Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accounting Policies [Abstract]
Impairment of investments			$ 0
Based on these sales prices reduced inventory and increased cost of goods sold		$ 276,000.0	1,100,000	$ 1,800,000
Reduced inventory and increased costs of goods sold		1,800,000		2,200,000
Revenue recorded from government contract	$ 270,000	$ 156,000	556,000	$ 553,000
Total value of the contract	$ 4,700,000		4,700,000
Value of contract recorded			$ 3,900,000