Note 10 - Disclosure of Credit Risk of Financial Instruments with Off-balance Sheet Risk (Details Textual)	12 Months Ended
Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Customer Concentration Risk [Member] \| Revenue Benchmark [Member] \| One Single Customer [Member]
Concentration Risk, Percentage	20.50%	17.70%	10.30%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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