Condensed Consolidated Statements of Operations (USD $) In Millions, except Per Share data	3 Months Ended			9 Months Ended
	Sep. 30, 2011	Jun. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Operating Revenues
Total operating revenues	$ 2,674		$ 2,685	$ 6,947	$ 7,033
Operating Costs and Expenses
Cost of operations	2,053		1,835	4,985	4,803
Depreciation and amortization	238		210	665	620
Impairment of Long-Lived Assets Held-for-use	160		0	160	0
Selling, general and administrative	169		172	479	441
Development costs	11		14	32	36
Total operating costs and expenses	2,631		2,231	6,321	5,900
Gain on sale of assets	0		0	0	23
Operating Income/(Loss)	43		454	626	1,156
Other Income/(Expense)
Equity in earnings of unconsolidated affiliates	16		16	26	41
Impairment charge on investment	(3)	(11)	0	(495)	0
Other income, net	5		11	13	34
Loss on debt extinguishment	(32)		(1)	(175)	(2)
Interest expense	(164)		(168)	(504)	(467)
Total other (expense)/income	(178)		(142)	(1,135)	(394)
(Loss)/Income Before Income Taxes	(135)		312	(509)	762
Income tax (benefit)/expense	(80)		89	(815)	271
Net Income	(55)		223	306	491
Less: Net loss attributable to noncontrolling interest	0		0	0	(1)
Net Income attributable to NRG Energy, Inc.	(55)		223	306	492
Dividends for preferred shares	2		2	7	7
Income available for common stockholders	$ (57)		$ 221	$ 299	$ 485
Earnings per share attributable to NRG Energy, Inc. Common Stockholders
Weighted average number of common shares outstanding - basic (in shares)	240		252	243	254
Net income per weighted average common share - basic (in dollars per share)	$ (0.24)		$ 0.88	$ 1.23	$ 1.91
Weighted average number of common shares outstanding - diluted (in shares)	240		253	245	255
Net income per weighted average common share - diluted (in dollars per share)	$ (0.24)		$ 0.87	$ 1.22	$ 1.90