New Neighbor Guaranty Allowance for Credit Losses - Additional Information (Detail) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
New Neighbor Guaranty [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for credit losses	$ 6,500	$ 20,000

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Name:	us-gaap_FinancingReceivableAllowanceForCreditLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant