Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Summary of computation of basic and diluted earnings per share [Abstract]
Common shares outstanding at the beginning of the period (shares)					9,364,062	9,351,694	9,346,449	9,336,441
Weighted average number of net shares (redeemed) issued (shares)	(7,765)	(160)	28,137	21,712
Weighted average shares outstanding (basic) (shares)	9,356,297	9,346,289	9,379,831	9,358,153
Weighted average of potential dilutive shares attributable to stock options granted, computed under the treasury stock method (shares)	3,592	4,284	3,673	4,146
Weighted average number of shares (diluted) (shares)	9,359,889	9,350,573	9,383,504	9,362,299
Net income (In thousands)	$ 11,430	$ 11,282	$ 30,216	$ 33,705
Earnings per share:
Basic (in dollars per share)	$ 1.22	$ 1.21	$ 3.22	$ 3.61
Diluted (in dollars per share)	$ 1.22	$ 1.21	$ 3.22	$ 3.61