Fair Value Option (Gains And Losses Due To Changes In Fair Value Of Investments) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Gains and losses due to changes in fair value of investments	$ 43,467	$ 49,343
Fixed maturity securities [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Gains and losses due to changes in fair value of investments	(10,411)	21,003
Equity securities [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Gains and losses due to changes in fair value of investments	54,026	28,496
Short-term investments [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Gains and losses due to changes in fair value of investments	$ (148)	$ (156)