Condensed Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 60,501		$ 71,971		$ 230,205		$ 134,753
Components of other comprehensive income (loss)
Unrealized holding gains (losses) arising on available-for-sale fixed maturity investments	(100,800)		(20,574)		471,537		(650,447)
Unrealized holding gains (losses) arising on cash flow hedges	7,408		(49,908)		11,302		(33,000)
Reclassification adjustment for (gains) losses realized in net income	(6,738)		(13,454)		(35,492)		(35,510)
Net unrealized gains (losses) related to investments	(100,130)		(83,936)		447,347		(718,957)
Future policy benefits, DAC and VOBA adjustments	405		26,455		(86,563)		162,987
Employee benefit plan adjustment	989		0		989		0
Other comprehensive income (loss) before income taxes	(98,736)		(57,481)		361,773		(555,970)
Income tax expense (benefit) related to items of other comprehensive income	(34,557)		(20,117)		126,621		(194,589)
Other comprehensive income (loss)	(64,179)	[1]	(37,364)	[1]	235,152	[1]	(361,381)	[1]
Total comprehensive income (loss)	(3,678)		34,607		465,357		(226,628)
Non-credit component of impaired losses on fixed maturities available-for-sale	$ (996)		$ 3,173		$ (3,812)		$ 9,818

[1] Other comprehensive income (loss) includes the non-credit component of impaired gains (losses) on fixed maturities available-for-sale in the amounts of $(996) and $3,173 for the three months ended September 30, 2014 and 2013, respectively, and $(3,812) and $9,818 for the nine months ended September 30, 2014 and 2013, respectively.