Note 11 - Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Apr. 30, 2016
Promissory notes	$ 2,604	$ 3,988
Long-term debt	5,644	7,682
	8,248	11,670
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Promissory notes
Long-term debt
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Promissory notes
Long-term debt
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Promissory notes	2,604	3,988
Long-term debt	5,644	7,682
	$ 8,248	$ 11,670