Guarantees Of Debt (Schedule Of Financial Statements Of Guarantors) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Operating Revenues	$ 2,098	$ 2,469	$ 4,973	$ 5,823
Operating Expenses	1,665	1,848	3,757	4,346
Operating Income (Loss)	433	621	1,216	1,477
Equity Earnings (Losses) of Subsidiaries	2	4	2	7
Other Income	51	55	95	131
Other Deductions	(19)	(15)	(35)	(28)
Other-Than-Temporary Impairments	(7)	(1)	(12)	(5)
Interest Expense	(103)	(117)	(204)	(244)
Income Tax Benefit (Expense)	(146)	(227)	(358)	(556)
Income (Loss) on Discontinued Operations, net of tax	0	3	0	67
Net Income	211	323	704	849
Net Cash Provided By (Used In) Operating Activities			1,378	1,395
Net Cash Provided By (Used In) Investing Activities			(1,339)	(673)
Current Assets	3,940		3,940		3,911
Net Cash Provided By (Used In) Financing Activities			(108)	(843)
Property, Plant and Equipment, net	18,590		18,590		17,849
Noncurrent Assets	7,612		7,612		8,061
Total Assets	30,142	29,821	30,142	29,821	29,821
Current Liabilities	2,816		2,816		2,957
Noncurrent Liabilities	9,344		9,344		9,131
Long-Term Debt	7,336		7,336		7,461
Member's Equity	10,646		10,646		10,272
TOTAL LIABILITIES AND CAPITALIZATION	30,142		30,142		29,821
Power [Member]
Operating Revenues	985	1,285	2,546	3,252
Operating Expenses	789	930	1,909	2,396
Operating Income (Loss)	196	355	637	856
Equity Earnings (Losses) of Subsidiaries	0	0	0	0
Other Income	37	49	67	119
Other Deductions	(17)	(14)	(32)	(26)
Other-Than-Temporary Impairments	(7)	(1)	(12)	(3)
Interest Expense	(32)	(41)	(62)	(92)
Income Tax Benefit (Expense)	(73)	(143)	(241)	(352)
Income (Loss) on Discontinued Operations, net of tax		3		67
Net Income	104	208	357	569
Net Cash Provided By (Used In) Operating Activities			852	1,146
Net Cash Provided By (Used In) Investing Activities			(189)	(181)
Current Assets	2,294		2,294		2,687
Net Cash Provided By (Used In) Financing Activities			(673)	(962)
Property, Plant and Equipment, net	6,793		6,793		6,731
Investment in Subsidiaries	0		0		0
Noncurrent Assets	1,662		1,662		1,669
Total Assets	10,749		10,749		11,087
Current Liabilities	890		890		902
Noncurrent Liabilities	2,246		2,246		2,056
Long-Term Debt	2,386		2,386		2,685
Member's Equity	5,227		5,227		5,444
TOTAL LIABILITIES AND CAPITALIZATION	10,749		10,749		11,087
Power [Member] | Guarantor Subsidiaries [Member]
Operating Revenues	1,329	1,619	3,202	3,897
Operating Expenses	1,135	1,263	2,568	3,037
Operating Income (Loss)	194	356	634	860
Equity Earnings (Losses) of Subsidiaries	(1)	0	(4)	59
Other Income	39	50	70	121
Other Deductions	(17)	(14)	(25)	(23)
Other-Than-Temporary Impairments	(7)	(1)	(12)	(2)
Interest Expense	(10)	(11)	(20)	(21)
Income Tax Benefit (Expense)	(82)	(160)	(267)	(392)
Income (Loss) on Discontinued Operations, net of tax		0		0
Net Income	116	220	376	602
Net Cash Provided By (Used In) Operating Activities			902	1,400
Net Cash Provided By (Used In) Investing Activities			(601)	(674)
Current Assets	7,718		7,718		7,248
Net Cash Provided By (Used In) Financing Activities			(310)	(725)
Property, Plant and Equipment, net	5,765		5,765		5,715
Investment in Subsidiaries	740		740		804
Noncurrent Assets	1,534		1,534		1,557
Total Assets	15,757		15,757		15,324
Current Liabilities	9,896		9,896		9,549
Noncurrent Liabilities	1,737		1,737		1,589
Long-Term Debt	0		0		0
Member's Equity	4,124		4,124		4,186
TOTAL LIABILITIES AND CAPITALIZATION	15,757		15,757		15,324
Power [Member] | Other Subsidiaries [Member]
Operating Revenues	31	27	57	77
Operating Expenses	28	28	55	80
Operating Income (Loss)	3	(1)	2	(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	(4)	(4)	(8)	(10)
Income Tax Benefit (Expense)	0	2	2	5
Income (Loss) on Discontinued Operations, net of tax		3		67
Net Income	(1)	0	(4)	59
Net Cash Provided By (Used In) Operating Activities			3	(148)
Net Cash Provided By (Used In) Investing Activities			(23)	317
Current Assets	906		906		951
Net Cash Provided By (Used In) Financing Activities			19	(168)
Property, Plant and Equipment, net	957		957		950
Investment in Subsidiaries	0		0		0
Noncurrent Assets	62		62		51
Total Assets	1,925		1,925		1,952
Current Liabilities	1,011		1,011		1,003
Noncurrent Liabilities	173		173		145
Long-Term Debt	0		0		0
Member's Equity	741		741		804
TOTAL LIABILITIES AND CAPITALIZATION	1,925		1,925		1,952
Power [Member] | Consolidating Adjustments [Member]
Operating Revenues	(375)	(361)	(713)	(722)
Operating Expenses	(376)	(360)	(714)	(722)
Operating Income (Loss)	1	(1)	1	0
Equity Earnings (Losses) of Subsidiaries	(115)	(220)	(372)	(661)
Other Income	(13)	(10)	(27)	(21)
Other Deductions	0	0	0	0
Other-Than-Temporary Impairments	0	0	0	0
Interest Expense	13	10	26	21
Income Tax Benefit (Expense)	(1)	1	0	0
Income (Loss) on Discontinued Operations, net of tax		0		0
Net Income	(115)	(220)	(372)	(661)
Net Cash Provided By (Used In) Operating Activities			(354)	(473)
Net Cash Provided By (Used In) Investing Activities			70	(413)
Current Assets	(10,401)		(10,401)		(9,823)
Net Cash Provided By (Used In) Financing Activities			284	887
Property, Plant and Equipment, net	0		0		0
Investment in Subsidiaries	(4,864)		(4,864)		(4,989)
Noncurrent Assets	(123)		(123)		(118)
Total Assets	(15,388)		(15,388)		(14,930)
Current Liabilities	(10,402)		(10,402)		(9,822)
Noncurrent Liabilities	(122)		(122)		(118)
Long-Term Debt	0		0		0
Member's Equity	(4,864)		(4,864)		(4,990)
TOTAL LIABILITIES AND CAPITALIZATION	(15,388)		(15,388)		(14,930)
Power Parent [Member] | Power [Member]
Operating Revenues	0	0	0	0
Operating Expenses	2	(1)	0	1
Operating Income (Loss)	(2)	1	0	(1)
Equity Earnings (Losses) of Subsidiaries	116	220	376	602
Other Income	11	9	24	19
Other Deductions	0	0	(7)	(3)
Other-Than-Temporary Impairments	0	0	0	(1)
Interest Expense	(31)	(36)	(60)	(82)
Income Tax Benefit (Expense)	10	14	24	35
Income (Loss) on Discontinued Operations, net of tax		0		0
Net Income	104	208	357	569
Net Cash Provided By (Used In) Operating Activities			301	367
Net Cash Provided By (Used In) Investing Activities			365	589
Current Assets	4,071		4,071		4,311
Net Cash Provided By (Used In) Financing Activities			(666)	(956)
Property, Plant and Equipment, net	71		71		66
Investment in Subsidiaries	4,124		4,124		4,185
Noncurrent Assets	189		189		179
Total Assets	8,455		8,455		8,741
Current Liabilities	385		385		172
Noncurrent Liabilities	458		458		440
Long-Term Debt	2,386		2,386		2,685
Member's Equity	5,226		5,226		5,444
TOTAL LIABILITIES AND CAPITALIZATION	$ 8,455		$ 8,455		$ 8,741