Condensed Consolidated Statements of Income (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Net sales	$ 231,404	$ 255,807	$ 785,551	$ 886,389
Cost of sales	180,967	203,947	601,478	674,362
Gross profit	50,437	51,860	184,073	212,027
Selling, general, administrative and engineering expenses	48,828	47,643	147,757	158,594
Restructuring and asset impairment charges	2,417	875	11,122	1,431
(Loss) income from operations	(808)	3,342	25,194	52,002
Interest expense	(96)	(167)	(253)	(1,299)
Other income, net of expenses	1,349	412	2,017	1,252
Income from operations before income taxes	445	3,587	26,958	51,955
Income tax (benefit) provision	(1,242)	632	(4,517)	11,420
Net income	1,687	2,955	31,475	40,535
Net (income) loss attributable to non-controlling interest	(39)	55	75	127
Net income attributable to controlling interest	$ 1,648	$ 3,010	$ 31,550	$ 40,662
Net income attributable to controlling interest:
Basic (in dollars per share)	$ 0.07	$ 0.13	$ 1.40	$ 1.81
Diluted (in dollars per share)	$ 0.07	$ 0.13	$ 1.38	$ 1.79
Weighted average number of common shares outstanding:
Basic (in shares)	22,615	22,523	22,593	22,510
Diluted (in shares)	22,946	22,684	22,838	22,666
Dividends declared per common share (in dollars per share)	$ 0.11	$ 0.11	$ 0.33	$ 0.33