Loans and ACL - Aging Analysis of Loans and Leases (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Current	$ 140,094	$ 133,667
30-89 Days Past Due	980	1,031
90 Days Or More Past Due	592	677
Nonaccrual	757	576
Total	142,423	135,951
Commercial and industrial
Current	51,332	48,157
30-89 Days Past Due	34	36
90 Days Or More Past Due	0	0
Nonaccrual	413	237
Total	51,779	48,430
CRE-income producing properties
Current	14,583	13,370
30-89 Days Past Due	3	13
90 Days Or More Past Due	0	0
Nonaccrual	38	38
Total	14,624	13,421
CRE-construction and development
Current	3,850	3,710
30-89 Days Past Due	2	9
90 Days Or More Past Due	0	0
Nonaccrual	12	13
Total	3,864	3,732
Dealer floor plan
Current	1,288	1,215
30-89 Days Past Due	0	0
90 Days Or More Past Due	0	0
Nonaccrual	0	0
Total	1,288	1,215
Commercial other lending subsidiaries
Current	7,396	6,771
30-89 Days Past Due	16	18
90 Days Or More Past Due	0	0
Nonaccrual	10	6
Total	7,422	6,795
Direct retail lending
Current	11,898	11,032
30-89 Days Past Due	62	58
90 Days Or More Past Due	7	7
Nonaccrual	55	43
Total	12,022	11,140
Revolving credit
Current	2,532	2,478
30-89 Days Past Due	20	22
90 Days Or More Past Due	9	10
Nonaccrual	0	0
Total	2,561	2,510
Residential mortgage-nonguaranteed
Current	28,906	29,038
30-89 Days Past Due	354	397
90 Days Or More Past Due	66	55
Nonaccrual	167	173
Total	29,493	29,663
Residential mortgage-government guaranteed
Current	350	306
30-89 Days Past Due	112	78
90 Days Or More Past Due	414	486
Nonaccrual	0	0
Total	876	870
Sales finance
Current	9,894	10,243
30-89 Days Past Due	60	72
90 Days Or More Past Due	4	5
Nonaccrual	6	7
Total	9,964	10,327
Retail other lending subsidiaries
Current	7,195	6,381
30-89 Days Past Due	272	286
90 Days Or More Past Due	0	0
Nonaccrual	56	59
Total	7,523	6,726
PCI
Current	870	966
30-89 Days Past Due	45	42
90 Days Or More Past Due	92	114
Nonaccrual	0	0
Total	$ 1,007	$ 1,122