RECLASSIFICATIONS OUT OF ACCUMULATED OTHER COMPREHENSIVE INCOME - Effects to Net Income of Amounts Reclassified Out of OCI (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net interest income	$ 836	$ 808
Provision for credit losses	58	121
Noninterest income	347	358
Noninterest expense	810	810
Income before income tax expense	315	235
Income tax expense	106	69
NET INCOME	209	166
Amount Reclassified from OCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net interest income	836	808
Provision for credit losses	58	121
Noninterest income	347	358
Noninterest expense	810	810
Income before income tax expense	315	235
Income tax expense	106	69
NET INCOME	209	166
Amount Reclassified from AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net interest income	3	(11)
Noninterest income	7	21
Noninterest expense	3	2
Income tax expense	3	2
NET INCOME	$ 4	$ 6