DERIVATIVE INSTRUMENTS - Offsetting of Financial Liabilities and Derivative Liabilities (Details) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Offsetting Liabilities [Line Items]
Gross amount of recognized derivative liabilities		$ (371)	$ (2,423)
Gross amount of assets offset in balance sheet		0	0
Net amount of derivative liabilities presented in balance sheet		(371)	(2,423)
Financial instruments, amount not offset against derivative liabilities in balance sheet		0	0
Derivative, Collateral, Right to Reclaim Securities		17	1,621	[1]
Derivative, Collateral, Right to Reclaim Cash		3
Derivative, Collateral, Right to Reclaim Securities and Cash	[2]	20
Derivative Liability, Fair Value, Amount Offset Against Collateral		(351)	(802)
Foreign currency swaps
Offsetting Liabilities [Line Items]
Gross amount of recognized derivative liabilities		(314)	(318)
Gross amount of assets offset in balance sheet		0	0
Net amount of derivative liabilities presented in balance sheet		(314)	(318)
Financial instruments, amount not offset against derivative liabilities in balance sheet		0	0
Derivative, Collateral, Right to Reclaim Securities			0
Derivative, Collateral, Right to Reclaim Securities and Cash		1
Derivative Liability, Fair Value, Amount Offset Against Collateral		(313)	(318)
Foreign currency forwards
Offsetting Liabilities [Line Items]
Gross amount of recognized derivative liabilities		(49)	(1,912)
Gross amount of assets offset in balance sheet		0	0
Net amount of derivative liabilities presented in balance sheet		(49)	(1,912)
Financial instruments, amount not offset against derivative liabilities in balance sheet		0	0
Derivative, Collateral, Right to Reclaim Securities			1,439
Derivative, Collateral, Right to Reclaim Securities and Cash		18
Derivative Liability, Fair Value, Amount Offset Against Collateral		(31)	(473)
Foreign currency options
Offsetting Liabilities [Line Items]
Gross amount of recognized derivative liabilities		(8)	(33)
Gross amount of assets offset in balance sheet		0	0
Net amount of derivative liabilities presented in balance sheet		(8)	(33)
Financial instruments, amount not offset against derivative liabilities in balance sheet		0	0
Derivative, Collateral, Right to Reclaim Securities			24
Derivative, Collateral, Right to Reclaim Securities and Cash		1
Derivative Liability, Fair Value, Amount Offset Against Collateral		(7)	(9)
Interest rate swaptions
Offsetting Liabilities [Line Items]
Gross amount of recognized derivative liabilities			(160)
Gross amount of assets offset in balance sheet			0
Net amount of derivative liabilities presented in balance sheet			(160)
Financial instruments, amount not offset against derivative liabilities in balance sheet			0
Derivative, Collateral, Right to Reclaim Securities			158
Derivative Liability, Fair Value, Amount Offset Against Collateral			(2)
Offsetting liabilities
Offsetting Liabilities [Line Items]
Gross amounts of recognized financial instruments		(1,312)	(4,616)
Gross amounts offset in balance sheet		0	0
Net amounts of financial instruments presented in balance sheet		(1,312)	(4,616)
Carrying value of financial instruments not offset in balance sheet		921	2,149
Collateral not offset in balance sheet		20	1,621
Financial instruments, amount offset against collateral		(371)	(846)
Offsetting liabilities | Securities lending and similar arrangements
Offsetting Liabilities [Line Items]
Gross amounts of recognized financial instruments		(941)	(2,193)
Gross amounts offset in balance sheet		0	0
Net amounts of financial instruments presented in balance sheet		(941)	(2,193)
Carrying value of financial instruments not offset in balance sheet		921	2,149
Collateral not offset in balance sheet		0	0
Financial instruments, amount offset against collateral		$ (20)	$ (44)

[1] Consists entirely of pledged securities.

[2] Consists of $17 of pledged securities and $3 of cash