Derivatives (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	$ 44,508	[1]	$ 18,518	[1]
Derivative Fair Value Of Derivative Liability	(14,010)	[1]	(30,502)	[1]
Fair value net	30,498		(11,984)
Foreign exchange forward contracts [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	1,249		7,889
Derivative Fair Value Of Derivative Liability	(8,648)		(17,395)
Net notional exposure	1,957,409		2,170,914
Fair value net	(7,399)		(9,506)
Foreign currency option contracts [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	0		1,410
Derivative Fair Value Of Derivative Liability	(535)		(186)
Net notional exposure	87,620		133,377
Fair value net	(535)		1,224
Futures contracts [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	41,031		1,956
Derivative Fair Value Of Derivative Liability	0		(1,352)
Net notional exposure	3,266,004		3,981,107
Fair value net	41,031		604
Credit default swaps (protection purchased) [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	0		6
Derivative Fair Value Of Derivative Liability	(71)		(807)
Net notional exposure	14,000		55,000
Fair value net	(71)		(801)
Credit default swaps (assumed risks) [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset			512
Derivative Fair Value Of Derivative Liability			0
Net notional exposure			17,500
Fair value net			512
Insurance-linked securities [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	0	[2]	0	[2]
Derivative Fair Value Of Derivative Liability	(268)	[2]	(2,173)	[2]
Net notional exposure	168,724	[2]	135,964	[2]
Fair value net	(268)	[2]	(2,173)	[2]
Total return swaps [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	79		6,630
Derivative Fair Value Of Derivative Liability	(599)		(546)
Net notional exposure	31,740		68,730
Fair value net	(520)		6,084
Interest rate swaps [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	2,147	[3]	0	[3]
Derivative Fair Value Of Derivative Liability	(2,558)	[3]	(7,880)	[3]
Net notional exposure	202,859	[3]	0	[3]
Fair value net	(411)	[3]	(7,880)	[3]
TBAs [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	2		115
Derivative Fair Value Of Derivative Liability	(1,331)		(163)
Net notional exposure	183,835		155,760
Fair value net	$ (1,329)		$ (48)

[1] Amounts include all derivative instruments, irrespective of whether there is a legally enforceable master netting arrangement in place.

[2] At December 31, 2013 and 2012, insurance-linked securities include a longevity swap for which the notional amount is not reflective of the overall potential exposure of the swap. As such, the Company has included the probable maximum loss under the swap within the net notional exposure as an approximation of the notional amount.

[3] The Company enters into interest rate swaps to mitigate notional exposures on certain total return swaps and certain fixed maturities. Only the notional value of interest rate swaps on fixed maturities is presented separately in the table.