Stockholders' Equity - Summary of Activity Related to Options Granted (Detail)	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of stock options outstanding, beginning balance	3,144,993	4,045,324
Number of stock options granted	100,000	252,000
Number of stock options exercised	(218,010)	(1,138,331)
Number of stock options forfeited		(14,000)
Number of stock options expired	889,983
Number of stock options outstanding, ending balance	2,137,000	3,144,993	4,045,324
Number of stock options exercisable	1,856,001
Weighted average exercise price, options outstanding, beginning balance | $ / shares	$ 2.39	$ 1.85
Number of stock options unvested ending balance	280,999
Weighted average exercise price, options granted | $ / shares	$ 0.60	3.80
Weighted average exercise price, options exercised | $ / shares	1.50	0.78
Weighted average exercise price, options forfeited | $ / shares		2.43
Weighted average exercise price, options expired | $ / shares	2.07
Weighted average exercise price, options outstanding, ending balance | $ / shares	2.53	$ 2.39	$ 1.85
Weighted average exercise price, options exercisable | $ / shares	$ 2.64
Weighted average remaining contractual term, options outstanding	9 months	1 year 5 months 23 days	2 years 18 days
Aggregate fair value, beginning balance | $	$ 5,406,610	$ 7,516,533	$ 7,483,849
Aggregate fair value, exercisable | $	$ 4,899,843