Inventory (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Inventory Disclosure [Abstract]
Raw materials	$ 482	$ 482		$ 813
Work-in-process	1,289	1,289		89
Finished goods	814	814		1,007
Total	2,585	2,585		1,909
Current portion	(903)	(903)		(1,096)
Non-current portion included in intangible and other assets, net	1,682	1,682		$ 813
Cost of product revenue
Inventory [Line Items]
Inventory write-down	$ 200	$ 300	$ 200