Revenue Recognition and Accounts Receivable - Summary of Consolidated Statement of Operations As Impact of Adoption (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue Recognition And Accounts Receivable [Line Items]
Net sales	$ 108,709	$ 102,738
Cost of sales	24,147	22,581
Gross profit	84,562	80,157
Sales and marketing	50,268	48,532
Operating income	7,873	5,919
Income tax expense	(5,373)	(3,924)
Net income (loss) from continuing operations	$ 5,229	$ (2,308)
Net income from continuing operations per common share—basic	$ 0.28	$ (0.13)
Net income from continuing operations per common share—diluted	$ 0.27	$ (0.13)
Topic 606 [Member]
Revenue Recognition And Accounts Receivable [Line Items]
Net sales	$ 108,709
Cost of sales	24,147
Gross profit	84,562
Sales and marketing	50,268
Other operating expenses	26,421
Operating income	7,873
Income tax expense	(5,373)
Net income (loss) from continuing operations	$ 5,229
Net income from continuing operations per common share—basic	$ 0.28
Net income from continuing operations per common share—diluted	$ 0.27
Topic 606 [Member] | Based on Historical Accounting under Topic 605 [Member]
Revenue Recognition And Accounts Receivable [Line Items]
Net sales	$ 101,362
Cost of sales	22,116
Gross profit	79,246
Sales and marketing	50,361
Other operating expenses	26,421
Operating income	2,464
Income tax expense	(3,918)
Net income (loss) from continuing operations	$ 1,275
Net income from continuing operations per common share—basic	$ 0.07
Net income from continuing operations per common share—diluted	$ 0.07
Topic 606 [Member] | Impact of Adoption of ASC 606
Revenue Recognition And Accounts Receivable [Line Items]
Net sales	$ 7,347
Cost of sales	2,031
Gross profit	5,316
Sales and marketing	(93)
Operating income	5,409
Income tax expense	(1,455)
Net income (loss) from continuing operations	$ 3,954
Net income from continuing operations per common share—basic	$ 0.21
Net income from continuing operations per common share—diluted	$ 0.20