Condensed Consolidated Statements of Income and Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Net sales	$ 110,985	$ 113,499	$ 288,943	$ 338,461
Cost of sales	26,243	24,896	72,818	74,416
Gross profit	84,742	88,603	216,125	264,045
Sales and marketing	52,926	54,805	150,718	165,363
General and administrative	16,541	21,090	49,453	63,497
Research and development	9,962	7,982	28,691	26,191
Acquisition-related amortization and remeasurement (Note 13)	1,138	23,608	(2,766)	31,873
Operating income (loss)	4,175	(18,882)	(9,971)	(22,879)
Interest income (expense), net	(731)	186	(2,055)	386
Other income (expense), net	1,817	(8,146)	6,088	(8,786)
Income (loss) before income taxes	5,261	(26,842)	(5,938)	(31,279)
Income tax benefit (expense)	(607)	(13,656)	17,833	(8,869)
Net income (loss)	$ 4,654	$ (40,498)	$ 11,895	$ (40,148)
Net income (loss) per common share:
Basic	$ 0.24	$ (2.14)	$ 0.62	$ (2.13)
Diluted	$ 0.24	$ (2.14)	$ 0.61	$ (2.13)
Weighted average number of common shares:
Basic	19,335,718	18,957,876	19,217,057	18,847,728
Diluted	19,398,567	18,957,876	19,319,302	18,847,728
Other comprehensive income (loss), before tax
Unrealized loss on debt security				$ (2,593)
Reclassification adjustment for amortization of historical unrealized gains on debt security		$ (345)		(1,034)
Reclassification adjustment for other-than-temporary impairment on debt security		(5,193)		(5,193)
Currency translation adjustment	$ 2,275	(1,893)	$ 2,048	(2,195)
Other comprehensive income (loss) before tax	2,275	(7,431)	2,048	(11,015)
Income tax related to other comprehensive income (loss)		1,388		2,200
Other comprehensive income (loss), net of tax	2,275	(6,043)	2,048	(8,815)
Comprehensive income (loss)	$ 6,929	$ (46,541)	$ 13,943	$ (48,963)