Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Allowance for loan losses	$ 26,568	$ 25,028
Common stock, no par value
Common shares, shares authorized	40,000,000	40,000,000
Common stock, shares issued	17,711,815	17,664,951
Treasury shares, common shares	2,681,843	1,766,919