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
	Mar. 31, 2012		Mar. 31, 2011
Amount of pre-tax gains recorded in AOCI	$ 18		$ 3
Interest Rate Contracts [Member]
Total Pre-tax (Losses) Reclassified from AOCI into Earnings	(1)	[1]	(1)	[1]
Amount of Pre-tax Gains Recorded in AOCI [Member]
Amount of pre-tax gains recorded in AOCI	18		3
Location of Pre-tax Losses Reclassified from AOCI into Earnings [Member] | Interest Rate Contracts [Member]
Total Pre-tax (Losses) Reclassified from AOCI into Earnings	$ (1)	[1]	$ (1)	[1]

[1] Represents the gains and losses on cash flow hedges previously recorded in AOCI during the term of the hedging relationship and reclassified into earnings during the current period.