SECURITIES - Schedule of Cumulative Credit Losses Recognized in Earnings (Details) (Available-for-sale Securities [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Available-for-sale Securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Cumulative balance at beginning of period	$ 56	$ 55	$ 38
Credit impairments recognized in earnings on securities not previously impaired	0	0	1
Credit impairments recognized in earnings on debt securities that have been previously impaired	10	8	23
Reductions due to increases in cash flow expectations on impaired securities	(4)	(7)	(7)
Cumulative balance at end of period	$ 62	$ 56	$ 55