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
|
|
|