CONSOLIDATED STATEMENTS OF CONDITION (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	500,000	500,000
Common stock, stated value	$ 0.83	$ 0.83
Common stock, shares authorized	42,000,000	42,000,000
Common stock, shares issued	20,342,881	20,074,766
Common stock, shares outstanding	18,974,703	18,926,810
Treasury stock, shares	1,368,178	1,147,956