Fair Value Measurements - Fair Value Measurements (Detail) - USD ($) $ in Thousands |
Jun. 30, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|---|---|---|---|
| Assets: | |||
| Restricted cash | $ 50 | $ 50 | $ 50 |
| Short-term investments | 2,000 | 5,500 | |
| Fair Value, Measurements, Recurring [Member] | |||
| Assets: | |||
| Restricted cash | 50 | 50 | 50 |
| Cash equivalents | 3,000 | 2,500 | 4,000 |
| Short-term investments | 2,000 | 5,500 | |
| Thera Warrant | 5 | ||
| Total | 5,055 | 8,050 | 4,050 |
| Fair Value, Measurements, Recurring [Member] | Other Significant Observable Inputs (Level 2) [Member] | |||
| Assets: | |||
| Restricted cash | 50 | 50 | 50 |
| Cash equivalents | 3,000 | 2,500 | 4,000 |
| Short-term investments | 2,000 | 5,500 | |
| Total | 5,050 | $ 8,050 | $ 4,050 |
| Fair Value, Measurements, Recurring [Member] | Unobservable Inputs (Level 3) [Member] | |||
| Assets: | |||
| Thera Warrant | 5 | ||
| Total | $ 5 |