Note 12 - Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Apr. 30, 2017
Promissory notes	$ 2,387	$ 2,604
Long-term debt	3,347	5,644
	5,734	8,248
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	2,387	2,604
Long-term debt	3,347	5,644
	$ 5,734	$ 8,248