DERIVATIVE FINANCIAL INSTRUMENTS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011		Jun. 30, 2012	Jun. 30, 2011		Dec. 31, 2011
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives, gross	$ (47,768)	$ (35,045)	[1]	$ (77,677)	$ (47,909)	[1]
Notional Amount, Other long-term investments	6,786,747			6,786,747			5,948,784
Fair Value, Other long-term investments	105,674			105,674			54,645
Notional Amount, Other liabilities	8,406,236			8,406,236			7,321,905
Fair Value, Other liabilities	549,828			549,828			455,710
Derivatives not designated as hedging instruments
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives related to variable annuity contracts, gross	4,628	(2,196)		(36,572)	(23,679)
Realized investment gains (losses) - derivatives, gross	(47,768)	(35,045)		(77,677)	(47,909)
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	69,196	9,039		35,790	3,369
Notional Amount, Other long-term investments	769,749			769,749			615,445
Fair Value, Other long-term investments	7,065			7,065			6,393
Notional Amount, Other liabilities	358,884			358,884			270,019
Fair Value, Other liabilities	625			625			1,148
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	(220)	(1,503)		(25,319)	(19,346)
Notional Amount, Other long-term investments							49,631
Fair Value, Other long-term investments							837
Notional Amount, Other liabilities	296,141			296,141			189,765
Fair Value, Other liabilities	14,964			14,964			1,454
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	1,764	(199)		780	(199)
Notional Amount, Other long-term investments	14,425			14,425			57,912
Fair Value, Other long-term investments	323			323			976
Notional Amount, Other liabilities	111,326			111,326			14,348
Fair Value, Other liabilities	1,835			1,835			126
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			(132)
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	1,063	(917)		(821)	(3,734)
Notional Amount, Other long-term investments	600			600
Fair Value, Other long-term investments	609			609
Notional Amount, Other liabilities	675			675
Fair Value, Other liabilities	1,430			1,430
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	3,153	(3,982)		(20,719)	(7,259)
Notional Amount, Other long-term investments	471,276			471,276			440,000
Fair Value, Other long-term investments	47,330			47,330			19,396
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	8,831			5,312
Notional Amount, Other long-term investments	400,000			400,000
Fair Value, Other long-term investments	18,942			18,942
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	5,954			3,826
Realized investment gains (losses) - derivatives, gross	(2,916)	(2,989)		(879)	(2,457)
Notional Amount, Other long-term investments	225,000			225,000			125,000
Fair Value, Other long-term investments	5,797			5,797			5,118
Notional Amount, Other liabilities	150,000			150,000			25,000
Fair Value, Other liabilities	4,462			4,462			3,064
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		915			915
Derivatives not designated as hedging instruments | Interest rate floor agreement/ YRT premium support
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives, gross	500	(50)		500	(451)
Notional Amount, Other long-term investments	775,198			775,198			796,713
Fair Value, Other long-term investments	6,900			6,900			6,400
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	(48,679)	(29,214)		(37,973)	(21,372)
Notional Amount, Other long-term investments	30,531			30,531			30,001
Fair Value, Other long-term investments	1,787			1,787			2,038
Notional Amount, Other liabilities	2,689,788			2,689,788			2,761,686
Fair Value, Other liabilities	317,520			317,520			279,799
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	(85,456)	(5,549)		(35,289)	2,575
Notional Amount, Other long-term investments	1,099,744			1,099,744			826,790
Fair Value, Other long-term investments	16,628			16,628			10,665
Notional Amount, Other liabilities	4,489,658			4,489,658			3,741,688
Fair Value, Other liabilities	199,067			199,067			157,813
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)			(2,515)
Notional Amount, Other long-term investments	3,000,000			3,000,000			3,000,000
Fair Value, Other long-term investments	152			152			2,666
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	(950)	(596)		(238)	50
Notional Amount, Other long-term investments	224			224			224
Fair Value, Other long-term investments	141			141			155
Cash flow hedges | Inflation
Notional amount and fair value of the entity's derivative financial instruments
Notional Amount, Other long-term investments							7,068
Fair Value, Other long-term investments							1
Notional Amount, Other liabilities	234,764			234,764			244,399
Fair Value, Other liabilities	8,115			8,115			8,863
Cash flow hedges | Interest rate swaps
Notional amount and fair value of the entity's derivative financial instruments
Notional Amount, Other liabilities	75,000			75,000			75,000
Fair Value, Other liabilities	$ 1,810			$ 1,810			$ 3,443

[1] Recast from previously reported information