Stock Options, Stock Purchase Plan and Warrants - Status of Our Stock Options and Stock Awards (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock options, beginning balance	4,012,096	5,725,298	5,777,212
Weighted average exercise price, beginning balance	$ 2.04	$ 1.22	$ 1.02
Stock options, granted	1,819,000	760,500	416,000
Stock options, exercised	(492,091)	(2,387,327)	(438,998)
Stock options, cancelled	(12,500)	(86,375)	(28,916)
Stock options, ending balance	5,326,505	4,012,096	5,725,298
Stock options, exercisable, ending balance	2,608,284
Weighted average exercise price, granted	$ 4.90	$ 4.21	$ 3.66
Weighted average exercise price, exercised	1.45	0.76	0.85
Weighted average exercise price, cancelled	3.19	2.39	1.47
Weighted average exercise price, ending balance	3.07	$ 2.04	$ 1.22
Weighted average exercise price, exercisable, ending balance	$ 1.69