PARENT COMPANY FINANCIALS - Condensed Statements of Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING INCOME:
Equity securities gains	$ 0	$ 0	$ 1
Total interest income	6,189	5,758	4,920
OPERATING EXPENSE:
Salaries and employee benefits	2,026	1,880	1,766
Interest expense	1,575	1,226	747
All other expenses	476	495	542
Income taxes	460	462	260
NET INCOME	1,791	1,721	1,652
Other comprehensive income (loss), net of income taxes:
Total other comprehensive income (loss), net of income taxes	680	(276)	(7)
Total comprehensive income	2,471	1,445	1,645
Parent company
OPERATING INCOME:
Dividends from banking subsidiaries	1,130	1,650	1,055
Interest	48	46	43
Management and service fees	42	22	31
Equity securities gains	0	0	1
All other operating income	1	1	1
Total interest income	1,233	1,726	1,136
OPERATING EXPENSE:
Salaries and employee benefits	35	25	40
Interest expense	87	89	97
All other expenses	27	23	22
Total operating expense	149	137	159
Income before taxes and undistributed income	1,084	1,589	977
Income taxes	(10)	(13)	(10)
Income before undistributed income of subsidiaries and associated companies	1,094	1,602	987
NET INCOME	1,791	1,721	1,652
Other comprehensive income (loss), net of income taxes:
Net pension plan activity arising during the period	(5)	5	(1)
Net unrealized derivative instrument gains arising during the period	2	2	1
Net other comprehensive loss	(3)	7	0
Other comprehensive income (loss) activity of Bank subsidiaries, net of income taxes	683	(283)	(7)
Total other comprehensive income (loss), net of income taxes	680	(276)	(7)
Total comprehensive income	2,471	1,445	1,645
Nonbank subsidiaries | Parent company
OPERATING INCOME:
Interest	4	2	1
Dividends from nonbank subsidiaries	8	5	4
OPERATING EXPENSE:
Equity in undistributed income (losses) of subsidiaries and associated companies	15	10	10
Bank subsidiaries | Parent company
OPERATING EXPENSE:
Equity in undistributed income (losses) of subsidiaries and associated companies	$ 682	$ 109	$ 655