Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets:
Fair value of financial assets	$ 372,881	$ 285,797
Level 1
Assets:
Fair value of financial assets	135,278	137,658
Level 2
Assets:
Fair value of financial assets	237,603	148,139
Level 3
Assets:
Fair value of financial assets	0	0
Money market funds
Assets:
Fair value of financial assets	135,278	137,658
Money market funds | Level 1
Assets:
Fair value of financial assets	135,278	137,658
Money market funds | Level 2
Assets:
Fair value of financial assets	0	0
Money market funds | Level 3
Assets:
Fair value of financial assets	0	0
U.S. government agencies securities
Assets:
Fair value of financial assets	98,609	98,653
U.S. government agencies securities | Level 1
Assets:
Fair value of financial assets	0	0
U.S. government agencies securities | Level 2
Assets:
Fair value of financial assets	98,609	98,653
U.S. government agencies securities | Level 3
Assets:
Fair value of financial assets	0	0
Corporate and agency bonds
Assets:
Fair value of financial assets	73,508	7,541
Corporate and agency bonds | Level 1
Assets:
Fair value of financial assets	0	0
Corporate and agency bonds | Level 2
Assets:
Fair value of financial assets	73,508	7,541
Corporate and agency bonds | Level 3
Assets:
Fair value of financial assets	0	0
Commercial paper
Assets:
Fair value of financial assets	65,486	41,945
Commercial paper | Level 1
Assets:
Fair value of financial assets	0	0
Commercial paper | Level 2
Assets:
Fair value of financial assets	65,486	41,945
Commercial paper | Level 3
Assets:
Fair value of financial assets	$ 0	$ 0