Derivatives (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	$ 23,797	[1]	$ 44,508	[1]
Derivative Fair Value Of Derivative Liability	(14,301)	[1]	(14,010)	[1]
Fair value net	9,496		30,498
Foreign exchange forward contracts [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	4,404		1,249
Derivative Fair Value Of Derivative Liability	(5,888)		(8,648)
Net notional exposure	2,270,300		1,957,409
Fair value net	(1,484)		(7,399)
Foreign currency option contracts [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	398		0
Derivative Fair Value Of Derivative Liability	0		(535)
Net notional exposure	103,887		87,620
Fair value net	398		(535)
Futures contracts [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	18,814		41,031
Derivative Fair Value Of Derivative Liability	(5)		0
Net notional exposure	3,271,970		3,266,004
Fair value net	18,809		41,031
Credit default swaps (protection purchased) [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset			0
Derivative Fair Value Of Derivative Liability			(71)
Net notional exposure			14,000
Fair value net			(71)
Insurance-linked securities [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	0	[2]	0	[2]
Derivative Fair Value Of Derivative Liability	(740)	[2]	(268)	[2]
Net notional exposure	170,252	[2]	168,724	[2]
Fair value net	(740)	[2]	(268)	[2]
Total return swaps [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	181		79
Derivative Fair Value Of Derivative Liability	(483)		(599)
Net notional exposure	42,736		31,740
Fair value net	(302)		(520)
Interest rate swaps [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	0	[3]	2,147	[3]
Derivative Fair Value Of Derivative Liability	(5,797)	[3]	(2,558)	[3]
Net notional exposure	202,481	[3]	202,859	[3]
Fair value net	(5,797)	[3]	(411)	[3]
TBAs [Member]
Derivative [Line Items]
Derivative Fair Value Of Derivative Asset	0		2
Derivative Fair Value Of Derivative Liability	(1,388)		(1,331)
Net notional exposure	143,110		183,835
Fair value net	$ (1,388)		$ (1,329)

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

[2] At March 31, 2014 and December 31, 2013, 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.