Treasury Stock - Schedule of repurchase of common stock (Details) - USD ($)	3 Months Ended	53 Months Ended
	Aug. 31, 2022	Aug. 31, 2022	May 31, 2022	Mar. 18, 2020
Stockholders' Equity Attributable to Parent [Abstract]
Authorized amount of stock to be repurchased			$ 50,000,000.0	$ 50,000,000.0
Total current Board authorizations	$ (5,100,000)	$ (21,200,000)
Less repurchases made under these authorizations	28,800,000	28,800,000
Treasury Stock, Value, Acquired, Cost Method	$ 5,100,000	$ 21,200,000