Finance Receivables - Summary of contracts and direct loans included in finance receivables (Details) - Finance receivables - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Allowance for credit losses	$ (11,248)	$ (11,162)	$ (16,112)	$ (16,932)
Contracts and direct loans
Accounts Notes And Loans Receivable [Line Items]
Finance receivables	208,808	219,366	235,931
Accrued interest receivable	3,035	3,164	3,158
Unearned dealer discounts	(7,944)	(8,056)	(9,533)
Unearned insurance and fee commissions	(2,557)	(2,616)	(2,715)
Purchase price discount	(766)	(915)	(1,303)
Finance receivables, net of unearned	200,576	210,943	225,538
Allowance for credit losses	(11,248)	(11,162)	(16,112)
Finance receivables, net	$ 189,328	$ 199,781	$ 209,426