Accumulated Other Comprehensive Income - Details about AOCI components (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized and unrealized gains (losses) on derivative instruments		$ 2,521	$ 53,123	$ 29,886
Operating Expenses		(2,063,362)	(1,966,939)	(1,341,315)
Exchange gains (losses) before tax		9,578	(22,504)	37,568
Amounts reclassified from AOCI		(344,393)	(326,979)	(128,094)
Provision for income tax		(42,129)	19,161	(96,897)
Unrealized Gains (Losses) on Investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	[1]	(353,910)	(346,911)	(143,330)
OTTI Losses Recognized in AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI		6,599	18,987	14,082
Foreign Currency Translation Adjustments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI		0	0	87
Underfunded Pension Liability
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI		3,100	1,145	812
Cash Flow Hedge
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI		(182)	(200)	255
Life Funds Withheld Assets
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold		152,589	223,272	5,067
OTTI on investments		(2,598)	(13,357)	(20,587)
Net adjustments related to future policy benefit reserves, net of tax		(51,100)	(125,747)
Net realized and unrealized gains (losses) on derivative instruments		(540,090)	(151,691)	$ (488,222)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI		(344,393)	(326,979)
Provision for income tax		8,950	7,164
Total amount reclassified from AOCI, net of tax		(335,443)	(319,815)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains (Losses) on Investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold		(350,875)	(316,508)
OTTI on investments		81,595	95,344
Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Investments Transferred From Available for sale To Equity Method		33,530	0
Amounts reclassified from AOCI		(353,910)	(346,911)
Provision for income tax		10,084	7,597
Total amount reclassified from AOCI, net of tax		(343,826)	(339,314)
Reclassification out of Accumulated Other Comprehensive Income [Member] | OTTI Losses Recognized in AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold		7,038	18,014
OTTI on investments		(439)	973
Amounts reclassified from AOCI		6,599	18,987
Provision for income tax		(49)	(32)
Total amount reclassified from AOCI, net of tax		6,550	18,955
Reclassification out of Accumulated Other Comprehensive Income [Member] | Underfunded Pension Liability
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Operating Expenses		3,100	1,145
Provision for income tax		(1,085)	(401)
Total amount reclassified from AOCI, net of tax		2,015	744
Reclassification out of Accumulated Other Comprehensive Income [Member] | Cash Flow Hedge
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI		(182)	(200)
Provision for income tax		0	0
Total amount reclassified from AOCI, net of tax		(182)	(200)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Life Funds Withheld Assets | Unrealized Gains (Losses) on Investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net adjustments related to future policy benefit reserves, net of tax		$ (51,100)	$ (125,747)

[1] Included in these amounts is the impact of Shadow Adjustments on future policy benefit reserves. As of December 31, 2015, $274.4 million was recorded. During the year ended December 31, 2016, additional net impacts of $(62.3) million were recorded, resulting in a total cumulative net impact of Shadow Adjustments on future policy benefit reserves of $212.1 million at December 31, 2016.