DERIVATIVE FINANCIAL INSTRUMENTS (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives related to variable annuity contracts, gross	$ (2,487,000)	$ 4,628,000	$ (13,235,000)	$ (36,572,000)
Realized investment gains (losses) - derivatives, gross	143,881,000	(48,268,000)	151,266,000	(78,177,000)
Notional Amount, Other long-term investments	6,441,180,000		6,441,180,000		6,163,061,000
Fair Value, Other long-term investments	228,155,000		228,155,000		113,364,000
Notional Amount, Other liabilities	8,525,426,000		8,525,426,000		9,672,554,000
Fair Value, Other liabilities	457,240,000		457,240,000		657,874,000
Cash posted as collateral	60,300,000		60,300,000
Securities posted as collateral	52,300,000		52,300,000
Cash collateral received	1,000,000		1,000,000		11,280,000
Embedded derivative - Modco reinsurance treaties
Notional amount and fair value of the entity's derivative financial instruments
Fair Value, Other liabilities	249,873,000		249,873,000		411,907,000
Embedded derivative - GMWB
Notional amount and fair value of the entity's derivative financial instruments
Fair Value, Other liabilities	84,582,000		84,582,000		199,530,000
Embedded derivative - FIA
Notional amount and fair value of the entity's derivative financial instruments
Fair Value, Other liabilities	1,126,000		1,126,000
Cash flow hedges. | Inflation
Notional amount and fair value of the entity's derivative financial instruments
Notional Amount, Other liabilities	182,965,000		182,965,000		182,965,000
Fair Value, Other liabilities	4,429,000		4,429,000		5,027,000
Derivatives not designated as hedging instruments | Interest rate swaps
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives related to variable annuity contracts, gross	(89,722,000)	5,954,000	(106,278,000)	3,826,000
Realized investment gains (losses) - derivatives, gross	1,909,000	(2,916,000)	2,912,000	(879,000)
Notional Amount, Other long-term investments	225,000,000		225,000,000		355,000,000
Fair Value, Other long-term investments	3,658,000		3,658,000		6,532,000
Notional Amount, Other liabilities	1,500,000,000		1,500,000,000		400,000,000
Fair Value, Other liabilities	111,748,000		111,748,000		10,025,000
Derivatives not designated as hedging instruments | Equity options
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives related to variable annuity contracts, gross	(8,131,000)	3,153,000	(36,537,000)	(20,719,000)
Notional Amount, Other long-term investments	1,211,937,000		1,211,937,000		573,493,000
Fair Value, Other long-term investments	93,124,000		93,124,000		61,833,000
Notional Amount, Other liabilities	32,125,000		32,125,000
Fair Value, Other liabilities	1,097,000		1,097,000
Derivatives not designated as hedging instruments | Variance swaps
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives related to variable annuity contracts, gross	2,214,000	1,063,000	(8,219,000)	(821,000)
Notional Amount, Other long-term investments	1,300,000		1,300,000		500,000
Fair Value, Other long-term investments	834,000		834,000		406,000
Notional Amount, Other liabilities					2,675,000
Fair Value, Other liabilities					12,198,000
Derivatives not designated as hedging instruments | Equity futures
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives related to variable annuity contracts, gross	(4,036,000)	(220,000)	(27,261,000)	(25,319,000)
Notional Amount, Other long-term investments	43,543,000		43,543,000		147,581,000
Fair Value, Other long-term investments	637,000		637,000		595,000
Notional Amount, Other liabilities	120,665,000		120,665,000		152,364,000
Fair Value, Other liabilities	711,000		711,000		3,316,000
Derivatives not designated as hedging instruments | Currency future
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives related to variable annuity contracts, gross	(112,000)	1,764,000	7,971,000	780,000
Notional Amount, Other long-term investments	152,545,000		152,545,000		15,944,000
Fair Value, Other long-term investments	3,258,000		3,258,000		784,000
Notional Amount, Other liabilities					131,979,000
Fair Value, Other liabilities					1,901,000
Derivatives not designated as hedging instruments | Interest rate caps
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives, gross		(351,000)		(2,515,000)
Notional Amount, Other long-term investments					3,000,000,000
Derivatives not designated as hedging instruments | Interest rate futures
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives related to variable annuity contracts, gross	(7,654,000)	69,196,000	(24,138,000)	35,790,000
Notional Amount, Other liabilities	246,042,000		246,042,000		893,476,000
Fair Value, Other liabilities	3,674,000		3,674,000		13,970,000
Derivatives not designated as hedging instruments | Embedded derivative - Modco reinsurance treaties
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives, gross	144,998,000	(48,679,000)	161,773,000	(37,973,000)
Notional Amount, Other long-term investments	45,580,000		45,580,000		30,244,000
Fair Value, Other long-term investments	1,069,000		1,069,000		1,330,000
Notional Amount, Other liabilities	2,610,999,000		2,610,999,000		2,655,134,000
Fair Value, Other liabilities	249,873,000		249,873,000		411,907,000
Derivatives not designated as hedging instruments | Embedded derivative - GMWB
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives related to variable annuity contracts, gross	103,315,000	(85,456,000)	183,690,000	(35,289,000)
Notional Amount, Other long-term investments	4,136,051,000		4,136,051,000		1,640,075,000
Fair Value, Other long-term investments	99,003,000		99,003,000		30,261,000
Notional Amount, Other liabilities	3,813,083,000		3,813,083,000		5,253,961,000
Fair Value, Other liabilities	84,582,000		84,582,000		199,530,000
Derivatives not designated as hedging instruments | Other.
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives, gross	(498,000)	(950,000)	(143,000)	(238,000)
Notional Amount, Other long-term investments	224,000		224,000		224,000
Fair Value, Other long-term investments	319,000		319,000		253,000
Derivatives not designated as hedging instruments | Embedded derivative - FIA
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives, gross	(41,000)		(41,000)
Notional Amount, Other liabilities	19,547,000		19,547,000
Fair Value, Other liabilities	1,126,000		1,126,000
Derivatives not designated as hedging instruments | Volatility futures
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives related to variable annuity contracts, gross		343,000		(132,000)
Positions held	0		0
Derivatives not designated as hedging instruments | Interest rate swaptions
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives related to variable annuity contracts, gross	1,639,000	8,831,000	(2,463,000)	5,312,000
Notional Amount, Other long-term investments	625,000,000		625,000,000		400,000,000
Fair Value, Other long-term investments	$ 26,253,000		$ 26,253,000		$ 11,370,000