DERIVATIVE INSTRUMENTS - Offsetting of Financial Assets and Derivative Assets (Details) - USD ($) $ in Millions	Mar. 31, 2016		Dec. 31, 2015
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	$ 1,144		$ 676
Gross amount of liabilities offset in balance sheet	0		0
Net amount of derivative assets presented in balance sheet	1,144		676
Financial instruments, amount not offset against derivative assets in balance sheet	0		0
Derivative, collateral, obligation to return cash and securities	(938)	[1]	(412)	[2]
Derivative asset, fair value, amount offset against collateral	206		264
Derivative, collateral, obligation to return securities	(661)		(86)
Derivative, Collateral, Obligation to Return Cash	(277)		(326)
Foreign currency swaps
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	493		563
Gross amount of liabilities offset in balance sheet	0		0
Net amount of derivative assets presented in balance sheet	493		563
Financial instruments, amount not offset against derivative assets in balance sheet	0		0
Derivative, collateral, obligation to return cash and securities	(308)		(313)
Derivative asset, fair value, amount offset against collateral	185		250
Foreign currency forwards
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	644		107
Gross amount of liabilities offset in balance sheet	0		0
Net amount of derivative assets presented in balance sheet	644		107
Financial instruments, amount not offset against derivative assets in balance sheet	0		0
Derivative, collateral, obligation to return cash and securities	(630)		(96)
Derivative asset, fair value, amount offset against collateral	14		11
Foreign currency options
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	5		5
Gross amount of liabilities offset in balance sheet	0		0
Net amount of derivative assets presented in balance sheet	5		5
Financial instruments, amount not offset against derivative assets in balance sheet	0		0
Derivative, collateral, obligation to return cash and securities	0		(3)
Derivative asset, fair value, amount offset against collateral	5		2
Credit default swaps
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	2		1
Gross amount of liabilities offset in balance sheet	0		0
Net amount of derivative assets presented in balance sheet	2		1
Financial instruments, amount not offset against derivative assets in balance sheet	0		0
Derivative, collateral, obligation to return cash and securities	0		0
Derivative asset, fair value, amount offset against collateral	2		1
Offsetting assets
Offsetting Assets [Line Items]
Gross amounts of recognized financial instruments	1,934		1,597
Gross amounts offset in balance sheet	0		0
Net amounts of assets presented in balance sheet	1,934		1,597
Carrying value of financial instruments not offset in balance sheet	0		0
Collateral not offset in balance sheet	(1,728)		(1,333)
Financial instruments, amount offset against collateral	206		264
Offsetting assets | Securities lending and similar arrangements
Offsetting Assets [Line Items]
Gross amounts of recognized financial instruments	790		921
Gross amounts offset in balance sheet	0		0
Net amounts of assets presented in balance sheet	790		921
Carrying value of financial instruments not offset in balance sheet	0		0
Collateral not offset in balance sheet	(790)		(921)
Financial instruments, amount offset against collateral	$ 0		$ 0

[1] Consists of $661 of pledged securities and $277 of cash.

[2] Consists of $86 of pledged securities and $326 of cash