Risk Management, Derivative Instruments And Hedging Activities (Cash Flow Hedges - Location And Amount Of Pre-Tax Recognized In Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Amount of pre-tax gains (losses) recorded in AOCI	$ (3)	$ (73)	$ (29)	$ (80)
Total Pre-tax Gains and (Losses) Reclassified from AOCI into Earnings	2	(1)	0	(4)
Interest Rate Contracts [Member]
Amount of pre-tax gains (losses) recorded in AOCI	(4)	(73)	(30)	(80)
Total Pre-tax Gains and (Losses) Reclassified from AOCI into Earnings	2	(1)	0	(4)
Commodity Contract [Member]
Amount of pre-tax gains (losses) recorded in AOCI	$ 1		$ 1