Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income		$ 98,626	$ 98,612
Components of other comprehensive income
Unrealized holding gains (losses), net, arising on available-for-sale fixed maturity investments		446,610	181,375
Unrealized holding gains (losses), net, arising on cash flow hedges		(1,604)	17,155
Reclassification adjustment for (gains) losses, net, realized in net income		(22,456)	(30,437)
Net unrealized gains (losses) related to investments		422,550	168,093
Future policy benefits, DAC and VOBA adjustments		(76,240)	(35,129)
Employee benefit plan adjustment		2,234	2,603
Other comprehensive income before income taxes		348,544	135,567
Income tax expense related to items of other comprehensive income		121,991	47,448
Other comprehensive income (loss)	[1]	226,553	88,119
Total comprehensive income		325,179	186,731
Non-credit component of impaired gains on fixed maturities available-for-sale		$ (1,895)	$ (2,543)

[1] Other comprehensive income includes the non-credit component of impaired gains (losses), net, on fixed maturities available-for-sale in the amounts of $(1,895) and $(2,543) for the three months ended March 31, 2016, and 2015, respectively.