CONDENSED CONSOLIDATED STATEMENT OF INCOME (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Net sales	$ 163,052	$ 142,820	$ 463,187	$ 401,252
Cost of sales	98,504	91,634	287,583	264,347
Gross margin	64,548	51,186	175,604	136,905
Selling and administrative expenses	30,182	25,582	92,279	76,335
Research and development expenses	5,977	5,364	17,259	16,883
Restructuring and impairment charges		1,231	0	5,756
Operating income	28,389	19,009	66,066	37,931
Equity income in unconsolidated joint ventures	953	1,754	2,992	3,045
Other income (expense), net	(107)	(101)	(1,374)	(867)
Interest income (expense), net	(698)	(881)	(2,167)	(2,616)
Income before income tax expense	28,537	19,781	65,517	37,493
Income tax expense	8,149	6,209	19,647	11,361
Income from continuing operations	20,388	13,572	45,870	26,132
Income (loss) from discontinued operations, net of income taxes	0	0	0	102
Net income	$ 20,388	$ 13,572	$ 45,870	$ 26,234
Basic net income per share:
Income from continuing operations (in dollars per share)	$ 1.12	$ 0.79	$ 2.53	$ 1.52
Income from discontinued operations (in dollars per share)		$ 0.00	$ 0.00	$ 0.01
Net income (in dollars per share)	$ 1.12	$ 0.79	$ 2.53	$ 1.53
Diluted net income per share:
Income from continuing operations (in dollars per share)	$ 1.09	$ 0.76	$ 2.46	$ 1.48
Income from discontinued operations (in dollars per share)		$ 0.00	$ 0.00	$ 0.01
Net income (in dollars per share)	$ 1.09	$ 0.76	$ 2.46	$ 1.49
Shares used in computing:
Basic net income per share (shares)	18,258,709	17,244,831	18,122,599	17,141,672
Diluted net income per share (shares)	18,733,777	17,863,035	18,657,258	17,711,972