Accumulated Other Comprehensive Income (Loss) - Changes in AOCI, net of tax (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2015		Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	$ 1,076,174		$ 1,207,034	$ 1,484,458		$ 736,657
OCI before Reclassifications	(28,508)		37,384	(322,827)		656,423
Amounts reclassified from AOCI	(92,063)		(22,547)	(242,696)		(114,253)
Tax benefit (expense)	(521)		10,058	36,147		(46,898)
Comprehensive income (loss)	(121,092)		24,895	(529,376)		495,272
Ending balance, net of tax	955,082		1,231,929	955,082		1,231,929
AOCI Other Details [Abstract]
Change in adjustments related to future policy benefit reserves, net of tax	(40,681)		(51,286)	(127,365)		423,179
Unrealized gains (losses) on investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	1,168,964	[1]	1,301,178	1,590,114	[1]	822,432
OCI before Reclassifications	(4,334)	[1]	51,133	(294,341)	[1]	679,732
Amounts reclassified from AOCI	(94,393)	[1]	(28,795)	(256,731)	[1]	(125,770)
Tax benefit (expense)	(2,213)	[1]	7,906	28,982	[1]	(44,972)
Comprehensive income (loss)	(100,940)	[1]	30,244	(522,090)	[1]	508,990
Ending balance, net of tax	1,068,024	[1]	1,331,422	1,068,024	[1]	1,331,422
AOCI Other Details [Abstract]
Change in adjustments related to future policy benefit reserves, net of tax				(127,400)
Cumulative impact on value of future policy benefit reserve, end of period	317,700			317,700			$ 445,100
OTTI losses recognized in AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	(64,614)		(84,258)	(76,047)		(89,190)
OCI before Reclassifications	0		0	0		0
Amounts reclassified from AOCI	2,318		6,078	13,916		11,127
Tax benefit (expense)	(181)		(115)	(346)		(232)
Comprehensive income (loss)	2,137		5,963	13,570		10,895
Ending balance, net of tax	(62,477)		(78,295)	(62,477)		(78,295)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	(9,508)		1,059	(11,188)		14,541
OCI before Reclassifications	(24,267)		(14,167)	(28,225)		(23,688)
Amounts reclassified from AOCI	0		87	0		87
Tax benefit (expense)	1,873		2,267	7,511		(1,694)
Comprehensive income (loss)	(22,394)		(11,813)	(20,714)		(25,295)
Ending balance, net of tax	(31,902)		(10,754)	(31,902)		(10,754)
Underfunded pension liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	(21,143)		(13,278)	(20,789)		(13,239)
OCI before Reclassifications	93		418	(261)		379
Amounts reclassified from AOCI	0		0	0		0
Tax benefit (expense)	0		0	0		0
Comprehensive income (loss)	93		418	(261)		379
Ending balance, net of tax	(21,050)		(12,860)	(21,050)		(12,860)
Cash flow hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	2,475		2,333	2,368		2,113
OCI before Reclassifications	0		0	0		0
Amounts reclassified from AOCI	12		83	119		303
Tax benefit (expense)	0		0	0		0
Comprehensive income (loss)	12		83	119		303
Ending balance, net of tax	$ 2,487		$ 2,416	$ 2,487		$ 2,416

[1] Included in these amounts is the impact of Shadow Adjustments as defined in Note 6, "Investments.". As of December 31, 2014 the cumulative impact of the Shadow Adjustments was $445.1 million. During the nine months ended September 30, 2015, net movements of $(127.4) million were recorded, resulting in a total cumulative net impact of Shadow Adjustments on future policy benefit reserves of $317.7 million as of September 30, 2015.