Other Comprehensive Income (Details 2) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Before-tax amount
Unrealized holding gains (losses) arising during the period on available-for-sale fixed maturity investments		$ (5,568)	$ (100,800)	$ (318,529)	$ 471,537
Unrealized holding gains (losses) arising during the period on cash flow hedges		14,804	7,408	15,326	11,302
Reclassification adjustment for (gains) losses realized in net income		(8,036)	(6,738)	(43,511)	(35,492)
Net unrealized gains (losses) related to investments		1,200	(100,130)	(346,714)	447,347
Future policy benefits, DAC and VOBA adjustments		(2,383)	405	42,075	(86,563)
Net unrealized gains (losses)		(1,183)	(99,725)	(304,639)	360,784
Employee benefit plan adjustment		3,098	989	8,635	989
Other comprehensive income (loss) before income taxes		1,915	(98,736)	(296,004)	361,773
Tax (expense) benefit
Unrealized holding gains (losses) arising during the period on available-for-sale fixed maturity investments		1,949	35,280	111,486	(165,038)
Unrealized holding gains (losses) arising during the period on cash flow hedges		(5,181)	(2,593)	(5,364)	(3,956)
Reclassification adjustment for (gains) losses realized in net income		2,813	2,358	15,229	12,422
Net unrealized gains (losses)		(419)	35,045	121,351	(156,572)
Future policy benefits, DAC and VOBA adjustments		834	(142)	(14,726)	30,297
Net unrealized gains (losses)		415	34,903	106,625	(126,275)
Employee benefit plan adjustment		(1,084)	(346)	(3,022)	(346)
Other comprehensive income (loss)		(669)	34,557	103,603	(126,621)
Net-of-tax amount
Unrealized holding gains (losses) arising during the period on available-for-sale fixed maturity investments		(3,619)	(65,520)	(207,043)	306,499
Unrealized holding gains (losses) arising during the period on cash flow hedges		9,623	4,815	9,962	7,346
Reclassification adjustment for (gains) losses realized in net income		(5,223)	(4,380)	(28,282)	(23,070)
Net unrealized gains (losses)		781	(65,085)	(225,363)	290,775
Future policy benefits, DAC and VOBA adjustments		(1,549)	263	27,349	(56,266)
Net unrealized gains (losses)		(768)	(64,822)	(198,014)	234,509
Employee benefit plan adjustment		2,014	643	5,613	643
Other comprehensive income (loss)	[1]	$ 1,246	$ (64,179)	$ (192,401)	$ 235,152

[1] Other comprehensive income (loss) includes the non-credit component of impaired gains (losses), net, on fixed maturities available-for-sale in the amounts of $(1,979) and $(996) for the three months ended September 30, 2015, and 2014, respectively, and $(3,208) and $(3,812) for the nine months ended September 30, 2015, and 2014, respectively.