Accumulated Other Comprehensive Income (Loss) - Details About AOCI Components (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax		$ (149,032)	$ (92,063)	$ (374,490)	$ (242,696)
Tax benefit (expense)		(17,749)	37,042	(42,511)	(20,135)
Unrealized gains (losses) on investments
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	[1]	(150,482)	(94,393)	(379,974)	(256,731)
OTTI losses recognized in AOCI
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax		1,497	2,318	5,618	13,916
Cash flow hedge
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax		(47)	12	(134)	119
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax		(149,032)	(92,063)	(374,490)	(242,696)
Tax benefit (expense)		5,255	1,243	8,463	5,009
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(143,777)	(90,820)	(366,027)	(237,687)
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		(150,661)	(97,761)	(407,106)	(247,339)
OTTI on investments		10,019	44,036	64,977	79,158
Reclassification adjustment for investments transferred to equity method		(4,531)	0	(4,531)	0
Total before tax		(150,482)	(94,393)	(379,974)	(256,731)
Tax benefit (expense)		5,291	1,253	8,501	5,034
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(145,191)	(93,140)	(371,473)	(251,697)
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		1,497	1,617	5,876	13,086
OTTI on investments		0	701	(258)	830
Total before tax		1,497	2,318	5,618	13,916
Tax benefit (expense)		(36)	(10)	(38)	(25)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		1,461	2,308	5,580	13,891
Reclassification out of Accumulated Other Comprehensive Income [Member] | Cash flow hedge
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax		(47)	12	(134)	119
Tax benefit (expense)		0	0	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(47)	12	(134)	119
Life Funds Withheld Assets
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold		44,011	53,780	108,541	174,555
OTTI on investments		0	(2,023)	(2,598)	(10,110)
Change in adjustments related to future policy benefit reserves, net of tax		(5,309)	(40,668)	(33,312)	(88,551)
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		$ (5,309)	$ (40,668)	$ (33,314)	$ (88,550)

[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. As of December 31, 2015, the cumulative impact of the Shadow Adjustments was $274.4 million. During the nine months ended September 30, 2016, net movements of $(27.8) million were recorded, resulting in a total cumulative net impact of Shadow Adjustments on future policy benefit reserves of $246.6 million as of September 30, 2016.