Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Basic
Net income available to common shareholders	$ 89,264	$ 77,588	$ 81,718
Less: income attributable to unvested stock-based compensation awards	(615)	(857)	(1,306)
Net earnings allocated to common shareholders	$ 88,649	$ 76,731	$ 80,412
Weighted average shares outstanding, including unvested stock-based compensation awards (in shares)	14,798,447	14,933,990	15,149,535
Less: average unvested stock-based compensation awards (in shares)	(229,684)	(230,600)	(242,478)
Weighted average shares outstanding - Basic (in shares)	14,568,763	14,703,390	14,907,057
Diluted
Net earnings allocated to common shareholders	$ 88,649	$ 76,731	$ 80,412
Weighted average shares outstanding - Basic (in shares)	14,568,763	14,703,390	14,907,057
Plus: incremental shares from assumed conversion of stock-based compensation awards (in shares)	79,404	38,650	66,894
Weighted average shares outstanding - Diluted (in shares)	14,648,167	14,742,040	14,973,951
Basic EPS (in dollars per share)	$ 6.08	$ 5.22	$ 5.39
Diluted EPS (in dollars per share)	$ 6.05	$ 5.20	$ 5.37
Antidilutive securities excluded from computation of earning per share (in shares)	4,984	7,591	14,982