BUSINESS SEGMENTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Net interest income	$ 3,402	$ 3,301	$ 3,058
Noninterest income	1,422	1,678	1,632
Total revenue	4,824	4,979	4,690
Noninterest expense	3,259	3,392	7,679
Profit (loss) before provision for credit losses	1,565	1,587	(2,989)
Provision for credit losses	302	319	479
Income (loss) before income tax expense (benefit)	1,263	1,268	(3,468)
Income tax expense	423	403	(42)
NET INCOME (LOSS)	840	865	(3,426)
Total average assets	135,070	127,624	120,866
Consumer Banking
Segment Reporting Information [Line Items]
Net interest income	2,198	2,151	2,176
Noninterest income	910	899	1,025
Total revenue	3,108	3,050	3,201
Noninterest expense	2,456	2,513	2,522
Profit (loss) before provision for credit losses	652	537	679
Provision for credit losses	252	259	308
Income (loss) before income tax expense (benefit)	400	278	371
Income tax expense	138	96	129
NET INCOME (LOSS)	262	182	242
Total average assets	52,848	48,939	46,465
Commercial Banking
Segment Reporting Information [Line Items]
Net interest income	1,162	1,073	1,031
Noninterest income	415	429	389
Total revenue	1,577	1,502	1,420
Noninterest expense	709	652	635
Profit (loss) before provision for credit losses	868	850	785
Provision for credit losses	(13)	(6)	(7)
Income (loss) before income tax expense (benefit)	881	856	792
Income tax expense	302	295	278
NET INCOME (LOSS)	579	561	514
Total average assets	42,800	38,483	35,229
Other
Segment Reporting Information [Line Items]
Net interest income	42	77	(149)
Noninterest income	97	350	218
Total revenue	139	427	69
Noninterest expense	94	227	4,522
Profit (loss) before provision for credit losses	45	200	(4,453)
Provision for credit losses	63	66	178
Income (loss) before income tax expense (benefit)	(18)	134	(4,631)
Income tax expense	(17)	12	(449)
NET INCOME (LOSS)	(1)	122	(4,182)
Total average assets	$ 39,422	$ 40,202	$ 39,172