Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Accounting Policies [Abstract]
Impairment of investments	$ 0
Based on these sales prices reduced inventory and increased cost of goods sold	1,100,000	139,000
Reduced inventory and increased costs of goods sold	363,000	209,000
Revenue recorded from government contract	125,000	98,000
Period of contract	3 years
Total value of the contract	4,700,000
Value of contract recognized	$ 2,800,000