Derivative Financial Instruments (Narrative) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
Derivative liability, fair value	742
Collateral already posted, aggregate fair value	366
Maximum additional amount of payments related to termination events	376
Fair Value Hedges [Member]
Securities weighted-average life, years	7.5	7.7
Subordinated note matures	2018
Fair Value Hedges [Member] | 4.956% Subordinated Note [Member]
Fixed interest rate	4.956%
Fair Value Hedges [Member] | 5.25% Subordinated Note [Member]
Fixed interest rate	5.25%
Cash Flow Hedge [Member]
Securities weighted-average life, years	3.3	3.8