Asset Quality (Summary of TDRs) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Troubled debt restructurings (TDRs)	$ 2,842	$ 2,859
Nonperforming Status [Member]
Troubled debt restructurings (TDRs)	1,531	1,589
Accruing [Member]
Troubled debt restructurings (TDRs)	1,103	1,037
Credit Card [Member]
Troubled debt restructurings (TDRs)	208	233
Total commercial lending [Member]
Troubled debt restructurings (TDRs)	599	541
Total consumer lending [Member]
Troubled debt restructurings (TDRs)	$ 2,243	$ 2,318