Note B - Summary of Significant Accounting Policies (Details Textual) - USD ($)	1 Months Ended	3 Months Ended	9 Months Ended		12 Months Ended
	May 30, 2016	Jan. 31, 2017	Jan. 31, 2017	Jan. 31, 2016	Apr. 30, 2016	Apr. 30, 2015
Number of Reportable Segments			1
Line of Credit Facility,Distribution Limitations Maximum Aggregate Amount of Stock Repurchases			$ 40,000,000
Line of Credit Facility, Distribution Limitations Percentage of Sum of Borrowing Bases			25.00%
Line of Credit Facility, Distribution Limitations Percentage of Consolidated Net Income			75.00%
Line of Credit Facility Distribution Limitations Minimum Percentage of Aggregate Funds Available			12.50%
Interest Earned on Financing Receivables			$ 2,300,000		$ 1,700,000
Finance Receivables, Customer Payments Due Either Weekly or Bi-Weekly, Percentage			73.00%
Financing Receivable, Greater Than or Equal to 30 Days Past Due, Percent of Portfolio		4.70%	4.70%	5.00%
Financing Receivable, Average Days Past Due At Charge Off		62 days
Financing Receivable, Weighted Average Contractual Term			2 years 237 days
Financing Receivable, Weighted Average Remaining Contractual Term			1 year 330 days
Financing Receivable, Allowance for Credit Losses		$ 111,818,000	$ 111,818,000	$ 104,228,000	102,485,000	$ 93,224,000
Finance Receivables, Percent of Principle Balance, Net Deferred Revenue		25.00%	25.00%
Finance Receivable Principal Balance		$ 475,354,000	$ 475,354,000	443,296,000	437,278,000
Percentage of Receivable Charge-Offs		50.00%	50.00%
Average Age of Account at Charge-Off Date			357 days
Financing Receivable, Recorded Investment Greater Than 90 Days Past Due		$ 2,037,000	$ 2,037,000	2,131,000	$ 1,089,000
Late Fee Income Generated by Servicing Financial Assets, Amount			$ 1,400,000	$ 1,500,000
Stock Repurchased During Period, Shares			300,838	342,171
Stock Repurchased During Period, Value			$ 8,200,000	$ 10,500,000
Treasury Stock, Shares to Establish Reserve Account to Secure Service Contracts					10,000
Payment Protection Plan Liability, Anticipated Losses in Excess of Deferred Revenues		0	0		$ 0
Goodwill, Impairment Loss			0		0
Income Tax Examination, Penalties and Interest Accrued		0	0		0
Service Life [Member] | GPS Units [Member]
Increase (Decrease) in Selling General and Administrative Expense			(350,000)
Payment Protection Plan [Member]
Deferred Revenue		18,158,000	18,158,000		17,304,000
Service Contract [Member]
Deferred Revenue		$ 9,924,000	$ 9,924,000		$ 10,035,000
Maximum [Member]
Financing Receivable Interest Rate	16.50%		16.50%		15.70%
Allowance for Credit Losses, Primary Factor Units Repossessed or Charged Off Evaluation Period			5 years
Minimum [Member]
Financing Receivable Interest Rate			15.00%
Allowance for Credit Losses, Primary Factor Units Repossessed or Charged Off Evaluation Period			1 year
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Arkansas, USA [Member]
Concentration Risk, Percentage			30.00%