Advances - Schedule of Advances from Nonaffiliated Collaboration (Detail) - USD ($) $ in Thousands |
Jun. 30, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
Jun. 18, 2008 |
|---|---|---|---|---|
| Advances [Abstract] | ||||
| Advances from nonaffiliated collaboration | $ 250 | $ 250 | $ 250 | $ 250 |