Fair Value Measurement - Carrying Amount and Fair Value of Financial Instruments Not Measured at Fair Value on a Recurring or Nonrecurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financial Assets:
Cash and due from financial institutions	$ 246,165	$ 128,222
Other securities	17,011	20,537
Loans, net of allowance	1,978,246	2,032,474
Bank owned life insurance	46,728	45,976
Accrued interest receivable	7,728	9,421
Financial Liabilities:
Long-term FHLB advances	75,000	125,000
Securities sold under agreement to repurchase	23,331	28,914
Carrying Amount [Member]
Financial Assets:
Cash and due from financial institutions	253,165	139,522
Other securities	17,011	20,537
Loans, held for sale	5,810	7,001
Loans, net of allowance	1,978,246	2,032,474
Bank owned life insurance	46,728	45,976
Accrued interest receivable	7,728	9,421
Financial Liabilities:
Nonmaturing deposits	2,181,931	1,902,560
Time deposits	252,835	286,838
Long-term FHLB advances	75,000	125,000
Securities sold under agreement to repurchase	23,331	28,914
Subordinated debentures	29,427	29,427
Accrued interest payable	115	204
Total Fair Value [Member]
Financial Assets:
Cash and due from financial institutions	253,165	139,522
Other securities	17,011	20,537
Loans, held for sale	5,926	7,141
Loans, net of allowance	1,996,174	2,063,249
Bank owned life insurance	46,728	45,976
Accrued interest receivable	7,728	9,421
Financial Liabilities:
Nonmaturing deposits	2,181,931	1,902,560
Time deposits	253,643	288,298
Long-term FHLB advances	76,617	130,942
Securities sold under agreement to repurchase	23,331	28,914
Subordinated debentures	29,534	31,479
Accrued interest payable	115	204
(Level 1) [Member]
Financial Assets:
Cash and due from financial institutions	253,165	139,522
Other securities	17,011	20,537
Loans, held for sale	5,926	7,141
Bank owned life insurance	46,728	45,976
Accrued interest receivable	7,728	9,421
Financial Liabilities:
Nonmaturing deposits	2,181,931	1,902,560
Securities sold under agreement to repurchase	23,331	28,914
Accrued interest payable	115	204
(Level 3) [Member]
Financial Assets:
Loans, net of allowance	1,996,174	2,063,249
Financial Liabilities:
Time deposits	253,643	288,298
Long-term FHLB advances	76,617	130,942
Subordinated debentures	$ 29,534	$ 31,479