Accumulated Other Comprehensive Income (Loss) - Changes in AOCI, net of tax (Details) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	$ 946,661,000		$ 1,405,122,000	$ 736,657,000		$ 1,520,020,000
OCI before Reclassifications	359,719,000		(726,980,000)	619,039,000		(819,335,000)
Amounts reclassified from AOCI	(72,587,000)		(40,858,000)	(91,706,000)		(77,257,000)
Tax benefit (expense)	(26,759,000)		73,475,000	(56,956,000)		87,331,000
Net current period OCI - net of tax	260,373,000		(694,363,000)	470,377,000		(809,261,000)
Ending balance, net of tax	1,207,034,000		710,759,000	1,207,034,000		710,759,000
Unrealized gains (losses) on investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	1,032,941,000	[1]	1,474,553,000	822,432,000	[1]	1,591,210,000
OCI before Reclassifications	363,348,000	[1]	(701,365,000)	628,599,000	[1]	(789,054,000)
Amounts reclassified from AOCI	(74,337,000)	[1]	(55,408,000)	(96,975,000)	[1]	(97,102,000)
Tax benefit (expense)	(20,774,000)	[1]	71,671,000	(52,878,000)	[1]	84,397,000
Net current period OCI - net of tax	268,237,000	[1]	(685,102,000)	478,746,000	[1]	(801,759,000)
Ending balance, net of tax	1,301,178,000	[1]	789,451,000	1,301,178,000	[1]	789,451,000
AOCI Other Details [Abstract]
Change in adjustments related to future policy benefit reserves, net of tax	(440,461,000)		(32,900,000)	(474,461,000)		(32,900,000)
Cumulative impact on value of future policy benefit reserve, end of period	519,200,000			519,200,000			44,700,000
OTTI losses recognized in AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	(85,894,000)		(116,189,000)	(89,190,000)		(121,371,000)
OCI before Reclassifications	0		0	0		0
Amounts reclassified from AOCI	1,640,000		14,440,000	5,049,000		19,625,000
Tax benefit (expense)	(4,000)		(2,000)	(117,000)		(5,000)
Net current period OCI - net of tax	1,636,000		14,438,000	4,932,000		19,620,000
Ending balance, net of tax	(84,258,000)		(101,751,000)	(84,258,000)		(101,751,000)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	10,661,000		65,480,000	14,541,000		69,399,000
OCI before Reclassifications	(3,621,000)		(25,524,000)	(9,521,000)		(30,576,000)
Amounts reclassified from AOCI	0		0	0		0
Tax benefit (expense)	(5,981,000)		1,806,000	(3,961,000)		2,939,000
Net current period OCI - net of tax	(9,602,000)		(23,718,000)	(13,482,000)		(27,637,000)
Ending balance, net of tax	1,059,000		41,762,000	1,059,000		41,762,000
Underfunded pension liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	(13,270,000)		(20,506,000)	(13,239,000)		(20,892,000)
OCI before Reclassifications	(8,000)		(91,000)	(39,000)		295,000
Amounts reclassified from AOCI	0		0	0		0
Tax benefit (expense)	0		0	0		0
Net current period OCI - net of tax	(8,000)		(91,000)	(39,000)		295,000
Ending balance, net of tax	(13,278,000)		(20,597,000)	(13,278,000)		(20,597,000)
Cash flow hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, net of tax	2,223,000		1,784,000	2,113,000		1,674,000
OCI before Reclassifications	0		0	0		0
Amounts reclassified from AOCI	110,000		110,000	220,000		220,000
Tax benefit (expense)	0		0	0		0
Net current period OCI - net of tax	110,000		110,000	220,000		220,000
Ending balance, net of tax	$ 2,333,000		$ 1,894,000	$ 2,333,000		$ 1,894,000

[1] Included in these amounts are the impact of Shadow Adjustments. During the year ended December 31, 2013, the initial impact of $44.7 million was recorded. During the six months ended June 30, 2014, additional impacts of $474.5 million were recorded, resulting in a total cumulative impact of shadow adjustments on future policy benefit reserves of $519.2 million at June 30, 2014.