Derivative Instruments - Derivatives Designated As Fair Value Hedges (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in income from ineffective portion of fair value hedges	$ 0	$ (2,050)	$ 0	$ (256)
Derivatives designated as hedging instruments \| Fair value hedges \| Net realized and unrealized gains (losses) on derivative instruments
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in income	0	(9,132)	0	(15,663)
Amount of gain (loss) recognized in income from ineffective portion of fair value hedges	0	(2,050)	0	(256)
Derivatives designated as hedging instruments \| Fair value hedges \| Net realized and unrealized gains (losses) on derivative instruments \| Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in income	0	0	0	0
Derivatives designated as hedging instruments \| Fair value hedges \| Net realized and unrealized gains (losses) on derivative instruments \| Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in income	0	(9,132)	0	(15,663)
Derivatives designated as hedging instruments \| Fair value hedges \| Net realized and unrealized gains (losses) on derivative instruments \| Fixed maturity investments
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in income	$ 0	$ 7,082	$ 0	$ 15,407

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Amount of gain (loss)recognized in the income statement from the hedging ineffectiveness of a fair value hedge.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 25

-Section 50

-Paragraph 1

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

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Total amount of gain (loss) derived from fair value hedges recognized 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

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624171-113959

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