Fair Value Option (Gains And Losses Due To Changes In Fair Value Of Investments) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
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	$ 44,783	$ (64,312)	$ 69,338	$ (22,878)
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	19,198	25,525	50,013	49,834
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	25,629	(87,009)	20,153	(69,858)
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	$ (44)	$ (2,828)	$ (828)	$ (2,854)