CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Net sales	$ 203,828	$ 160,566
Cost of sales	123,478	100,058
Gross margin	80,350	60,508
Selling, general and administrative expenses	34,165	29,860
Research and development expenses	6,961	6,549
Restructuring and impairment charges	725	0
Gain on sale of long-lived asset	(942)	0
Operating income	39,441	24,099
Equity income in unconsolidated joint ventures	1,009	613
Other income (expense), net	715	(546)
Interest expense, net	(1,248)	(1,121)
Income before income tax expense	39,917	23,045
Income tax expense	12,885	8,117
Net income	$ 27,032	$ 14,928
Basic earnings per share (in dollars per share)	$ 1.50	$ 0.83
Diluted earnings per share (in dollars per share)	$ 1.47	$ 0.82
Shares used in computing:
Basic earnings per share (shares)	18,056	17,966
Diluted earnings per share (shares)	18,373	18,214