CONDENSED CONSOLIDATED BALANCE SHEETS (Parentheticals) - $ / shares	Nov. 30, 2020	May 31, 2020	Nov. 30, 2019
Preferred stock at par value per share (in dollars per share)	$ 1.00	$ 1.00	$ 1.00
Preferred stock, shares authorized	2,000,000.0	2,000,000.0	2,000,000.0
Preferred stock, shares issued	0	0	0
Preferred stock, shares outstanding	0		0
Common Stock, par value per share (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized	70,000,000.0	70,000,000.0	70,000,000.0
Common stock, shares issued	42,900,000	42,900,000	42,900,000
Common stock, shares outstanding	32,600,000	33,000,000.0	32,500,000
Treasury stock (in shares)	10,300,000	10,400,000	9,900,000
Common Class A
Common Stock, par value per share (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized	4,000,000.0	4,000,000.0	4,000,000.0
Common stock, shares issued	1,700,000	1,700,000	1,700,000
Common stock, shares outstanding	1,700,000	1,700,000	1,700,000