Loans - Summary of Composition of Loan Portfolio (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 2,995,829	$ 2,426,119
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	789,836	786,102
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	448,436	371,897
Consumer Portfolio Segment Other Than Overdrafts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	20,007	21,071
Municipal [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	137,607	120,455
Construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	10,909	8,992
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,314,245	812,417
Home Equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	274,357	304,363
Overdrafts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 432	$ 822