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Short-term Investments - Additional Information (Detail) - USD ($) $ in Thousands | Sep. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Summary Of Investment Holdings [Line Items] |  |
Short-term investments | $ 0 | $ 108,919
US Treasury Securities |  |
Summary Of Investment Holdings [Line Items] |  |
Available-for-sale securities, amortized cost |  | 108,800
Available-for-sale securities, fair value |  | 108,900
Available-for-sale securities, unrealized loss position |  | $ 0

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- Definition 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 -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121558606&loc=SL82898722-210454 + Details
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