Loans and ACL (Aging Analysis of Past Due Loans and Leases) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Loans and leases, current	$ 117,425	$ 112,638
Loans and leases, 30-89 days past due	898	1,112
Loans and leases, 90 days or more past due	945	1,232
Nonaccrual loans and leases	616	935
Total loans and leases	119,884	115,917
Commercial and Industrial [Member]
Loans and leases, current	41,192	38,110
Loans and leases, 30-89 days past due	23	35
Nonaccrual loans and leases	239	363
Total loans and leases	41,454	38,508
CRE Income Producing Properties [Member]
Loans and leases, current	10,644	10,107
Loans and leases, 30-89 days past due	4	8
Nonaccrual loans and leases	74	113
Total loans and leases	10,722	10,228
CRE Construction And Development [Member]
Loans and leases, current	2,708	2,329
Loans and leases, 30-89 days past due	1	2
Nonaccrual loans and leases	26	51
Total loans and leases	2,735	2,382
Commercial Other Lending Subsidiaries [Member]
Loans and leases, current	5,337	4,482
Loans and leases, 30-89 days past due	15	14
Loans and leases, 90 days or more past due	0	5
Nonaccrual loans and leases	4	1
Total loans and leases	5,356	4,502
Direct Retail Lending [Member]
Loans and leases, current	8,045	15,595
Loans and leases, 30-89 days past due	41	132
Loans and leases, 90 days or more past due	12	33
Nonaccrual loans and leases	48	109
Total loans and leases	8,146	15,869
Retail Revolving Credit [Member]
Loans and leases, current	2,428	2,370
Loans and leases, 30-89 days past due	23	23
Loans and leases, 90 days or more past due	9	10
Nonaccrual loans and leases	0	0
Total loans and leases	2,460	2,403
Retail Residential Mortgage-Nonguaranteed [Member]
Loans and leases, current	29,468	22,747
Loans and leases, 30-89 days past due	392	454
Loans and leases, 90 days or more past due	83	69
Nonaccrual loans and leases	164	243
Total loans and leases	30,107	23,513
Retail Residential Mortgage-Government Guaranteed [Member]
Loans and leases, current	251	236
Loans and leases, 30-89 days past due	82	93
Loans and leases, 90 days or more past due	648	806
Nonaccrual loans and leases	2	0
Total loans and leases	983	1,135
Retail Sales Finance [Member]
Loans and leases, current	10,528	9,316
Loans and leases, 30-89 days past due	62	56
Loans and leases, 90 days or more past due	5	5
Nonaccrual loans and leases	5	5
Total loans and leases	10,600	9,382
Retail Other Lending Subsidiaries [Member]
Loans and leases, current	5,830	5,703
Loans and leases, 30-89 days past due	222	207
Nonaccrual loans and leases	54	50
Total loans and leases	6,106	5,960
Acquired from FDIC [Member]
Loans and leases, current	994	1,643
Loans and leases, 30-89 days past due	33	88
Loans and leases, 90 days or more past due	188	304
Nonaccrual loans and leases	0	0
Total loans and leases	$ 1,215	$ 2,035