Fair Value Measurements and Fair Value of Financial Instruments - Schedule of Financial Instruments Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Assets:
Investments, Fair Value		$ 171,934
Fair Value, Recurring
Assets:
Cash and cash equivalents, Amortized Cost		198,941
Cash and cash equivalents, Gross Unrealized Losses		(2)
Cash and cash equivalents, Fair Value		198,939
Investments, Amortized Cost		171,979
Investments, Gross Unrealized Losses		(45)
Investments, Fair Value		171,934
Total assets measured at fair value, Amortized Cost		370,920	$ 386,200
Total assets measured at fair value, Gross Unrealized Losses		(47)
Total assets measured at fair value, Fair Value		370,873	386,200
Fair Value, Recurring | Cash | Level 1
Assets:
Cash and cash equivalents, Amortized Cost		26,226	4,788
Cash and cash equivalents, Fair Value		26,226	4,788
Fair Value, Recurring | Money Market Funds | Level 1
Assets:
Cash and cash equivalents, Amortized Cost	[1]	113,718	381,412
Cash and cash equivalents, Fair Value	[1]	113,718	$ 381,412
Fair Value, Recurring | Commercial Paper | Level 2
Assets:
Cash and cash equivalents, Amortized Cost	[1]	58,997
Cash and cash equivalents, Gross Unrealized Losses	[1]	(2)
Cash and cash equivalents, Fair Value	[1]	58,995
Fair Value, Recurring | U.S. Government Agency Securities | Level 2
Assets:
Investments, Amortized Cost		9,100
Investments, Fair Value		9,100
Fair Value, Recurring | U.S. Treasury Securities | Level 1
Assets:
Investments, Amortized Cost		35,431
Investments, Gross Unrealized Losses		(5)
Investments, Fair Value		35,426
Fair Value, Recurring | Corporate Debt | Level 2
Assets:
Investments, Amortized Cost		37,517
Investments, Gross Unrealized Losses		(28)
Investments, Fair Value		37,489
Fair Value, Recurring | Commercial Paper, Not Included with Cash and Cash Equivalents | Level 2
Assets:
Investments, Amortized Cost		89,931
Investments, Gross Unrealized Losses		(12)
Investments, Fair Value		$ 89,919

[1] Included within cash and cash equivalents on the condensed balance sheets.