Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Income Statement [Abstract]
Net sales		$ 552,560		$ 309,285		$ 396,753
Cost of sales		323,758		198,702		215,013
Gross profit		228,802		110,583		181,740
Operating expenses:
Selling and marketing		78,337		94,595		115,920
General and administrative		36,176		30,242		28,226
Research and development		15,812		14,282		16,825
Loss on disposal group, goodwill and other intangible impairment charge		20,668		72,008		0
Total operating expenses		150,993		211,127		160,971
Operating income (loss)		77,809		(100,544)		20,769
Other income (expense):
Interest income		11		162		1,044
Interest expense		(1,498)		(980)		(1,051)
Other, net		(3,587)		(470)		239
Total other (expense) income, net		(5,074)		(1,288)		232
Income (loss) from continuing operations before income taxes		72,735		(101,832)		21,001
Income tax expense (benefit)		12,198		(9,537)		5,891
Income (loss) from continuing operations		60,537		(92,295)		15,110
Discontinued operations:
Loss from discontinued operations before income taxes		(162)		(206)		(206)
Income tax expense				299		246
Loss from discontinued operations		(689)		(505)		(452)
Net income (loss)		$ 59,848		$ (92,800)		$ 14,658
Basic net income (loss) per share(1)
Basic income per share from continuing operations (in dollars per share)		$ 2.02		$ (3.11)		$ 0.50
Basic income (loss) per share from discontinued operations (in dollars per share)		(0.03)		(0.02)		(0.02)
Basic net income per share (in dollars per share)	[1]	1.99		(3.13)		0.49
Diluted net income (loss) per share(1)
Diluted income per share from continuing operations (in dollars per share)		1.88		(3.11)		0.50
Diluted income (loss) per share from discontinued operations (in dollars per share)		(0.02)		(0.02)		(0.01)
Diluted net income per share (in dollars per share)		$ 1.86	[1]	$ (3.13)	[1]	$ 0.48
Shares used in per share calculations:
Basic (in shares)		30,007		29,684		30,099
Diluted (in shares)		32,123		29,684		30,355

[1] May not add due to rounding.