Condensed Consolidated Statements of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Operating Revenues
Total operating revenues	$ 2,929	$ 2,166	$ 5,010	$ 4,028
Operating Costs and Expenses
Cost of operations	2,059	1,337	3,824	2,920
Depreciation and amortization	305	234	603	464
Selling, general and administrative	213	183	442	389
Acquisition-related transaction and integration costs	37	0	69	0
Development activity expenses	20	15	36	28
Total operating costs and expenses	2,634	1,769	4,974	3,801
Operating Income	295	397	36	227
Other Income/(Expense)
Equity in earnings of unconsolidated affiliates	8	14	11	22
Other income, net	0	2	4	3
Loss on debt extinguishment	(21)	0	(49)	0
Interest expense	(206)	(167)	(402)	(332)
Total other expense	(219)	(151)	(436)	(307)
Income/(Loss) Before Income Taxes	76	246	(400)	(80)
Income tax benefit	(61)	(13)	(210)	(133)
Net Income/(Loss)	137	259	(190)	53
Less: Net income attributable to noncontrolling interest	7	8	8	9
Net Income/(Loss) Attributable to NRG Energy, Inc.	130	251	(198)	44
Dividends for preferred shares	3	3	5	5
Income/(Loss) Available for Common Stockholders	$ 127	$ 248	$ (203)	$ 39
Earnings/(Loss) Per Share Attributable to NRG Energy, Inc. Common Stockholders
Weighted average number of common shares outstanding	323	228	323	228
Earnings/(Loss) per Weighted Average Common Share — Basic	$ 0.39	$ 1.09	$ (0.63)	$ 0.17
Weighted average number of shares outstanding, diluted	327	229	323	229
Net loss per weighted average common share — diluted	$ 0.39	$ 1.08	$ (0.63)	$ 0.17
Dividends Per Common Share	$ 0.12	$ 0.00	$ 0.21	$ 0.00