Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income		$ 67,573	$ 60,501	$ 159,172	$ 230,205
Components of other comprehensive income (loss)
Unrealized holding gains (losses), net, arising on available-for-sale fixed maturity investments		(5,568)	(100,800)	(318,529)	471,537
Unrealized holding gains (losses), net, arising on cash flow hedges		14,804	7,408	15,326	11,302
Reclassification adjustment for (gains) losses, net, 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)
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
Income tax expense (benefit) related to items of other comprehensive income (loss)		669	(34,557)	(103,603)	126,621
Other comprehensive income (loss)	[1]	1,246	(64,179)	(192,401)	235,152
Total comprehensive income (loss)		68,819	(3,678)	(33,229)	465,357
Non-credit component of impaired losses on fixed maturities available-for-sale		$ (1,979)	$ (996)	$ (3,208)	$ (3,812)

[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.