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Fair Value Measurements - Summary of Financial Assets Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Money Market Funds | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents and marketable securities, Amortized Cost	$ 37,951	$ 61,104
Cash equivalents and marketable securities, Fair Market Value	37,951	61,104
U.S Government Treasury Securities | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents and marketable securities, Amortized Cost	357,725	227,446
Cash equivalents and marketable securities, Unrealized Gains	620	149
Cash equivalents and marketable securities, Unrealized Losses	(6)	(8)
Cash equivalents and marketable securities, Fair Market Value	358,339	227,587
Corporate Bonds | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents and marketable securities, Amortized Cost	5,000	10,103
Cash equivalents and marketable securities, Unrealized Gains		3
Cash equivalents and marketable securities, Unrealized Losses		(2)
Cash equivalents and marketable securities, Fair Market Value	5,000	10,104
Cash Equivalents and Marketable Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents and marketable securities, Amortized Cost	400,676	342,388
Cash equivalents and marketable securities, Unrealized Gains	620	152
Cash equivalents and marketable securities, Unrealized Losses	(6)	(10)
Cash equivalents and marketable securities, Fair Market Value	$ 401,290	342,530
Commercial Paper | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents and marketable securities, Amortized Cost		43,735
Cash equivalents and marketable securities, Fair Market Value		$ 43,735

X

- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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