Components of Inventories (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Inventory [Line Items]
Raw materials	$ 2,500	$ 2,400
Finished goods, net	32,900	26,100
Total	35,400	28,500
Less: Provision for obsolescence	(1,800)	(1,800)
Inventories, net	$ 33,638	$ 26,678