Net Loss per Share Attributable to Common Stockholders - Common Shares Excluded from the Calculation of Net Loss per Common Share Attributable to Common Stockholders (Detail) - shares
|
6 Months Ended |
12 Months Ended |
Jun. 30, 2016 |
Jun. 30, 2015 |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
|
| Total amount of anti-dilutive securities excluded from computation of earnings per share |
2,946,935
|
2,930,334
|
2,889,366
|
1,930,585
|
| Options to Purchase Common Stock [Member] |
|
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
|
| Total amount of anti-dilutive securities excluded from computation of earnings per share |
389,969
|
333,368
|
332,400
|
300,026
|
| Common Stock Underlying Series A and Series A-1 Convertible Preferred Stock [Member] |
|
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
|
| Total amount of anti-dilutive securities excluded from computation of earnings per share |
|
|
|
1,630,097
|
| Warrants to Purchase Common Stock [Member] |
|
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
|
| Total amount of anti-dilutive securities excluded from computation of earnings per share |
2,556,966
|
2,596,966
|
2,556,966
|
462
|