Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic
Net income	$ 3,817	$ 3,595	$ 2,416	$ 3,299	$ 4,181	$ 4,000	$ 3,836	$ 4,740	$ 13,127	$ 16,757	$ 14,253
Undistributed earnings allocated to participating securities									(195)	(383)	(422)
Net income allocated to common shares									$ 12,932	$ 16,374	$ 13,831
Weighted average common shares outstanding									15,196,351	15,741,926	15,104,939
Basic earnings per common share	$ 0.25	$ 0.23	$ 0.16	$ 0.21	$ 0.26	$ 0.25	$ 0.24	$ 0.29	$ 0.85	$ 1.04	$ 0.92
Diluted
Net income allocated to common shares									$ 12,932	$ 16,374	$ 13,831
Weighted average common shares outstanding									15,196,351	15,741,926	15,104,939
Add: Dilutive effects of assumed exercises of stock options									27,537	193,388	446,124
Average shares and dilutive potential common shares									15,223,888	15,935,314	15,551,063
Diluted earnings per common share	$ 0.25	$ 0.23	$ 0.16	$ 0.21	$ 0.26	$ 0.24	$ 0.23	$ 0.29	$ 0.85	$ 1.03	$ 0.89