CONDENSED CONSOLIDATED STATEMENT OF INCOME (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Statement [Abstract]
Net sales	$ 146,640	$ 125,979
Cost of sales	92,721	84,690
Gross margin	53,919	41,289
Selling and administrative expenses	27,599	25,206
Research and development expenses	4,863	5,269
Operating income	21,457	10,814
Equity income in unconsolidated joint ventures	977	529
Other income (expense), net	(1,191)	(589)
Interest income (expense), net	(748)	(905)
Income before income tax expense	20,495	9,849
Income tax expense	5,915	2,873
Income from continuing operations	14,580	6,976
Income (loss) from discontinued operations, net of income taxes	0	120
Net income (loss)	$ 14,580	$ 7,096
Basic net income per share:
Income from continuing operations (in dollars per share)	$ 0.81	$ 0.41
Income from discontinued operations (in dollars per share)		$ 0.01
Net income (loss) (in dollars per share)	$ 0.81	$ 0.42
Diluted net income per share:
Income from continuing operations (in dollars per share)	$ 0.79	$ 0.39
Income from discontinued operations (in dollars per share)		$ 0.01
Net income (in dollars per share)	$ 0.79	$ 0.40
Shares used in computing:
Basic net income per share (shares)	17,950,843	17,072,459
Diluted net income per share (shares)	18,549,458	17,673,399