Fair Value Option (Gains And Losses Due To Changes In Fair Value Of Investments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
(Losses) gains due to changes in fair value of investments	$ 21,857	$ 18,531
Fixed maturity securities [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
(Losses) gains due to changes in fair value of investments	10,288	11,563
Equity Securities [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
(Losses) gains due to changes in fair value of investments	11,541	6,907
Short-term investments [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
(Losses) gains due to changes in fair value of investments	$ 28	$ 61