Finance Receivables - Special Product (New Neighbor Guaranty program) - Schedule of Delinquent Assessments and Accrued Charges (Detail) - Special Product [Member]	9 Months Ended	12 Months Ended
Sep. 30, 2018 USD ($) Unit	Dec. 31, 2017 USD ($) Unit
Accounts Notes And Loans Receivable [Line Items]
Finance receivables, net	$ 264,000	$ 339,000
Delinquent assessments	799,000	1,200,000
Accrued interest and late fees	$ 515,000	$ 728,000
Number of active units with delinquent assessments \| Unit	68	97

Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_NotesReceivableNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant