Fair Values of Assets and Liabilities (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Fair Values of Assets and Liabilities (Textual) [Abstract]
Fair value measurement transfers from one level to another	$ 0	$ 0
Mortgage loans held for sale measured at fair value gain losses	19	(125)
Percentage of assumed minimum pull-through rate used to determine fair value of interest rate lock commitments	26.00%
Percentage of assumed maximum pull-through rate used to determine fair value of interest rate lock commitments	100.00%
Percentage of assumed average pull-through rate used to determine fair value of interest rate lock commitments	77.00%
Inherent MSR minimum value in underlying loan value used to determine fair value of interest rate lock commitments	63
Inherent Msr maximum value in underlying loan value used to determine fair value of interest rate lock commitments	204
Inherent MSR average value in underlying loan value used to determine fair value of interest rate lock commitments	113
Assumed minimum credit valuation adjustment as percentage of underlying fair value of underlying derivative contracts	0.00%
Assumed maximum credit valuation adjustment as percentage of underlying fair value of underlying derivative contracts	875.00%
Assumed average credit valuation adjustment as percentage of underlying fair value of underlying derivative contracts	10.00%
Carrying value of unfunded commitments and standby letters of credit	386		381
Carrying value of other guarantees	408		359
Net gains and losses on available for sale securities included in securities gains (losses)	(9)	(6)
Net gains and losses on available for sale securities included in interest income	14	16
Net gains and losses on net derivative assets and liabilities included in noninterest income	(22)	(5)
Net gains and losses on net derivative assets and liabilities included in mortgage banking revenue	353	48
Net change in net derivative assets and liabilities in unrealized gains (losses) included in noninterest income	(103)	(129)
Net change in net derivative assets and liabilities in unrealized gains (losses) included in mortgage banking revenue	$ (358)	$ (10)