DERIVATIVE INSTRUMENTS - Offsetting of Financial Assets and Derivative Assets (Details) - USD ($) $ in Millions	Dec. 31, 2015		Dec. 31, 2014
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	$ 676		$ 802
Gross amount of liabilities offset in balance sheet	0		0
Net amount of derivative assets presented in balance sheet	676		802
Financial instruments, amount not offset against derivative assets in balance sheet	0		0
Derivative, Collateral, Obligation to Return Cash and Securities	(412)	[1]	(619)	[2]
Derivative asset, fair value, amount offset against collateral	264		183
Derivative, Collateral, Obligation to Return Securities	(86)		(153)
Derivative, Collateral, Obligation to Return Cash	(326)		(466)
Foreign currency swaps
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	563		746
Gross amount of liabilities offset in balance sheet	0		0
Net amount of derivative assets presented in balance sheet	563		746
Financial instruments, amount not offset against derivative assets in balance sheet	0		0
Derivative, Collateral, Obligation to Return Cash and Securities	(313)		(568)
Derivative asset, fair value, amount offset against collateral	250		178
Foreign currency forwards
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	107		56
Gross amount of liabilities offset in balance sheet	0		0
Net amount of derivative assets presented in balance sheet	107		56
Financial instruments, amount not offset against derivative assets in balance sheet	0		0
Derivative, Collateral, Obligation to Return Cash and Securities	(96)		(51)
Derivative asset, fair value, amount offset against collateral	11		5
Foreign currency options
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	5
Gross amount of liabilities offset in balance sheet	0
Net amount of derivative assets presented in balance sheet	5
Financial instruments, amount not offset against derivative assets in balance sheet	0
Derivative, Collateral, Obligation to Return Cash and Securities	(3)
Derivative asset, fair value, amount offset against collateral	2
Credit default swaps
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	1
Gross amount of liabilities offset in balance sheet	0
Net amount of derivative assets presented in balance sheet	1
Financial instruments, amount not offset against derivative assets in balance sheet	0
Derivative, Collateral, Obligation to Return Cash and Securities	0
Derivative asset, fair value, amount offset against collateral	1
Offsetting assets
Offsetting Assets [Line Items]
Gross amounts of recognized financial instruments	1,597		2,951
Gross amounts offset in balance sheet	0		0
Net amounts of financial instruments presented in balance sheet	1,597		2,951
Carrying value of financial instruments not offset in balance sheet	0		0
Collateral not offset in balance sheet	(1,333)		(2,768)
Financial instruments, amount offset against collateral	264		183
Offsetting assets | Securities lending and similar arrangements
Offsetting Assets [Line Items]
Gross amounts of recognized financial instruments	921		2,149
Gross amounts offset in balance sheet	0		0
Net amounts of financial instruments presented in balance sheet	921		2,149
Carrying value of financial instruments not offset in balance sheet	0		0
Collateral not offset in balance sheet	(921)		(2,149)
Financial instruments, amount offset against collateral	$ 0		$ 0

[1] Consists of $86 of pledged securities and $326 of cash.

[2] Consists of $153 of pledged securities and $466 of cash.