BUSINESS SEGMENTS (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Net interest income	$ 3,301	$ 3,058	$ 3,227
Noninterest income	1,678	1,632	1,667
Total revenue	4,979	4,690	4,894
Noninterest expense	3,392	7,679	3,457
Profit (loss) before provision for credit losses	1,587	(2,989)	1,437
Provision for credit losses	319	479	413
Income (loss) before income tax expense (benefit)	1,268	(3,468)	1,024
Income tax expense (benefit)	403	(42)	381
NET INCOME (LOSS)	865	(3,426)	643
Total Average Assets	127,624	120,866	127,666
Consumer Banking
Segment Reporting Information [Line Items]
Net interest income	2,151	2,176	2,197
Noninterest income	899	1,025	1,187
Total revenue	3,050	3,201	3,384
Noninterest expense	2,513	2,522	2,691
Profit (loss) before provision for credit losses	537	679	693
Provision for credit losses	259	308	408
Income (loss) before income tax expense (benefit)	278	371	285
Income tax expense (benefit)	96	129	100
NET INCOME (LOSS)	182	242	185
Total Average Assets	48,939	46,465	47,824
Commercial Banking
Segment Reporting Information [Line Items]
Net interest income	1,073	1,031	1,036
Noninterest income	429	389	349
Total revenue	1,502	1,420	1,385
Noninterest expense	652	635	625
Profit (loss) before provision for credit losses	850	785	760
Provision for credit losses	(6)	(7)	63
Income (loss) before income tax expense (benefit)	856	792	697
Income tax expense (benefit)	295	278	244
NET INCOME (LOSS)	561	514	453
Total Average Assets	38,483	35,229	33,474
Other
Segment Reporting Information [Line Items]
Net interest income	77	(149)	(6)
Noninterest income	350	218	131
Total revenue	427	69	125
Noninterest expense	227	4,522	141
Profit (loss) before provision for credit losses	200	(4,453)	(16)
Provision for credit losses	66	178	(58)
Income (loss) before income tax expense (benefit)	134	(4,631)	42
Income tax expense (benefit)	12	(449)	37
NET INCOME (LOSS)	122	(4,182)	5
Total Average Assets	$ 40,202	$ 39,172	$ 46,368