Stockholders' Equity - Summary of Option Activity (Details) - $ / shares |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Number of Options | |||
| Outstanding at beginning of period (in options) | 459,271 | 286,188 | 218,458 |
| Granted (in options) | 340,500 | 326,250 | 207,950 |
| Canceled (in options) | (147,152) | (145,873) | (138,220) |
| Exercised (in options) | (50,412) | (7,294) | (2,000) |
| Outstanding at end of period (in options) | 602,207 | 459,271 | 286,188 |
| Vested and expected to vest (in options) | 565,137 | ||
| Exercisable (in options) | 304,610 | ||
| Weighted Average Exercise Price Per Share | |||
| Outstanding at beginning of period (in dollars per share) | $ 8.95 | $ 15.30 | $ 22.00 |
| Granted (in dollars per share) | 8.65 | 4.76 | 3.15 |
| Canceled (in dollars per share) | 10.10 | 12.38 | 7.74 |
| Exercised (in dollars per share) | 4.69 | 2.30 | 5.15 |
| Outstanding at end of period (in dollars per share) | 8.58 | $ 8.95 | $ 15.30 |
| Vested and expected to vest (in dollars per share) | 8.71 | ||
| Exercisable (in dollars per share) | $ 9.38 | ||