Derivatives And Hedging Activities (Activity Related To Fully Effective Interest Rate Swaps Designated As Fair Value Hedges) (Details) (Fair Value Hedging [Member], USD $) In Millions	3 Months Ended						6 Months Ended
	Jun. 30, 2011		Mar. 31, 2011		Jun. 30, 2010	Mar. 31, 2010	Jun. 30, 2011	Jun. 30, 2010
Interest Rate Swap [Member] | Added [Member]
Interest rate swap agreements outstanding	$ 100	[1]	$ 100	[1]	$ 0	$ 0	$ 200	$ 0
Interest Rate Swap [Member] | Terminated [Member]
Interest rate swap agreements outstanding	0		0		100	700	0	800
Interest Rate Swap [Member] | Not Designated [Member]
Interest rate swap agreements outstanding	$ 0		$ 0		$ 2	$ 0	$ 0	$ 2
Fixed To Floating Interest Rate Swap, Maturing April 2015 [Member] | Added [Member]
Interest rate swap, maturity period	Apr. 01, 2015
Fixed To Floating Interest Rate Swap, Maturing June 2014 [Member] | Added [Member]
Interest rate swap, maturity period	Jun. 01, 2014

[1] Fixed-to-floating interest rate swaps were effective when issued and mature in June 2014 and April 2015.