Short-Term Investments - Summary of Short-term Investments (Details) - USD ($) $ in Thousands |
Jun. 30, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Schedule Of Available For Sale Securities [Line Items] | ||
| Amortized Cost | $ 10,983 | $ 42,163 |
| Gross Unrealized Gains | 4 | |
| Gross Unrealized Loss | (17) | |
| Fair Value | 10,987 | 42,146 |
| Corporate Bonds and Commercial Paper | ||
| Schedule Of Available For Sale Securities [Line Items] | ||
| Amortized Cost | 5,989 | 37,168 |
| Gross Unrealized Gains | 3 | |
| Gross Unrealized Loss | (17) | |
| Fair Value | 5,992 | 37,151 |
| U.S. Government Securities | ||
| Schedule Of Available For Sale Securities [Line Items] | ||
| Amortized Cost | 4,994 | 4,995 |
| Gross Unrealized Gains | 1 | |
| Fair Value | $ 4,995 | $ 4,995 |