RECLASSIFICATIONS OUT OF ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 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	$ 10	$ 4	(2)	(21)
Ending balance	20,064	20,226	20,064	20,226
Total AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(683)	(236)	(668)	(387)
Other comprehensive income before reclassifications	82	77	84	264
Other-than-temporary impairment not recognized in earnings on securities	10	4	(2)	(21)
Amounts reclassified from other comprehensive (loss) income	(2)	(4)	(7)	(15)
Net other comprehensive income	90	77	75	228
Ending balance	(593)	(159)	(593)	(159)
Net Unrealized (Losses) Gains on Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(97)	35	(88)	10
Other comprehensive income before reclassifications	26	13	23	46
Other-than-temporary impairment not recognized in earnings on securities	0	0	0	0
Amounts reclassified from other comprehensive (loss) income	(5)	(9)	(11)	(17)
Net other comprehensive income	21	4	12	29
Ending balance	(76)	39	(76)	39
Net Unrealized (Losses) Gains on Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(195)	96	(186)	(28)
Other comprehensive income before reclassifications	56	64	61	218
Other-than-temporary impairment not recognized in earnings on securities	10	4	(2)	(21)
Amounts reclassified from other comprehensive (loss) income	1	2	(1)	(3)
Net other comprehensive income	67	70	58	194
Ending balance	(128)	166	(128)	166
Employee Benefit Plans
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(391)	(367)	(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	2	3	5	5
Net other comprehensive income	2	3	5	5
Ending balance	$ (389)	$ (364)	$ (389)	$ (364)