Finance Receivables - Original Product - Schedule of Finance Receivables for Original Product (Detail) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Accounts Notes And Loans Receivable [Line Items]
Finance receivables, net	$ 44,000	$ 53,000
Original Product [Member]
Accounts Notes And Loans Receivable [Line Items]
Finance receivables outstanding	168,000	258,000
Reserve for credit losses	(90,000)	(142,000)
Finance receivables, net	78,000	116,000
Original Product [Member] | Funded During The Current Year [Member]
Accounts Notes And Loans Receivable [Line Items]
Finance receivables outstanding	16,000	25,000
Original Product [Member] | 1-2 Years Outstanding [Member]
Accounts Notes And Loans Receivable [Line Items]
Finance receivables outstanding	6,000	12,000
Original Product [Member] | 2-3 Years Outstanding [Member]
Accounts Notes And Loans Receivable [Line Items]
Finance receivables outstanding	4,000	9,000
Original Product [Member] | 3-4 Years Outstanding [Member]
Accounts Notes And Loans Receivable [Line Items]
Finance receivables outstanding	5,000	12,000
Original Product [Member] | Greater Than 4 Years Outstanding [Member]
Accounts Notes And Loans Receivable [Line Items]
Finance receivables outstanding	$ 137,000	$ 200,000