Fair Value Disclosures (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Corporate Debt Securities [Member] | Available-for-sale Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Balance beginning	$ 974,191,000	$ 872,179,000	$ 994,219,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liabilities Gain Loss Included In Earnings [Abstract]
Investment income, net of related expenses	(6,839,000)	218,000	657,000
Investment related gains (losses), net	(2,884,000)	1,863,000	839,000
Claims and other policy benefits	0	0	0
Interest credited	0	0	0
Policy acquisition costs and other insurance expenses	0	0	0
Included in other comprehensive income	34,488,000	21,011,000	34,319,000
Purchases, sales and settlements			71,695,000
Purchases	853,848,000	305,401,000
Sales	(60,224,000)	(48,653,000)
Settlements	(144,667,000)	(125,797,000)
Transfers into Level 3	65,283,000	80,302,000	126,133,000
Transfers out of Level 3	(44,611,000)	(132,333,000)	(355,683,000)
Balance ending	1,668,563,000	974,191,000	872,179,000
Included in Earnings [Abstract]
Investment income, net of related expenses	(6,852,000)	162,000	548,000
Investment related gains (losses), net	(1,329,000)	(1,223,000)	(594,000)
Claims and other policy benefits	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Interest Credited	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Policy Acquisition Costs And Other Insurance Expenses	0	0	0
Residential Mortgage Backed Securities [Member] | Available-for-sale Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Balance beginning	81,655,000	183,291,000	144,457,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liabilities Gain Loss Included In Earnings [Abstract]
Investment income, net of related expenses	431,000	836,000	1,763,000
Investment related gains (losses), net	(311,000)	(2,032,000)	(7,479,000)
Claims and other policy benefits	0	0	0
Interest credited	0	0	0
Policy acquisition costs and other insurance expenses	0	0	0
Included in other comprehensive income	2,863,000	4,580,000	26,808,000
Purchases, sales and settlements			(43,236,000)
Purchases	77,781,000	6,478,000
Sales	(48,828,000)	(21,178,000)
Settlements	(8,541,000)	(16,672,000)
Transfers into Level 3	19,632,000	30,159,000	102,939,000
Transfers out of Level 3	(30,751,000)	(103,807,000)	(41,961,000)
Balance ending	93,931,000	81,655,000	183,291,000
Included in Earnings [Abstract]
Investment income, net of related expenses	295,000	816,000	1,592,000
Investment related gains (losses), net	(269,000)	(594,000)	(4,637,000)
Claims and other policy benefits	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Interest Credited	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Policy Acquisition Costs And Other Insurance Expenses	0	0	0
Asset-backed Securities [Member] | Available-for-sale Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Balance beginning	193,492,000	228,558,000	262,767,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liabilities Gain Loss Included In Earnings [Abstract]
Investment income, net of related expenses	1,214,000	1,686,000	2,843,000
Investment related gains (losses), net	(516,000)	(10,236,000)	(7,494,000)
Claims and other policy benefits	0	0	0
Interest credited	0	0	0
Policy acquisition costs and other insurance expenses	0	0	0
Included in other comprehensive income	21,463,000	3,902,000	31,340,000
Purchases, sales and settlements			(45,677,000)
Purchases	111,567,000	65,467,000
Sales	(13,140,000)	(27,844,000)
Settlements	(16,235,000)	(24,092,000)
Transfers into Level 3	11,832,000	45,984,000	78,880,000
Transfers out of Level 3	(77,286,000)	(89,933,000)	(94,101,000)
Balance ending	232,391,000	193,492,000	228,558,000
Included in Earnings [Abstract]
Investment income, net of related expenses	1,156,000	1,595,000	2,731,000
Investment related gains (losses), net	(849,000)	(5,058,000)	(4,052,000)
Claims and other policy benefits	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Interest Credited	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Policy Acquisition Costs And Other Insurance Expenses	0	0	0
Commercial Mortgage Backed Securities [Member] | Available-for-sale Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Balance beginning	115,976,000	147,556,000	329,559,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liabilities Gain Loss Included In Earnings [Abstract]
Investment income, net of related expenses	2,032,000	2,321,000	3,467,000
Investment related gains (losses), net	(9,503,000)	(12,354,000)	(6,369,000)
Claims and other policy benefits	0	0	0
Interest credited	0	0	0
Policy acquisition costs and other insurance expenses	0	0	0
Included in other comprehensive income	24,663,000	8,060,000	22,907,000
Purchases, sales and settlements			37,476,000
Purchases	31,699,000	7,683,000
Sales	(14,060,000)	0
Settlements	(813,000)	(3,548,000)
Transfers into Level 3	64,116,000	76,955,000	73,653,000
Transfers out of Level 3	(47,104,000)	(110,697,000)	(313,137,000)
Balance ending	167,006,000	115,976,000	147,556,000
Included in Earnings [Abstract]
Investment income, net of related expenses	2,032,000	2,307,000	3,449,000
Investment related gains (losses), net	(14,163,000)	(12,366,000)	(6,563,000)
Claims and other policy benefits	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Interest Credited	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Policy Acquisition Costs And Other Insurance Expenses	0	0	0
US Treasury and Government [Member] | Available-for-sale Securities [Member]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liabilities Gain Loss Included In Earnings [Abstract]
Investment income, net of related expenses	(89,000)
Investment related gains (losses), net	0
Claims and other policy benefits	0
Interest credited	0
Policy acquisition costs and other insurance expenses	0
Included in other comprehensive income	(12,000)
Purchases	4,639,000
Sales	0
Settlements	0
Transfers into Level 3	0
Transfers out of Level 3	0
Balance ending	4,538,000
Included in Earnings [Abstract]
Investment income, net of related expenses	(89,000)
Investment related gains (losses), net	0
Claims and other policy benefits	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Interest Credited	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Policy Acquisition Costs And Other Insurance Expenses	0
US States and Political Subdivisions Debt Securities [Member] | Available-for-sale Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Balance beginning	10,373,000	6,983,000	12,080,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liabilities Gain Loss Included In Earnings [Abstract]
Investment income, net of related expenses	14,000	361,000	118,000
Investment related gains (losses), net	(16,000)	(15,000)	(14,000)
Claims and other policy benefits	0	0	0
Interest credited	0	0	0
Policy acquisition costs and other insurance expenses	0	0	0
Included in other comprehensive income	4,491,000	3,390,000	961,000
Purchases, sales and settlements			34,841,000
Purchases	0	2,334,000
Sales	0	0
Settlements	(413,000)	(88,000)
Transfers into Level 3	37,588,000	48,469,000	1,820,000
Transfers out of Level 3	(8,825,000)	(51,061,000)	(42,823,000)
Balance ending	43,212,000	10,373,000	6,983,000
Included in Earnings [Abstract]
Investment income, net of related expenses	14,000	361,000	118,000
Investment related gains (losses), net	0	0	0
Claims and other policy benefits	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Interest Credited	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Policy Acquisition Costs And Other Insurance Expenses	0	0	0
Foreign Government Debt Securities [Member] | Available-for-sale Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Balance beginning	0	6,736,000	59,975,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liabilities Gain Loss Included In Earnings [Abstract]
Investment income, net of related expenses	(44,000)	2,000	2,000
Investment related gains (losses), net	0	0	(10,000)
Claims and other policy benefits	0	0	0
Interest credited	0	0	0
Policy acquisition costs and other insurance expenses	0	0	0
Included in other comprehensive income	(139,000)	4,000	304,000
Purchases, sales and settlements			1,416,000
Purchases	28,463,000	0
Sales	0	0
Settlements	0	0
Transfers into Level 3	0	20,000	2,178,000
Transfers out of Level 3	0	(6,762,000)	(57,129,000)
Balance ending	28,280,000	0	6,736,000
Included in Earnings [Abstract]
Investment income, net of related expenses	(44,000)	0	6,000
Investment related gains (losses), net	0	0	0
Claims and other policy benefits	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Interest Credited	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Policy Acquisition Costs And Other Insurance Expenses	0	0	0
Funds Withheld At Interest Embedded Derivatives [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Balance beginning	(361,456,000)	(274,220,000)	(434,494,000)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liabilities Gain Loss Included In Earnings [Abstract]
Investment income, net of related expenses	0	0	0
Investment related gains (losses), net	118,279,000	(87,236,000)	160,274,000
Claims and other policy benefits	0	0	0
Interest credited	0	0	0
Policy acquisition costs and other insurance expenses	0	0	0
Included in other comprehensive income	0	0	0
Purchases, sales and settlements			0
Purchases	0	0
Sales	0	0
Settlements	0	0
Transfers into Level 3	0	0	0
Transfers out of Level 3	0	0	0
Balance ending	(243,177,000)	(361,456,000)	(274,220,000)
Included in Earnings [Abstract]
Investment income, net of related expenses	0	0	0
Investment related gains (losses), net	118,279,000	(87,236,000)	160,274,000
Claims and other policy benefits	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Interest Credited	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Policy Acquisition Costs And Other Insurance Expenses	0	0	0
Nonredeemable Preferred Stock [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Balance beginning		420,000	6,775,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liabilities Gain Loss Included In Earnings [Abstract]
Investment income, net of related expenses		0	0
Investment related gains (losses), net		0	550,000
Claims and other policy benefits		0	0
Interest credited		0	0
Policy acquisition costs and other insurance expenses		0	0
Included in other comprehensive income		0	160,000
Purchases, sales and settlements			(5,146,000)
Purchases		0
Sales		(420,000)
Settlements		0
Transfers into Level 3		0	0
Transfers out of Level 3		0	(1,919,000)
Balance ending		0	420,000
Included in Earnings [Abstract]
Investment income, net of related expenses		0	(1,000)
Investment related gains (losses), net		0	(32,000)
Claims and other policy benefits		0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Interest Credited		0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Policy Acquisition Costs And Other Insurance Expenses		0	0
Equity Securities, Other [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Balance beginning	11,489,000	16,416,000	10,436,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liabilities Gain Loss Included In Earnings [Abstract]
Investment income, net of related expenses	0	0	0
Investment related gains (losses), net	1,098,000	3,504,000	0
Claims and other policy benefits	0	0	0
Interest credited	0	0	0
Policy acquisition costs and other insurance expenses	0	0	0
Included in other comprehensive income	843,000	(4,663,000)	4,848,000
Purchases, sales and settlements			1,132,000
Purchases	108,000	797,000
Sales	(3,788,000)	(4,565,000)
Settlements	0	0
Transfers into Level 3	0	0	0
Transfers out of Level 3	(9,750,000)	0	0
Balance ending	0	11,489,000	16,416,000
Included in Earnings [Abstract]
Investment income, net of related expenses	0	0	0
Investment related gains (losses), net	(183,000)	0	0
Claims and other policy benefits	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Interest Credited	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Policy Acquisition Costs And Other Insurance Expenses	0	0	0
Reinsurance Ceded Receivable Embedded Derivatives [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Balance beginning	4,945,000	75,431,000	68,873,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liabilities Gain Loss Included In Earnings [Abstract]
Investment income, net of related expenses	0	0	0
Investment related gains (losses), net	0	0	0
Claims and other policy benefits	0	0	0
Interest credited	0	0	0
Policy acquisition costs and other insurance expenses	(449,000)	9,421,000	7,621,000
Included in other comprehensive income	0	0	0
Purchases, sales and settlements			(1,063,000)
Purchases	0	6,201,000
Sales	0	0
Settlements	(4,496,000)	(86,108,000)
Transfers into Level 3	0	0	0
Transfers out of Level 3	0	0	0
Balance ending	0	4,945,000	75,431,000
Included in Earnings [Abstract]
Investment income, net of related expenses	0	0	0
Investment related gains (losses), net	0	0	0
Claims and other policy benefits	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Interest Credited	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Policy Acquisition Costs And Other Insurance Expenses	(33,000)	18,589,000	7,621,000
Interest Sensitive Contract Liabilities Embedded Derivatives [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Balance beginning	(1,028,241,000)	(721,485,000)	(608,654,000)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liabilities Gain Loss Included In Earnings [Abstract]
Investment income, net of related expenses	0	0	0
Investment related gains (losses), net	104,613,000	(224,184,000)	(28,786,000)
Claims and other policy benefits	770,000	(2,230,000)	(872,000)
Interest credited	(31,552,000)	(88,255,000)	(52,569,000)
Policy acquisition costs and other insurance expenses	0	0	0
Included in other comprehensive income	0	0	0
Purchases, sales and settlements			(30,604,000)
Purchases	(63,934,000)	(71,505,000)
Sales	0	0
Settlements	105,983,000	79,418,000
Transfers into Level 3	0	0	0
Transfers out of Level 3	0	0	0
Balance ending	(912,361,000)	(1,028,241,000)	(721,485,000)
Included in Earnings [Abstract]
Investment income, net of related expenses	0	0	0
Investment related gains (losses), net	97,216,000	(228,910,000)	(28,786,000)
Claims and other policy benefits	56,000	(2,346,000)	(2,824,000)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Interest Credited	(129,828,000)	(167,673,000)	(101,970,000)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Policy Acquisition Costs And Other Insurance Expenses	0	0	0
Short-term Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Balance beginning			443,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liabilities Gain Loss Included In Earnings [Abstract]
Investment income, net of related expenses	(11,000)		0
Investment related gains (losses), net	0		0
Claims and other policy benefits	0		0
Interest credited	0		0
Policy acquisition costs and other insurance expenses	0		0
Included in other comprehensive income	28,000		0
Purchases, sales and settlements			381,000
Purchases	22,014,000
Sales	0
Settlements	0
Transfers into Level 3	0		0
Transfers out of Level 3	0		(824,000)
Balance ending	22,031,000		0
Included in Earnings [Abstract]
Investment income, net of related expenses	(11,000)		0
Investment related gains (losses), net	0		0
Claims and other policy benefits	0		0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Interest Credited	0		0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset And Liabilities Unrealized Gain Loss Still Held Included In Earnings In Policy Acquisition Costs And Other Insurance Expenses	$ 0		$ 0