BUSINESS SEGMENTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net interest income	$ 3,758	$ 3,402	$ 3,301
Noninterest income	1,497	1,422	1,678
Total revenue	5,255	4,824	4,979
Noninterest expense	3,352	3,259	3,392
Profit (loss) before provision for credit losses	1,903	1,565	1,587
Provision for credit losses	369	302	319
Income before income tax expense	1,534	1,263	1,268
Income tax expense	489	423	403
NET INCOME	1,045	840	865
Total average assets	143,183	135,070	127,624
Consumer Banking
Segment Reporting Information [Line Items]
Net interest income	2,443	2,198	2,151
Noninterest income	883	910	899
Total revenue	3,326	3,108	3,050
Noninterest expense	2,547	2,456	2,513
Profit (loss) before provision for credit losses	779	652	537
Provision for credit losses	243	252	259
Income before income tax expense	536	400	278
Income tax expense	191	138	96
NET INCOME	345	262	182
Total average assets	56,388	52,848	48,939
Commercial Banking
Segment Reporting Information [Line Items]
Net interest income	1,288	1,162	1,073
Noninterest income	466	415	429
Total revenue	1,754	1,577	1,502
Noninterest expense	741	709	652
Profit (loss) before provision for credit losses	1,013	868	850
Provision for credit losses	47	(13)	(6)
Income before income tax expense	966	881	856
Income tax expense	335	302	295
NET INCOME	631	579	561
Total average assets	47,159	42,800	38,483
Other
Segment Reporting Information [Line Items]
Net interest income	27	42	77
Noninterest income	148	97	350
Total revenue	175	139	427
Noninterest expense	64	94	227
Profit (loss) before provision for credit losses	111	45	200
Provision for credit losses	79	63	66
Income before income tax expense	32	(18)	134
Income tax expense	(37)	(17)	12
NET INCOME	69	(1)	122
Total average assets	$ 39,636	$ 39,422	$ 40,202