CONSOLIDATED INCOME STATEMENTS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Net sales	$ 147,551	$ 146,315	$ 280,256	$ 276,160
Cost of sales	107,271	102,757	202,567	196,056
Gross profit	40,280	43,558	77,689	80,104
Research and development expenses	4,096	4,119	8,530	8,396
Selling, general and administrative expenses	25,784	27,765	52,656	54,044
Operating income	10,400	11,674	16,503	17,664
Interest income (expense), net	104	(71)	214	(87)
Other income (expense), net	56	(334)	286	(683)
Income before provision for income taxes	10,560	11,269	17,003	16,894
Provision for income taxes	2,185	2,781	3,439	4,133
Net income	$ 8,375	$ 8,488	$ 13,564	$ 12,761
Earnings per share:
Basic (in dollars per share)	$ 0.53	$ 0.54	$ 0.86	$ 0.81
Diluted (in dollars per share)	$ 0.52	$ 0.53	$ 0.84	$ 0.79
Shares used in computing earnings per share:
Basic (in shares)	15,732	15,784	15,819	15,785
Diluted (in shares)	16,029	16,141	16,136	16,151