Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net income	$ 49,990	$ 47,319	$ 87,651
Denominator:
Weighted average shares outstanding - basic (in shares)	18,681,000	18,573,000	18,374,000
Effect of dilutive shares (in shares)	25,000	140,000	285,000
Weighted average shares outstanding - diluted (in shares)	18,706,000	18,713,000	18,659,000
Basic earnings per share (in dollars per share)	$ 2.68	$ 2.55	$ 4.77
Diluted earnings per share (in dollars per share)	$ 2.67	$ 2.53	$ 4.70
Antidilutive securities excluded from computation of earnings per share (in shares)	8,454	20,520	36,642