Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Net sales	$ 108,709	$ 102,738
Cost of sales	24,147	22,581
Gross profit	84,562	80,157
Sales and marketing	50,268	48,532
General and administrative	19,484	18,282
Research and development	6,937	7,424
Operating income	7,873	5,919
Interest income (expense), net	(183)	45
Other income (expense), net	2,912	(4,348)
Income before income taxes	10,602	1,616
Income tax expense	(5,373)	(3,924)
Net income (loss) from continuing operations	5,229	(2,308)
Discontinued operations (Note 5)
Loss from discontinued operations	(3)	(527)
Income tax benefit		181
Net loss from discontinued operations	(3)	(346)
Net income (loss)	$ 5,226	$ (2,654)
Net income (loss) per common share—basic
Net income (loss) from continuing operations	$ 0.28	$ (0.13)
Net loss from discontinued operations		(0.02)
Net income (loss) per common share—basic	0.28	(0.15)
Net income (loss) per common share—diluted
Net income (loss) from continuing operations	0.27	(0.13)
Net loss from discontinued operations		(0.02)
Net income (loss) per common share—diluted	$ 0.27	$ (0.15)
Weighted average number of common shares:
Basic	18,404,856	17,979,675
Diluted	18,874,591	17,979,675
Other comprehensive income, before tax
Unrealized gain (loss) on debt securities		$ (3,220)
Reclassification adjustment for loss on debt securities in net income		5,585
Currency translation adjustment	$ 697	234
Other comprehensive income before tax	697	2,599
Income tax related to items of other comprehensive loss		(900)
Other comprehensive income, net of tax	697	1,699
Comprehensive income (loss)	$ 5,923	$ (955)