Loans and ACL - Collectively Evaluated for Impairment (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Recorded Investment	$ 298,401	$ 147,329
Related ALLL	1,396	1,383
Commercial: | Commercial and industrial
Recorded Investment	129,889	61,629
Related ALLL	540	521
Commercial: | CRE
Recorded Investment	26,803	16,714
Related ALLL	148	134
Commercial: | Commercial construction
Recorded Investment	6,167	4,246
Related ALLL	45	47
Commercial: | Lease financing
Recorded Investment	6,113	2,015
Related ALLL	10	11
Consumer: | Residential Mortgage
Recorded Investment	51,452	30,539
Related ALLL	134	164
Consumer: | Residential home equity and direct
Recorded Investment	26,983	11,707
Related ALLL	102	99
Consumer: | Indirect auto
Recorded Investment	24,084	10,962
Related ALLL	240	242
Consumer: | Indirect other
Recorded Investment	11,095	6,137
Related ALLL	59	57
Consumer: | Student
Recorded Investment	6,743	0
Related ALLL	0	0
Credit card
Recorded Investment	5,588	2,914
Related ALLL	110	99
PCI
Recorded Investment	3,484	466
Related ALLL	$ 8	$ 9