Investments (Amortized Cost And Estimated Fair Value Of Debt Securities By Contractual Maturity) (Details) $ in Thousands	Mar. 31, 2021 USD ($)
Securities Available-for-Sale, Amortized Cost
Due in one year or less	$ 16,063
Due after one year through five years	33,304
Due after five years through ten years	292,485
Due after ten years	813,283
Total	1,155,135
Securities Available-for-Sale, Estimated Fair Value
Due in one year or less	4,470
Due after one year through five years	34,628
Due after five years through ten years	303,519
Due after ten years	840,636
Total	$ 1,183,253