Treasury Stock - Schedule of repurchase of common stock (Details) - USD ($)		3 Months Ended		9 Months Ended	47 Months Ended
	Jan. 19, 2022	Feb. 28, 2022	Nov. 30, 2021	Feb. 28, 2022	Feb. 28, 2022	May 31, 2021	Mar. 18, 2020	Mar. 21, 2018
Stockholders' Equity Attributable to Parent [Abstract]
Authorized amount of stock to be repurchased						$ 100,000,000.0	$ 50,000,000.0	$ 50,000,000.0
Total current Board authorizations		$ (15,400,000)	$ (4,200,000)	$ (19,600,000)	$ (52,300,000)
Less repurchases made under these authorizations		47,700,000		47,700,000	47,700,000
Equity, Class of Treasury Stock [Line Items]
Treasury Stock, Value, Acquired, Cost Method		$ 15,400,000	$ 4,200,000	$ 19,600,000	$ 52,300,000
Repurchase of Common Stock | Former Chief Executive Officer, Estate
Stockholders' Equity Attributable to Parent [Abstract]
Total current Board authorizations	$ (12,200,000)
Equity, Class of Treasury Stock [Line Items]
Treasury Stock, Value, Acquired, Cost Method	$ 12,200,000