Condensed Consolidated Statements of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 15, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Operating Revenues
Total operating revenues		$ 2,331	$ 2,674	$ 6,359	$ 6,947
Operating Costs and Expenses
Cost of operations		1,726	2,053	4,618	4,985
Depreciation and amortization		239	238	703	665
Impairment charge on emission allowances		0	160	0	160
Selling, general and administrative		253	169	681	479
Acquisition-related transactions and integration costs		18	0	18	0
Development costs		9	11	26	32
Total operating costs and expenses		2,245	2,631	6,046	6,321
Operating Income		86	43	313	626
Other Income/(Expense)
Equity in earnings of unconsolidated affiliates		4	16	26	26
Impairment charge on investment		(1)	(3)	(2)	(495)
Other income, net		10	5	14	13
Loss on debt extinguishment		(41)	(32)	(41)	(175)
Interest expense		(163)	(164)	(495)	(504)
Total other expense		(191)	(178)	(498)	(1,135)
Income/(Loss) Before Income Taxes		(105)	(135)	(185)	(509)
Income tax expense		(113)	(80)	(246)	(815)
Net Income/(Loss)		8	(55)	61	306
Less: Net income attributable to noncontrolling interest		9	0	18	0
Net (loss)/Income attributable to NRG Energy, Inc.		(1)	(55)	43	306
Dividends for preferred shares		2	2	7	7
(Loss)/Income available for common stockholders		$ (3)	$ (57)	$ 36	$ 299
(Loss)/Earnings per share attributable to NRG Energy, Inc. Common Stockholders
Weighted average number of common shares outstanding, basic		228	240	228	243
Net (loss)/income per weighted average common share - basic		$ (0.01)	$ (0.24)	$ 0.16	$ 1.23
Weighted average number of common shares outstanding-diluted		228	240	230	245
Net (loss)/income per weighted average common share - diluted		$ (0.01)	$ (0.24)	$ 0.16	$ 1.22
Dividends Per Common Share	$ 0.09	$ 0.09	$ 0.00	$ 0.09	$ 0.00