CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Net sales	$ 364,810	$ 342,029	$ 341,159
Cost of sales	(95,691)	(91,037)	(90,937)
Gross profit	269,119	250,992	250,222
Operating expenses:
Volume incentives	125,337	119,970	119,910
Selling, general and administrative	138,431	129,635	120,273
Operating income	5,351	1,387	10,039
Other income (expense):
Interest and other income (expense), net	(67)	144	591
Interest expense	(387)	(289)	(16)
Foreign exchange gains (losses), net	(1,697)	1,980	(1,348)
Other income (expense), net	(2,151)	1,835	(773)
Income from continuing operations before provision for income taxes	3,200	3,222	9,266
Provision for income taxes	4,402	17,039	8,591
Net income (loss) from continuing operations	(1,202)	(13,817)	675
Net loss attributable to noncontrolling interests	(348)	(875)	(1,464)
Net income (loss) attributable to common shareholders	$ (854)	$ (12,942)	$ 2,139
Basic and diluted net income (loss) per common share
Basic earnings (loss) per share attributable to common shareholders (in dollars per share)	$ (0.04)	$ (0.69)	$ 0.11
Diluted earnings (loss) per share attributable to common shareholders (in dollars per share)	$ (0.04)	$ (0.69)	$ 0.11
Weighted average basic common shares outstanding (in shares)	19,123	18,882	18,731
Weighted average diluted common shares outstanding (in shares)	19,123	18,882	19,056
Dividends declared per common share (in dollars per share)	$ 0	$ 0.1	$ 0.4