Condensed Consolidating Financial Information (Details 3) (USD $) In Millions	Sep. 30, 2011		Dec. 31, 2010		Sep. 30, 2010		Dec. 31, 2009
Current Assets
Cash and cash equivalents	$ 1,127		$ 2,951		$ 3,447		$ 2,304
Funds deposited by counterparties	259		408
Restricted cash	441		8
Accounts receivable-trade, net	1,042		734
Inventory	320		453
Derivative instruments valuation	2,588		1,964
Cash collateral paid in support of energy risk management activities	316		323
Prepayments and other current assets	245		296
Total current assets	6,338		7,137
Net property, plant and equipment	12,843		12,517
Other Assets
Investment in subsidiaries	0		0
Equity investments in affiliates	576		536
Note receivable - affiliate and capital leases, less current portion	327		384
Goodwill	1,859		1,868
Intangible assets, net	1,561		1,776
Nuclear decommissioning trust fund	399		412
Derivative instruments valuation	533		758
Restricted cash supporting Funded Letter of Credit Facility	0		1,300
Other non-current assets	324		208
Total other assets	5,579		7,242
Total Assets	24,760		26,896
Current Liabilities
Current portion of long-term debt and capital leases	81		463
Accounts payable	974		783
Derivative instruments valuation	2,089		1,685
Deferred income taxes	65		108
Cash collateral received in support of energy risk management activities	259		408
Accrued expenses and other current liabilities	527		773
Total current liabilities	3,995		4,220
Other Liabilities
Long-term debt and capital leases	9,208		8,748
Funded letter of credit	0	[1]	1,300	[1]
Nuclear decommissioning reserve	331		317
Nuclear decommissioning trust liability	237		272
Deferred income taxes	1,588		1,989
Derivative instruments valuation	408		365
Out-of-market contracts	191		223
Other non-current liabilities	622		1,142
Total non-current liabilities	12,585		14,356
Total Liabilities	16,580		18,576
3.625% Preferred Stock	248		248
Total Stockholders' Equity	7,932		8,072
Total Liabilities and Stockholders' Equity	24,760		26,896
Guarantor Subsidiaries
Current Assets
Cash and cash equivalents	16		168		25		20
Funds deposited by counterparties	259		408
Restricted cash	57		2
Accounts receivable-trade, net	995		693
Inventory	311		445
Derivative instruments valuation	2,588		1,964
Cash collateral paid in support of energy risk management activities	316		321
Prepayments and other current assets	116		112
Total current assets	4,658		4,113
Net property, plant and equipment	10,545		10,816
Other Assets
Investment in subsidiaries	220		811
Equity investments in affiliates	37		47
Note receivable - affiliate and capital leases, less current portion	0		6,507
Goodwill	1,859		1,868
Intangible assets, net	1,284		1,716
Nuclear decommissioning trust fund	399		412
Derivative instruments valuation	533		758
Restricted cash supporting Funded Letter of Credit Facility			0
Other non-current assets	51		42
Total other assets	4,383		12,161
Total Assets	19,586		27,090
Current Liabilities
Current portion of long-term debt and capital leases	1,150		1,150
Accounts payable	(6)		(2,665)
Derivative instruments valuation	2,086		1,665
Deferred income taxes	504		515
Cash collateral received in support of energy risk management activities	259		408
Accrued expenses and other current liabilities	339		399
Total current liabilities	4,332		1,472
Other Liabilities
Long-term debt and capital leases	242		1,857
Funded letter of credit			0
Nuclear decommissioning reserve	331		317
Nuclear decommissioning trust liability	237		272
Deferred income taxes	1,441		1,464
Derivative instruments valuation	326		294
Out-of-market contracts	216		248
Other non-current liabilities	493		504
Total non-current liabilities	3,286		4,956
Total Liabilities	7,618		6,428
3.625% Preferred Stock	0		0
Total Stockholders' Equity	11,968		20,662
Total Liabilities and Stockholders' Equity	19,586		27,090
Non-Guarantor Subsidiaries
Current Assets
Cash and cash equivalents	108		111		119		120
Funds deposited by counterparties	0		0
Restricted cash	322		6
Accounts receivable-trade, net	47		38
Inventory	9		8
Derivative instruments valuation	0		0
Cash collateral paid in support of energy risk management activities	0		2
Prepayments and other current assets	34		60
Total current assets	520		225
Net property, plant and equipment	2,254		1,515
Other Assets
Investment in subsidiaries	481		248
Equity investments in affiliates	539		489
Note receivable - affiliate and capital leases, less current portion	327		380
Goodwill	0		0
Intangible assets, net	84		58
Nuclear decommissioning trust fund	0		0
Derivative instruments valuation	0		0
Restricted cash supporting Funded Letter of Credit Facility			1,300
Other non-current assets	61		22
Total other assets	1,492		2,497
Total Assets	4,266		4,237
Current Liabilities
Current portion of long-term debt and capital leases	65		223
Accounts payable	326		229
Derivative instruments valuation	3		3
Deferred income taxes	(51)		(51)
Cash collateral received in support of energy risk management activities	0		0
Accrued expenses and other current liabilities	30		34
Total current liabilities	373		438
Other Liabilities
Long-term debt and capital leases	1,620		991
Funded letter of credit			0
Nuclear decommissioning reserve	0		0
Nuclear decommissioning trust liability	0		0
Deferred income taxes	272		279
Derivative instruments valuation	52		34
Out-of-market contracts	6		6
Other non-current liabilities	45		29
Total non-current liabilities	1,995		1,339
Total Liabilities	2,368		1,777
3.625% Preferred Stock	0		0
Total Stockholders' Equity	1,898		2,460
Total Liabilities and Stockholders' Equity	4,266		4,237
NRG Energy, Inc.
Current Assets
Cash and cash equivalents	1,003		2,672		3,303		2,164
Funds deposited by counterparties	0		0
Restricted cash	62		0
Accounts receivable-trade, net	0		3
Inventory	0		0
Derivative instruments valuation	0		0
Cash collateral paid in support of energy risk management activities	0		0
Prepayments and other current assets	1,303		1,313
Total current assets	2,368		3,988
Net property, plant and equipment	61		186
Other Assets
Investment in subsidiaries	12,978		22,046
Equity investments in affiliates	0		0
Note receivable - affiliate and capital leases, less current portion	311		2,130
Goodwill	0		0
Intangible assets, net	231		33
Nuclear decommissioning trust fund	0		0
Derivative instruments valuation	0		0
Restricted cash supporting Funded Letter of Credit Facility			0
Other non-current assets	213		144
Total other assets	13,733		24,353
Total Assets	16,162		28,527
Current Liabilities
Current portion of long-term debt and capital leases	16		240
Accounts payable	654		3,219
Derivative instruments valuation	0		17
Deferred income taxes	(388)		(356)
Cash collateral received in support of energy risk management activities	0		0
Accrued expenses and other current liabilities	216		379
Total current liabilities	498		3,499
Other Liabilities
Long-term debt and capital leases	7,657		14,533
Funded letter of credit			1,300
Nuclear decommissioning reserve	0		0
Nuclear decommissioning trust liability	0		0
Deferred income taxes	(125)		246
Derivative instruments valuation	30		37
Out-of-market contracts	0		0
Other non-current liabilities	84		609
Total non-current liabilities	7,646		16,725
Total Liabilities	8,144		20,224
3.625% Preferred Stock	248		248
Total Stockholders' Equity	7,770		8,055
Total Liabilities and Stockholders' Equity	16,162		28,527
Eliminations
Current Assets
Cash and cash equivalents	0	[2]	0	[2]	0	[2]	0	[2]
Funds deposited by counterparties	0	[2]	0	[2]
Restricted cash	0	[2]	0	[2]
Accounts receivable-trade, net	0	[2]	0	[2]
Inventory	0	[2]	0	[2]
Derivative instruments valuation	0	[2]	0	[2]
Cash collateral paid in support of energy risk management activities	0	[2]	0	[2]
Prepayments and other current assets	(1,208)	[2]	(1,189)	[2]
Total current assets	(1,208)	[2]	(1,189)	[2]
Net property, plant and equipment	(17)	[2]	0	[2]
Other Assets
Investment in subsidiaries	(13,679)	[2]	(23,105)	[2]
Equity investments in affiliates	0	[2]	0	[2]
Note receivable - affiliate and capital leases, less current portion	(311)	[2]	(8,633)	[2]
Goodwill	0	[2]	0	[2]
Intangible assets, net	(38)	[2]	(31)	[2]
Nuclear decommissioning trust fund	0	[2]	0	[2]
Derivative instruments valuation	0	[2]	0	[2]
Restricted cash supporting Funded Letter of Credit Facility			0	[2]
Other non-current assets	(1)	[2]	0	[2]
Total other assets	(14,029)	[2]	(31,769)	[2]
Total Assets	(15,254)	[2]	(32,958)	[2]
Current Liabilities
Current portion of long-term debt and capital leases	(1,150)	[2]	(1,150)	[2]
Accounts payable	0	[2]	0	[2]
Derivative instruments valuation	0	[2]	0	[2]
Deferred income taxes	0	[2]	0	[2]
Cash collateral received in support of energy risk management activities	0	[2]	0	[2]
Accrued expenses and other current liabilities	(58)	[2]	(39)	[2]
Total current liabilities	(1,208)	[2]	(1,189)	[2]
Other Liabilities
Long-term debt and capital leases	(311)	[2]	(8,633)	[2]
Funded letter of credit			0	[2]
Nuclear decommissioning reserve	0	[2]	0	[2]
Nuclear decommissioning trust liability	0	[2]	0	[2]
Deferred income taxes	0	[2]	0	[2]
Derivative instruments valuation	0	[2]	0	[2]
Out-of-market contracts	(31)	[2]	(31)	[2]
Other non-current liabilities	0	[2]	0	[2]
Total non-current liabilities	(342)	[2]	(8,664)	[2]
Total Liabilities	(1,550)	[2]	(9,853)	[2]
3.625% Preferred Stock	0	[2]	0	[2]
Total Stockholders' Equity	(13,704)	[2]	(23,105)	[2]
Total Liabilities and Stockholders' Equity	$ (15,254)	[2]	$ (32,958)	[2]

[1] On July 1, 2011, the Term loan facility, due 2013-2015 and Funded letter of credit were repaid and replaced, as described below under Senior Credit Facility.

[2] All significant intercompany transactions have been eliminated in consolidation.