Pension And OPEB (Components Of Net Periodic Benefit Cost) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 25	$ 24
Interest Cost	56	58
Expected Return on Plan Assets	(76)	(81)
Amortization of Net Transition Obligation	0	0
Amortization of Net Prior Service Cost	(5)	0
Amortization of Net Actuarial Loss	42	30
Net Periodic Benefit Cost	42	31
Effect of Regulatory Asset	0	0
Total Benefit Costs, Including Effect of Regulatory Asset	42	31
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	4	4
Interest Cost	16	15
Expected Return on Plan Assets	(4)	(4)
Amortization of Net Transition Obligation	1	2
Amortization of Net Prior Service Cost	(4)	(3)
Amortization of Net Actuarial Loss	8	3
Net Periodic Benefit Cost	21	17
Effect of Regulatory Asset	5	5
Total Benefit Costs, Including Effect of Regulatory Asset	$ 26	$ 22