Other Comprehensive Income (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Before-tax amount
Unrealized gains (losses) arising during the year on fixed maturities, available-for-sale	$ (588,693)	[1]	$ 172,325	[1]	$ (629,873)	[1]	$ 207,058	[1]
Net changes during the year related to cash flow hedges	(7,040)		11,585		16,908		7,039
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, DAC and VOBA adjustments	121,174		(40,732)		136,532		(28,624)
Net unrealized gains (losses)	(472,035)		118,302		(498,489)		142,706
Other comprehensive income (loss) before income taxes	(472,035)		118,302		(498,489)		142,706
Tax (expense) benefit
Unrealized gains (losses) arising during the year on fixed maturities, available-for-sale	206,043		(60,314)		220,455		(72,470)
Net changes during the year related to cash flow hedges	2,464		(4,055)		(5,918)		(2,464)
Reclassification adjustment for gains realized in net income	(883)		8,708		7,720		14,969
Net unrealized gains (losses)	207,624		(55,661)		222,257		(59,965)
Future policy benefits, deferred acquisition costs and value of business acquired adjustments	(42,411)		14,255		(47,785)		10,018
Net unrealized gains (losses)	165,213		(41,406)		174,472		(49,947)
Other comprehensive income (loss)	165,213		(41,406)		174,472		(49,947)
Net-of-tax amount
Unrealized gains (losses) arising during the year on fixed maturities, available-for-sale	(382,650)		112,011		(409,418)		134,588
Net changes during the year related to cash flow hedges	(4,576)		7,530		10,990		4,575
Reclassification adjustment for gains realized in net income	1,641		(16,168)		(14,336)		(27,798)
Net unrealized gains (losses)	(385,585)		103,373		(412,764)		111,365
Future policy benefits, deferred acquisition costs and value of business acquired adjustments	78,763		(26,477)		88,747		(18,606)
Net unrealized gains (losses)	(306,822)		76,896		(324,017)		92,759
Other comprehensive income (loss)	$ (306,822)		$ 76,896		$ (324,017)		$ 92,759

[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.