Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Net sales	$ 111,708	$ 105,247	$ 331,964	$ 316,927
Cost of sales	24,020	23,717	71,002	69,475
Gross profit	87,688	81,530	260,962	247,452
Sales and marketing	49,898	47,493	151,695	146,496
General and administrative	22,705	18,068	64,457	56,759
Research and development	9,598	6,935	24,426	21,246
Changes in fair value of contingent consideration	1,580		2,689
Operating income	3,907	9,034	17,695	22,951
Interest income (expense), net	(181)	(15)	(615)	106
Other income (expense), net	(5,054)	479	(5,785)	(3,284)
Income (loss) before income taxes	(1,328)	9,498	11,295	19,773
Income tax benefit (expense)	115	(6,150)	(6,346)	(13,998)
Net income (loss) from continuing operations	(1,213)	3,348	4,949	5,775
Discontinued operations (Note 6)
Income (loss) from discontinued operations		65	(3)	(1,762)
Income tax benefit (expense)	2	43	(6)	642
Net income (loss) from discontinued operations	2	108	(9)	(1,120)
Net income (loss)	$ (1,211)	$ 3,456	$ 4,940	$ 4,655
Net income (loss) per common share—basic
Net income (loss) from continuing operations	$ (0.07)	$ 0.18	$ 0.26	$ 0.32
Net income (loss) from discontinued operations		0.01		(0.06)
Net income (loss) per common share—basic	(0.07)	0.19	0.26	0.26
Net income (loss) per common share—diluted
Net income (loss) from continuing operations	(0.07)	0.18	0.26	0.31
Net income (loss) from discontinued operations		0.01		(0.06)
Net income (loss) per common share—diluted	$ (0.07)	$ 0.19	$ 0.26	$ 0.25
Weighted average number of common shares:
Basic	18,562,204	18,180,845	18,460,848	18,071,093
Diluted	18,562,204	18,572,791	18,864,169	18,394,542
Other comprehensive income, before tax
Unrealized gain (loss) on debt securities	$ 1,240		$ 3,200	$ (3,220)
Reclassification adjustment for loss on debt securities in net income				5,585
Currency translation adjustment	(844)	$ 1,111	(1,322)	3,993
Other comprehensive income before tax	396	1,111	1,878	6,358
Income tax related to items of other comprehensive income	(366)		(798)	(900)
Other comprehensive income, net of tax	30	1,111	1,080	5,458
Comprehensive income (loss)	$ (1,181)	$ 4,567	$ 6,020	$ 10,113