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
	Mar. 31, 2017	Mar. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net interest income	$ 1,005	$ 904
Provision for credit losses	96	91
Noninterest income	379	330
Noninterest expense	854	811
Income before income tax expense	434	332
Income tax expense	114	109
NET INCOME	320	223
Amount Reclassified from AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net interest income	10	14
Noninterest income	3	8
Noninterest expense	5	4
Income tax expense	3	7
NET INCOME	$ 5	$ 11