Investment Securities - Summary of Amortized Cost and Fair Value by Contractual Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Amortized Cost, 1 year or less	$ 3,275
Amortized Cost, Due after one year through five years	60,013
Amortized Cost, Due after five years through ten years	23,607
Amortized Cost, Due after ten years	32,933
Amortized Cost	119,828	$ 121,408
Fair Value, 1 year or less	3,280
Fair Value, Due after one year through five years	60,751
Fair Value, Due after five years through ten years	24,126
Fair Value, Due after ten years	34,591
Fair Value	$ 122,748	$ 125,447

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 second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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