Significant Accounting Policies (Components Of Net Periodic Benefit Cost) (Details) (USD $) In Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Pension Benefits [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Service cost for benefits earned	$ 76		$ 70		$ 240		$ 209
Interest cost	167		162		495		484
Expected return on plan assets	(168)		(155)		(502)		(467)
Amortization of transition obligation
Amortization of prior service cost	8		13		26		39
Amortization of unrecognized loss	13		11		37		32
Net periodic benefit cost	96		101		296		297
Less: transfer to regulatory account	(32)	[1]	(60)	[1]	(104)	[2]	(175)	[2]
Total	64		41		192		122
Other Benefits [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Service cost for benefits earned	9		8		31		27
Interest cost	23		21		69		66
Expected return on plan assets	(22)		(18)		(62)		(55)
Amortization of transition obligation	7		6		19		19
Amortization of prior service cost	8		7		20		19
Amortization of unrecognized loss	1		1		3		2
Net periodic benefit cost	26		25		80		78
Less: transfer to regulatory account		[1]		[1]
Total	$ 26		$ 25		$ 80		$ 78

[1] The Utility recorded $32 million and $60 million for the three month periods ended September 30, 2011 and 2010, respectively, to a regulatory account as the amounts are probable of recovery from customers in future rates.

[2] The Utility recorded $104 million and $175 million for the nine month periods ended September 30, 2011 and 2010, respectively, to a regulatory account as the amounts are probable of recovery from customers in future rates.