Note 11 - Finance Lease Right-of-use Assets - Adoptiong of ASU 2016-02 (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2019	Jul. 31, 2018
Increase in depreciation	$ 1,239	$ 388
Increase in interest expense	1,097	70
Decrease in net income for the three months ended July 31, 2019	(2,061)	$ (509)
Accounting Standards Update 2016-02 [Member]
Increase in depreciation	693
Increase in interest expense	1,035
Decrease in rent expense	(1,218)
Decrease in net income for the three months ended July 31, 2019	$ 510