Inventory (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets
Finished goods	$ 1,322	$ 1,140
Total inventory, current	1,322	1,140
Non-Current assets
Raw materials	745	659
Work-in-process	4,109	1,109
Finished goods	527	1,056
Total inventory, non-current	5,381	2,824
Total inventory	$ 6,703	$ 3,964