FAIR VALUE MEASUREMENTS (Details 6) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, Sales, Issues and Settlements, Net, assets	$ (4,131,000,000)	$ 2,503,000,000
Securities purchased through FRBNY's auction of ML III assets	7,100,000,000
Transfers into Level 3 at end of reporting period, net gains (losses) not included in realized and unrealized gains and losses related to Level 3 for the period	143,000,000
Transfers out Level 3 at end of reporting period, net gains (losses) not included in realized and unrealized gains and losses related to Level 3 for the period.	92,000,000
Liabilities
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, liabilities	11,000,000	43,000,000
Sales, liabilities	(27,000,000)	(70,000,000)
Settlements, liabilities	887,000,000	817,000,000
Purchases, Sales, Issues and Settlements, Net, liabilities	871,000,000	790,000,000
Policyholder contract deposits
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Sales, liabilities	(25,000,000)	(70,000,000)
Settlements, liabilities	33,000,000	26,000,000
Purchases, Sales, Issues and Settlements, Net, liabilities	8,000,000	(44,000,000)
Derivative liabilities, net
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, liabilities	11,000,000	43,000,000
Sales, liabilities	(2,000,000)
Settlements, liabilities	612,000,000	236,000,000
Purchases, Sales, Issues and Settlements, Net, liabilities	621,000,000	279,000,000
Other long-term debt
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Settlements, liabilities	242,000,000	555,000,000
Purchases, Sales, Issues and Settlements, Net, liabilities	242,000,000	555,000,000
Assets
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, assets	13,904,000,000	8,850,000,000
Sales, assets	(1,670,000,000)	(1,112,000,000)
Settlements, assets	(16,365,000,000)	(5,235,000,000)
Purchases, Sales, Issues and Settlements, Net, assets	(4,131,000,000)	2,503,000,000
Bonds available for sale
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, assets	5,330,000,000	7,275,000,000
Sales, assets	(1,342,000,000)	(273,000,000)
Settlements, assets	(3,549,000,000)	(3,523,000,000)
Purchases, Sales, Issues and Settlements, Net, assets	439,000,000	3,479,000,000
Bonds available for sale | Obligations of states, municipalities and political subdivisions
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, assets	477,000,000	305,000,000
Sales, assets	(219,000,000)	(4,000,000)
Settlements, assets	(174,000,000)	(5,000,000)
Purchases, Sales, Issues and Settlements, Net, assets	84,000,000	296,000,000
Bonds available for sale | Non-U.S. government
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, assets	5,000,000	4,000,000
Sales, assets	(3,000,000)	(2,000,000)
Settlements, assets	(1,000,000)	3,000,000
Purchases, Sales, Issues and Settlements, Net, assets	1,000,000	5,000,000
Bonds available for sale | Corporate debt
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, assets	283,000,000	497,000,000
Sales, assets	(75,000,000)	(27,000,000)
Settlements, assets	(184,000,000)	(299,000,000)
Purchases, Sales, Issues and Settlements, Net, assets	24,000,000	171,000,000
Bonds available for sale | Residential mortgage backed securities (RMBS)
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, assets	2,308,000,000	4,932,000,000
Sales, assets	(723,000,000)	(205,000,000)
Settlements, assets	(1,901,000,000)	(1,495,000,000)
Purchases, Sales, Issues and Settlements, Net, assets	(316,000,000)	3,232,000,000
Bonds available for sale | Commercial mortgage-backed securities (CMBS)
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, assets	1,137,000,000	470,000,000
Sales, assets	(318,000,000)	(34,000,000)
Settlements, assets	(183,000,000)	(229,000,000)
Purchases, Sales, Issues and Settlements, Net, assets	636,000,000	207,000,000
Bonds available for sale | Collateralized Debt Obligations/Asset Backed Securities (CDO/ABS)
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, assets	1,120,000,000	1,067,000,000
Sales, assets	(4,000,000)	(1,000,000)
Settlements, assets	(1,106,000,000)	(1,498,000,000)
Purchases, Sales, Issues and Settlements, Net, assets	10,000,000	(432,000,000)
Bond trading securities
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, assets	7,607,000,000	857,000,000
Sales, assets	(172,000,000)	(512,000,000)
Settlements, assets	(11,678,000,000)	(535,000,000)
Purchases, Sales, Issues and Settlements, Net, assets	(4,243,000,000)	(190,000,000)
Bond trading securities | Corporate debt
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Settlements, assets	(7,000,000)	(11,000,000)
Purchases, Sales, Issues and Settlements, Net, assets	(7,000,000)	(11,000,000)
Bond trading securities | Residential mortgage backed securities (RMBS)
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, assets		305,000,000
Sales, assets	(45,000,000)	(1,000,000)
Settlements, assets	(64,000,000)	(65,000,000)
Purchases, Sales, Issues and Settlements, Net, assets	(109,000,000)	239,000,000
Bond trading securities | Commercial mortgage-backed securities (CMBS)
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, assets	225,000,000	221,000,000
Sales, assets	(106,000,000)	(207,000,000)
Settlements, assets	(278,000,000)	(109,000,000)
Purchases, Sales, Issues and Settlements, Net, assets	(159,000,000)	(95,000,000)
Bond trading securities | Collateralized Debt Obligations/Asset Backed Securities (CDO/ABS)
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, assets	7,382,000,000	331,000,000
Sales, assets	(21,000,000)	(304,000,000)
Settlements, assets	(11,329,000,000)	(350,000,000)
Purchases, Sales, Issues and Settlements, Net, assets	(3,968,000,000)	(323,000,000)
Equity securities
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, assets	67,000,000
Sales, assets	(56,000,000)	(31,000,000)
Settlements, assets	(80,000,000)	(17,000,000)
Purchases, Sales, Issues and Settlements, Net, assets	(69,000,000)	(48,000,000)
Mortgage and other loans receivable, net of allowance
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Settlements, assets	(1,000,000)	1,000,000
Purchases, Sales, Issues and Settlements, Net, assets	(1,000,000)	1,000,000
Other invested assets
Fair value assets and liabilities measured on recurring basis, unobservable input reconciliation
Purchases, assets	900,000,000	718,000,000
Sales, assets	(100,000,000)	(296,000,000)
Settlements, assets	(1,057,000,000)	(1,161,000,000)
Purchases, Sales, Issues and Settlements, Net, assets	$ (257,000,000)	$ (739,000,000)