RECLASSIFICATIONS OUT OF ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Effects to Net Income of Amounts Reclassified Out of OCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net interest income	$ 945	$ 856	$ 2,772	$ 2,532
Provision for credit losses	86	76	267	211
Noninterest income	435	353	1,120	1,060
Noninterest expense	867	798	2,505	2,449
Income before income tax expense	427	335	1,120	932
Income tax expense	130	115	357	313
NET INCOME	297	220	763	619
Amount Reclassified from AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net interest income	15	7	42	13
Noninterest income	(8)	0	(3)	14
Noninterest expense	4	3	12	10
Income tax expense	1	3	10	7
NET INCOME	$ 2	$ 1	$ 17	$ 10