RECLASSIFICATIONS OUT OF ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ (387)	$ (372)
Other comprehensive income before reclassifications	187	155
Other-than-temporary impairment not recognized in earnings on securities	(25)	(19)
Amounts reclassified from other comprehensive (loss) income	(11)	(4)
Net other comprehensive income	151	132
Ending balance	(236)	(240)
Net Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	10	(69)
Other comprehensive income before reclassifications	33	65
Other-than-temporary impairment not recognized in earnings on securities	0	0
Amounts reclassified from other comprehensive (loss) income	(8)	(2)
Net other comprehensive income	25	63
Ending balance	35	(6)
Net Unrealized Gains (Losses) on Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(28)	74
Other comprehensive income before reclassifications	154	90
Other-than-temporary impairment not recognized in earnings on securities	(25)	(19)
Amounts reclassified from other comprehensive (loss) income	(5)	(4)
Net other comprehensive income	124	67
Ending balance	96	141
Defined Benefit Pension Plans
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(369)	(377)
Other comprehensive income before reclassifications	0	0
Other-than-temporary impairment not recognized in earnings on securities	0	0
Amounts reclassified from other comprehensive (loss) income	2	2
Net other comprehensive income	2	2
Ending balance	$ (367)	$ (375)