Guarantees Of Debt (Schedule Of Financial Statements Of Guarantors) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Operating Revenues	$ 3,223	$ 2,786
Operating Expenses	2,518	2,176
Operating Income (Loss)	705	610
Equity Earnings (Losses) of Subsidiaries	4	2
Other Income	48	61
Other Deductions	(12)	(29)
Other-Than-Temporary Impairments	(2)	(2)
Interest Expense	(97)	(102)
Income Tax Expense	(260)	(220)
Net Income	386	320
Net Cash Provided By (Used In) Operating Activities	1,116	877
Net Cash Provided By (Used In) Investing Activities	(629)	(733)
Net Cash Provided By (Used In) Financing Activities	(325)	(103)
Current Assets	3,853		3,614
Property, Plant and Equipment, net	21,933		21,645
Noncurrent Assets	7,540		7,263
Total Assets	33,326		32,522
Current Liabilities	3,357		3,063
Noncurrent Liabilities	10,367		9,988
Long-Term Debt	7,802		7,862
Member's Equity	11,800		11,609
TOTAL LIABILITIES AND CAPITALIZATION	33,326		32,522
Power [Member]
Operating Revenues	1,700	1,451
Operating Expenses	1,418	1,209
Operating Income (Loss)	282	242
Equity Earnings (Losses) of Subsidiaries	4	3
Other Income	33	47
Other Deductions	(10)	(28)
Other-Than-Temporary Impairments	(2)	(2)
Interest Expense	(32)	(30)
Income Tax Expense	(111)	(91)
Net Income	164	141
Net Cash Provided By (Used In) Operating Activities	674	575
Net Cash Provided By (Used In) Investing Activities	(295)	(329)
Net Cash Provided By (Used In) Financing Activities	(375)	(247)
Current Assets	2,299		2,476
Property, Plant and Equipment, net	7,335		7,367
Noncurrent Assets	2,154		2,159
Total Assets	11,788		12,002
Current Liabilities	781		800
Noncurrent Liabilities	2,857		2,847
Long-Term Debt	2,497		2,497
Member's Equity	5,653		5,858
TOTAL LIABILITIES AND CAPITALIZATION	11,788		12,002
Power Senior Notes [Member] | Power Parent [Member]
Operating Revenues	0	0
Operating Expenses	4	2
Operating Income (Loss)	(4)	(2)
Equity Earnings (Losses) of Subsidiaries	177	153
Other Income	8	9
Other Deductions	(4)	(8)
Other-Than-Temporary Impairments	0	0
Interest Expense	(28)	(27)
Income Tax Expense	15	16
Net Income	164	141
Comprehensive Income (Loss)	170	173
Net Cash Provided By (Used In) Operating Activities	291	189
Net Cash Provided By (Used In) Investing Activities	87	56
Net Cash Provided By (Used In) Financing Activities	(375)	(245)
Current Assets	4,109		4,160
Property, Plant and Equipment, net	81		81
Investment in Subsidiaries	4,570		4,645
Noncurrent Assets	301		222
Total Assets	9,061		9,108
Current Liabilities	603		444
Noncurrent Liabilities	308		309
Long-Term Debt	2,497		2,497
Member's Equity	5,653		5,858
TOTAL LIABILITIES AND CAPITALIZATION	9,061		9,108
Power Senior Notes [Member] | Power [Member]
Operating Revenues	1,700	1,451
Operating Expenses	1,418	1,209
Operating Income (Loss)	282	242
Equity Earnings (Losses) of Subsidiaries	4	3
Other Income	33	47
Other Deductions	(10)	(28)
Other-Than-Temporary Impairments	(2)	(2)
Interest Expense	(32)	(30)
Income Tax Expense	(111)	(91)
Net Income	164	141
Comprehensive Income (Loss)	170	173
Net Cash Provided By (Used In) Operating Activities	674	575
Net Cash Provided By (Used In) Investing Activities	(295)	(329)
Net Cash Provided By (Used In) Financing Activities	(375)	(247)
Current Assets	2,299		2,476
Property, Plant and Equipment, net	7,335		7,367
Investment in Subsidiaries	0		0
Noncurrent Assets	2,154		2,159
Total Assets	11,788		12,002
Current Liabilities	781		800
Noncurrent Liabilities	2,857		2,847
Long-Term Debt	2,497		2,497
Member's Equity	5,653		5,858
TOTAL LIABILITIES AND CAPITALIZATION	11,788		12,002
Power Senior Notes [Member] | Guarantor Subsidiaries [Member]
Operating Revenues	2,077	1,803
Operating Expenses	1,797	1,562
Operating Income (Loss)	280	241
Equity Earnings (Losses) of Subsidiaries	0	0
Other Income	33	48
Other Deductions	(6)	(20)
Other-Than-Temporary Impairments	(2)	(2)
Interest Expense	(7)	(10)
Income Tax Expense	(125)	(108)
Net Income	173	149
Comprehensive Income (Loss)	176	172
Net Cash Provided By (Used In) Operating Activities	603	574
Net Cash Provided By (Used In) Investing Activities	(315)	(353)
Net Cash Provided By (Used In) Financing Activities	(287)	(221)
Current Assets	9,145		8,916
Property, Plant and Equipment, net	6,082		6,108
Investment in Subsidiaries	727		729
Noncurrent Assets	1,832		1,847
Total Assets	17,786		17,600
Current Liabilities	11,103		10,919
Noncurrent Liabilities	2,323		2,247
Long-Term Debt	0		0
Member's Equity	4,360		4,434
TOTAL LIABILITIES AND CAPITALIZATION	17,786		17,600
Power Senior Notes [Member] | Consolidating Adjustments [Member]
Operating Revenues	(417)	(389)
Operating Expenses	(417)	(388)
Operating Income (Loss)	0	(1)
Equity Earnings (Losses) of Subsidiaries	(177)	(153)
Other Income	(8)	(10)
Other Deductions	0	0
Other-Than-Temporary Impairments	0	0
Interest Expense	8	11
Income Tax Expense	0	0
Net Income	(177)	(153)
Comprehensive Income (Loss)	(180)	(176)
Net Cash Provided By (Used In) Operating Activities	(221)	(189)
Net Cash Provided By (Used In) Investing Activities	(67)	(24)
Net Cash Provided By (Used In) Financing Activities	288	212
Current Assets	(11,906)		(11,544)
Property, Plant and Equipment, net	0		0
Investment in Subsidiaries	(5,297)		(5,374)
Noncurrent Assets	(117)		(48)
Total Assets	(17,320)		(16,966)
Current Liabilities	(11,905)		(11,545)
Noncurrent Liabilities	(118)		(47)
Long-Term Debt	0		0
Member's Equity	(5,297)		(5,374)
TOTAL LIABILITIES AND CAPITALIZATION	(17,320)		(16,966)
Power Senior Notes [Member] | Non-Guarantor Subsidiaries [Member]
Operating Revenues	40	37
Operating Expenses	34	33
Operating Income (Loss)	6	4
Equity Earnings (Losses) of Subsidiaries	4	3
Other Income	0	0
Other Deductions	0	0
Other-Than-Temporary Impairments	0	0
Interest Expense	(5)	(4)
Income Tax Expense	(1)	1
Net Income	4	4
Comprehensive Income (Loss)	4	4
Net Cash Provided By (Used In) Operating Activities	1	1
Net Cash Provided By (Used In) Investing Activities	0	(8)
Net Cash Provided By (Used In) Financing Activities	(1)	7
Current Assets	951		944
Property, Plant and Equipment, net	1,172		1,178
Investment in Subsidiaries	0		0
Noncurrent Assets	138		138
Total Assets	2,261		2,260
Current Liabilities	980		982
Noncurrent Liabilities	344		338
Long-Term Debt	0		0
Member's Equity	937		940
TOTAL LIABILITIES AND CAPITALIZATION	$ 2,261		$ 2,260