Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Net operating loss carryforwards	$ 3,924	$ 3,255
Intangible assets	2,935	2,351
Sale-leaseback, net	628	888
Allowance for returns and discounts	5,358	4,043
Stock-based compensation	5,933	10,963
Tax credit carryforwards	5,247	3,430
Other, net	4,580	4,066
Total deferred tax assets	28,605	28,996
Valuation allowance for deferred tax assets	(15,204)	(7,774)
Total deferred tax assets	13,401	21,222
Deferred tax liabilities:
Convertible Senior Notes	(3,633)	(7,592)
Intangible assets	(2,935)	(7,557)
Property, plant and equipment	(7,263)	(6,131)
Deferred Tax Liabilities, Gross	(13,831)	(21,280)
Total deferred tax liabilities	$ (430)	$ (58)