Restatement of Previously Issued Condensed Consolidated Financial Statements (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Net income (loss)	$ (4,054)		$ 66,025		$ 62,780		$ 115,948
Unrealized gains (losses) arising on fixed maturities, available-for-sale	(588,693)	[1]	172,325	[1]	(629,873)	[1]	207,058	[1]
Reclassification adjustment for (gains) losses realized in net income	2,524		(24,876)		(22,056)		(42,767)
Net unrealized (gains) losses related to investments	(593,209)		159,034		(635,021)		171,330
Future policy benefits, deferred acquisition costs and value of business acquired adjustments	121,174		(40,732)		136,532		(28,624)
Other comprehensive income (loss) before income taxes	(472,035)		118,302		(498,489)		142,706
Income tax (benefit) expense related to items of other comprehensive income (loss)	(165,213)		41,406		(174,472)		49,947
Other comprehensive income (loss)	(306,822)		76,896		(324,017)		92,759
Comprehensive income (loss)	(310,876)		142,921		(261,237)		208,707
As previously reported
Net income (loss)	43,413		61,048		117,640		112,042
Unrealized gains (losses) arising on fixed maturities, available-for-sale	(612,083)		177,624		(652,701)		211,734
Reclassification adjustment for (gains) losses realized in net income	2,251		(27,290)		(19,436)		(44,681)
Net unrealized (gains) losses related to investments	(616,872)		161,919		(655,229)		174,092
Future policy benefits, deferred acquisition costs and value of business acquired adjustments	125,324		(41,214)		140,011		(29,063)
Other comprehensive income (loss) before income taxes	(491,548)		120,705		(515,218)		145,029
Income tax (benefit) expense related to items of other comprehensive income (loss)	(172,042)		42,247		(180,327)		50,760
Other comprehensive income (loss)	(319,506)		78,458		(334,891)		94,269
Comprehensive income (loss)	(276,093)		139,506		(217,251)		206,311
Adjustments for accounting for forward settling to be announced (TBA) security transactions, plan sponsor expense accounts, and deferred acquisition costs (DAC) | Retrospective adoption
Net income (loss)	(47,467)		4,977		(54,860)		3,906
Unrealized gains (losses) arising on fixed maturities, available-for-sale	23,390		(5,299)		22,828		(4,676)
Reclassification adjustment for (gains) losses realized in net income	273		2,414		(2,620)		1,914
Net unrealized (gains) losses related to investments	23,663		(2,885)		20,208		(2,762)
Future policy benefits, deferred acquisition costs and value of business acquired adjustments	(4,150)		482		(3,479)		439
Other comprehensive income (loss) before income taxes	19,513		(2,403)		16,729		(2,323)
Income tax (benefit) expense related to items of other comprehensive income (loss)	6,829		(841)		5,855		(813)
Other comprehensive income (loss)	12,684		(1,562)		10,874		(1,510)
Comprehensive income (loss)	$ (34,783)		$ 3,415		$ (43,986)		$ 2,396

[1] Other comprehensive income (loss) includes the non-credit component of impaired losses on fixed maturities available-for-sale in the amounts of $2,919 and $1,215 for the three months ended June 30, 2013 and 2012, respectively, and $6,645 and $6,933 for the six months ended June 30, 2013 and 2012, respectively.