Securities - Summary of Amortized Cost and Fair Value of Debt Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Available-for-sale
Due in one year or less, Amortized Cost	$ 3,700
Due after one through five years, Amortized Cost	9,242
Due after five through ten years, Amortized Cost	17,330
Due after ten years, Amortized Cost	80,780
Amortized Cost, Available-for-sale	111,052	$ 111,874
Due in one year or less, Fair Value	3,739
Due after one through five years, Fair Value	9,352
Due after five through ten years, Fair Value	17,640
Due after ten years, Fair Value	81,548
Total debt securities available-for-sale, Fair Value	112,279	112,146
Held-to-maturity
Due in one year or less, Amortized Cost	3,425
Due after ten years, Amortized Cost	6,476
Amortized Cost, Held to maturity	9,901	13,869
Due in one year or less, Fair Value	3,425
Due after ten years, Fair Value	6,695
Total debt securities held-to-maturity, Fair Value	$ 10,120	$ 13,950