Allowance for Loan Losses - Summary of Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Allowance for Loan Losses:
Allowance for loan losses, beginning of period	$ 29,585	$ 28,543
Charge-offs	(62)	(142)
Recoveries	206	72
Provision	1,075	375
Allowance for loan losses, end of period	30,804	28,848
Amount of allowance for loan losses for loans deemed to be impaired	85	100
Amount of allowance for loan losses for loans not deemed to be impaired	30,719	28,748
Loans:
Total loans, net	2,498,894	2,310,660	$ 2,426,119
Loans deemed to be impaired	2,945	3,266
Loans not deemed to be impaired	2,495,949	2,307,394
Construction and Land Development [Member]
Allowance for Loan Losses:
Allowance for loan losses, beginning of period	331	1,092
Provision	(85)	(81)
Allowance for loan losses, end of period	246	1,011
Amount of allowance for loan losses for loans not deemed to be impaired	246	1,011
Loans:
Total loans, net	6,493	13,305	8,992
Loans not deemed to be impaired	6,493	13,305
Commercial and Industrial [Member]
Allowance for Loan Losses:
Allowance for loan losses, beginning of period	11,596	10,998
Charge-offs	(5)	(43)
Recoveries	164	18
Provision	673	183
Allowance for loan losses, end of period	12,428	11,156
Amount of allowance for loan losses for loans deemed to be impaired		6
Amount of allowance for loan losses for loans not deemed to be impaired	12,428	11,150
Loans:
Total loans, net	867,599	767,436	812,417
Loans deemed to be impaired	623	320
Loans not deemed to be impaired	866,976	767,116
Municipal [Member]
Allowance for Loan Losses:
Allowance for loan losses, beginning of period	2,566	1,838
Provision	323	160
Allowance for loan losses, end of period	2,889	1,998
Amount of allowance for loan losses for loans not deemed to be impaired	2,889	1,998
Loans:
Total loans, net	141,588	105,288	120,455
Loans not deemed to be impaired	141,588	105,288
Commercial Real Estate [Member]
Allowance for Loan Losses:
Allowance for loan losses, beginning of period	11,464	10,663
Provision	(343)	104
Allowance for loan losses, end of period	11,121	10,767
Amount of allowance for loan losses for loans deemed to be impaired	85	94
Amount of allowance for loan losses for loans not deemed to be impaired	11,036	10,673
Loans:
Total loans, net	761,464	746,703	786,102
Loans deemed to be impaired	2,322	2,946
Loans not deemed to be impaired	759,142	743,757
Residential Real Estate [Member]
Allowance for Loan Losses:
Allowance for loan losses, beginning of period	2,194	2,190
Provision	255	(55)
Allowance for loan losses, end of period	2,449	2,135
Amount of allowance for loan losses for loans not deemed to be impaired	2,449	2,135
Loans:
Total loans, net	393,338	349,966	371,897
Loans not deemed to be impaired	393,338	349,966
Consumer [Member]
Allowance for Loan Losses:
Allowance for loan losses, beginning of period	312	365
Charge-offs	(57)	(99)
Recoveries	37	54
Provision	4	22
Allowance for loan losses, end of period	296	342
Amount of allowance for loan losses for loans not deemed to be impaired	296	342
Loans:
Total loans, net	21,039	22,123	21,893
Loans not deemed to be impaired	21,039	22,123
Home Equity [Member]
Allowance for Loan Losses:
Allowance for loan losses, beginning of period	1,065	1,111
Recoveries	5
Provision	67	(10)
Allowance for loan losses, end of period	1,137	1,101
Amount of allowance for loan losses for loans not deemed to be impaired	1,137	1,101
Loans:
Total loans, net	307,373	305,839	$ 304,363
Loans not deemed to be impaired	307,373	305,839
Unallocated [Member]
Allowance for Loan Losses:
Allowance for loan losses, beginning of period	57	286
Provision	181	52
Allowance for loan losses, end of period	238	338
Amount of allowance for loan losses for loans not deemed to be impaired	$ 238	$ 338

Amount of allowance for loans losses for loans not deemed to be impaired.

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Provision for loan losses gains expensed.

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Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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The recorded amount of loans and debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it was probable, at acquisition, that the investor would be unable to collect all contractually required payments receivable, but which are not deemed to be impaired since the acquisition by transfer. Therefore, no allowance for credit losses is recorded.

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Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Amount of allowance for credit losses related to recorded investment.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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