Loans - Modified in TDRs (Details 4) (USD $) In Millions	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010
Wholesale
Loans modified in troubled debt restructurings	$ 928	$ 1,000	$ 1,143
TDRs on nonaccrual status	853		1,018
Additional commitments to lend to borrowers whose loans have been modified in TDRs	220		1
Wholesale | Commercial and industrial [Member]
Loans modified in troubled debt restructurings	625		212
TDRs on nonaccrual status	574		163
Additional commitments to lend to borrowers whose loans have been modified in TDRs	220		1
Wholesale | Real estate [Member]
Loans modified in troubled debt restructurings	261		907
TDRs on nonaccrual status	243		831
Additional commitments to lend to borrowers whose loans have been modified in TDRs	0		0
Wholesale | Financial institutions [Member]
Loans modified in troubled debt restructurings	2		1
TDRs on nonaccrual status	0		1
Additional commitments to lend to borrowers whose loans have been modified in TDRs	0		0
Wholesale | Government agencies [Member]
Loans modified in troubled debt restructurings	17		22
TDRs on nonaccrual status	17		22
Additional commitments to lend to borrowers whose loans have been modified in TDRs	0		0
Wholesale | Other [Member]
Loans modified in troubled debt restructurings	23		1
TDRs on nonaccrual status	19		1
Additional commitments to lend to borrowers whose loans have been modified in TDRs	0		0
Other Consumer [Member]
Loans modified in troubled debt restructurings	516		486
TDRs on nonaccrual status	311		307
Consumer Loans Auto Financing Receivable [Member]
Loans modified in troubled debt restructurings	86		91
TDRs on nonaccrual status	37		39
Consumer business banking
Loans modified in troubled debt restructurings	430		395
TDRs on nonaccrual status	$ 274		$ 268