RECLASSIFICATIONS OUT OF ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			$ 19,747	$ 19,646
Other-than-temporary impairment not recognized in earnings on securities	$ 0	$ 3	(2)	(18)
Ending balance	20,109	20,181	20,109	20,181
Total AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(593)	(159)	(668)	(387)
Other comprehensive income before reclassifications	12	(29)	96	235
Other-than-temporary impairment not recognized in earnings on securities	0	3	(2)	(18)
Amounts reclassified from other comprehensive (loss) income	0	(2)	(7)	(17)
Net other comprehensive income	12	(28)	87	200
Ending balance	(581)	(187)	(581)	(187)
Net Unrealized (Losses) Gains on Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(76)	39	(88)	10
Other comprehensive income before reclassifications	(1)	(1)	22	45
Other-than-temporary impairment not recognized in earnings on securities	0	0	0	0
Amounts reclassified from other comprehensive (loss) income	(2)	(6)	(13)	(23)
Net other comprehensive income	(3)	(7)	9	22
Ending balance	(79)	32	(79)	32
Net Unrealized (Losses) Gains on Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(128)	166	(186)	(28)
Other comprehensive income before reclassifications	13	(28)	74	190
Other-than-temporary impairment not recognized in earnings on securities	0	3	(2)	(18)
Amounts reclassified from other comprehensive (loss) income	(1)	2	(2)	(1)
Net other comprehensive income	12	(23)	70	171
Ending balance	(116)	143	(116)	143
Employee Benefit Plans
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(389)	(364)	(394)	(369)
Other comprehensive income before reclassifications	0	0	0	0
Other-than-temporary impairment not recognized in earnings on securities	0	0	0	0
Amounts reclassified from other comprehensive (loss) income	3	2	8	7
Net other comprehensive income	3	2	8	7
Ending balance	$ (386)	$ (362)	$ (386)	$ (362)