Note 4 - Fair Value of Financial Instruments and Long Term Debt (Details) - Long-term Debt at Carrying Amount (Parentheticals)	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013
Minimum [Member] | Capital Lease Obligations [Member]
Note 4 - Fair Value of Financial Instruments and Long Term Debt (Details) - Long-term Debt at Carrying Amount (Parentheticals) [Line Items]
Discount Rate Of Capitalized Lease Obligations	5.22%	5.22%
Maximum [Member] | Capital Lease Obligations [Member]
Note 4 - Fair Value of Financial Instruments and Long Term Debt (Details) - Long-term Debt at Carrying Amount (Parentheticals) [Line Items]
Discount Rate Of Capitalized Lease Obligations	7.09%	7.09%
Senior Notes 5.72% [Member]
Note 4 - Fair Value of Financial Instruments and Long Term Debt (Details) - Long-term Debt at Carrying Amount (Parentheticals) [Line Items]
Stated Interest Rate	5.72%	5.72%
Senior Notes 5.22% [Member]
Note 4 - Fair Value of Financial Instruments and Long Term Debt (Details) - Long-term Debt at Carrying Amount (Parentheticals) [Line Items]
Stated Interest Rate	5.22%	5.22%
Senior Notes Series A, 3.67% [Member]
Note 4 - Fair Value of Financial Instruments and Long Term Debt (Details) - Long-term Debt at Carrying Amount (Parentheticals) [Line Items]
Stated Interest Rate	3.67%
Senior Notes Series B, 3.75% [Member]
Note 4 - Fair Value of Financial Instruments and Long Term Debt (Details) - Long-term Debt at Carrying Amount (Parentheticals) [Line Items]
Stated Interest Rate	3.75%