Allowance for Loan Losses - Changes in the Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	$ 20,420	$ 13,786	$ 14,767	$ 13,679
Charge-offs	(185)	(36)	(325)	(431)
Recoveries	152	244	333	746
Provision	2,250	150	7,862	150
Ending Balance	22,637	14,144	22,637	14,144
Commercial and Agriculture [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	2,799	1,828	2,219	1,747
Charge-offs			(15)	(27)
Recoveries	1	61	5	65
Provision	(139)	43	452	147
Ending Balance	2,661	1,932	2,661	1,932
Commercial Real Estate Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	3,411	2,009	2,541	1,962
Charge-offs	(147)		(148)	(60)
Recoveries	6	43	20	282
Provision	685	85	1,542	(47)
Ending Balance	3,955	2,137	3,955	2,137
Commercial Real Estate Non Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	9,169	5,867	6,584	5,803
Recoveries	3	55	44	99
Provision	1,406	226	3,950	246
Ending Balance	10,578	6,148	10,578	6,148
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	2,434	1,698	1,582	1,531
Charge-offs	(11)	(20)	(108)	(223)
Recoveries	117	67	196	229
Provision	(83)	(136)	787	72
Ending Balance	2,457	1,609	2,457	1,609
Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	1,844	1,135	1,250	1,046
Charge-offs				(24)
Recoveries	1	1	3	1
Provision	500	47	1,092	160
Ending Balance	2,345	1,183	2,345	1,183
Farm Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	361	365	344	397
Recoveries	3	1	10	3
Provision	(4)	1	6	(33)
Ending Balance	360	367	360	367
Consumer and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	247	201	247	284
Charge-offs	(27)	(16)	(54)	(97)
Recoveries	21	16	55	67
Provision	(21)	52	(28)	(1)
Ending Balance	220	253	220	253
Unallocated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	155	683		909
Provision	(94)	(168)	61	(394)
Ending Balance	$ 61	$ 515	$ 61	$ 515