CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net sales	$ 162,523	$ 177,580	$ 327,221	$ 338,986
Cost of sales	135,764	133,829	263,260	254,201
Gross profit	26,759	43,751	63,961	84,785
Research and development expenses	6,059	4,946	12,110	10,444
Factory transition restructuring charges	0	449	0	5,699
Selling, general and administrative expenses	30,570	31,053	60,817	61,704
Operating income (loss)	(9,870)	7,303	(8,966)	6,938
Interest income (expense), net	(1,279)	(562)	(2,349)	(955)
Gain on sale of Guangzhou factory	36,978	0	36,978	0
Other income (expense), net	(1,082)	(642)	(1,669)	(59)
Income before provision for income taxes	24,747	6,099	23,994	5,924
Provision for income taxes	2,088	1,415	1,922	1,121
Net income	$ 22,659	$ 4,684	$ 22,072	$ 4,803
Earnings per share:
Basic (in dollars per share)	$ 1.61	$ 0.33	$ 1.57	$ 0.33
Diluted (in dollars per share)	$ 1.60	$ 0.32	$ 1.55	$ 0.33
Shares used in computing earnings per share:
Basic (in shares)	14,070	14,404	14,078	14,427
Diluted (in shares)	14,158	14,683	14,195	14,700