Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ 73,799	$ (7,015)	$ 172,421	$ 91,598
Components of other comprehensive income (loss)
Unrealized holding gains (losses), net, arising on available-for-sale fixed maturity investments		393,130	(494,336)	839,740	(312,961)
Unrealized holding gains (losses), net, arising on cash flow hedges		6,102	(16,633)	4,498	522
Reclassification adjustment for (gains) losses, net, realized in net income		(28,635)	(5,038)	(51,091)	(35,475)
Net unrealized gains (losses) related to investments		370,597	(516,007)	793,147	(347,914)
Future policy benefits, DAC and VOBA adjustments		(96,531)	79,587	(172,771)	44,458
Employee benefit plan adjustment		2,234	2,934	4,468	5,537
Other comprehensive income (loss) before income taxes		276,300	(433,486)	624,844	(297,919)
Income tax expense (benefit) related to items of other comprehensive income (loss)		96,704	(151,720)	218,695	(104,272)
Other comprehensive income (loss)	[1]	179,596	(281,766)	406,149	(193,647)
Total comprehensive income (loss)		253,395	(288,781)	578,570	(102,049)
Non-credit component of impaired gains on fixed maturities available-for-sale		$ (2,472)	$ 1,314	$ (4,367)	$ (1,229)

[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 $(2,472) and $1,314 for the three months ended June 30, 2016, and 2015, respectively, and $(4,367) and $(1,229) for the six months ended June 30, 2016, and 2015, respectively.