Guarantees Of Debt (Schedule Of Financial Statements Of Guarantors) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating Revenues	$ 2,641		$ 2,554		$ 8,113	$ 7,650
Operating Expenses	1,895		1,842		6,297	5,716
Operating Income (Loss)	746		712		1,816	1,934
Equity Earnings (Losses) of Subsidiaries	3		4		10	9
Other Income	75		59		185	172
Other Deductions	(9)		(12)		(31)	(54)
Other-Than-Temporary Impairments	(10)		(3)		(14)	(7)
Interest Expense	(100)		(100)		(291)	(303)
Income Tax Expense	(261)		(270)		(633)	(708)
Net Income	444		390		1,042	1,043
Net Cash Provided By (Used In) Operating Activities					2,536	2,435
Net Cash Provided By (Used In) Investing Activities					(1,988)	(2,088)
Net Cash Provided By (Used In) Financing Activities					(338)	(278)
Current Assets	3,846				3,846		3,614
Property, Plant and Equipment, net	22,836				22,836		21,645
Noncurrent Assets	7,465				7,465		7,263
Total Assets	34,147				34,147		32,522
Current Liabilities	3,136				3,136		3,063
Noncurrent Liabilities	10,538				10,538		9,988
Long-Term Debt	8,389				8,389		7,862
Member's Equity	12,084				12,084		11,609
TOTAL LIABILITIES AND CAPITALIZATION	34,147				34,147		32,522
Power Senior Notes [Member]
Operating Revenues	1,138	1,700	1,174	1,451	3,824	3,818	5,063	4,873	6,150
Operating Expenses	785	1,418	804	1,209	3,122	2,855	3,993	3,750	4,377
Operating Income (Loss)	353	282	370	242	702	963	1,070	1,123	1,773
Equity Earnings (Losses) of Subsidiaries	4	4	4	3	11	12	16	15	14
Other Income	56	33	45	47	135	127	154	201	190
Other Deductions	(6)	(10)	(11)	(28)	(25)	(49)	(49)	(90)	(79)
Other-Than-Temporary Impairments	(10)	(2)	(3)	(2)	(14)	(7)	(12)	(18)	(20)
Interest Expense	(31)	(32)	(26)	(30)	(92)	(85)	(116)	(132)	(175)
Income Tax Expense	(144)	(111)	(153)	(91)	(277)	(384)	(419)	(433)	(690)
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest									96
Net Income	222	164	226	141	440	577	644	666	1,109
Comprehensive Income (Loss)	195	170	250	173	432	626	909	614	928
Net Cash Provided By (Used In) Operating Activities		674		575	1,110	1,314	1,347	1,453	1,817
Net Cash Provided By (Used In) Investing Activities		(295)		(329)	(326)	(329)	(861)	(472)	(578)
Net Cash Provided By (Used In) Financing Activities		(375)		(247)	(778)	(983)	(487)	(986)	(1,238)
Current Assets	2,130	2,299			2,130		2,476	2,236
Property, Plant and Equipment, net	7,384	7,335			7,384		7,367	7,222
Investment in Subsidiaries	0	0			0		0	0
Noncurrent Assets	2,236	2,154			2,236		2,159	1,865
Total Assets	11,750	11,788			11,750		12,002	11,323
Current Liabilities	747	781			747		800	968
Noncurrent Liabilities	2,945	2,857			2,945		2,847	2,685
Long-Term Debt	2,543	2,497			2,543		2,497	2,040
Member's Equity	5,515	5,653			5,515		5,858	5,630
TOTAL LIABILITIES AND CAPITALIZATION	11,750	11,788			11,750		12,002	11,323
Power Senior Notes [Member] | Guarantor Subsidiaries [Member]
Operating Revenues	1,125	1,684	1,163	1,441	3,781	3,787	5,022	4,850	6,139
Operating Expenses	772	1,404	797	1,200	3,079	2,832	3,945	3,730	4,360
Operating Income (Loss)	353	280	366	241	702	955	1,077	1,120	1,779
Equity Earnings (Losses) of Subsidiaries	(1)	0	(1)	0	(4)	(3)	(5)	(10)	92
Other Income	55	33	47	48	135	130	157	206	195
Other Deductions	(4)	(6)	(11)	(20)	(18)	(40)	(35)	(59)	(51)
Other-Than-Temporary Impairments	(10)	(2)	(3)	(2)	(14)	(7)	(12)	(18)	(19)
Interest Expense	(10)	(7)	(13)	(10)	(23)	(29)	(42)	(51)	(56)
Income Tax Expense	(161)	(125)	(160)	(108)	(329)	(419)	(474)	(501)	(762)
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest									0
Net Income	222	173	225	149	449	587	666	687	1,178
Comprehensive Income (Loss)	191	176	242	172	433	612	713	681	1,055
Net Cash Provided By (Used In) Operating Activities		603		574	1,252	1,360	1,503	1,562	2,427
Net Cash Provided By (Used In) Investing Activities		(315)		(353)	(559)	(869)	(1,092)	(1,206)	(1,171)
Net Cash Provided By (Used In) Financing Activities		(287)		(221)	(693)	(492)	(412)	(361)	(1,256)
Current Assets	1,891	2,097			1,891		2,076	1,898
Property, Plant and Equipment, net	6,140	6,082			6,140		6,108	5,988
Investment in Subsidiaries	120	122			120		124	128
Noncurrent Assets	1,901	1,832			1,901		1,847	1,660
Total Assets	10,052	10,133			10,052		10,155	9,674
Current Liabilities	3,510	3,450			3,510		3,474	3,396
Noncurrent Liabilities	2,379	2,323			2,379		2,247	1,960
Long-Term Debt	0	0			0		0	0
Member's Equity	4,163	4,360			4,163		4,434	4,318
TOTAL LIABILITIES AND CAPITALIZATION	10,052	10,133			10,052		10,155	9,674
Power Senior Notes [Member] | Power Parent [Member]
Operating Revenues	0	0	0	0	0	0	0	0	0
Operating Expenses	3	4	2	2	12	6	23	7	5
Operating Income (Loss)	(3)	(4)	(2)	(2)	(12)	(6)	(23)	(7)	(5)
Equity Earnings (Losses) of Subsidiaries	225	177	231	153	459	603	684	707	1,186
Other Income	9	8	8	9	25	27	35	45	40
Other Deductions	(3)	(4)	1	(8)	(7)	(9)	(14)	(31)	(28)
Other-Than-Temporary Impairments	0	0	0	0	0	0	0	0	(1)
Interest Expense	(24)	(28)	(19)	(27)	(79)	(72)	(93)	(118)	(146)
Income Tax Expense	18	15	7	16	54	34	55	70	63
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest									0
Net Income	222	164	226	141	440	577	644	666	1,109
Comprehensive Income (Loss)	195	170	250	173	432	626	909	614	928
Net Cash Provided By (Used In) Operating Activities		291		189	471	425	288	298	609
Net Cash Provided By (Used In) Investing Activities		(122)		(213)	187	40	(395)	(14)	(268)
Net Cash Provided By (Used In) Financing Activities		(166)		24	(652)	(461)	107	(284)	(341)
Current Assets	4,163	4,436			4,163		4,413	4,255
Property, Plant and Equipment, net	81	81			81		81	80
Investment in Subsidiaries	4,358	4,570			4,358		4,645	4,508
Noncurrent Assets	293	301			293		222	201
Total Assets	8,895	9,388			8,895		9,361	9,044
Current Liabilities	518	930			518		697	815
Noncurrent Liabilities	319	308			319		309	559
Long-Term Debt	2,543	2,497			2,543		2,497	2,040
Member's Equity	5,515	5,653			5,515		5,858	5,630
TOTAL LIABILITIES AND CAPITALIZATION	8,895	9,388			8,895		9,361	9,044
Power Senior Notes [Member] | Consolidating Adjustments [Member]
Operating Revenues	(23)	(24)	(60)	(27)	(75)	(114)	(149)	(112)	(144)
Operating Expenses	(22)	(24)	(61)	(26)	(75)	(114)	(149)	(112)	(145)
Operating Income (Loss)	(1)	0	1	(1)	0	0	0	0	1
Equity Earnings (Losses) of Subsidiaries	(224)	(177)	(230)	(153)	(455)	(600)	(679)	(697)	(1,278)
Other Income	(8)	(8)	(10)	(10)	(25)	(30)	(38)	(52)	(45)
Other Deductions	1	0	(1)	0	0	0	0	0	0
Other-Than-Temporary Impairments	0	0	0	0	0	0	0	0	0
Interest Expense	7	8	10	11	24	30	38	53	45
Income Tax Expense	0	0	0	0	0	0	0	0	0
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest									(1)
Net Income	(225)	(177)	(230)	(153)	(456)	(600)	(679)	(696)	(1,278)
Comprehensive Income (Loss)	(194)	(180)	(247)	(176)	(440)	(625)	(724)	(690)	(1,155)
Net Cash Provided By (Used In) Operating Activities		(221)		(189)	(666)	(506)	(526)	(474)	(940)
Net Cash Provided By (Used In) Investing Activities		142		245	70	540	697	899	267
Net Cash Provided By (Used In) Financing Activities		79		(57)	596	(35)	(171)	(424)	673
Current Assets	(4,035)	(4,341)			(4,035)		(4,115)	(4,021)
Property, Plant and Equipment, net	0	0			0		0	0
Investment in Subsidiaries	(4,478)	(4,692)			(4,478)		(4,769)	(4,636)
Noncurrent Assets	(97)	(117)			(97)		(48)	(141)
Total Assets	(8,610)	(9,150)			(8,610)		(8,932)	(8,798)
Current Liabilities	(4,035)	(4,340)			(4,035)		(4,116)	(4,021)
Noncurrent Liabilities	(97)	(118)			(97)		(47)	(140)
Long-Term Debt	0	0			0		0	0
Member's Equity	(4,478)	(4,692)			(4,478)		(4,769)	(4,637)
TOTAL LIABILITIES AND CAPITALIZATION	(8,610)	(9,150)			(8,610)		(8,932)	(8,798)
Power Senior Notes [Member] | Non-Guarantor Subsidiaries [Member]
Operating Revenues	36	40	71	37	118	145	190	135	155
Operating Expenses	32	34	66	33	106	131	174	125	157
Operating Income (Loss)	4	6	5	4	12	14	16	10	(2)
Equity Earnings (Losses) of Subsidiaries	4	4	4	3	11	12	16	15	14
Other Income	0	0	0	0	0	0	0	2	0
Other Deductions	0	0	0	0	0	0	0	0	0
Other-Than-Temporary Impairments	0	0	0	0	0	0	0	0	0
Interest Expense	(4)	(5)	(4)	(4)	(14)	(14)	(19)	(16)	(18)
Income Tax Expense	(1)	(1)	0	1	(2)	1	0	(2)	9
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest									97
Net Income	3	4	5	4	7	13	13	9	100
Comprehensive Income (Loss)	3	4	5	4	7	13	11	9	100
Net Cash Provided By (Used In) Operating Activities		1		1	53	35	82	67	(279)
Net Cash Provided By (Used In) Investing Activities		0		(8)	(24)	(40)	(71)	(151)	594
Net Cash Provided By (Used In) Financing Activities		(1)		7	(29)	5	(11)	83	(314)
Current Assets	111	107			111		102	104
Property, Plant and Equipment, net	1,163	1,172			1,163		1,178	1,154
Investment in Subsidiaries	0	0			0		0	0
Noncurrent Assets	139	138			139		138	145
Total Assets	1,413	1,417			1,413		1,418	1,403
Current Liabilities	754	741			754		745	778
Noncurrent Liabilities	344	344			344		338	306
Long-Term Debt	0	0			0		0	0
Member's Equity	315	332			315		335	319
TOTAL LIABILITIES AND CAPITALIZATION	1,413	1,417			1,413		1,418	1,403
Increase (Decrease) from Previously Reported | Power Senior Notes [Member]
Operating Revenues		0	0	0		0	0	0	0
Operating Expenses		0	0	0		0	0	0	0
Net Cash Provided By (Used In) Investing Activities		0		0		0	0	0	0
Net Cash Provided By (Used In) Financing Activities		0		0		0	0	0	0
Current Assets		0					0	0
Investment in Subsidiaries		0					0	0
Total Assets		0					0	0
Current Liabilities		0					0	0
Member's Equity		0					0	0
TOTAL LIABILITIES AND CAPITALIZATION		0					0	0
Increase (Decrease) from Previously Reported | Power Senior Notes [Member] | Guarantor Subsidiaries [Member]
Operating Revenues		(393)	(348)	(362)		(1,062)	(1,468)	(1,388)	(1,313)
Operating Expenses		(393)	(348)	(362)		(1,062)	(1,468)	(1,388)	(1,313)
Net Cash Provided By (Used In) Investing Activities		0		0		0	0	0	0
Net Cash Provided By (Used In) Financing Activities		0		0		0	0	0	0
Current Assets		(7,048)					(6,840)	(6,186)
Investment in Subsidiaries		(605)					(605)	(605)
Total Assets		(7,653)					(7,445)	(6,791)
Current Liabilities		(7,653)					(7,445)	(6,791)
Member's Equity		0					0	0
TOTAL LIABILITIES AND CAPITALIZATION		(7,653)					(7,445)	(6,791)
Increase (Decrease) from Previously Reported | Power Senior Notes [Member] | Power Parent [Member]
Operating Revenues		0	0	0		0	0	0	0
Operating Expenses		0	0	0		0	0	0	0
Net Cash Provided By (Used In) Investing Activities		(209)		(269)		(520)	(588)	(729)	(864)
Net Cash Provided By (Used In) Financing Activities		209		269		520	588	679	869
Current Assets		327					253	333
Investment in Subsidiaries		0					0	0
Total Assets		327					253	333
Current Liabilities		327					253	333
Member's Equity		0					0	0
TOTAL LIABILITIES AND CAPITALIZATION		327					253	333
Increase (Decrease) from Previously Reported | Power Senior Notes [Member] | Consolidating Adjustments [Member]
Operating Revenues		393	348	362		1,062	1,468	1,388	1,313
Operating Expenses		393	348	362		1,062	1,468	1,388	1,313
Net Cash Provided By (Used In) Investing Activities		209		269		520	588	729	864
Net Cash Provided By (Used In) Financing Activities		(209)		(269)		(520)	(588)	(679)	(869)
Current Assets		7,565					7,429	6,691
Investment in Subsidiaries		605					605	605
Total Assets		8,170					8,034	7,296
Current Liabilities		7,565					7,429	6,691
Member's Equity		605					605	605
TOTAL LIABILITIES AND CAPITALIZATION		8,170					8,034	7,296
Increase (Decrease) from Previously Reported | Power Senior Notes [Member] | Non-Guarantor Subsidiaries [Member]
Operating Revenues		0	0	0		0	0	0	0
Operating Expenses		0	0	0		0	0	0	0
Net Cash Provided By (Used In) Investing Activities		0		0		0	0	0	0
Net Cash Provided By (Used In) Financing Activities		0		0		0	0	0	0
Current Assets		(844)					(842)	(838)
Investment in Subsidiaries		0					0	0
Total Assets		(844)					(842)	(838)
Current Liabilities		(239)					(237)	(233)
Member's Equity		(605)					(605)	(605)
TOTAL LIABILITIES AND CAPITALIZATION		$ (844)					$ (842)	$ (838)