Derivative Instruments - Components of life retrocession embedded derivative (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivative [Line Items]
Net realized and unrealized gains (losses) on derivative instruments	$ 48,509	$ 11,599	$ 65,030	$ 13,409
Life Funds Withheld Assets
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	273,224	(17,546)	69,494	(17,546)
Net adjustments related to future policy benefit reserves, net of tax	(35,929)		(47,883)
Net realized and unrealized gains (losses) on derivative instruments - Life Funds Withheld Assets	1,879	0	(11,804)	0
Net realized and unrealized gains (losses) on derivative instruments	239,174	(17,546)	9,807	(17,546)
Life Funds Withheld Assets \| Interest income
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	(47,873)	(19,944)	(98,869)	(19,944)
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	321,038	1,893	168,208	1,893
Life Funds Withheld Assets \| Other income
Derivative [Line Items]
Net realized and unrealized gains (losses) on life retrocession embedded derivative	$ 59	505	$ 155	505
Life Funds Withheld Assets \| Unrealized gains (losses) on investments
Derivative [Line Items]
Net adjustments related to future policy benefit reserves, net of tax		$ 0		$ 0

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

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-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

-Topic 815

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