Significant Accounting Policies - Potential Dilutive Securities Excluded from Computation of Dilutive Weighted Average Shares Outstanding (Details) - shares |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | |||
| Potential dilutive securities excluded from computation of dilutive weighted average shares outstanding | 9,133,466 | 7,898,679 | 5,951,315 |
| Warrants [Member] | |||
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | |||
| Potential dilutive securities excluded from computation of dilutive weighted average shares outstanding | 1,288,500 | 1,288,500 | 1,969,250 |
| Stock Options [Member] | |||
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | |||
| Potential dilutive securities excluded from computation of dilutive weighted average shares outstanding | 7,844,966 | 6,610,179 | 3,982,065 |