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Investments (Estimated Fair Value Of Investments) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Fixed maturity securities:    
Due in one year or less $ 105,929  
Due after one year through five years 548,638  
Due after five years through ten years 287,005  
Due after ten years 2,151,703  
Total $ 3,093,275 $ 2,985,161
External credit rating, non investment grade [Member]    
Credit Derivatives [Line Items]    
Percentage of fixed maturities 1.30%