PARENT COMPANY FINANCIALS - Condensed Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
ASSETS:
Cash and due from banks	$ 1,175	$ 1,081
Other assets	5,878	4,754
TOTAL ASSETS	165,733	160,518
LIABILITIES:
Long-term borrowed funds	14,047	15,925
Other liabilities	2,912	2,019
TOTAL LIABILITIES	143,532	139,701
TOTAL STOCKHOLDERS’ EQUITY	22,201	20,817	$ 20,270	$ 19,747
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	165,733	160,518
Parent company
ASSETS:
Cash and due from banks	1,418	961
Other assets	127	117
TOTAL ASSETS	24,883	22,979
LIABILITIES:
Long-term borrowed funds	2,484
Other liabilities	197	175
TOTAL LIABILITIES	2,682	2,162
TOTAL STOCKHOLDERS’ EQUITY	22,201	20,817
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	24,883	22,979
Bank subsidiaries | Parent company
ASSETS:
Loans and advances	1,146	1,158
Investments in subsidiaries	21,973	20,590
Nonbank subsidiaries | Parent company
ASSETS:
Loans and advances	120	70
Investments in subsidiaries	99	83
Unaffiliated companies | Parent company
LIABILITIES:
Long-term borrowed funds	$ 2,485	$ 1,987