Earnings per Common Share (Calculation of Earnings per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Earnings Per Share [Abstract]
Net income	$ 18,668	$ 18,751	$ 55,108	$ 56,682
Less dividends and undistributed earnings allocated to participating securities	(53)	(55)	(164)	(163)
Net income available to common shareholders	$ 18,615	$ 18,696	$ 54,944	$ 56,519
Weighted average common shares outstanding - basic	17,174,000	17,320,000	17,269,000	17,303,000
Dilutive effect of common stock equivalents	124,000	124,000	120,000	148,000
Weighted average common shares outstanding - diluted	17,298,000	17,444,000	17,389,000	17,451,000
Basic earnings per common share	$ 1.08	$ 1.08	$ 3.18	$ 3.27
Diluted earnings per common share	$ 1.08	$ 1.07	$ 3.16	$ 3.24
Antidilutive common stock equivalents	137,886	148,542	140,777	149,675