BUSINESS SEGMENTS (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Net interest income	$ 840	$ 833	$ 1,676	$ 1,641
Noninterest income	360	640	707	998
Total revenue	1,200	1,473	2,383	2,639
Noninterest expense	841	948	1,651	1,758
Profit (loss) before provision for credit losses	359	525	732	881
Provision for credit losses	77	49	135	170
Income before income tax expense	282	476	597	711
Income tax expense (benefit)	92	163	198	232
NET INCOME	190	313	399	479
Total average assets	135,521	127,148	134,429	125,535
Consumer Banking
Segment Reporting Information [Line Items]
Net interest income	544	546	1,077	1,083
Noninterest income	230	236	449	455
Total revenue	774	782	1,526	1,538
Noninterest expense	613	655	1,209	1,293
Profit (loss) before provision for credit losses	161	127	317	245
Provision for credit losses	60	59	123	129
Income before income tax expense	101	68	194	116
Income tax expense (benefit)	35	24	67	40
NET INCOME	66	44	127	76
Total average assets	52,489	48,556	52,048	48,085
Commercial Banking
Segment Reporting Information [Line Items]
Net interest income	286	264	562	520
Noninterest income	108	107	208	214
Total revenue	394	371	770	734
Noninterest expense	181	157	354	310
Profit (loss) before provision for credit losses	213	214	416	424
Provision for credit losses	7	(2)	(14)	(7)
Income before income tax expense	206	216	430	431
Income tax expense (benefit)	71	75	148	149
NET INCOME	135	141	282	282
Total average assets	42,617	38,022	42,114	37,491
Other
Segment Reporting Information [Line Items]
Net interest income	10	23	37	38
Noninterest income	22	297	50	329
Total revenue	32	320	87	367
Noninterest expense	47	136	88	155
Profit (loss) before provision for credit losses	(15)	184	(1)	212
Provision for credit losses	10	(8)	26	48
Income before income tax expense	(25)	192	(27)	164
Income tax expense (benefit)	(14)	64	(17)	43
NET INCOME	(11)	128	(10)	121
Total average assets	$ 40,415	$ 40,570	$ 40,267	$ 39,959