments Accounted for by the Equity Method
Equity investments in affiliates	$ 387		$ 412
Generation capacity (in MW) | MW	23,000
Current assets	$ 3		3
Net property, plant and equipment	75		76
Other long-term assets	27		28
Total assets	105		107
Current liabilities	1		2
Long-term debt	29		29
Other long-term liabilities	8		7
Total liabilities	38		38
Redeemable noncontrolling interest	18		19
Net assets less noncontrolling interests	49		$ 50
Agua Caliente
Investments Accounted for by the Equity Method
Equity investments in affiliates	201
Ivampah Master Holdings LLC
Investments Accounted for by the Equity Method
Equity investments in affiliates	$ 20
Economic interest in equity method investments (as a percent)	54.50%
Number of solar electric generating projects | project	3
Generation capacity (in MW) | MW	393
Release of reserve funds		$ (95)

Changes in Capital Structure -

Changes in Capital Structure - Narrative (Details) - USD ($)	May 02, 2019	Apr. 30, 2019	Mar. 31, 2019	Mar. 12, 2019	Mar. 31, 2019	Mar. 31, 2018	Feb. 28, 2019	Dec. 31, 2018
Capital Structure
Common stock, shares authorized (in shares)			500,000,000		500,000,000			500,000,000
Employee Stock Purchase Plan, minimum percentage of eligible compensation to purchase shares			1.00%
Employee Stock Purchase Plan, maximum percentage of eligible compensation			10.00%
Employee Stock Purchase Plan, exercise price as percentage of fair value			95.00%
Shares repurchased, value					$ 749,000,000	$ 93,000,000
Total number of shares purchased (in shares)					17,608,957
Additional Paid-in Capital
Capital Structure
Shares repurchased, value					$ 10,000,000
Accelerated Share Repurchase Program
Capital Structure
Shares repurchased, value				$ 390,000,000
Stock repurchase program, authorized amount							$ 400,000,000
Shares repurchased (in shares)				9,086,903
Accelerated Share Repurchase Program | Subsequent Event
Capital Structure
Shares repurchased (in shares)		351,768
Average price paid per share (in usd per share)		$ 42.38
Accelerated Share Repurchase Program | Additional Paid-in Capital | Subsequent Event
Capital Structure
Remaining amount recorded in additional paid in capital		$ 10,000,000
2018 Capital Allocation Plan
Capital Structure
Shares repurchased, value					$ 250,000,000
Total number of shares purchased (in shares)					6,153,415
Amounts paid for shares purchased					$ 250,000,000
Capital Allocation Plan, Accelerated Repurchase Agreement February 2019
Capital Structure
Total number of shares purchased (in shares)				9,086,903
Amounts paid for shares purchased				$ 400,000,000
Capital Allocation Plan, Accelerated Repurchase Agreement February 2019 | Subsequent Event
Capital Structure
Total number of shares purchased (in shares)		351,768
Amounts paid for shares purchased		$ 0
2019 Capital Allocation Plan
Capital Structure
Total number of shares purchased (in shares)			2,368,639
Amounts paid for shares purchased			$ 99,000,000
2019 Capital Allocation Plan | Subsequent Event
Capital Structure
Total number of shares purchased (in shares)		39,140
Amounts paid for shares purchased		$ 1,000,000
Capital Allocation Plan
Capital Structure
Stock repurchase program, authorized amount							$ 1,000,000,000
Total number of shares purchased (in shares)					17,608,957
Amounts paid for shares purchased					$ 749,000,000
Capital Allocation Plan | Subsequent Event
Capital Structure
Shares repurchased, value	$ 500,000,000
Average price paid per share (in usd per share)	$ 42.21
Total number of shares purchased (in shares)	17,999,865
Amounts paid for shares purchased	$ 750,000,000

Changes in Capital Structure _2

Changes in Capital Structure - Changes in NRG's common shares outstanding and issued (Details) - shares	May 02, 2019	Mar. 31, 2019
Schedule of Stock by Class, Equity [Roll Forward]
Balance as of beginning of period (in shares)		420,288,886
Treasury shares, balance as of beginning of period (in shares)		(136,638,847)
Outstanding, as of beginning of period (in shares)		283,650,039
Shares issued under LTIPs (in shares)		1,497,175
Shares repurchased (in shares)		(17,608,957)
Balance as of end of period (in shares)		421,786,061
Treasury shares, balance as of end of the period (in shares)		(154,247,804)
Outstanding, as of end of period (in shares)		267,538,257
Issued
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		1,497,175
Shares repurchased (in shares)		0
Treasury
Schedule of Stock by Class, Equity [Roll Forward]
Shares issued under LTIPs (in shares)		0
Shares repurchased (in shares)		(17,608,957)
Capital Allocation Plan
Schedule of Stock by Class, Equity [Roll Forward]
Shares repurchased (in shares)		(17,608,957)
Capital Allocation Plan | Subsequent Event
Schedule of Stock by Class, Equity [Roll Forward]
Shares repurchased (in shares)	(17,999,865)

Changes in Capital Structure _3

Changes in Capital Structure - NRG Common Stock Dividends Paid (Details) - $ / shares	May 15, 2019	Apr. 08, 2019	Mar. 31, 2019	Mar. 31, 2018
Dividends [Abstract]
Dividends Per Common Share (in usd per share)			$ 0.03	$ 0.03
Subsequent Event
Subsequent Event [Line Items]
Common stock dividends declared (in usd per share)		$ 0.03
Common stock dividends proposed annual amount (in usd per share)	$ 0.12

Earnings Per Share - Reconcilia

Earnings Per Share - Reconciliation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Basic income per share attributable to NRG Energy, Inc;
Net income attributable to NRG Energy, Inc. common stockholders	$ 482	$ 279
Weighted average number of common shares outstanding — basic (in shares)	278	318
Income per weighted average common share — basic (in usd per share)	$ 1.73	$ 0.88
Diluted income per share attributable to NRG Energy, Inc;
Net income attributable to NRG Energy, Inc. available to common shareholders	$ 482	$ 279
Weighted average number of common shares outstanding - diluted (in shares)	278	318
Incremental shares attributable to the issuance of equity compensation (treasury stock method) (in shares)	2	4
Total dilutive shares (in shares)	280	322
Income per weighted average common share — diluted (in usd per share)	$ 1.72	$ 0.87

Earnings Per Share - Anti-dilut

Earnings Per Share - Anti-dilutive Securities (Details) - shares shares in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Equity compensation plans
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	1

Segment Reporting (Details)

Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Segment Reporting Information
Total operating revenues	$ 2,165	$ 2,065
Depreciation and amortization	85	120
Reorganization costs	13	20
Equity in losses of unconsolidated affiliates	(21)	1
Income/(loss) from continuing operations before income taxes	98	244
Income/(loss) from continuing operations	94	238
Income/(Loss) from discontinued operations, net of income tax	388	(5)
Net Income	482	233
Net Income/(Loss)attributable to NRG Energy, Inc.	482	279
Total assets	9,530		$ 10,628
Eliminations
Segment Reporting Information
Total operating revenues	(266)	314
Depreciation and amortization	0	(1)
Reorganization costs	0	0
Equity in losses of unconsolidated affiliates	(28)	0
Income/(loss) from continuing operations before income taxes	(27)	1
Income/(loss) from continuing operations	(27)	1
Income/(Loss) from discontinued operations, net of income tax	0	0
Net Income		1
Net Income/(Loss)attributable to NRG Energy, Inc.	(27)	1
Total assets	(4,948)
Retail | Operating Segments
Segment Reporting Information
Total operating revenues	1,607	1,480
Depreciation and amortization	31	26
Reorganization costs	1	3
Equity in losses of unconsolidated affiliates	0	0
Income/(loss) from continuing operations before income taxes	111	944
Income/(loss) from continuing operations	111	944
Income/(Loss) from discontinued operations, net of income tax	0	0
Net Income		944
Net Income/(Loss)attributable to NRG Energy, Inc.	111	943
Total assets	3,309
Retail | Eliminations
Segment Reporting Information
Total operating revenues	(3)	(1)
Generation | Operating Segments
Segment Reporting Information
Total operating revenues	823	270
Depreciation and amortization	46	86
Reorganization costs	1	4
Equity in losses of unconsolidated affiliates	(20)	2
Income/(loss) from continuing operations before income taxes	114	(573)
Income/(loss) from continuing operations	114	(573)
Income/(Loss) from discontinued operations, net of income tax	0	0
Net Income		(573)
Net Income/(Loss)attributable to NRG Energy, Inc.	114	(565)
Total assets	5,489
Generation | Eliminations
Segment Reporting Information
Total operating revenues	(235)	309
Corporate | Operating Segments
Segment Reporting Information
Total operating revenues	1	1
Depreciation and amortization	8	9
Reorganization costs	11	13
Equity in losses of unconsolidated affiliates	27	(1)
Income/(loss) from continuing operations before income taxes	(100)	(128)
Income/(loss) from continuing operations	(104)	(134)
Income/(Loss) from discontinued operations, net of income tax	388	(5)
Net Income		(139)
Net Income/(Loss)attributable to NRG Energy, Inc.	284	(100)
Total assets	5,680
Corporate | Eliminations
Segment Reporting Information
Total operating revenues	$ (28)	$ 6

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Effective Tax Rate
Income before income taxes	$ 98	$ 244
Income tax expense from continuing operations	$ 4	$ 6
Effective income tax rate	4.10%	2.50%
Uncertain Tax Benefits
Non-current tax liability for uncertain tax benefits	$ 31
Uncertain tax benefits, penalties and interest accrued	$ 5

Related Party Transactions - Sc

Related Party Transactions - Schedule of NRG's Material Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Related Party Transaction [Line Items]
Revenue from related parties	$ 12	$ 23
Gladstone
Related Party Transaction [Line Items]
Revenue from related parties	1	1
GenConn
Related Party Transaction [Line Items]
Revenue from related parties	0	1
Ivanpah
Related Party Transaction [Line Items]
Revenue from related parties	10	0
Midway-Sunset
Related Party Transaction [Line Items]
Revenue from related parties	1	0
GenOn
Related Party Transaction [Line Items]
Revenue from related parties	$ 0	$ 21

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	Jun. 01, 2001	Mar. 31, 2019	Aug. 18, 2016
CDWR and SDGE v Sunrise Power
Loss Contingencies
PPA period	10 years
Damages sought, amount		$ 1.2
Remaining term		70 years
Lignite Contract With Texas Westmoreland Coal Co.
Loss Contingencies
Bond obligation			$ 99

Condensed Consolidating Finan_3

Condensed Consolidating Financial Information - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Amount outstanding	$ 6,656	$ 6,691
Recourse Debt
Debt Instrument [Line Items]
Amount outstanding	6,519	$ 6,523
Senior Notes | Recourse Debt
Debt Instrument [Line Items]
Amount outstanding	$ 4,400

Condensed Consolidating Finan_4

Condensed Consolidating Financial Information - STATEMENTS OF OPERATIONS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating Revenues
Total operating revenues	$ 2,165	$ 2,065
Operating Costs and Expenses
Cost of operations	1,651	1,385
Depreciation and amortization	85	120
Selling, general and administrative	194	176
Reorganization costs	13	20
Development costs	2	5
Total operating costs and expenses	1,945	1,706
Gain/(loss) on sale of assets	1	2
Operating Income/(Loss)	221	361
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries	0	0
Equity in (losses)/earnings of unconsolidated affiliates	(21)	1
Other income/(expense), net	12	0
Loss on debt extinguishment, net	0	(2)
Interest expense	(114)	(116)
Total other income/(expense)	(123)	(117)
Income from Continuing Operations Before Income Taxes	98	244
Income tax expense/(benefit)	4	6
Income from Continuing Operations	94	238
Income/(Loss) from discontinued operations, net of income tax	388	(5)
Net Income	482	233
Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests	0	(46)
Net income attributable to NRG Energy, Inc.	482	279
Eliminations
Operating Revenues
Total operating revenues	1	(8)
Operating Costs and Expenses
Cost of operations	1	(8)
Depreciation and amortization	0	0
Selling, general and administrative	0	0
Reorganization costs	0	0
Development costs	0	0
Total operating costs and expenses	1	(8)
Gain/(loss) on sale of assets	0	0
Operating Income/(Loss)	0	0
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries	(309)	(333)
Equity in (losses)/earnings of unconsolidated affiliates	0	0
Other income/(expense), net	0	0
Loss on debt extinguishment, net		0
Interest expense	0	0
Total other income/(expense)	(309)	(333)
Income from Continuing Operations Before Income Taxes	(309)	(333)
Income tax expense/(benefit)	0	0
Income from Continuing Operations	(309)	(333)
Income/(Loss) from discontinued operations, net of income tax	0	0
Net Income	(309)	(333)
Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests		0
Net income attributable to NRG Energy, Inc.	(309)	(333)
Guarantor Subsidiaries
Operating Revenues
Total operating revenues	1,769	1,744
Operating Costs and Expenses
Cost of operations	1,358	1,155
Depreciation and amortization	54	60
Selling, general and administrative	122	104
Reorganization costs	0	2
Development costs	0	0
Total operating costs and expenses	1,534	1,321
Gain/(loss) on sale of assets	1	3
Operating Income/(Loss)	236	426
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries	10	1
Equity in (losses)/earnings of unconsolidated affiliates	0	0
Other income/(expense), net	4	5
Loss on debt extinguishment, net		0
Interest expense	(4)	(3)
Total other income/(expense)	10	3
Income from Continuing Operations Before Income Taxes	246	429
Income tax expense/(benefit)	0	113
Income from Continuing Operations	246	316
Income/(Loss) from discontinued operations, net of income tax	9	15
Net Income	255	331
Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests		0
Net income attributable to NRG Energy, Inc.	255	331
Non-Guarantor Subsidiaries
Operating Revenues
Total operating revenues	395	329
Operating Costs and Expenses
Cost of operations	283	224
Depreciation and amortization	23	52
Selling, general and administrative	16	11
Reorganization costs	0	0
Development costs	0	1
Total operating costs and expenses	322	288
Gain/(loss) on sale of assets	0	(1)
Operating Income/(Loss)	73	40
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries	0	0
Equity in (losses)/earnings of unconsolidated affiliates	(21)	2
Other income/(expense), net	1	(7)
Loss on debt extinguishment, net		0
Interest expense	(4)	(21)
Total other income/(expense)	(24)	(26)
Income from Continuing Operations Before Income Taxes	49	14
Income tax expense/(benefit)	0	55
Income from Continuing Operations	49	(41)
Income/(Loss) from discontinued operations, net of income tax	5	(20)
Net Income	54	(61)
Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests		(63)
Net income attributable to NRG Energy, Inc.	54	2
NRG Energy, Inc. (Note Issuer)
Operating Revenues
Total operating revenues	0	0
Operating Costs and Expenses
Cost of operations	9	14
Depreciation and amortization	8	8
Selling, general and administrative	56	61
Reorganization costs	13	18
Development costs	2	4
Total operating costs and expenses	88	105
Gain/(loss) on sale of assets	0	0
Operating Income/(Loss)	(88)	(105)
Other Income/(Expense)
Equity in earnings of consolidated subsidiaries	299	332
Equity in (losses)/earnings of unconsolidated affiliates	0	(1)
Other income/(expense), net	7	2
Loss on debt extinguishment, net		(2)
Interest expense	(106)	(92)
Total other income/(expense)	200	239
Income from Continuing Operations Before Income Taxes	112	134
Income tax expense/(benefit)	4	(162)
Income from Continuing Operations	108	296
Income/(Loss) from discontinued operations, net of income tax	374	0
Net Income	482	296
Less: Net (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interests		17
Net income attributable to NRG Energy, Inc.	$ 482	$ 279

Condensed Consolidating Finan_5

Condensed Consolidating Financial Information - COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Condensed Financial Statements, Captions [Line Items]
Net Income	$ 482	$ 233
Other Comprehensive Income/(Loss), net of tax
Unrealized gain on derivatives, net	0	14
Foreign currency translation adjustments, net	1	(2)
Defined benefit plans, net	(3)	(1)
Other comprehensive (loss)/income	(2)	11
Comprehensive Income/(Loss)	480	244
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest	0	(38)
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.	480	282
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net Income	(309)	(333)
Other Comprehensive Income/(Loss), net of tax
Unrealized gain on derivatives, net		(17)
Foreign currency translation adjustments, net	(2)	5
Defined benefit plans, net	0	0
Other comprehensive (loss)/income	(2)	(12)
Comprehensive Income/(Loss)		(345)
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest		(16)
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.	(311)	(329)
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net Income	255	331
Other Comprehensive Income/(Loss), net of tax
Unrealized gain on derivatives, net		0
Foreign currency translation adjustments, net	1	(2)
Defined benefit plans, net	0	0
Other comprehensive (loss)/income	1	(2)
Comprehensive Income/(Loss)		329
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest		0
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.	256	329
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net Income	54	(61)
Other Comprehensive Income/(Loss), net of tax
Unrealized gain on derivatives, net		16
Foreign currency translation adjustments, net	1	(2)
Defined benefit plans, net	0	0
Other comprehensive (loss)/income	1	14
Comprehensive Income/(Loss)		(47)
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest		(46)
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.	55	(1)
NRG Energy, Inc. (Note Issuer)
Condensed Financial Statements, Captions [Line Items]
Net Income	482	296
Other Comprehensive Income/(Loss), net of tax
Unrealized gain on derivatives, net		15
Foreign currency translation adjustments, net	1	(3)
Defined benefit plans, net	(3)	(1)
Other comprehensive (loss)/income	(2)	11
Comprehensive Income/(Loss)		307
Less: Comprehensive (loss)/income attributable to noncontrolling interest and redeemable noncontrolling interest		24
Comprehensive Income/(Loss) Attributable to NRG Energy, Inc.	$ 480	$ 283

Condensed Consolidating Finan_6

Condensed Consolidating Financial Information - BALANCE SHEETS (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 859	$ 563	$ 514	$ 770
Funds deposited by counterparties	11	33	241	37
Restricted cash	15	17	261	279
Accounts receivable, net	898	1,024
Inventory	391	412
Derivative instruments	611	764
Cash collateral paid in support of energy risk management activities	388	287
Prepayments and other current assets	285	302
Current assets - held for sale	0	1
Current assets - discontinued operations	0	197
Total current assets	3,458	3,600
Property, plant and equipment, net	2,650	3,048
Other Assets
Investment in subsidiaries	0	0
Equity investments in affiliates	387	412
Operating lease right-of-use assets, net	517	0
Goodwill	573	573
Intangible assets, net	580	591
Nuclear decommissioning trust fund	718	663
Derivative instruments	347	317
Deferred income tax	45	46
Other non-current assets	255	289
Non-current assets - held-for-sale	0	77
Non-current assets - discontinued operations	0	1,012
Total other assets	3,422	3,980
Total Assets	9,530	10,628
Current Liabilities
Current portion of long-term debt and capital leases	124	72
Current portion of operating lease liabilities	74	0
Accounts payable	697	863
Derivative instruments	489	673
Cash collateral received in support of energy risk management activities	11	33
Accrued expenses and other current liabilities	550	680
Current liabilities - held-for-sale	0	5
Current liabilities - discontinued operations	0	72
Total current liabilities	1,945	2,398
Other Liabilities
Long-term debt and capital leases	6,366	6,449
Non-current operating lease liabilities	529	0
Nuclear decommissioning reserve	286	282
Nuclear decommissioning trust liability	423	371
Derivative instruments	350	304
Deferred income taxes	62	65
Other non-current liabilities	1,089	1,274
Non-current liabilities - held-for-sale	0	65
Non-current liabilities - discontinued operations	0	635
Total other liabilities	9,105	9,445
Total Liabilities	11,050	11,843
Redeemable noncontrolling interest in subsidiaries	18	19
Total Stockholders’ Equity	(1,538)	(1,234)	$ 2,258	$ 1,968
Total Liabilities and Stockholders’ Equity	9,530	10,628
Eliminations
Current Assets
Cash and cash equivalents	0	0
Funds deposited by counterparties	0	0
Restricted cash	0	0
Accounts receivable, net	(688)	(754)
Inventory	0	0
Derivative instruments	(35)	(81)
Cash collateral paid in support of energy risk management activities	0	0
Prepayments and other current assets	0	0
Current assets - held for sale		0
Current assets - discontinued operations		0
Total current assets	(723)	(835)
Property, plant and equipment, net	0	0
Other Assets
Investment in subsidiaries	(4,242)	(5,153)
Equity investments in affiliates	0	0
Operating lease right-of-use assets, net	0
Goodwill	0	0
Intangible assets, net	0	0
Nuclear decommissioning trust fund	0	0
Derivative instruments	(9)	(5)
Deferred income tax	0	0
Other non-current assets	(12)	(12)
Non-current assets - held-for-sale		0
Non-current assets - discontinued operations		0
Total other assets	(4,263)	(5,170)
Total Assets	(4,986)	(6,005)
Current Liabilities
Current portion of long-term debt and capital leases	0	0
Current portion of operating lease liabilities	0
Accounts payable	(688)	(754)
Derivative instruments	(35)	(81)
Cash collateral received in support of energy risk management activities	0	0
Accrued expenses and other current liabilities	0	0
Current liabilities - held-for-sale		0
Current liabilities - discontinued operations		0
Total current liabilities	(723)	(835)
Other Liabilities
Long-term debt and capital leases	(12)	(12)
Non-current operating lease liabilities	0
Nuclear decommissioning reserve	0	0
Nuclear decommissioning trust liability	0	0
Derivative instruments	(9)	(5)
Deferred income taxes	0	0
Other non-current liabilities	0	0
Non-current liabilities - held-for-sale		0
Non-current liabilities - discontinued operations		0
Total other liabilities	(21)	(17)
Total Liabilities	(744)	(852)
Redeemable noncontrolling interest in subsidiaries	0	0
Total Stockholders’ Equity	(4,242)	(5,153)
Total Liabilities and Stockholders’ Equity	(4,986)	(6,005)
Guarantor Subsidiaries
Current Assets
Cash and cash equivalents	0	55
Funds deposited by counterparties	11	33
Restricted cash	12	7
Accounts receivable, net	1,228	1,354
Inventory	277	278
Derivative instruments	610	779
Cash collateral paid in support of energy risk management activities	367	275
Prepayments and other current assets	192	180
Current assets - held for sale		0
Current assets - discontinued operations		177
Total current assets	2,697	3,138
Property, plant and equipment, net	1,512	1,938
Other Assets
Investment in subsidiaries	477	446
Equity investments in affiliates	0	0
Operating lease right-of-use assets, net	95
Goodwill	360	359
Intangible assets, net	414	422
Nuclear decommissioning trust fund	718	663
Derivative instruments	334	296
Deferred income tax	6	6
Other non-current assets	143	133
Non-current assets - held-for-sale		0
Non-current assets - discontinued operations		405
Total other assets	2,547	2,730
Total Assets	6,756	7,806
Current Liabilities
Current portion of long-term debt and capital leases	0	0
Current portion of operating lease liabilities	23
Accounts payable	1,515	1,368
Derivative instruments	505	713
Cash collateral received in support of energy risk management activities	11	33
Accrued expenses and other current liabilities	244	291
Current liabilities - held-for-sale		0
Current liabilities - discontinued operations		24
Total current liabilities	2,298	2,429
Other Liabilities
Long-term debt and capital leases	245	244
Non-current operating lease liabilities	77
Nuclear decommissioning reserve	286	282
Nuclear decommissioning trust liability	423	371
Derivative instruments	354	306
Deferred income taxes	112	112
Other non-current liabilities	408	402
Non-current liabilities - held-for-sale		0
Non-current liabilities - discontinued operations		58
Total other liabilities	1,905	1,775
Total Liabilities	4,203	4,204
Redeemable noncontrolling interest in subsidiaries	0	0
Total Stockholders’ Equity	2,553	3,602
Total Liabilities and Stockholders’ Equity	6,756	7,806
Non-Guarantor Subsidiaries
Current Assets
Cash and cash equivalents	27	28
Funds deposited by counterparties	0	0
Restricted cash	3	10
Accounts receivable, net	199	115
Inventory	114	134
Derivative instruments	21	50
Cash collateral paid in support of energy risk management activities	21	12
Prepayments and other current assets	11	32
Current assets - held for sale		1
Current assets - discontinued operations		20
Total current assets	396	402
Property, plant and equipment, net	987	957
Other Assets
Investment in subsidiaries	0	0
Equity investments in affiliates	387	412
Operating lease right-of-use assets, net	289
Goodwill	213	214
Intangible assets, net	166	169
Nuclear decommissioning trust fund	0	0
Derivative instruments	8	4
Deferred income tax	(145)	(143)
Other non-current assets	30	71
Non-current assets - held-for-sale		77
Non-current assets - discontinued operations		607
Total other assets	948	1,411
Total Assets	2,331	2,770
Current Liabilities
Current portion of long-term debt and capital leases	108	55
Current portion of operating lease liabilities	30
Accounts payable	(218)	(185)
Derivative instruments	19	41
Cash collateral received in support of energy risk management activities	0	0
Accrued expenses and other current liabilities	57	36
Current liabilities - held-for-sale		5
Current liabilities - discontinued operations		48
Total current liabilities	(4)	0
Other Liabilities
Long-term debt and capital leases	112	192
Non-current operating lease liabilities	320
Nuclear decommissioning reserve	0	0
Nuclear decommissioning trust liability	0	0
Derivative instruments	5	3
Deferred income taxes	60	61
Other non-current liabilities	149	320
Non-current liabilities - held-for-sale		65
Non-current liabilities - discontinued operations		577
Total other liabilities	646	1,218
Total Liabilities	642	1,218
Redeemable noncontrolling interest in subsidiaries	18	19
Total Stockholders’ Equity	1,671	1,533
Total Liabilities and Stockholders’ Equity	2,331	2,770
NRG Energy, Inc. (Note Issuer)
Current Assets
Cash and cash equivalents	832	480
Funds deposited by counterparties	0	0
Restricted cash	0	0
Accounts receivable, net	159	309
Inventory	0	0
Derivative instruments	15	16
Cash collateral paid in support of energy risk management activities	0	0
Prepayments and other current assets	82	90
Current assets - held for sale		0
Current assets - discontinued operations		0
Total current assets	1,088	895
Property, plant and equipment, net	151	153
Other Assets
Investment in subsidiaries	3,765	4,707
Equity investments in affiliates	0	0
Operating lease right-of-use assets, net	133
Goodwill	0	0
Intangible assets, net	0	0
Nuclear decommissioning trust fund	0	0
Derivative instruments	14	22
Deferred income tax	184	183
Other non-current assets	94	97
Non-current assets - held-for-sale		0
Non-current assets - discontinued operations		0
Total other assets	4,190	5,009
Total Assets	5,429	6,057
Current Liabilities
Current portion of long-term debt and capital leases	16	17
Current portion of operating lease liabilities	21
Accounts payable	88	434
Derivative instruments	0	0
Cash collateral received in support of energy risk management activities	0	0
Accrued expenses and other current liabilities	249	353
Current liabilities - held-for-sale		0
Current liabilities - discontinued operations		0
Total current liabilities	374	804
Other Liabilities
Long-term debt and capital leases	6,021	6,025
Non-current operating lease liabilities	132
Nuclear decommissioning reserve	0	0
Nuclear decommissioning trust liability	0	0
Derivative instruments	0	0
Deferred income taxes	(110)	(108)
Other non-current liabilities	532	552
Non-current liabilities - held-for-sale		0
Non-current liabilities - discontinued operations		0
Total other liabilities	6,575	6,469
Total Liabilities	6,949	7,273
Redeemable noncontrolling interest in subsidiaries	0	0
Total Stockholders’ Equity	(1,520)	(1,216)
Total Liabilities and Stockholders’ Equity	$ 5,429	$ 6,057

Condensed Consolidating Finan_7

Condensed Consolidating Financial Information - CASH FLOWS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash Flows from Operating Activities
Net Income	$ 482	$ 233
Income/(loss) from discontinued operations	388	(5)
Net income	94	238
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Equity in losses of unconsolidated affiliates	21	(1)
Depreciation, amortization and accretion	92	131
Provision for bad debts	26	15
Amortization of nuclear fuel	13	13
Amortization of financing costs and debt discount/premiums	7	6
Adjustment for debt extinguishment	0	2
Amortization of intangibles and out-of-market contracts	6	9
Amortization of unearned equity compensation	4	6
Loss (gain) on sale of assets	3	(10)
Changes in derivative instruments	(15)	(203)
Changes in deferred income taxes and liability for uncertain tax benefits	(2)	(1)
Changes in collateral deposits in support of energy risk management activities	(123)	163
Changes in nuclear decommissioning trust liability	9	34
Changes in other working capital	(270)	(156)
Cash used by continuing operations	(135)	246
Cash provided/(used) by discontinued operations	8	104
Net Cash Provided/(Used) by Operating Activities	(127)	350
Cash Flows from Investing Activities
Payments for acquisitions of businesses	(16)	(2)
Capital expenditures	(49)	(155)
Proceeds from sale of emission allowances	0	6
Investments in nuclear decommissioning trust fund securities	(122)	(216)
Proceeds from the sale of nuclear decommissioning trust fund securities	113	182
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees	1,313	53
Changes in investments in unconsolidated affiliates	4	(8)
Contributions to discontinued operations	(44)	(29)
Other	(1)	0
Cash (used)/provided by continuing operations	1,198	(169)
Cash used by discontinued operations	(2)	(291)
Net Cash (Used)/Provided by Investing Activities	1,196	(460)
Cash Flows from Financing Activities
Payments (for)/from intercompany loans	0	0
Payments of dividends to common stockholders	(8)	(10)
Payments for treasury stock	(747)	(93)
Distributions to noncontrolling interests from subsidiaries	(1)	(10)
Proceeds from issuance of common stock	2	7
Payment of debt issuance costs	0	(2)
Payments for long-term debt	(37)	(39)
Cash used by continuing operations	(791)	(147)
Cash provided by discontinued operations	43	133
Net Cash Used by Financing Activities	(748)	(14)
Change in Cash from discontinued operations	49	(54)
Net Increase/(Decrease) in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash	272	(70)
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period	613	1,086
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	885	1,016
Eliminations
Cash Flows from Operating Activities
Net Income	(309)	(333)
Income/(loss) from discontinued operations	0	0
Net income	(309)	(333)
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Equity in losses of unconsolidated affiliates	0	0
Depreciation, amortization and accretion	0	0
Provision for bad debts	0	0
Amortization of nuclear fuel	0	0
Amortization of financing costs and debt discount/premiums	0	0
Adjustment for debt extinguishment		0
Amortization of intangibles and out-of-market contracts	0	0
Amortization of unearned equity compensation	0	0
Loss (gain) on sale of assets	0	0
Changes in derivative instruments	0	(17)
Changes in deferred income taxes and liability for uncertain tax benefits	0	0
Changes in collateral deposits in support of energy risk management activities	0	0
Changes in nuclear decommissioning trust liability	0	0
Changes in other working capital	309	350
Cash used by continuing operations	0	0
Cash provided/(used) by discontinued operations	0	0
Net Cash Provided/(Used) by Operating Activities	0	0
Cash Flows from Investing Activities
Payments for acquisitions of businesses	0	0
Capital expenditures	0	0
Proceeds from sale of emission allowances		0
Investments in nuclear decommissioning trust fund securities	0	0
Proceeds from the sale of nuclear decommissioning trust fund securities	0	0
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees	0	0
Changes in investments in unconsolidated affiliates	0	0
Contributions to discontinued operations	0	0
Other	0
Cash (used)/provided by continuing operations	0	0
Cash used by discontinued operations	0	0
Net Cash (Used)/Provided by Investing Activities	0	0
Cash Flows from Financing Activities
Payments (for)/from intercompany loans	0	0
Payments of dividends to common stockholders	0	0
Payments for treasury stock	0	0
Distributions to noncontrolling interests from subsidiaries	0	0
Proceeds from issuance of common stock	0	0
Payment of debt issuance costs		0
Payments for long-term debt	0	0
Cash used by continuing operations	0	0
Cash provided by discontinued operations	0	0
Net Cash Used by Financing Activities	0	0
Change in Cash from discontinued operations	0	0
Net Increase/(Decrease) in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash	0	0
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period	0	0
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	0	0
Guarantor Subsidiaries
Cash Flows from Operating Activities
Net Income	255	331
Income/(loss) from discontinued operations	9	15
Net income	246	316
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Equity in losses of unconsolidated affiliates	0	0
Depreciation, amortization and accretion	59	67
Provision for bad debts	23	15
Amortization of nuclear fuel	13	13
Amortization of financing costs and debt discount/premiums	0	0
Adjustment for debt extinguishment		0
Amortization of intangibles and out-of-market contracts	6	7
Amortization of unearned equity compensation	0	0
Loss (gain) on sale of assets	0	(11)
Changes in derivative instruments	(29)	(203)
Changes in deferred income taxes and liability for uncertain tax benefits	0	113
Changes in collateral deposits in support of energy risk management activities	(114)	162
Changes in nuclear decommissioning trust liability	9	34
Changes in other working capital	(221)	277
Cash used by continuing operations	(8)	790
Cash provided/(used) by discontinued operations	17	32
Net Cash Provided/(Used) by Operating Activities	9	822
Cash Flows from Investing Activities
Payments for acquisitions of businesses	(16)	(2)
Capital expenditures	(36)	(60)
Proceeds from sale of emission allowances		6
Investments in nuclear decommissioning trust fund securities	(122)	(216)
Proceeds from the sale of nuclear decommissioning trust fund securities	113	182
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees	1	11
Changes in investments in unconsolidated affiliates	0	0
Contributions to discontinued operations	0	0
Other	0
Cash (used)/provided by continuing operations	(60)	(79)
Cash used by discontinued operations	0	(1)
Net Cash (Used)/Provided by Investing Activities	(60)	(80)
Cash Flows from Financing Activities
Payments (for)/from intercompany loans	(4)	(481)
Payments of dividends to common stockholders	0	0
Payments for treasury stock	0	0
Distributions to noncontrolling interests from subsidiaries	0	0
Proceeds from issuance of common stock	0	0
Payment of debt issuance costs		0
Payments for long-term debt	0	0
Cash used by continuing operations	(4)	(481)
Cash provided by discontinued operations	0	0
Net Cash Used by Financing Activities	(4)	(481)
Change in Cash from discontinued operations	17	31
Net Increase/(Decrease) in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash	(72)	230
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period	95	41
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	23	271
Non-Guarantor Subsidiaries
Cash Flows from Operating Activities
Net Income	54	(61)
Income/(loss) from discontinued operations	5	(20)
Net income	49	(41)
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Equity in losses of unconsolidated affiliates	21	(2)
Depreciation, amortization and accretion	25	56
Provision for bad debts	3	0
Amortization of nuclear fuel	0	0
Amortization of financing costs and debt discount/premiums	0	0
Adjustment for debt extinguishment		0
Amortization of intangibles and out-of-market contracts	0	2
Amortization of unearned equity compensation	0	0
Loss (gain) on sale of assets	0	1
Changes in derivative instruments	5	2
Changes in deferred income taxes and liability for uncertain tax benefits	1	29
Changes in collateral deposits in support of energy risk management activities	(9)	1
Changes in nuclear decommissioning trust liability	0	0
Changes in other working capital	(137)	(339)
Cash used by continuing operations	(42)	(291)
Cash provided/(used) by discontinued operations	(9)	72
Net Cash Provided/(Used) by Operating Activities	(51)	(219)
Cash Flows from Investing Activities
Payments for acquisitions of businesses	0	0
Capital expenditures	(6)	(74)
Proceeds from sale of emission allowances		0
Investments in nuclear decommissioning trust fund securities	0	0
Proceeds from the sale of nuclear decommissioning trust fund securities	0	0
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees	404	0
Changes in investments in unconsolidated affiliates	4	(8)
Contributions to discontinued operations	(44)	(29)
Other	0
Cash (used)/provided by continuing operations	358	(111)
Cash used by discontinued operations	(2)	(290)
Net Cash (Used)/Provided by Investing Activities	356	(401)
Cash Flows from Financing Activities
Payments (for)/from intercompany loans	(290)	417
Payments of dividends to common stockholders	0	0
Payments for treasury stock	0	0
Distributions to noncontrolling interests from subsidiaries	(1)	(10)
Proceeds from issuance of common stock	0	0
Payment of debt issuance costs		0
Payments for long-term debt	(33)	(34)
Cash used by continuing operations	(324)	373
Cash provided by discontinued operations	43	133
Net Cash Used by Financing Activities	(281)	506
Change in Cash from discontinued operations	32	(85)
Net Increase/(Decrease) in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash	(8)	(29)
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period	38	425
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	30	396
NRG Energy, Inc. (Note Issuer)
Cash Flows from Operating Activities
Net Income	482	296
Income/(loss) from discontinued operations	374	0
Net income	108	296
Adjustments to reconcile net income to net cash provided/(used) by operating activities:
Equity in losses of unconsolidated affiliates	0	1
Depreciation, amortization and accretion	8	8
Provision for bad debts	0	0
Amortization of nuclear fuel	0	0
Amortization of financing costs and debt discount/premiums	7	6
Adjustment for debt extinguishment		2
Amortization of intangibles and out-of-market contracts	0	0
Amortization of unearned equity compensation	4	6
Loss (gain) on sale of assets	3	0
Changes in derivative instruments	9	15
Changes in deferred income taxes and liability for uncertain tax benefits	(3)	(143)
Changes in collateral deposits in support of energy risk management activities	0	0
Changes in nuclear decommissioning trust liability	0	0
Changes in other working capital	(221)	(444)
Cash used by continuing operations	(85)	(253)
Cash provided/(used) by discontinued operations	0	0
Net Cash Provided/(Used) by Operating Activities	(85)	(253)
Cash Flows from Investing Activities
Payments for acquisitions of businesses	0	0
Capital expenditures	(7)	(21)
Proceeds from sale of emission allowances		0
Investments in nuclear decommissioning trust fund securities	0	0
Proceeds from the sale of nuclear decommissioning trust fund securities	0	0
Proceeds from sale of assets, net of cash disposed and sale of discontinued operations, net of fees	908	42
Changes in investments in unconsolidated affiliates	0	0
Contributions to discontinued operations	0	0
Other	(1)
Cash (used)/provided by continuing operations	900	21
Cash used by discontinued operations	0	0
Net Cash (Used)/Provided by Investing Activities	900	21
Cash Flows from Financing Activities
Payments (for)/from intercompany loans	294	64
Payments of dividends to common stockholders	(8)	(10)
Payments for treasury stock	(747)	(93)
Distributions to noncontrolling interests from subsidiaries	0	0
Proceeds from issuance of common stock	2	7
Payment of debt issuance costs		(2)
Payments for long-term debt	(4)	(5)
Cash used by continuing operations	(463)	(39)
Cash provided by discontinued operations	0	0
Net Cash Used by Financing Activities	(463)	(39)
Change in Cash from discontinued operations	0	0
Net Increase/(Decrease) in Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash	352	(271)
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at Beginning of Period	480	620
Cash and Cash Equivalents, Funds Deposited by Counterparties and Restricted Cash at End of Period	$ 832	$ 349