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Cash, Cash Equivalents, and Marketable Debt Securities - Additional Information (Details) - USD ($) | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2021 | Dec. 31, 2020
Financial Instruments [Line Items] |  |
Impairment of marketable debt securities | $ 0 | $ 0
Allowance for credit loss | $ 0 | $ 0
Minimum |  |
Financial Instruments [Line Items] |  |
Long-term marketable debt securities maturity period | 1 year |
Maximum |  |
Financial Instruments [Line Items] |  |
Long-term marketable debt securities maturity period | 2 years |

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- Definition Period between issuance and maturity of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258 + Details
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