Investments and Fair Value Measurements - Schedule of Changes in Fair Value of Estimated Contingent Consideration (Detail) - Level 3 - USD ($) $ in Thousands  | 
9 Months Ended | 12 Months Ended | 
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Sep. 30, 2020  | 
Dec. 31, 2019  | 
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| Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items] | ||
| Balance at January 1, 2019 | $ 15,921 | $ 755 | 
| Additions to estimated contingent consideration | 15,417 | |
| Payments of contingent consideration | (741) | (425) | 
| Non-cash changes in fair value of estimated contingent consideration | (347) | 174 | 
| Balance at December 31, 2019 | $ 14,833 | $ 15,921 | 
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- Definition Fair value measurement with unobservable inputs non cash changes in fair value of estimated contingent consideration. No definition available. 
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- Definition Amount of liability recognized arising from contingent consideration in a business combination. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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- Definition Amount of purchases of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Details 
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