Guarantees Of Debt (Schedule Of Financial Statements Of Guarantors) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Operating Revenues	$ 2,249	$ 2,310	$ 5,472	$ 5,096
Operating Expenses	1,884	1,698	4,402	3,874
Operating Income (Loss)	365	612	1,070	1,222
Equity Earnings (Losses) of Subsidiaries	3	3	7	5
Other Income	62	52	110	113
Other Deductions	(10)	(13)	(22)	(42)
Other-Than-Temporary Impairments	(2)	(2)	(4)	(4)
Interest Expense	(94)	(101)	(191)	(203)
Income Tax Expense	(112)	(218)	(372)	(438)
Net Income	212	333	598	653
Net Cash Provided By (Used In) Operating Activities			1,448	1,343
Net Cash Provided By (Used In) Investing Activities			(1,282)	(1,379)
Net Cash Provided By (Used In) Financing Activities			(89)	(179)
Current Assets	3,794		3,794		3,614
Property, Plant and Equipment, net	22,310		22,310		21,645
Noncurrent Assets	7,596		7,596		7,263
Total Assets	33,700		33,700		32,522
Current Liabilities	3,463		3,463		3,063
Noncurrent Liabilities	10,461		10,461		9,988
Long-Term Debt	7,932		7,932		7,862
Member's Equity	11,844		11,844		11,609
TOTAL LIABILITIES AND CAPITALIZATION	33,700		33,700		32,522
Power Senior Notes [Member]
Operating Revenues	986	1,193	2,686	2,644
Operating Expenses	919	842	2,337	2,051
Operating Income (Loss)	67	351	349	593
Equity Earnings (Losses) of Subsidiaries	3	5	7	8
Other Income	46	35	79	82
Other Deductions	(9)	(10)	(19)	(38)
Other-Than-Temporary Impairments	(2)	(2)	(4)	(4)
Interest Expense	(29)	(29)	(61)	(59)
Income Tax Expense	(22)	(140)	(133)	(231)
Net Income	54	210	218	351
Comprehensive Income (Loss)	67	203	237	376
Net Cash Provided By (Used In) Operating Activities			814	866
Net Cash Provided By (Used In) Investing Activities			(236)	(81)
Net Cash Provided By (Used In) Financing Activities			(578)	(788)
Current Assets	2,179		2,179		2,476
Property, Plant and Equipment, net	7,305		7,305		7,367
Investment in Subsidiaries	0		0		0
Noncurrent Assets	2,247		2,247		2,159
Total Assets	11,731		11,731		12,002
Current Liabilities	813		813		800
Noncurrent Liabilities	2,900		2,900		2,847
Long-Term Debt	2,498		2,498		2,497
Member's Equity	5,520		5,520		5,858
TOTAL LIABILITIES AND CAPITALIZATION	11,731		11,731		12,002
Power Senior Notes [Member] | Power Parent [Member]
Operating Revenues	0	0	0	0
Operating Expenses	5	2	9	4
Operating Income (Loss)	(5)	(2)	(9)	(4)
Equity Earnings (Losses) of Subsidiaries	57	219	234	372
Other Income	8	10	16	19
Other Deductions	0	(2)	(4)	(10)
Other-Than-Temporary Impairments	0	0	0	0
Interest Expense	(27)	(26)	(55)	(53)
Income Tax Expense	21	11	36	27
Net Income	54	210	218	351
Comprehensive Income (Loss)	67	203	237	376
Net Cash Provided By (Used In) Operating Activities			292	386
Net Cash Provided By (Used In) Investing Activities			138	138
Net Cash Provided By (Used In) Financing Activities			(430)	(524)
Current Assets	4,186		4,186		4,413
Property, Plant and Equipment, net	79		79		81
Investment in Subsidiaries	4,426		4,426		4,645
Noncurrent Assets	322		322		222
Total Assets	9,013		9,013		9,361
Current Liabilities	647		647		697
Noncurrent Liabilities	348		348		309
Long-Term Debt	2,498		2,498		2,497
Member's Equity	5,520		5,520		5,858
TOTAL LIABILITIES AND CAPITALIZATION	9,013		9,013		9,361
Power Senior Notes [Member] | Guarantor Subsidiaries [Member]
Operating Revenues	972	1,183	2,656	2,624
Operating Expenses	903	835	2,307	2,035
Operating Income (Loss)	69	348	349	589
Equity Earnings (Losses) of Subsidiaries	(3)	(2)	(3)	(2)
Other Income	47	35	80	83
Other Deductions	(8)	(9)	(14)	(29)
Other-Than-Temporary Impairments	(2)	(2)	(4)	(4)
Interest Expense	(6)	(6)	(13)	(16)
Income Tax Expense	(43)	(151)	(168)	(259)
Net Income	54	213	227	362
Comprehensive Income (Loss)	66	198	242	370
Net Cash Provided By (Used In) Operating Activities			950	884
Net Cash Provided By (Used In) Investing Activities			(415)	(411)
Net Cash Provided By (Used In) Financing Activities			(534)	(476)
Current Assets	1,923		1,923		2,076
Property, Plant and Equipment, net	6,065		6,065		6,108
Investment in Subsidiaries	121		121		124
Noncurrent Assets	1,923		1,923		1,847
Total Assets	10,032		10,032		10,155
Current Liabilities	3,468		3,468		3,474
Noncurrent Liabilities	2,340		2,340		2,247
Long-Term Debt	0		0		0
Member's Equity	4,224		4,224		4,434
TOTAL LIABILITIES AND CAPITALIZATION	10,032		10,032		10,155
Power Senior Notes [Member] | Consolidating Adjustments [Member]
Operating Revenues	(28)	(27)	(52)	(54)
Operating Expenses	(29)	(27)	(53)	(53)
Operating Income (Loss)	1	0	1	(1)
Equity Earnings (Losses) of Subsidiaries	(54)	(217)	(231)	(370)
Other Income	(9)	(10)	(17)	(20)
Other Deductions	(1)	1	(1)	1
Other-Than-Temporary Impairments	0	0	0	0
Interest Expense	9	9	17	20
Income Tax Expense	0	0	0	0
Net Income	(54)	(217)	(231)	(370)
Comprehensive Income (Loss)	(66)	(202)	(246)	(378)
Net Cash Provided By (Used In) Operating Activities			(460)	(419)
Net Cash Provided By (Used In) Investing Activities			57	218
Net Cash Provided By (Used In) Financing Activities			403	201
Current Assets	(4,039)		(4,039)		(4,115)
Property, Plant and Equipment, net	0		0		0
Investment in Subsidiaries	(4,547)		(4,547)		(4,769)
Noncurrent Assets	(134)		(134)		(48)
Total Assets	(8,720)		(8,720)		(8,932)
Current Liabilities	(4,039)		(4,039)		(4,116)
Noncurrent Liabilities	(134)		(134)		(47)
Long-Term Debt	0		0		0
Member's Equity	(4,547)		(4,547)		(4,769)
TOTAL LIABILITIES AND CAPITALIZATION	(8,720)		(8,720)		(8,932)
Power Senior Notes [Member] | Non-Guarantor Subsidiaries [Member]
Operating Revenues	42	37	82	74
Operating Expenses	40	32	74	65
Operating Income (Loss)	2	5	8	9
Equity Earnings (Losses) of Subsidiaries	3	5	7	8
Other Income	0	0	0	0
Other Deductions	0	0	0	0
Other-Than-Temporary Impairments	0	0	0	0
Interest Expense	(5)	(6)	(10)	(10)
Income Tax Expense	0	0	(1)	1
Net Income	0	4	4	8
Comprehensive Income (Loss)	0	4	4	8
Net Cash Provided By (Used In) Operating Activities			32	15
Net Cash Provided By (Used In) Investing Activities			(16)	(26)
Net Cash Provided By (Used In) Financing Activities			(17)	11
Current Assets	109		109		102
Property, Plant and Equipment, net	1,161		1,161		1,178
Investment in Subsidiaries	0		0		0
Noncurrent Assets	136		136		138
Total Assets	1,406		1,406		1,418
Current Liabilities	737		737		745
Noncurrent Liabilities	346		346		338
Long-Term Debt	0		0		0
Member's Equity	323		323		335
TOTAL LIABILITIES AND CAPITALIZATION	1,406		1,406		1,418
Increase (Decrease) from Previously Reported | Power Senior Notes [Member]
Current Assets					0
Investment in Subsidiaries					0
Total Assets					0
Current Liabilities					0
Member's Equity					0
TOTAL LIABILITIES AND CAPITALIZATION					0
Increase (Decrease) from Previously Reported | Power Senior Notes [Member] | Power Parent [Member]
Current Assets					253
Investment in Subsidiaries					0
Total Assets					253
Current Liabilities					253
Member's Equity					0
TOTAL LIABILITIES AND CAPITALIZATION					253
Increase (Decrease) from Previously Reported | Power Senior Notes [Member] | Guarantor Subsidiaries [Member]
Operating Revenues		(352)		(714)
Operating Expenses		(352)		(714)
Current Assets					(6,840)
Investment in Subsidiaries					(605)
Total Assets					(7,445)
Current Liabilities					(7,445)
Member's Equity					0
TOTAL LIABILITIES AND CAPITALIZATION					(7,445)
Increase (Decrease) from Previously Reported | Power Senior Notes [Member] | Consolidating Adjustments [Member]
Operating Revenues		352		714
Operating Expenses		352		714
Current Assets					7,429
Investment in Subsidiaries					605
Total Assets					8,034
Current Liabilities					7,429
Member's Equity					605
TOTAL LIABILITIES AND CAPITALIZATION					8,034
Increase (Decrease) from Previously Reported | Power Senior Notes [Member] | Non-Guarantor Subsidiaries [Member]
Current Assets					(842)
Investment in Subsidiaries					0
Total Assets					(842)
Current Liabilities					(237)
Member's Equity					(605)
TOTAL LIABILITIES AND CAPITALIZATION					$ (842)