Investments (Amortized Cost And Estimated Fair Value Of Debt Securities By Contractual Maturity) (Details) $ in Thousands	Mar. 31, 2020 USD ($)
Securities Available-for-Sale, Amortized Cost
Securities Available-for-Sale, Due in one year or less, Cost	$ 2,091
Securities Available-for-Sale, Due after one year through five years, Cost	14,955
Securities Available-for-Sale, Due after five years through ten years, Cost	235,144
Securities Available-for-Sale, Due after ten years, Cost	635,509
Securities Available-for-Sale, Cost, Total	887,699
Securities Available-for-Sale, Estimated Fair Value
Securities Available-for-Sale, Due in one year or less, Estimated Fair Value	2,108
Securities Available-for-Sale, Due after one year through five years, Estimated Fair Value	15,386
Securities Available-for-Sale, Due after five years through ten years, Estimated Fair Value	248,975
Securities Available-for-Sale, Due after ten years, Estimated Fair Value	665,403
Securities Available-for-Sale, Estimated Fair Value, Total	$ 931,872

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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