Stockholders' Equity - Summary of Activity Related to Options Granted (Detail) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of stock options outstanding, beginning balance	4,045,324	3,640,324
Number of stock options granted		446,000
Number of stock options exercised	(163,331)	(30,500)
Number of stock options forfeited		(10,500)
Number of stock options expired
Number of stock options outstanding, ending balance	3,881,993	4,045,324
Number of stock options exercisable	3,728,329
Weighted average exercise price, options outstanding, beginning balance	$ 1.85	$ 1.76
Number of stock options unvested ending balance	584,332
Weighted average exercise price, options granted		$ 2.61
Weighted average exercise price, options exercised	$ 1.37	$ 2.67
Weighted average exercise price, options forfeited		$ 2.35
Weighted average exercise price, options expired
Weighted average exercise price, options outstanding, ending balance	$ 1.87	$ 1.85
Weighted average remaining contractual term, options outstanding, beginning balance	2 years 18 days	2 years 8 months 9 days
Weighted average exercise price, options exercisable	$ 1.84
Weighted average remaining contractual term, options outstanding, ending balance		2 years 18 days
Weighted average remaining contractual term, exercisable options, ending Balance	1 year 10 months 10 days
Aggregate fair value, beginning balance	$ 7,483,849	$ 6,406,970
Aggregate fair value, ending balance	7,259,326	7,483,849
Aggregate fair value, exercisable	$ 6,860,125