Loans and ACL - Collectively Evaluated for Impairment (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Recorded Investment	$ 140,581	$ 134,427
Related ALLL	1,315	1,300
Commercial and industrial
Recorded Investment	51,276	48,110
Related ALLL	472	439
CRE-income producing properties
Recorded Investment	14,545	13,339
Related ALLL	106	127
CRE-construction and development
Recorded Investment	3,837	3,697
Related ALLL	24	32
Dealer floor plan
Recorded Investment	1,288	1,215
Related ALLL	10	8
Commercial other lending subsidiaries
Recorded Investment	7,410	6,789
Related ALLL	27	21
Direct retail lending
Recorded Investment	11,940	11,055
Related ALLL	92	93
Revolving credit
Recorded Investment	2,531	2,477
Related ALLL	87	91
Residential mortgage-nonguaranteed
Recorded Investment	29,035	29,228
Related ALLL	141	153
Residential mortgage-government guaranteed
Recorded Investment	463	553
Related ALLL	6	1
Sales finance
Recorded Investment	9,947	10,308
Related ALLL	35	39
Retail other lending subsidiaries
Recorded Investment	7,302	6,534
Related ALLL	252	235
PCI
Recorded Investment	1,007	1,122
Related ALLL	$ 63	$ 61