Loans and ACL - Collectively Evaluated for Impairment (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Recorded Investment	$ 147,354	$ 147,329
Related ALLL	1,373	1,383
Commercial | Commercial and industrial
Recorded Investment	61,683	61,629
Related ALLL	522	521
Commercial | CRE
Recorded Investment	20,721	20,960
Related ALLL	175	181
Commercial | Lease financing
Recorded Investment	2,097	2,015
Related ALLL	11	11
Retail | Residential mortgage
Recorded Investment	30,697	30,539
Related ALLL	159	164
Retail | Direct
Recorded Investment	11,398	11,517
Related ALLL	91	92
Retail | Indirect
Recorded Investment	17,194	17,099
Related ALLL	299	299
Revolving credit
Recorded Investment	3,123	3,104
Related ALLL	108	106
PCI
Recorded Investment	441	466
Related ALLL	$ 8	$ 9