Guarantees Of Debt (Schedule Of Financial Statements Of Guarantors) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Operating Revenues	$ 2,402	$ 2,620	$ 7,375	$ 8,443
Operating Expenses	1,808	2,064	5,565	6,410
Operating Income (Loss)	594	556	1,810	2,033
Equity Earnings (Losses) of Subsidiaries	7	1	9	8
Other Income	121	45	216	176
Other Deductions	(26)	(11)	(61)	(39)
Other-Than-Temporary Impairments	(2)	(8)	(14)	(13)
Interest Expense	(106)	(117)	(310)	(361)
Income Tax Benefit (Expense)	(241)	(201)	(599)	(757)
Income (Loss) on Discontinued Operations, net of tax	0	29	0	96
Net Income	347	294	1,051	1,143
Net Cash Provided By (Used In) Operating Activities			2,311	2,409
Net Cash Provided By (Used In) Investing Activities			(2,051)	(827)
Net Cash Provided By (Used In) Financing Activities			(314)	(620)
Current Assets	3,978		3,978		3,911
Property, Plant and Equipment, net	19,103		19,103		17,849
Noncurrent Assets	7,625		7,625		8,061
Total Assets	30,706	29,821	30,706	29,821	29,821
Current Liabilities	3,039		3,039		2,957
Noncurrent Liabilities	9,525		9,525		9,131
Long-Term Debt	7,334		7,334		7,461
Member's Equity	10,808		10,808		10,272
TOTAL LIABILITIES AND CAPITALIZATION	30,706		30,706		29,821
Power [Member]
Operating Revenues	1,038	1,398	3,584	4,650
Operating Expenses	771	915	2,680	3,311
Operating Income (Loss)	267	483	904	1,339
Equity Earnings (Losses) of Subsidiaries	0	0	0	0
Other Income	104	37	171	156
Other Deductions	(20)	(10)	(52)	(37)
Other-Than-Temporary Impairments	(2)	(8)	(14)	(10)
Interest Expense	(35)	(42)	(97)	(134)
Income Tax Benefit (Expense)	(133)	(187)	(374)	(539)
Income (Loss) on Discontinued Operations, net of tax		29		96
Net Income	181	302	538	871
Comprehensive Income (Loss)	166	222	549	759
Net Cash Provided By (Used In) Operating Activities			1,172	1,487
Net Cash Provided By (Used In) Investing Activities			(506)	(1,018)
Net Cash Provided By (Used In) Financing Activities			(673)	(466)
Current Assets	2,381		2,381		2,687
Property, Plant and Equipment, net	6,872		6,872		6,731
Investment in Subsidiaries	0		0		0
Noncurrent Assets	1,741		1,741		1,669
Total Assets	10,994		10,994		11,087
Current Liabilities	927		927		902
Noncurrent Liabilities	2,288		2,288		2,056
Long-Term Debt	2,386		2,386		2,685
Member's Equity	5,393		5,393		5,444
TOTAL LIABILITIES AND CAPITALIZATION	10,994		10,994		11,087
Power [Member] | Guarantor Subsidiaries [Member]
Operating Revenues	1,358	1,725	4,560	5,622
Operating Expenses	1,095	1,241	3,663	4,278
Operating Income (Loss)	263	484	897	1,344
Equity Earnings (Losses) of Subsidiaries	0	29	(4)	88
Other Income	106	38	176	159
Other Deductions	(20)	(8)	(45)	(32)
Other-Than-Temporary Impairments	(2)	(9)	(14)	(10)
Interest Expense	(15)	(17)	(35)	(38)
Income Tax Benefit (Expense)	(142)	(200)	(409)	(592)
Income (Loss) on Discontinued Operations, net of tax		0		0
Net Income	190	317	566	919
Comprehensive Income (Loss)	168	233	556	761
Net Cash Provided By (Used In) Operating Activities			1,259	2,029
Net Cash Provided By (Used In) Investing Activities			(897)	(935)
Net Cash Provided By (Used In) Financing Activities			(368)	(1,091)
Current Assets	7,926		7,926		7,248
Property, Plant and Equipment, net	5,835		5,835		5,715
Investment in Subsidiaries	740		740		804
Noncurrent Assets	1,631		1,631		1,557
Total Assets	16,132		16,132		15,324
Current Liabilities	10,183		10,183		9,549
Noncurrent Liabilities	1,754		1,754		1,589
Long-Term Debt	0		0		0
Member's Equity	4,195		4,195		4,186
TOTAL LIABILITIES AND CAPITALIZATION	16,132		16,132		15,324
Power [Member] | Other Subsidiaries [Member]
Operating Revenues	36	29	93	106
Operating Expenses	32	29	87	109
Operating Income (Loss)	4	0	6	(3)
Equity Earnings (Losses) of Subsidiaries	0	0	0	0
Other Income	0	0	0	0
Other Deductions	0	0	0	0
Other-Than-Temporary Impairments	0	0	0	0
Interest Expense	(5)	(3)	(13)	(13)
Income Tax Benefit (Expense)	1	1	3	6
Income (Loss) on Discontinued Operations, net of tax		29		96
Net Income	0	27	(4)	86
Comprehensive Income (Loss)	0	27	(4)	86
Net Cash Provided By (Used In) Operating Activities			(3)	(319)
Net Cash Provided By (Used In) Investing Activities			(24)	652
Net Cash Provided By (Used In) Financing Activities			26	(332)
Current Assets	919		919		951
Property, Plant and Equipment, net	948		948		950
Investment in Subsidiaries	0		0		0
Noncurrent Assets	62		62		51
Total Assets	1,929		1,929		1,952
Current Liabilities	984		984		1,003
Noncurrent Liabilities	204		204		145
Long-Term Debt	0		0		0
Member's Equity	741		741		804
TOTAL LIABILITIES AND CAPITALIZATION	1,929		1,929		1,952
Power [Member] | Consolidating Adjustments [Member]
Operating Revenues	(356)	(356)	(1,069)	(1,078)
Operating Expenses	(355)	(356)	(1,069)	(1,078)
Operating Income (Loss)	(1)	0	0	0
Equity Earnings (Losses) of Subsidiaries	(191)	(344)	(563)	(1,005)
Other Income	(13)	(10)	(40)	(31)
Other Deductions	0	(1)	0	(1)
Other-Than-Temporary Impairments	0	0	0	0
Interest Expense	14	11	40	32
Income Tax Benefit (Expense)	1	0	1	0
Income (Loss) on Discontinued Operations, net of tax		0		0
Net Income	(190)	(344)	(562)	(1,005)
Comprehensive Income (Loss)	(168)	(260)	(552)	(847)
Net Cash Provided By (Used In) Operating Activities			(493)	(593)
Net Cash Provided By (Used In) Investing Activities			158	(821)
Net Cash Provided By (Used In) Financing Activities			335	1,413
Current Assets	(10,646)		(10,646)		(9,823)
Property, Plant and Equipment, net	1		1		0
Investment in Subsidiaries	(4,933)		(4,933)		(4,989)
Noncurrent Assets	(127)		(127)		(118)
Total Assets	(15,705)		(15,705)		(14,930)
Current Liabilities	(10,643)		(10,643)		(9,822)
Noncurrent Liabilities	(126)		(126)		(118)
Long-Term Debt	0		0		0
Member's Equity	(4,936)		(4,936)		(4,990)
TOTAL LIABILITIES AND CAPITALIZATION	(15,705)		(15,705)		(14,930)
Power Parent [Member] | Power [Member]
Operating Revenues	0	0	0	0
Operating Expenses	(1)	1	(1)	2
Operating Income (Loss)	1	(1)	1	(2)
Equity Earnings (Losses) of Subsidiaries	191	315	567	917
Other Income	11	9	35	28
Other Deductions	0	(1)	(7)	(4)
Other-Than-Temporary Impairments	0	1	0	0
Interest Expense	(29)	(33)	(89)	(115)
Income Tax Benefit (Expense)	7	12	31	47
Income (Loss) on Discontinued Operations, net of tax		0		0
Net Income	181	302	538	871
Comprehensive Income (Loss)	166	222	549	759
Net Cash Provided By (Used In) Operating Activities			409	370
Net Cash Provided By (Used In) Investing Activities			257	86
Net Cash Provided By (Used In) Financing Activities			(666)	(456)
Current Assets	4,182		4,182		4,311
Property, Plant and Equipment, net	88		88		66
Investment in Subsidiaries	4,193		4,193		4,185
Noncurrent Assets	175		175		179
Total Assets	8,638		8,638		8,741
Current Liabilities	403		403		172
Noncurrent Liabilities	456		456		440
Long-Term Debt	2,386		2,386		2,685
Member's Equity	5,393		5,393		5,444
TOTAL LIABILITIES AND CAPITALIZATION	$ 8,638		$ 8,638		$ 8,741