Equity Award Plans - Options to Purchase Series A Preferred Stock - Fair Value Assumptions (Details) - Series A convertible preferred stock - Options to purchase common stock |
3 Months Ended | |
|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
|
| Fair value assumptions | ||
| Risk-free interest rate (as a percent) | 2.74% | 2.17% |
| Expected term (in years) | 6 years 3 months | 6 years 3 months |
| Expected volatility (as a percent) | 43.85% | 47.42% |
| Expected dividend yield (as a percent) | 0.00% | 0.00% |