Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value On Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Cash equivalents:
Cash equivalents	$ 127,151	$ 56,434
Short-term investments:
Short-term investments	236,238	64,993
U.S. Treasury Securities and Government Treasury Securities
Short-term investments:
Short-term investments	236,238
U.S. Government Treasury Bills and Bonds
Short-term investments:
Short-term investments		64,993
Level 1
Cash equivalents:
Cash equivalents	127,151	56,434
Short-term investments:
Short-term investments	236,238	64,993
Level 1 | U.S. Treasury Securities and Government Treasury Securities
Short-term investments:
Short-term investments	236,238
Level 1 | U.S. Government Treasury Bills and Bonds
Short-term investments:
Short-term investments		64,993
Money Market Fund
Cash equivalents:
Cash equivalents	127,151	46,407
Money Market Fund | Level 1
Cash equivalents:
Cash equivalents	$ 127,151	46,407
Demand Deposit
Cash equivalents:
Cash equivalents		10,027
Demand Deposit | Level 1
Cash equivalents:
Cash equivalents		$ 10,027