Loans and ACL (Summary of the primary reason loan modifications were classified as restructurings) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Commercial and Industrial, Excluding Covered [Member]
Summary Of Reason Modifications Were Considered TDRs [Line Items]
TDR rate modification	$ 42	$ 8	$ 80	$ 22
TDR structure modification	8	12	23	51
TDR increase to allowance	1	0	2	0
CRE - Other, Excluding Covered [Member]
Summary Of Reason Modifications Were Considered TDRs [Line Items]
TDR rate modification	21	5	58	35
TDR structure modification	15	26	44	40
TDR increase to allowance	0	0	1	0
CRE - Residential ADC, Excluding Covered [Member]
Summary Of Reason Modifications Were Considered TDRs [Line Items]
TDR rate modification	1	3	16	25
TDR structure modification	3	3	8	24
TDR increase to allowance	0	0	(2)	(2)
Direct Retail Lending, Excluding Covered [Member]
Summary Of Reason Modifications Were Considered TDRs [Line Items]
TDR rate modification	10	15	31	31
TDR structure modification	1	6	6	12
TDR increase to allowance	2	3	4	6
Retail Revolving Credit, Excluding Covered [Member]
Summary Of Reason Modifications Were Considered TDRs [Line Items]
TDR rate modification	7	8	21	23
TDR structure modification	0	0	0	0
TDR increase to allowance	0	1	3	4
Retail Residential Mortgage, Excluding Covered [Member]
Summary Of Reason Modifications Were Considered TDRs [Line Items]
TDR rate modification	39	10	74	92
TDR structure modification	15	18	62	64
TDR increase to allowance	3	2	9	11
Retail Sales Finance, Excluding Covered [Member]
Summary Of Reason Modifications Were Considered TDRs [Line Items]
TDR rate modification	1	1	4	4
TDR structure modification	2	0	5	0
TDR increase to allowance	1	0	3	0
Retail Other Lending Subsidiaries, Excluding Covered [Member]
Summary Of Reason Modifications Were Considered TDRs [Line Items]
TDR rate modification	40	19	132	48
TDR structure modification	0	0	0	2
TDR increase to allowance	$ 6	$ 9	$ 30	$ 17