Calculation of Earnings Per Share - Additional Information (Details)	3 Months Ended
	Aug. 31, 2019 Number shares
Schedule Of Earning Per Share [Line Items]
Limit of cash dividends Class B common stock (percent)	90.00%
Common stock options anti-dilutive	1,502,000
Common Stock
Schedule Of Earning Per Share [Line Items]
Common stock shares, authorized	17,000,000
Common Class B
Schedule Of Earning Per Share [Line Items]
Common stock shares, authorized	3,000,000
Number of votes per share | Number	10