Derivative Instruments - Components of life retrocession embedded derivative (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets	$ 2,521	$ 53,123	$ 29,886
Life Funds Withheld Assets
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	(473,806)	(13,084)
Net adjustments related to future policy benefit reserves, net of tax	(51,100)	(125,747)
Net realized and unrealized gains (losses) on derivative instruments - Life Funds Withheld Assets	(15,184)	(12,860)
Net realized and unrealized gains (losses) on life retrocession embedded derivative and derivative instruments - Life Funds Withheld Assets	(540,090)	(151,691)	$ (488,222)
Life Funds Withheld Assets \| Interest income
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	(161,887)	(193,569)
Life Funds Withheld Assets \| Net realized and unrealized gains (losses
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	(312,074)	180,134
Life Funds Withheld Assets \| Other
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	$ 155	$ 351

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=64837297&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=64837297&loc=SL5624171-113959

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+ 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=64837297&loc=SL5624171-113959

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