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Note 8 - Stockholders' Equity (Details Textual)												3 Months Ended		9 Months Ended
	Mar. 01, 2020 shares	Jan. 22, 2020 $ / shares	Oct. 22, 2019 $ / shares	Sep. 01, 2019 shares	Jun. 28, 2019	Jun. 03, 2019	Apr. 25, 2019 $ / shares	Mar. 01, 2019 shares	Jan. 23, 2019 $ / shares	Oct. 24, 2018 $ / shares	Sep. 01, 2018 shares	May 31, 2020 $ / shares	May 31, 2019 $ / shares	May 31, 2020 $ / shares shares	May 31, 2019 $ / shares shares
Stockholders' Equity Note, Stock Split, Conversion Ratio					2	2
Common Stock, Dividends, Per Share, Declared (in dollars per share) | $ / shares		$ 0.065	$ 0.065				$ 0.06		$ 0.06	$ 0.06		$ 0	$ 0.06	$ 0.13	$ 0.18
Stock Repurchased and Retired During Period, Shares (in shares)														0	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)														300,770	141,768
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares)														6,823	0
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in shares)	2,754			3,597				2,462			1,748
The 2019 Plan [member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)														300,770
The 2019 Plan [member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)														300,770	141,768
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share) | $ / shares														$ 10.87
The 2007 Plan [Member]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share) | $ / shares															$ 18.23

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Aggregate dividends declared during the period for each share of common stock outstanding.

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