Derivative Instruments (Location and Amounts of Unrealized And Realized Gains (Losses) On Derivatives Recorded In The Condensed Consolidated Income Statements) (Details) (Not Designated as Hedging Instrument [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	$ (15,318)	$ 10,527	$ (29,106)	$ 8,806
Foreign exchange (loss) gain
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	(1,598)	1,989	(2,466)	1,245
Foreign exchange (loss) gain | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	(1,598)	1,989	(2,466)	1,245
Net realized investment gains
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	(13,720)	8,538	(26,640)	7,561
Net realized investment gains | Put options
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	0	(90)	0	(3,822)
Net realized investment gains | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	(286)	4,274	(844)	6,089
Net realized investment gains | Interest rate futures
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	$ (13,434)	$ 4,354	$ (25,796)	$ 5,294