Treasury Stock - Schedule of repurchase of common stock (Details) - USD ($)		3 Months Ended					9 Months Ended	35 Months Ended
	Oct. 25, 2022	Feb. 28, 2023	Nov. 30, 2022	Aug. 31, 2022	Feb. 28, 2022	Nov. 30, 2021	Feb. 28, 2023	Feb. 28, 2023	Dec. 14, 2022	Mar. 18, 2020
Equity, Class of Treasury Stock [Line Items]
Authorized amount of stock to be repurchased		$ 98,800,000					$ 98,800,000	$ 98,800,000	$ 48,800,000	$ 50,000,000.0
Less repurchases made under these authorizations	$ (23,300,000)	(46,900,000)	$ (26,000,000.0)	$ (5,100,000)	$ (15,400,000)	$ (4,200,000)	(78,000,000.0)
Remaining Board authorization at February 28, 2023		$ 28,200,000					$ 28,200,000	28,200,000
Under the December 2022 Board Authorization
Equity, Class of Treasury Stock [Line Items]
Less repurchases made under these authorizations								$ (70,600,000)