Notes Receivable from Partners - Additional Information (Detail) - Partners - USD ($) |
9 Months Ended | ||
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Sep. 30, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
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| Related Party Transaction [Line Items] | |||
| Term of promissory notes receivable | in the form of five or six year interest-bearing promissory notes and/or in the form of nine year interest-bearing limited recourse promissory notes | ||
| Notes receivable from partners | $ 604,000 | $ 353,000 | $ 645,000 |
| Allowance for credit losses on notes receivable | 0 | 0 | |
| Full Recourse | |||
| Related Party Transaction [Line Items] | |||
| Notes receivable from partners | 604,000 | 353,000 | |
| Limited Recourse | |||
| Related Party Transaction [Line Items] | |||
| Notes receivable from partners | $ 0 | $ 0 |
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- Definition Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement. 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 Description of the terms and manner of settlement of the related party transaction. No definition available.
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