Variable Interest Entities (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 years	Dec. 31, 2010 years	Dec. 31, 2009
Variable Interest Entities [Abstract]
Investment securities related to state and political subdivisions	$ 2,810,000,000	$ 2,850,000,000
Variable interest entity, other short-term borrowings	2,290,000,000	2,480,000,000
Weighted-average life of trusts, years	7.4	7.7
Total standby bond-purchase agreement committed to trusts	2,350,000,000
Letters of credit	669,000,000
Number of standby purchase agreements utilized	0
Asset-backed securities, fair value	264,000,000	5,010,000,000
Receivable loans purchased	935,000,000	2,200,000,000
Commercial paper	2,380,000,000	2,800,000,000
Aggregate notional value of CDOs	400,000,000	1,000,000,000
Carrying value of the underlying collateral	166,000,000	323,000,000
Pre-tax extraordinary loss			6,100,000,000
After-tax extraordinary loss			(3,684,000,000)
Accretion in interest revenue	$ 220,000,000	$ 712,000,000	$ 621,000,000