Income Tax (Schedule Of Components Of Income Tax) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Tax [Abstract]
State - Current	$ 56	$ 23	$ (12)
State - Deferred	63	106	118
Federal - Current	53	(144)	16
Federal - Deferred	434	569	324
Amortization of investment tax credits	(6)	(6)	(6)
Total charge to income tax expense	$ 600	$ 548	$ 440