CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Net sales	$ 184,163	$ 164,698
Cost of sales	144,289	127,496
Gross profit	39,874	37,202
Research and development expenses	6,791	6,051
Selling, general and administrative expenses	31,420	30,247
Operating income	1,663	904
Interest income (expense), net	(1,206)	(1,070)
Other income (expense), net	(466)	(587)
Income (loss) before provision for income taxes	(9)	(753)
Provision for income taxes (benefit)	996	(166)
Net income (loss)	$ (1,005)	$ (587)
Earnings (loss) per share:
Basic (in dollars per share)	$ (0.07)	$ (0.04)
Diluted (in dollars per share)	$ (0.07)	$ (0.04)
Shares used in computing earnings (loss) per share:
Basic (in shares)	13,827	14,087
Diluted (in shares)	13,827	14,087