Financial Instruments - Summary of Amortized Cost and Fair Value of Securities Available-for-Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Securities, Amortized Cost/Cost	$ 325,932	$ 106,247
Available-for-Sale Securities, Unrealized (Losses) Gains		19
Available-for-Sale Securities , Unrealized Losses	(39)
Available-for-Sale Securities, Fair Value	325,893	106,266
Money Market Fund
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Securities, Amortized Cost/Cost	25,711	63,744
Available-for-Sale Securities, Fair Value	25,711	63,744
U.S. Government Agency Securities and Treasuries
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Securities, Amortized Cost/Cost	300,221	42,503
Available-for-Sale Securities, Unrealized (Losses) Gains		19
Available-for-Sale Securities , Unrealized Losses	(39)
Available-for-Sale Securities, Fair Value	$ 300,182	$ 42,522

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).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount before tax of unrealized gain (loss) in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 210
-Section S99
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