Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Employee	Common Stock	Common Stock Director	Common Stock Employee	Paid-in capital	Paid-in capital Employee	Retained earnings	Accumulated other comprehensive loss
Beginning Balance (in shares) at Dec. 31, 2014			13,712,000
Balance at beginning of year at Dec. 31, 2014	$ 188,233		$ 137			$ 160,315		$ 37,703	$ (9,922)
Comprehensive (loss) income:
Net income	12,278							12,278
Translation adjustment	(5,281)								(5,281)
Derivative fair value adjustment (Note G)	(2)								(2)
Effect of retirement benefit obligations	1,020								1,020
Comprehensive income (loss)	8,015
Restricted shares issued to employees/directors (Note H)				28,000
Shares issued to employees/directors (Note H) (in shares)					189,000
Shares issued to employees/directors (Note H)		$ 1,657			$ 2		$ 1,655
Stock compensation expense (Note H)	3,105					3,105
Tax benefit (deficiency) from stock options, net	$ (138)					(138)
Exercise of stock options (in shares)	110,375		101,000
Exercise of stock options	$ 844		$ 1			843
Dividends (Note H)	(2,248)							(2,248)
Ending Balance (in shares) at Dec. 31, 2015			14,030,000
Balance at end of year at Dec. 31, 2015	199,468		$ 140			165,780		47,733	(14,185)
Comprehensive (loss) income:
Net income	15,720							15,720
Translation adjustment	(22,683)								(22,683)
Derivative fair value adjustment (Note G)	17								17
Effect of retirement benefit obligations	(148)								(148)
Comprehensive income (loss)	(7,094)
Restricted shares issued to employees/directors (Note H)				27,000
Shares issued to employees/directors (Note H) (in shares)					234,000
Shares issued to employees/directors (Note H)		2,127			$ 3		2,124
Stock compensation expense (Note H)	2,911					2,911
Tax benefit (deficiency) from stock options, net	$ 435					435
Exercise of stock options (in shares)	272,325		265,000
Exercise of stock options	$ 2,353		$ 3			2,350
Dividends (Note H)	(2,472)							(2,472)
Ending Balance (in shares) at Dec. 31, 2016			14,556,000
Balance at end of year at Dec. 31, 2016	197,728		$ 146			173,600		60,981	(36,999)
Comprehensive (loss) income:
Net income	2,154							2,154
Translation adjustment	7,823								7,823
Derivative fair value adjustment (Note G)	17								17
Effect of retirement benefit obligations	(166)								(166)
Comprehensive income (loss)	9,828
Restricted shares issued to employees/directors (Note H)				30,000	97,000
Restricted shares issued to employees/directors (Note H)		$ 2			$ 1		$ 1
Stock compensation expense (Note H)	$ 3,390					3,390
Exercise of stock options (in shares)	300,000		254,000
Exercise of stock options	$ 2,537		$ 2			2,535
Units effectively repurchased for required employee withholding taxes (in shares)			(34,000)
Units effectively repurchased for required employee withholding taxes	(694)					(694)
Adoption of ASU 2016-09	31					77		(46)
Dividends (Note H)	(2,543)							(2,543)
Ending Balance (in shares) at Dec. 31, 2017			14,903,000
Balance at end of year at Dec. 31, 2017	$ 210,279		$ 149			$ 178,909		$ 60,546	$ (29,325)