Accumulated Other Comprehensive Income (Loss) - Details About AOCI Components (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017		Jun. 30, 2016
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	$ (93,128)	$ (110,615)	$ (144,276)		$ (225,457)
Operating expenses	472,778	522,521	940,816		1,037,902
Provision (benefit) for income tax	(29,006)	(2,467)	(42,098)		(24,762)
Unrealized gains (losses) on investments
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(94,591)	(112,377)	(147,146)	[1]	(229,491)	[1]
OTTI losses recognized in AOCI
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	1,511	1,810	2,966		4,121
Cash flow hedge
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(48)	(48)	(96)		(87)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	0	0	0		0
Underfunded pension liability
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	0	0	0		0
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(93,128)	(110,615)	(144,276)		(225,457)
Provision (benefit) for income tax	629	1,675	142		3,208
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(92,499)	(108,940)	(144,134)		(222,249)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized gains (losses) on investments
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold	(81,618)	(139,457)	(128,638)		(256,446)
OTTI on investments transferred to (from) OCI	1,160	33,030	8,034		54,958
Reclassification adjustment for investments transferred to equity method	0	0	0		0
Total before tax	(94,591)	(112,377)	(147,146)		(229,491)
Provision (benefit) for income tax	643	1,633	169		3,210
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(93,948)	(110,744)	(146,977)		(226,281)
Reclassification out of Accumulated Other Comprehensive Income [Member] | OTTI losses recognized in AOCI
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold	1,461	2,066	2,916		4,379
OTTI on investments transferred to (from) OCI	50	(256)	50		(258)
Total before tax	1,511	1,810	2,966		4,121
Provision (benefit) for income tax	(14)	42	(27)		(2)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1,497	1,852	2,939		4,119
Reclassification out of Accumulated Other Comprehensive Income [Member] | Cash flow hedge
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(48)	(48)	(96)		(87)
Provision (benefit) for income tax	0	0	0		0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(48)	(48)	(96)		(87)
Life Funds Withheld Assets
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold	29,778	30,114	64,252		64,530
OTTI on investments transferred to (from) OCI	0	(252)	0		(2,598)
Life Funds Withheld Assets | Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized gains (losses) on investments
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Change in adjustments related to future policy benefit reserves, net of tax	$ (14,133)	$ (5,950)	$ (26,542)		$ (28,003)

[1] For certain annuity contracts that are subject to the GreyCastle Life Retro Arrangements, policy benefit reserves were historically increased for the impact of changes in unrealized gains on investments supporting such contracts as if the gains had been realized, with a corresponding entry to other comprehensive income ("Shadow Adjustments"). Upon completion of the GreyCastle Life Retro Arrangements, no further Shadow Adjustments were recorded. At December 31, 2016, the cumulative impact of the Shadow Adjustments was $212.1 million. During the six months ended June 30, 2017, net movements of $(8.6) million were recorded, resulting in a total cumulative net impact of Shadow Adjustments on future policy benefit reserves of $203.5 million at June 30, 2017.