Investments (Estimated Fair Value Of Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fixed maturity securities:
Due in one year or less	$ 246,708
Due after one year through five years	693,068
Due after five years through ten years	540,052
Due after ten years	2,069,982
Total	$ 3,549,810	$ 3,093,275
External credit rating, non investment grade [Member]
Credit Derivatives [Line Items]
Percentage of fixed maturities	1.30%