SECURITIES - Schedule of Cumulative Credit Losses Recognized in Earnings (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Credit impairments recognized in earnings on securities that have been previously impaired	$ 2	$ 1	$ 5	$ 7
Available-for-sale Securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Cumulative balance at beginning of period	62	60	62	56
Credit impairments recognized in earnings on securities not previously impaired	0	0	0	0
Credit impairments recognized in earnings on securities that have been previously impaired	2	1	5	7
Reductions due to increases in cash flow expectations on impaired securities	(1)	(1)	(4)	(3)
Cumulative balance at end of period	$ 63	$ 60	$ 63	$ 60