Inventory (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Inventory Disclosure [Abstract]
Raw materials	$ 482		$ 813
Work-in-process	626		89
Finished goods	847		1,007
Total	1,955		1,909
Current portion	(936)		(1,096)
Non-current portion included in intangible and other assets, net	1,019		$ 813
Cost of product revenue [Member]
Inventory write-down	$ 47	$ 217