Loans and Allowance for Credit Losses (Details 1) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Carrying amount of the covered assets
Purchased impaired loans	$ 6,113	$ 6,143
Purchased non-impaired loans	6,845	8,762
Other assets	2,733	3,590
Total	15,691	18,495
Commercial loans [Member]
Carrying amount of the covered assets
Purchased impaired loans	68	70
Purchased non-impaired loans	160	260
Total	228	330
Commercial real estate loans [Member]
Carrying amount of the covered assets
Purchased impaired loans	2,092	2,254
Purchased non-impaired loans	4,385	5,952
Total	6,477	8,206
Residential mortgage loans [Member]
Carrying amount of the covered assets
Purchased impaired loans	3,953	3,819
Purchased non-impaired loans	1,417	1,620
Total	5,370	5,439
Credit card portfolio segment [Member]
Carrying amount of the covered assets
Purchased non-impaired loans	5	5
Total	5	5
Other retail portfolio segment [Member]
Carrying amount of the covered assets
Purchased non-impaired loans	878	925
Total	878	925
Losses reimbursable by FDIC [Member]
Carrying amount of the covered assets
Other assets	2,440	3,137
Total	2,440	3,137
Covered portfolio segment [Member]
Carrying amount of the covered assets
Purchased impaired loans	6,113	6,143
Purchased non-impaired loans	6,845	8,762
Other assets	2,440	3,137
Total	15,398	18,042
Foreclosed real estate [Member]
Carrying amount of the covered assets
Purchased impaired loans		0
Purchased non-impaired loans		0
Other assets	293	453
Total	$ 293	$ 453