Financial Derivatives (Risk Participation Agreements Sold) (Details) (Risk Participation Agreements Sold [Member], USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Risk Participation Agreements Sold [Member]
Notional Amount of Credit Risk Derivatives	$ 1,727	$ 1,367
Estimated Net Fair Value	$ (3)	$ (2)
Weighted-Average Remaining Maturity In Years of Risk Participation Agreements Sold	6.9	2.0