Fair Value of Financial Instruments - Financial Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	$ 407,500	$ 307,812
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	63,360
Level 1 [Member] | Fair Value on a Recurring Basis [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	63,360
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	340,192	306,250
Level 2 [Member] | Fair Value on a Recurring Basis [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	340,192	306,250
Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	3,948	1,562
Level 3 [Member] | Fair Value on a Recurring Basis [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	3,948	1,562
U.S. Treasury [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	63,360
U.S. Treasury [Member] | Level 1 [Member] | Fair Value on a Recurring Basis [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	63,360
U.S. Government Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	150,604	124,241
U.S. Government Agencies [Member] | Level 2 [Member] | Fair Value on a Recurring Basis [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	150,604	124,241
Mortgage-backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	128,573	113,056
Mortgage-backed Securities [Member] | Level 2 [Member] | Fair Value on a Recurring Basis [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	128,573	113,056
State and Local Governments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	64,963	70,515
State and Local Governments [Member] | Level 2 [Member] | Fair Value on a Recurring Basis [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	61,015	68,953
State and Local Governments [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	3,948	1,562
State and Local Governments [Member] | Level 3 [Member] | Fair Value on a Recurring Basis [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total Securities Available-for-Sale	$ 3,948	$ 1,562