Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income		$ 34,830	$ 98,626
Components of other comprehensive income
Unrealized holding gains (losses), net, arising on available-for-sale fixed maturity investments		130,229	446,610
Unrealized holding gains (losses), net, arising on cash flow hedges		(6,955)	(1,604)
Reclassification adjustment for (gains) losses, net, realized in net income		1,475	(22,456)
Net unrealized gains (losses) related to investments		124,749	422,550
Future policy benefits, DAC and VOBA adjustments		(28,466)	(76,240)
Employee benefit plan adjustment		2,146	2,234
Other comprehensive income before income taxes		98,429	348,544
Income tax expense related to items of other comprehensive income		34,450	121,991
Other comprehensive income (loss)	[1]	63,979	226,553
Total comprehensive income		$ 98,809	$ 325,179

[1] Other comprehensive income includes the non-credit component of impaired gains (losses), net, on fixed maturities available-for-sale in the amounts of $(1,089) and $(1,895) for the three months ended March 31, 2017, and 2016, respectively