SECURITIES - Schedule of Cumulative Credit Losses Recognized in Earnings (Details) - Available-for-sale Securities - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Cumulative balance at beginning of period	$ 66	$ 62	$ 66	$ 62	$ 62
Credit impairments recognized in earnings on securities that have been previously impaired	7	2	8	3	5
Reductions due to increases in cash flow expectations on impaired securities	0	(2)	(1)	(3)
Cumulative balance at end of period	$ 73	$ 62	$ 73	$ 62	$ 73