Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net sales	$ 433,823	$ 409,788	$ 396,489
Cost of sales	93,037	87,853	86,525
Gross profit	340,786	321,935	309,964
Sales and marketing	198,370	181,287	178,080
General and administrative	74,388	74,404	87,157
Research and development	29,700	28,803	26,389
SEC / FCPA matters and related costs	(2,483)	2,005	9,083
Charges related to U.S. Government resolutions (Note 11)		14,369
Operating income	40,811	21,067	9,255
Interest income (expense), net	(416)	763	(489)
Other expense, net	(4,004)	(2,806)	(259)
Income before income taxes	36,391	19,024	8,507
Income tax expense	(29,100)	(15,527)	(10,849)
Net income (loss) from continuing operations	7,291	3,497	(2,342)
Discontinued operations (Note 11)
Loss from discontinued operations	(1,759)	(638)	(1,827)
Income tax benefit	691	197	1,360
Net loss from discontinued operations	(1,068)	(441)	(467)
Net income (loss)	$ 6,223	$ 3,056	$ (2,809)
Net income (loss) per common share—basic
Net income (loss) from continuing operations	$ 0.40	$ 0.19	$ (0.12)
Net loss from discontinued operations	(0.06)	(0.02)	(0.03)
Net income (loss) per common share—basic	0.34	0.17	(0.15)
Net income (loss) per common share—diluted
Net income (loss) from continuing operations	0.39	0.19	(0.12)
Net loss from discontinued operations	(0.05)	(0.02)	(0.03)
Net income (loss) per common share—diluted	$ 0.34	$ 0.17	$ (0.15)
Weighted average number of common shares:
Basic	18,117,405	18,144,019	18,795,194
Diluted	18,498,745	18,463,161	18,795,194
Other comprehensive income (loss), before tax
Unrealized gain (loss) on derivative instrument		$ (360)	$ 202
Unrealized gain (loss) on debt securities	$ 3,830	(1,744)	(3,348)
Reclassification adjustment for loss on debt securities in net income	5,585	2,727
Currency translation adjustment	4,552	(726)	(3,907)
Other comprehensive income (loss) before tax	13,967	(103)	(7,053)
Income tax benefit (expense) related to items of other comprehensive income (loss)	(3,600)	(245)	1,203
Other comprehensive income (loss), net of tax	10,367	(348)	(5,850)
Comprehensive income (loss)	$ 16,590	$ 2,708	$ (8,659)