Consolidated Statement of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive (Loss) Income	Treasury Stock
Balance, shares at Dec. 31, 2019		33,192					906
Balance, value at Dec. 31, 2019	$ 673,964	$ 332	$ 295,582	$ 405,668	$ (291)	$ (5,391)	$ (22,227)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	12,059			12,059
Foreign currency translation adjustment	(5,898)					(5,898)
Minimum post retirement benefit plan adjustments, net of taxes	18					18
Stock compensation expense	1,665		1,665
Stock options exercised, shares		3
Stock options exercised	24		24
Net settlement of restricted stock units, shares		193					80
Net settlement of restricted stock units	(4,184)	$ 2	(2)				$ (4,184)
Balance, shares at Mar. 31, 2020		33,388					986
Balance, value at Mar. 31, 2020	677,357	$ 334	297,269	417,436		(11,271)	$ (26,411)
Balance, shares at Dec. 31, 2020		33,568					1,028
Balance, value at Dec. 31, 2020	743,805	$ 336	304,870	469,943		(2,461)	$ (28,883)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	12,762			12,762
Foreign currency translation adjustment	3,198					3,198
Minimum post retirement benefit plan adjustments, net of taxes	27					27
Stock compensation expense	2,368		2,368
Stock options exercised, shares		25
Stock options exercised	910		910
Net settlement of restricted stock units, shares		118					54
Net settlement of restricted stock units	(4,662)	$ 1	(1)				$ (4,662)
Balance, shares at Mar. 31, 2021		33,711					1,082
Balance, value at Mar. 31, 2021	$ 758,408	$ 337	$ 308,147	$ 482,705		$ 764	$ (33,545)