New And Significant Accounting Policies (Reclassifications Out Of Accumulated Other Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	$ 50		$ (101)
Gain on investments	5		6
Net current period other comprehensive income	5		10
Ending balance	55		(91)
Net actuarial loss tax	0		3
Gain on investments tax	4		4
Other Comprehensive Income Before Reclassifications [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Gain on investments	5		6
Amounts Reclassified From Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Amortization of prior service cost	7	[1]	6	[1]
Amortization of net actuarial loss			17	[1]
Transfer to regulatory account	(7)	[1]	(19)	[1]
Pension Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(7)		(28)
Amortization of prior service cost	5		5
Amortization of net actuarial loss	0		27
Net current period other comprehensive income	0		0
Ending balance	(7)		(28)
Pension Benefits [Member] | Other Comprehensive Income Before Reclassifications [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Gain on investments	0		0
Gain on investments tax	0		0
Pension Benefits [Member] | Amounts Reclassified From Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Transfer to regulatory account tax	2		13
Amortization of prior service cost	3	[1]	3	[1]
Amortization of net actuarial loss			16	[1]
Net actuarial loss tax			11
Transfer to regulatory account	(3)	[1]	(19)	[1]
Amortization of prior service cost tax	2		2
Other Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	15		(77)
Amortization of prior service cost	6		6
Amortization of net actuarial loss	0		1
Net current period other comprehensive income	0		4
Ending balance	15		(73)
Other Benefits [Member] | Other Comprehensive Income Before Reclassifications [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Gain on investments	0		0
Gain on investments tax	0		0
Other Benefits [Member] | Amounts Reclassified From Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Transfer to regulatory account tax	2		0
Amortization of prior service cost	4	[1]	3	[1]
Amortization of net actuarial loss			1	[1]
Net actuarial loss tax			0
Transfer to regulatory account	(4)	[1]	0	[1]
Amortization of prior service cost tax	2		3
Other Investments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	42		4
Net current period other comprehensive income	5		6
Ending balance	47		10
Other Investments [Member] | Other Comprehensive Income Before Reclassifications [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Gain on investments	5		6
Gain on investments tax	4		4
Other Investments [Member] | Amounts Reclassified From Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Transfer to regulatory account tax	0		0
Amortization of prior service cost	0	[1]	0	[1]
Amortization of net actuarial loss			0	[1]
Net actuarial loss tax			0
Transfer to regulatory account	0	[1]	0	[1]
Amortization of prior service cost tax	$ 0		$ 0

[1] These components are included in the computation of net periodic pension and other postretirement costs. (See the Pension and Other Postretirement Benefits table above for additional details.)