Note C - Finance Receivables, Net (Details Textual)	3 Months Ended		12 Months Ended
	Apr. 30, 2021 USD ($) $ / shares	Apr. 30, 2020 USD ($) $ / shares	Apr. 30, 2022 USD ($)	Apr. 30, 2021 USD ($) $ / shares	Apr. 30, 2020 USD ($) $ / shares	Jan. 31, 2021	Jan. 31, 2020	Jul. 31, 2019	Apr. 30, 2019 USD ($)
Finance Receivables, Number of Loan Classes			1
Finance Receivables, Number of Risk Pools			1
Financing Receivable, after Allowance for Credit Loss, Total	$ 625,119,000	$ 466,141,000	$ 854,290,000	$ 625,119,000	$ 466,141,000				$ 415,486,000
Financing Receivable, Allowance for Credit Loss, Recovery			$ 2,400,000	$ 1,900,000	$ 1,700,000
Finance Receivables, Allowance, Percent of Principle Balance	24.50%	26.50%	24.50%	24.50%	26.50%	26.50%	24.50%	24.50%	25.00%
Delinquencies Greater Than 30 Days as Percentage of Average Financing Receivables	2.60%	6.20%	3.00%	2.60%	6.20%		2.90%
Financing Receivable, Credit Loss, Expense (Reversal)	$ (15,100,000)	$ 9,100,000	$ 257,101,000	$ 163,662,000	$ 162,246,000
After Tax Effect of Increase to Provision for Credit Losses	$ (11,500,000)	$ 7,000,000.0
After Tax Effect Of Change To Provision For Credit Losses, Per Diluted Share (in dollars per share) | $ / shares	$ 1.65	$ 1.02		$ 1.65	$ 1.02
Financing Receivable, Credit Loss, Expense (Reversal)	$ (15,100,000)	$ 9,100,000	$ 257,101,000	$ 163,662,000	$ 162,246,000
Net Charge Offs as Percentage of Average Finance Receivables			20.20%	19.30%
Collections as Percentage of Average Financing Receivables			43.50%	53.20%
Increase (Decrease) in Average Selling Price			$ 3,028
Increase (Decrease) in Average Selling Price, Percentage			22.20%
Automobile Loan [Member] | Asset Pledged as Collateral [Member] | Notes Payable [Member]
Financing Receivable, after Allowance for Credit Loss, Total			$ 550,300,000
Maximum [Member]
Financing Receivable Interest Rate			16.50%
Financing Receivable Payment Period (Month)			54 months
Maximum [Member] | ILLINOIS
Financing Receivable Interest Rate			21.50%
Minimum [Member]
Financing Receivable Payment Period (Month)			18 months
Minimum [Member] | ILLINOIS
Financing Receivable Interest Rate			19.50%