Stock Based Compensation Assumptions (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
|
| Employees and directors | ||||
| Assumptions | ||||
| Risk free interest rate | 1.30% | 1.80% | 1.40% | 1.70% |
| Expected term | 6 years 3 months | 6 years 3 months | 6 years 3 months | 6 years 3 months |
| Expected volatility | 76.50% | 79.20% | 78.90% | 80.00% |
| Employees | ||||
| Assumptions | ||||
| Unrecognized stock-based compensation expense | $ 22.8 | $ 22.8 | ||
| Period for recognition | 3 years | |||
| Non-employees | ||||
| Assumptions | ||||
| Risk free interest rate | 1.60% | 2.20% | 1.60% | 2.20% |
| Expected term | 9 years 9 months 18 days | |||
| Expected volatility | 76.50% | 80.00% | 76.50% | 79.60% |