Loans - Schedule of Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Receivables [Abstract]
Impaired loans without a valuation allowance	$ 3,063	$ 5,172	$ 2,695	$ 3,063	$ 2,695	$ 5,172
Impaired loans with a valuation allowance	8,976	9,360	9,872	8,976	9,872	9,360
Total impaired loans	12,039	14,532	12,567	12,039	12,567	14,532
Valuation allowance related to impaired loans	1,156	1,657	1,170	1,156	1,170	1,657
Total non-accrual loans	7,031	9,404	8,473	7,031	8,473	9,404
Total loans past-due ninety days or more and still accruing		0	0		0	0
Average investment in impaired loans	$ 12,206	$ 14,868	$ 8,352	$ 12,836	$ 6,333	$ 10,234