Securities - Amortized Cost and Fair Value of Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Amortized Cost, Due in one year or less	$ 12,161
Amortized Cost, Due after one year through five years	31,649
Amortized Cost, Due after five years through ten years	45,020
Amortized Cost, Due after ten years	186,341
Amortized Cost, Mortgage-backed securities	159,353
Amortized Cost, Total securities available for sale	434,524	$ 336,316
Fair Value, Due in one year or less	12,246
Fair Value, Due after one year through five years	31,878
Fair Value, Due after five years through ten years	46,966
Fair Value, Due after ten years	203,282
Fair Value, Mortgage-backed securities	163,432
Fair Value, Total securities available for sale	$ 457,804	$ 363,464

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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