Accumulated Other Comprehensive Income (Loss) - Changes in AOCI, net of tax (Details) (USD $)	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	$ 1,484,458,000		$ 736,657,000
OCI before Reclassifications	287,646,000		259,319,000
Amounts reclassified from AOCI	(64,750,000)		(19,119,000)
Tax benefit (expense)	(2,184,000)		(30,196,000)
Comprehensive income (loss)	220,712,000		210,004,000
Ending balance, net of tax	1,705,170,000		946,661,000
AOCI Other Details [Abstract]
Change in adjustments related to future policy benefit reserves, net of tax	(60,356,000)		34,004,000
Unrealized gains (losses) on investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	1,590,114,000	[1]	822,432,000
OCI before Reclassifications	254,267,000	[1]	265,250,000
Amounts reclassified from AOCI	(74,781,000)	[1]	(22,638,000)
Tax benefit (expense)	(5,805,000)	[1]	(32,103,000)
Comprehensive income (loss)	173,681,000	[1]	210,509,000
Ending balance, net of tax	1,763,795,000	[1]	1,032,941,000
AOCI Other Details [Abstract]
Change in adjustments related to future policy benefit reserves, net of tax	(60,400,000)
Cumulative impact on value of future policy benefit reserve, end of period	384,800,000			445,100,000
OTTI losses recognized in AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	(76,047,000)		(89,190,000)
OCI before Reclassifications	0		0
Amounts reclassified from AOCI	9,936,000		3,409,000
Tax benefit (expense)	(78,000)		(113,000)
Comprehensive income (loss)	9,858,000		3,296,000
Ending balance, net of tax	(66,189,000)		(85,894,000)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	(11,188,000)		14,541,000
OCI before Reclassifications	32,404,000		(5,900,000)
Amounts reclassified from AOCI	0		0
Tax benefit (expense)	3,699,000		2,020,000
Comprehensive income (loss)	36,103,000		(3,880,000)
Ending balance, net of tax	24,915,000		10,661,000
Underfunded pension liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	(20,789,000)		(13,239,000)
OCI before Reclassifications	975,000		(31,000)
Amounts reclassified from AOCI	0		0
Tax benefit (expense)	0		0
Comprehensive income (loss)	975,000		(31,000)
Ending balance, net of tax	(19,814,000)		(13,270,000)
Cash flow hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	2,368,000		2,113,000
OCI before Reclassifications	0		0
Amounts reclassified from AOCI	95,000		110,000
Tax benefit (expense)	0		0
Comprehensive income (loss)	95,000		110,000
Ending balance, net of tax	$ 2,463,000		$ 2,223,000

[1] Included in these amounts is the impact of Shadow Adjustments. As of December 31, 2014 the cumulative impact of these adjustments was $445.1 million. During the three months ended March 31, 2015, net movements of $(60.4) million were recorded, resulting in a total cumulative net impact of Shadow Adjustments on future policy benefit reserves of $384.8 million as of March 31, 2015.