Note 10 - Contingency (Details Textual) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Nov. 30, 2018	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Refund of Tax		$ 1,330		$ 1,610
Appeal of BHCMC, LLC [Member]
Refund of Tax		$ 1,300		$ 1,600
Appeal of BHCMC, LLC [Member] | Subsequent Event [Member]
Refund of Tax	$ 368