Consolidated Statement of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Balance, shares at Dec. 31, 2018		32,887				796
Balance, value at Dec. 31, 2018	$ 596,693	$ 329	$ 282,525	$ 338,995	$ (7,234)	$ (17,922)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	6,345			6,345
Foreign currency translation adjustment	842				842
Minimum pension and post retirement benefit plan adjustments, net of taxes of $7	12				12
Stock compensation expense	2,371		2,371
Stock options exercised, shares		12
Stock options exercised	139		139
Net settlement of restricted stock units, shares		127				59
Net settlement of restricted stock units	(2,151)	$ 1	(1)			$ (2,151)
Balance, shares at Mar. 31, 2019		33,026				855
Balance, value at Mar. 31, 2019	605,833	$ 330	285,034	346,922	(6,380)	$ (20,073)
Balance, shares at Dec. 31, 2019		33,192				906
Balance, value at Dec. 31, 2019	673,964	$ 332	295,582	405,668	(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 pension and post retirement benefit plan adjustments, net of taxes of $7	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)