Derivative Instruments (Location and Amounts of Unrealized And Realized Gains (Losses) On Derivatives Recorded In The Condensed Consolidated Income Statements) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	$ 10,527	$ (6,273)	$ 8,806	$ 1,350
Foreign exchange (loss) gain [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	1,989	(359)	1,245	580
Foreign exchange (loss) gain [Member] | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	1,989	(359)	1,245	580
Net realized investment gains [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	8,538	(5,914)	7,561	770
Net realized investment gains [Member] | Put options [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	(90)	0	(3,822)	(336)
Net realized investment gains [Member] | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	4,274	4,415	6,089	2,110
Net realized investment gains [Member] | Interest rate futures and swaps
Derivative Instruments, Gain (Loss) [Line Items]
Total realized and unrealized losses on derivatives	$ 4,354	$ (10,329)	$ 5,294	$ (1,004)