Investment Securities (Amortized Cost and Fair Value of Debt Securities by Contractual Maturity Date) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Investment Securities [Abstract]
Amortized cost: Due in one year or less	$ 967
Amortized cost: Due after one year through five years	5,961
Amortized cost: Due after five years through ten years	73,232
Amortized cost: Due after ten years	205,075
Amortized cost: MBS - GSE residential	149,915
Amortized cost: Total available-for-sale debt securities	435,150	$ 381,088
Fair value: Due in one year or less	1,007
Fair value: Due after one year through five years	6,298
Fair value: Due after five years through ten years	70,598
Fair value: Due after ten years	207,108
Fair value: MBS - GSE residential	151,611
Fair value: Total available-for-sale debt securities	$ 436,622	$ 392,420

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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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth fiscal year through tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Fair value of investment in debt security, measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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