Investments (Amortized Cost And Estimated Fair Value Of Debt Securities By Contractual Maturity) (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Investments [Abstract]
Securities Available-for-Sale, Due in one year or less, Cost	$ 5,211
Securities Available-for-Sale, Due after one year through five years, Cost	32,776
Securities Available-for-Sale, Due after five years through ten years, Cost	276,898
Securities Available-for-Sale, Due after ten years, Cost	813,278
Securities Available-for-Sale, Cost, Total	1,128,163
Securities Available-for-Sale, Due in one year or less, Estimated Fair Value	5,307
Securities Available-for-Sale, Due after one year through five years, Estimated Fair Value	34,499
Securities Available-for-Sale, Due after five years through ten years, Estimated Fair Value	293,388
Securities Available-for-Sale, Due after ten years, Estimated Fair Value	843,603
Securities Available-for-Sale, Estimated Fair Value, Total	$ 1,176,797

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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