DERIVATIVE FINANCIAL INSTRUMENTS (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 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	$ (10,748,000)	$ (41,200,000)
Realized investment gains (losses) - derivatives, gross	7,385,000	(29,909,000)
Notional Amount, Other long-term investments	7,883,547,000		6,163,061,000
Fair Value, Other long-term investments	139,595,000		113,364,000
Notional Amount, Other liabilities	8,747,588,000		9,672,554,000
Fair Value, Other liabilities	589,561,000		657,874,000
Cash posted as collateral	20,100,000
Securities posted as collateral	54,600,000
Cash collateral received	2,500,000
Embedded derivative - Modco reinsurance treaties
Notional amount and fair value of the entity's derivative financial instruments
Fair Value, Other long-term investments	1,321,000
Fair Value, Other liabilities	395,123,000
Embedded derivative - GMWB
Notional amount and fair value of the entity's derivative financial instruments
Fair Value, Other long-term investments	55,796,000
Fair Value, Other liabilities	144,691,000
Cash flow hedges. | Inflation
Notional amount and fair value of the entity's derivative financial instruments
Notional Amount, Other long-term investments	135,531,000
Fair Value, Other long-term investments	251,000
Notional Amount, Other liabilities	47,434,000		182,965,000
Fair Value, Other liabilities	65,000		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	(16,556,000)	(2,128,000)
Realized investment gains (losses) - derivatives, gross	1,003,000	2,037,000
Notional Amount, Other long-term investments	300,000,000		355,000,000
Fair Value, Other long-term investments	5,368,000		6,532,000
Notional Amount, Other liabilities	1,105,000,000		400,000,000
Fair Value, Other liabilities	25,057,000		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	(28,406,000)	(23,872,000)
Notional Amount, Other long-term investments	840,276,000		573,493,000
Fair Value, Other long-term investments	64,559,000		61,833,000
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	(10,433,000)	(1,884,000)
Notional Amount, Other long-term investments	400,000		500,000
Fair Value, Other long-term investments	20,000		406,000
Notional Amount, Other liabilities	4,075,000		2,675,000
Fair Value, Other liabilities	22,245,000		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	(23,225,000)	(25,099,000)
Notional Amount, Other long-term investments	55,441,000		147,581,000
Fair Value, Other long-term investments	1,040,000		595,000
Notional Amount, Other liabilities	106,724,000		152,364,000
Fair Value, Other liabilities	1,126,000		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	8,083,000	(984,000)
Notional Amount, Other long-term investments	31,948,000		15,944,000
Fair Value, Other long-term investments	531,000		784,000
Notional Amount, Other liabilities	101,339,000		131,979,000
Fair Value, Other liabilities	1,254,000		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		(2,164,000)
Notional Amount, Other long-term investments	3,000,000,000		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	(16,484,000)	(33,406,000)
Notional Amount, Other long-term investments	473,257,000
Fair Value, Other long-term investments	3,201,000
Notional Amount, Other liabilities			893,476,000
Fair Value, Other liabilities			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	16,775,000	10,706,000
Notional Amount, Other long-term investments	30,561,000		30,244,000
Fair Value, Other long-term investments	1,321,000		1,330,000
Notional Amount, Other liabilities	2,636,425,000		2,655,134,000
Fair Value, Other liabilities	395,123,000		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	80,375,000	50,167,000
Notional Amount, Other long-term investments	2,615,909,000		1,640,075,000
Fair Value, Other long-term investments	55,796,000		30,261,000
Notional Amount, Other liabilities	4,746,591,000		5,253,961,000
Fair Value, Other liabilities	144,691,000		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	355,000	712,000
Notional Amount, Other long-term investments	224,000		224,000
Fair Value, Other long-term investments	240,000		253,000
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	(4,102,000)	(3,519,000)
Notional Amount, Other long-term investments	400,000,000		400,000,000
Fair Value, Other long-term investments	7,268,000		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	$ 0	$ (475,000)
Positions held	0