Treasury Stock - Schedule of repurchase of common stock (Details) - USD ($)		3 Months Ended			6 Months Ended	32 Months Ended
	Oct. 25, 2022	Nov. 30, 2022	Aug. 31, 2022	Nov. 30, 2021	Nov. 30, 2022	Nov. 30, 2022	May 31, 2022	Mar. 18, 2020
Equity, Class of Treasury Stock [Line Items]
Authorized amount of stock to be repurchased							$ 50,000,000.0	$ 50,000,000.0
Less repurchases made under this authorization	$ (23,300,000)	$ (26,000,000.0)	$ (5,100,000)	$ (4,200,000)	$ (31,100,000)
Remaining Board authorization at November 30, 2022		$ 26,200,000			$ 26,200,000	$ 26,200,000
Does Not Include Dutch Auction Tender Offer For Period Presented
Equity, Class of Treasury Stock [Line Items]
Less repurchases made under this authorization						$ (23,800,000)