Derivative Instruments - Components of life retrocession embedded derivative (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Derivative [Line Items]
Net realized and unrealized gains (losses) on derivative instruments	$ 906	$ 48,509	$ (2,716)	$ 65,030
Life Funds Withheld Assets
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	(218,299)	273,224	(436,195)	69,493
Net adjustments related to future policy benefit reserves, net of tax	(5,950)	(35,929)	(28,003)	(47,883)
Net realized and unrealized gains (losses) on derivative instruments - Life Funds Withheld Assets	(5,493)	1,879	(1,624)	(11,803)
Net realized and unrealized gains (losses) on derivative instruments	(229,742)	239,174	(465,822)	9,807
Life Funds Withheld Assets \| Interest income
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	(41,455)	(47,873)	(84,565)	(98,870)
Life Funds Withheld Assets \| Net realized and unrealized gains (losses) on derivative instruments
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	(176,868)	321,038	(351,801)	168,208
Life Funds Withheld Assets \| Other income
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	$ 24	$ 59	$ 171	$ 155

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a),(c),(d),(e)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

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Net Increase or Decrease in the fair value of the embedded derivative or group of embedded derivatives included in earnings in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

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Cumulative adjustment to future policy benefit reserve, excluding foreign exchange effects.

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