DERIVATIVE INSTRUMENTS - Offsetting of Financial Assets and Derivative Assets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	$ 1,080	$ 574
Gross amount of liabilities offset in balance sheet	0	0
Net amount of derivative assets presented in balance sheet	1,080	574
Financial instruments, amounts not offset	(698)	(51)
Derivative, collateral, obligation to return securities	0	(190)
Derivative, collateral, obligation to return cash	(382)	(326)
Derivative asset, fair value, amount offset against collateral, subject to master netting agreement	0	7
Derivative asset, not subject to master netting arrangement	127	102
Derivative asset, fair value, amount offset against collateral, not subject to master netting agreement	127	102
Derivative asset, fair value, gross asset including not subject to master netting arrangement	1,207	676
Net amount of derivative assets presented in balance sheet	1,207	676
Derivative asset, fair value, amount offset against collateral	127	109
Offsetting assets
Offsetting Assets [Line Items]
Gross amounts of recognized financial instruments	1,720	1,597
Gross amounts offset in balance sheet	0	0
Net amounts of financial instruments presented in balance sheet	1,720	1,597
Carrying value of financial instruments not offset in balance sheet	(698)	(51)
Securities collateral, not offset in balance sheet	0	(190)
Cash collateral, not offset in balance sheet	(895)	(1,247)
Financial instruments, amount offset against collateral	127	109
Offsetting assets | Securities lending and similar arrangements
Offsetting Assets [Line Items]
Gross amounts of recognized financial instruments	513	921
Gross amounts offset in balance sheet	0	0
Net amounts of financial instruments presented in balance sheet	513	921
Carrying value of financial instruments not offset in balance sheet	0	0
Securities collateral, not offset in balance sheet	0	0
Cash collateral, not offset in balance sheet	(513)	(921)
Financial instruments, amount offset against collateral	$ 0	$ 0