Note 8 - Stockholders' Equity - Schedule of Dividends Payable (Details) - $ / shares							3 Months Ended		9 Months Ended
	Apr. 25, 2019	Jan. 23, 2019	Oct. 24, 2018	Apr. 25, 2018	Jan. 24, 2018	Nov. 20, 2017	May 31, 2019	May 31, 2018	May 31, 2019	May 31, 2018
Amount (in dollars per share)	$ 0.06	$ 0.06	$ 0.06	$ 0.05	$ 0.05	$ 0.05	$ 0.06	$ 0.05	$ 0.18	$ 0.15
Record Date	May 09, 2019	Feb. 06, 2019	Nov. 07, 2018	May 09, 2018	Feb. 08, 2018	Dec. 08, 2017
Payable Date	May 23, 2019	Feb. 22, 2019	Nov. 21, 2018	May 23, 2018	Feb. 21, 2018	Dec. 21, 2017