Consolidated Statement of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	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	$ (291)	$ 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, 2019			33,192					906
Balance, value at Dec. 31, 2019	673,964	$ (291)	$ 332	295,582	405,668	$ (291)	(5,391)	$ (22,227)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	39,351
Foreign currency translation adjustment	(3,083)
Balance, shares at Jun. 30, 2020			33,413					993
Balance, value at Jun. 30, 2020	709,764		$ 334	299,829	444,728		(8,438)	$ (26,689)
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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	27,292				27,292
Foreign currency translation adjustment	2,815						2,815
Minimum post retirement benefit plan adjustments, net of taxes	18						18
Stock compensation expense	2,506			2,506
Stock options exercised, shares			6
Stock options exercised	54			54
Awards of common shares (in shares)			4
Net settlement of restricted stock units, shares			15					7
Net settlement of restricted stock units	(278)		$ 0	0				$ (278)
Balance, shares at Jun. 30, 2020			33,413					993
Balance, value at Jun. 30, 2020	709,764		$ 334	299,829	444,728		(8,438)	$ (26,689)
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)
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	38,711
Foreign currency translation adjustment	3,959
Balance, shares at Jun. 30, 2021			33,718					1,083
Balance, value at Jun. 30, 2021	787,608		$ 337	310,728	508,654		1,552	$ (33,663)
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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	25,949				25,949
Foreign currency translation adjustment	761						761
Minimum post retirement benefit plan adjustments, net of taxes	27						27
Stock compensation expense	2,567			2,567
Stock options exercised, shares			1
Stock options exercised	14			14
Awards of common shares (in shares)			3
Net settlement of restricted stock units, shares			3					1
Net settlement of restricted stock units	(118)		$ 0	0				$ (118)
Balance, shares at Jun. 30, 2021			33,718					1,083
Balance, value at Jun. 30, 2021	$ 787,608		$ 337	$ 310,728	$ 508,654		$ 1,552	$ (33,663)