Investments (Amortized Cost And Estimated Fair Value Of Debt Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Amortized Cost
Due in one year or less	$ 2,783
Due after one year through five years	71,423
Due after five years through ten years	480,331
Due after ten years	1,018,159
Total	1,572,696	$ 1,673,864
Estimated Fair Value
Due in one year or less	2,686
Due after one year through five years	66,477
Due after five years through ten years	429,944
Due after ten years	859,112
Total	$ 1,358,219	$ 1,505,520