PARENT COMPANY FINANCIALS - Condensed Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
ASSETS:
Cash and due from banks	$ 1,081	$ 987
Other assets	4,754	3,429
TOTAL ASSETS	160,518	152,336
LIABILITIES:
Long-term borrowed funds	14,433	11,765
Other liabilities	2,019	1,660
TOTAL LIABILITIES	139,701	132,066
TOTAL STOCKHOLDERS’ EQUITY	20,817	20,270	$ 19,747	$ 19,646
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	160,518	152,336
Parent company
ASSETS:
Cash and due from banks	961	563
Other assets	117	125
TOTAL ASSETS	22,979	22,756
LIABILITIES:
Long-term borrowed funds	1,987
Other liabilities	175	166
TOTAL LIABILITIES	2,162	2,486
TOTAL STOCKHOLDERS’ EQUITY	20,817	20,270
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	22,979	22,756
Bank subsidiaries | Parent company
ASSETS:
Loans and advances	1,158	1,160
Investments in subsidiaries	20,590	20,765
Nonbank subsidiaries | Parent company
ASSETS:
Loans and advances	70	70
Investments in subsidiaries	83	73
Unaffiliated companies | Parent company
LIABILITIES:
Long-term borrowed funds	$ 1,987	$ 2,320