Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net Income Available to Common Shareholders	$ 23,386	$ 22,732	$ 22,148	$ 19,814	$ 22,222	$ 20,126	$ 18,251	$ 28,996	$ 88,080	$ 89,595	$ 89,352
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic									843	887	806
Distributed earnings allocated to common shares outstanding									34,901	35,745	35,542
Undistributed earnings allocated to common shares outstanding									52,336	52,963	53,004
Net earnings allocated to common shareholders	$ 23,161	$ 22,499	$ 21,942	$ 19,635	$ 21,992	$ 19,929	$ 18,051	$ 28,736	$ 87,237	$ 88,708	$ 88,546
Average shares outstanding, basic	15,026	15,279	15,573	15,656	15,708	15,950	16,081	16,080	15,381	15,975	16,314
Effect of dilutive securities									26	20	19
Average shares outstanding, diluted	15,056	15,302	15,594	15,687	15,733	15,970	16,097	16,101	15,407	15,995	16,333
Basic earnings per share	$ 1.54	$ 1.47	$ 1.41	$ 1.25	$ 1.40	$ 1.25	$ 1.12	$ 1.79	$ 5.67	$ 5.55	$ 5.43
Diluted earnings per share	$ 1.54	$ 1.47	$ 1.41	$ 1.25	$ 1.40	$ 1.25	$ 1.12	$ 1.78	$ 5.66	$ 5.55	$ 5.42