CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Net sales	$ 193,896	$ 162,523	$ 378,059	$ 327,221
Cost of sales	159,903	135,764	304,192	263,260
Gross profit	33,993	26,759	73,867	63,961
Research and development expenses	7,163	6,059	13,954	12,110
Selling, general and administrative expenses	30,756	30,570	62,176	60,817
Operating loss	(3,926)	(9,870)	(2,263)	(8,966)
Interest income (expense), net	(1,098)	(1,279)	(2,304)	(2,349)
Gain on sale of Guangzhou factory	0	36,978	0	36,978
Other income (expense), net	188	(1,082)	(278)	(1,669)
Income (loss) before provision for income taxes	(4,836)	24,747	(4,845)	23,994
Provision for income taxes	225	2,088	1,221	1,922
Net income (loss)	$ (5,061)	$ 22,659	$ (6,066)	$ 22,072
Earnings (loss) per share:
Basic (in dollars per share)	$ (0.37)	$ 1.61	$ (0.44)	$ 1.57
Diluted (in dollars per share)	$ (0.37)	$ 1.60	$ (0.44)	$ 1.55
Shares used in computing earnings (loss) per share:
Basic (in shares)	13,863	14,070	13,845	14,078
Diluted (in shares)	13,863	14,158	13,845	14,195