Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income		$ 40,017	$ 67,573	$ 212,439	$ 159,172
Components of other comprehensive income (loss)
Unrealized holding gains (losses), net, arising on available-for-sale fixed maturity investments		55,849	(5,568)	895,589	(318,529)
Unrealized holding gains (losses), net, arising on cash flow hedges		(7,805)	14,804	(3,307)	15,326
Reclassification adjustment for (gains) losses, net, realized in net income		(10,284)	(8,036)	(61,375)	(43,511)
Net unrealized gains (losses) related to investments		37,760	1,200	830,907	(346,714)
Future policy benefits, DAC and VOBA adjustments		(18,214)	(2,383)	(190,985)	42,075
Employee benefit plan adjustment		2,494	3,098	6,962	8,635
Other comprehensive income (loss) before income taxes		22,040	1,915	646,884	(296,004)
Income tax expense (benefit) related to items of other comprehensive income (loss)		7,715	669	226,410	(103,603)
Other comprehensive income (loss)	[1]	14,325	1,246	420,474	(192,401)
Total comprehensive income (loss)		54,342	68,819	632,913	(33,229)
Non-credit component of impaired gains on fixed maturities available-for-sale		$ (959)	$ (1,979)	$ (5,326)	$ (3,208)

[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 $(959) and $(1,979) for the three months ended September 30, 2016, and 2015, respectively, and $(5,326) and $(3,208) for the nine months ended September 30, 2016, and 2015, respectively.