Allowance for Loan Losses - ALL by Loan Type (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 of period	$ 12,007	$ 7,479	$ 7,562	$ 7,902
Charge-offs	(111)	(554)	(618)	(1,531)
Recoveries	134	75	282	253
Provision (recovery of)	869	495	5,673	871
Ending of period	12,899	7,495	12,899	7,495
Mortgage Loans on Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning of period	8,863	5,052	5,372	4,967
Charge-offs	(64)	(209)	(315)	(368)
Recoveries	72	24	84	67
Provision (recovery of)	716	214	4,446	415
Ending of period	9,587	5,081	9,587	5,081
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning of period	2,626	1,537	1,571	1,374
Recoveries		1		1
Provision (recovery of)	263	114	1,318	277
Ending of period	2,889	1,652	2,889	1,652
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning of period	518	890	619	1,561
Charge-offs	(47)	(345)	(303)	(1,163)
Recoveries	62	50	198	185
Provision (recovery of)	(110)	167	(91)	179
Ending of period	$ 423	$ 762	$ 423	$ 762