Note 8 - Stockholders' Equity - Cash Dividends Declared (Details) - $ / shares						3 Months Ended			12 Months Ended
	Jul. 21, 2021	Apr. 23, 2021	Jan. 15, 2021	Jan. 22, 2020	Oct. 22, 2019	Nov. 30, 2020	Aug. 31, 2020	May 31, 2020	Aug. 31, 2021	Aug. 31, 2020
Amount (in dollars per share)	$ 0.065	$ 0.065	$ 0.065	$ 0.065	$ 0.065	$ 0	$ 0	$ 0	$ 0.20	$ 0.13
Record date	Aug. 04, 2021	May 05, 2021	Feb. 03, 2021	Feb. 05, 2020	Nov. 06, 2019
Payable date	Aug. 18, 2021	May 19, 2021	Feb. 17, 2021	Feb. 19, 2020	Nov. 20, 2019