DERIVATIVE FINANCIAL INSTRUMENTS (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives related to variable annuity contracts, gross	$ (102,832,000)	$ (5,823,000)	$ (64,021,000)
Realized investment gains (losses) - derivatives, gross	(238,480,000)	(155,251,000)	(138,249,000)
Notional Amount, Other long-term investments	6,163,061,000	5,152,071,000
Fair Value, Other long-term investments	113,364,000	48,245,000
Notional Amount, Other liabilities	9,672,554,000	7,321,905,000
Fair Value, Other liabilities	657,874,000	455,710,000
Collateral posted	34,800,000
Collateral received as cash	11,600,000
Additional collateral required to be posted	54,900,000
Cash flow hedges. | Inflation
Notional amount and fair value of the entity's derivative financial instruments
Notional Amount, Other long-term investments		7,068,000
Fair Value, Other long-term investments		1,000
Notional Amount, Other liabilities	182,965,000	244,399,000
Fair Value, Other liabilities	5,027,000	8,863,000
Cash flow hedges. | Interest rate swaps
Notional amount and fair value of the entity's derivative financial instruments
Notional Amount, Other liabilities		75,000,000
Fair Value, Other liabilities		3,443,000
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	3,264,000	7,718,000
Realized investment gains (losses) - derivatives, gross	(87,000)	(11,264,000)	(8,427,000)
Notional Amount, Other long-term investments	355,000,000	125,000,000
Fair Value, Other long-term investments	6,532,000	5,118,000
Notional Amount, Other liabilities	400,000,000	25,000,000
Fair Value, Other liabilities	10,025,000	3,064,000
Derivatives not designated as hedging instruments | Credit default swaps
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives related to variable annuity contracts, gross		(7,851,000)
Realized investment gains (losses) - derivatives, gross		(548,000)	1,389,000
Net settlements received	2,500,000
Realized loss on terminated contracts	10,400,000
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	(37,370,000)	(15,051,000)	(1,824,000)
Notional Amount, Other long-term investments	573,493,000	440,000,000
Fair Value, Other long-term investments	61,833,000	19,396,000
Derivatives not designated as hedging instruments | Volatility swaps
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives related to variable annuity contracts, gross	(11,792,000)	(239,000)	(2,433,000)
Notional Amount, Other long-term investments	500,000
Fair Value, Other long-term investments	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	(50,797,000)	(30,061,000)	(42,258,000)
Notional Amount, Other long-term investments	147,581,000	49,631,000
Fair Value, Other long-term investments	595,000	837,000
Notional Amount, Other liabilities	152,364,000	189,765,000
Fair Value, Other liabilities	3,316,000	1,454,000
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	(2,763,000)	2,977,000
Notional Amount, Other long-term investments	15,944,000	57,912,000
Fair Value, Other long-term investments	784,000	976,000
Notional Amount, Other liabilities	131,979,000	14,348,000
Fair Value, Other liabilities	1,901,000	126,000
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	(2,666,000)	(2,801,000)
Notional Amount, Other long-term investments	3,000,000,000	3,000,000,000
Fair Value, Other long-term investments		2,666,000
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	21,138,000	164,221,000	(11,778,000)
Notional Amount, Other long-term investments		615,445,000
Fair Value, Other long-term investments		6,393,000
Notional Amount, Other liabilities	893,476,000	270,019,000
Fair Value, Other liabilities	13,970,000	1,148,000
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	(132,816,000)	(134,340,000)	(67,989,000)
Notional Amount, Other long-term investments	30,244,000	30,001,000
Fair Value, Other long-term investments	1,330,000	2,038,000
Notional Amount, Other liabilities	2,655,134,000	2,761,686,000
Fair Value, Other liabilities	411,907,000	279,799,000
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	(22,120,000)	(127,537,000)	(5,728,000)
Notional Amount, Other long-term investments	1,640,075,000	826,790,000
Fair Value, Other long-term investments	30,261,000	10,665,000
Notional Amount, Other liabilities	5,253,961,000	3,741,688,000
Fair Value, Other liabilities	199,530,000	157,813,000
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	(79,000)	(475,000)	799,000
Notional Amount, Other long-term investments	224,000	224,000
Fair Value, Other long-term investments	253,000	155,000
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	(2,260,000)
Notional Amount, Other long-term investments	400,000,000
Fair Value, Other long-term investments	11,370,000
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	$ (132,000)