CONDENSED CONSOLIDATED BALANCE SHEETS (Parentheticals) - $ / shares	Feb. 28, 2019	May 31, 2018	Feb. 28, 2018
Preferred stock at par value per share (in dollars per share)	$ 1	$ 1	$ 1
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	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	70,000,000
Common stock, shares issued	42,900,000	42,900,000	42,900,000
Common stock, shares outstanding	33,600,000	33,300,000	33,200,000
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	4,000,000	4,000,000
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