DERIVATIVE FINANCIAL INSTRUMENTS (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives, gross	$ (34,993,000)	$ (119,888,000)	$ (47,679,000)	$ (142,960,000)
Notional Amount, Other long-term investments	2,262,991,000		2,262,991,000		1,249,465,000
Fair Value, Other long-term investments	38,610,000		38,610,000		35,667,000
Notional Amount, Other liabilities	6,191,418,000		6,191,418,000		6,105,014,000
Fair Value, Other liabilities	246,744,000		246,744,000		243,511,000
Cash flow hedges. | Inflation
Notional amount and fair value of the entity's derivative financial instruments
Notional Amount, Other long-term investments	29,828,000		29,828,000
Fair Value, Other long-term investments	13,000		13,000
Notional Amount, Other liabilities	263,551,000		263,551,000		293,379,000
Fair Value, Other liabilities	8,152,000		8,152,000		12,005,000
Cash flow hedges. | Interest rate swaps
Notional amount and fair value of the entity's derivative financial instruments
Base of floating rate interest rate payments			LIBOR
Notional Amount, Other liabilities	75,000,000		75,000,000		75,000,000
Fair Value, Other liabilities	5,315,000		5,315,000		6,747,000
Derivatives not designated as hedging instruments
Notional amount and fair value of the entity's derivative financial instruments
Realized investment gains (losses) - derivatives, gross	(34,993,000)	(119,888,000)	(47,679,000)	(142,960,000)
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, gross	(2,989,000)	(6,382,000)	(2,457,000)	(8,774,000)
Notional Amount, Other long-term investments	25,000,000		25,000,000		25,000,000
Fair Value, Other long-term investments	3,596,000		3,596,000		3,808,000
Notional Amount, Other liabilities	110,000,000		110,000,000		110,000,000
Fair Value, Other liabilities	8,618,000		8,618,000		9,137,000
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, gross	917,000	(1,142,000)	694,000	(637,000)
Notional Amount, Other long-term investments	80,000,000		80,000,000
Fair Value, Other long-term investments	465,000		465,000
Notional Amount, Other liabilities	165,000,000		165,000,000		25,000,000
Fair Value, Other liabilities	4,422,000		4,422,000		1,099,000
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, gross	(3,982,000)		(7,259,000)
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, gross	(917,000)		(3,734,000)
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, gross	(1,503,000)		(19,346,000)
Notional Amount, Other long-term investments	581,000		581,000
Fair Value, Other long-term investments	11,000		11,000
Notional Amount, Other liabilities	89,808,000		89,808,000		327,321,000
Fair Value, Other liabilities	3,045,000		3,045,000		7,231,000
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, gross	(199,000)		(199,000)
Notional Amount, Other long-term investments	38,085,000		38,085,000
Fair Value, Other long-term investments	420,000		420,000
Notional Amount, Other liabilities	13,581,000		13,581,000
Fair Value, Other liabilities	2,000		2,000
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, gross	9,039,000		3,369,000
Notional Amount, Other liabilities	381,653,000		381,653,000		598,357,000
Fair Value, Other liabilities	3,531,000		3,531,000		16,764,000
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	(29,214,000)	(63,063,000)	(21,372,000)	(94,157,000)
Notional Amount, Other long-term investments	30,030,000		30,030,000		29,563,000
Fair Value, Other long-term investments	1,988,000		1,988,000		2,687,000
Notional Amount, Other liabilities	2,799,920,000		2,799,920,000		2,842,862,000
Fair Value, Other liabilities	166,779,000		166,779,000		146,105,000
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, gross	(5,533,000)	(49,326,000)	2,662,000	(40,202,000)
Notional Amount, Other long-term investments	1,645,178,000		1,645,178,000		1,094,395,000
Fair Value, Other long-term investments	25,540,000		25,540,000		22,346,000
Notional Amount, Other liabilities	2,052,821,000		2,052,821,000		1,493,745,000
Fair Value, Other liabilities	42,481,000		42,481,000		41,948,000
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	(612,000)	25,000	(37,000)	810,000
Notional Amount, Other long-term investments	414,289,000		414,289,000		100,507,000
Fair Value, Other long-term investments	6,577,000		6,577,000		6,826,000
Notional Amount, Other liabilities	240,084,000		240,084,000		339,350,000
Fair Value, Other liabilities	4,399,000		4,399,000		2,475,000
Credit default protection on liquid traded indices
Notional amount and fair value of the entity's derivative financial instruments
Attachment point (as a percent)			10.00%
Exhaustion point (as a percent)			15.00%
Maximum potential amount of future payments (undiscounted) that the entity could be required to make under the credit derivatives	25,000,000		25,000,000
Collateral posted	1,800,000		1,800,000
Fair Value, Other liabilities	1,500,000		1,500,000
Credit default protection on single name entities
Notional amount and fair value of the entity's derivative financial instruments
Maximum potential amount of future payments (undiscounted) that the entity could be required to make under the credit derivatives	220,000,000		220,000,000
Additional collateral required to be posted	2,500,000		2,500,000
Fair Value, Other liabilities	$ 2,500,000		$ 2,500,000