LOANS - Corporate Loan Delinquency (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Non-Accrual Details
Loans, net of unearned income	$ 653,183	$ 624,369
Loans at fair value	4,308	3,486
Corporate
Non-Accrual Details
90 days past due and accruing	1,385	997
Total non-accrual	2,054	2,421
Total current	319,887	292,431
Loans, net of unearned income	327,607	299,306
Loans at fair value	4,281	3,457
Purchased distressed loans	$ 0	0
Number of days past due, non-accrual status	90 days
Loans less than this number of days past due are considered current	30 days
Corporate | Commercial and industrial
Non-Accrual Details
90 days past due and accruing	$ 266	195
Total non-accrual	1,468	1,909
Total current	139,508	127,012
Loans, net of unearned income	141,242	129,116
Corporate | Financial institutions
Non-Accrual Details
90 days past due and accruing	349	121
Total non-accrual	224	185
Total current	69,232	61,254
Loans, net of unearned income	69,805	61,560
Corporate | Mortgage and real estate
Non-Accrual Details
90 days past due and accruing	289	285
Total non-accrual	169	139
Total current	49,176	43,607
Loans, net of unearned income	49,634	44,031
Corporate | Leases
Non-Accrual Details
90 days past due and accruing	49	35
Total non-accrual	60	56
Total current	1,590	1,678
Loans, net of unearned income	1,699	1,769
Corporate | Other
Non-Accrual Details
90 days past due and accruing	432	361
Total non-accrual	133	132
Total current	60,381	58,880
Loans, net of unearned income	60,946	59,373
Corporate | 30 to 89 Days Past Due
Non-Accrual Details
90 days past due and accruing	1,269	786
Corporate | 30 to 89 Days Past Due | Commercial and industrial
Non-Accrual Details
90 days past due and accruing	208	143
Corporate | 30 to 89 Days Past Due | Financial institutions
Non-Accrual Details
90 days past due and accruing	348	119
Corporate | 30 to 89 Days Past Due | Mortgage and real estate
Non-Accrual Details
90 days past due and accruing	280	148
Corporate | 30 to 89 Days Past Due | Leases
Non-Accrual Details
90 days past due and accruing	31	27
Corporate | 30 to 89 Days Past Due | Other
Non-Accrual Details
90 days past due and accruing	402	349
Corporate | Equal to greater than 90 days past due and accruing
Non-Accrual Details
90 days past due and accruing	116	211
Corporate | Equal to greater than 90 days past due and accruing | Commercial and industrial
Non-Accrual Details
90 days past due and accruing	58	52
Corporate | Equal to greater than 90 days past due and accruing | Financial institutions
Non-Accrual Details
90 days past due and accruing	1	2
Corporate | Equal to greater than 90 days past due and accruing | Mortgage and real estate
Non-Accrual Details
90 days past due and accruing	9	137
Corporate | Equal to greater than 90 days past due and accruing | Leases
Non-Accrual Details
90 days past due and accruing	18	8
Corporate | Equal to greater than 90 days past due and accruing | Other
Non-Accrual Details
90 days past due and accruing	$ 30	$ 12