Note 6 - Acquisitions (Details) - Allocation of The Purchase Price For Acquisitions (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Jan. 31, 2014	Jan. 31, 2013
Note 6 - Acquisitions (Details) - Allocation of The Purchase Price For Acquisitions [Line Items]
Inventories	$ 1,409
Property and equipment	19,994
Total assets	21,403
Total liabilities	110
Net tangible assets acquired, net of cash	21,293
Goodwill and other intangible assets	5,290
Total consideration paid, net of cash acquired	26,583	25,198
Accrued Liabilities [Member]
Note 6 - Acquisitions (Details) - Allocation of The Purchase Price For Acquisitions [Line Items]
Accrued expenses	$ 110