Inventory - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Raw materials	$ 7,941	$ 14,142
Work in process	8,653	8,590
Finished goods	41,473	35,357
Total inventory, gross	58,067	58,089
Inventory cost adjustment	(158)	(287)
Inventory	$ 57,909	$ 57,802