Finance Receivables - Special Product (New Neighbor Guaranty program) - Additional Information (Detail) - USD ($)	9 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Special Product [Member]
Accounts Notes And Loans Receivable [Line Items]
Delinquent assessments maximum due period purchases basis	48 months
Maximum future contingent payments	$ 34,000
New Neighbor Guaranty (NNG) [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for credit losses	$ 7,000	$ 20,000

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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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Name:	us-gaap_FinancingReceivableAllowanceForCreditLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant