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Fair Value Measurements - Fair Values of Financial Assets Measured on Recurring Basis (Detail) - USD ($) $ in Thousands | Dec. 31, 2021 | Dec. 31, 2020
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | $ 401,763 | $ 8,388
Corporate bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 182,646 |
Commercial paper [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 68,079 |
Asset-backed securities [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 27,087 |
Foreign government bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 9,154 |
Bond and mutual funds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments |  | 8,144
Equity investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments |  | 244
Fair Value, Measurements, Recurring [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Total fair value of financial assets | 461,564 | 598,735
Fair Value, Measurements, Recurring [Member] | Money market funds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Assets fair value disclosure | 58,801 | 590,347
Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 182,646 |
Fair Value, Measurements, Recurring [Member] | Commercial paper [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 69,079 |
Fair Value, Measurements, Recurring [Member] | U.S. government bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 91,522 |
Fair Value, Measurements, Recurring [Member] | Agency bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 23,275 |
Fair Value, Measurements, Recurring [Member] | Asset-backed securities [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 27,087 |
Fair Value, Measurements, Recurring [Member] | Foreign government bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 9,154 |
Fair Value, Measurements, Recurring [Member] | Bond and mutual funds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments |  | 8,144
Fair Value, Measurements, Recurring [Member] | Equity investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments |  | 244
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Total fair value of financial assets | 150,323 | 590,591
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Money market funds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Assets fair value disclosure | 58,801 | 590,347
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Corporate bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 0 |
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Commercial paper [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 0 |
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | U.S. government bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 91,522 |
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Agency bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 0 |
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Asset-backed securities [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 0 |
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Foreign government bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 0 |
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Bond and mutual funds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments |  | 0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Equity investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments |  | 244
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Total fair value of financial assets | 311,241 | 8,144
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Money market funds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Assets fair value disclosure | 0 | 0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 182,646 |
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Commercial paper [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 69,079 |
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | U.S. government bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 0 |
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Agency bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 23,275 |
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Asset-backed securities [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 27,087 |
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Foreign government bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 9,154 |
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Bond and mutual funds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments |  | 8,144
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Equity investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments |  | 0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Total fair value of financial assets | 0 | 0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Money market funds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Assets fair value disclosure | 0 | 0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Corporate bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 0 |
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Commercial paper [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 0 |
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | U.S. government bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 0 |
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Agency bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 0 |
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Asset-backed securities [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | 0 |
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Foreign government bonds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments | $ 0 |
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Bond and mutual funds [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments |  | 0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Equity investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Investments |  | $ 0

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- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258 + Details
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- Definition 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 -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 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=124258926&loc=SL82898722-210454 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
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- Definition Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References No definition available. + Details
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