Consolidated Statement of Shareholders' Equity - 3 months ended Mar. 31, 2017 - 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, 2016		32,085				530
Balance, value at Dec. 31, 2016	$ 460,880	$ 320	$ 264,418	$ 211,748	$ (7,721)	$ (7,885)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,996			3,996
Foreign currency translation adjustment	679				679
Adjustment to retirement benefit liability, net of taxes of ($2)	(3)				(3)
Adjustment to post employment health care benefit liability, net of taxes of $19	29				29
Stock compensation expense	1,635		1,635
Cumulative effect of accounting change (see Note 2)	0		(254)	254
Stock options exercised, shares		1
Stock options exercised	11	$ 0	11
Net settlement of restricted stock units, shares		47				22
Net settlement of restricted stock units	(922)	$ 1	(1)			$ (922)
Balance, shares at Mar. 31, 2017		32,133				552
Balance, value at Mar. 31, 2017	$ 466,305	$ 321	$ 265,809	$ 215,998	$ (7,016)	$ (8,807)