Investments (Estimated Fair Value Of Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fixed maturity securities:
Due in one year or less	$ 381,189
Due after one year through five years	515,049
Due after five years through ten years	316,173
Due after ten years	1,602,142
Total	$ 2,814,553	$ 2,880,003
External credit rating, non investment grade [Member]
Credit Derivatives [Line Items]
Percentage of fixed maturities	3.90%