Revenues - Deferred Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2025	Aug. 31, 2024	May 31, 2025
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 184.7	$ 180.2	$ 183.0
Contract with customer, liability, revenue recognized	37.0	29.2
Book fairs incentive credits
Deferred Revenue Arrangement [Line Items]
Deferred revenue	104.0	99.4	122.1
Magazines+ subscriptions
Deferred Revenue Arrangement [Line Items]
Deferred revenue	19.3	22.2	3.9
U.S. digital subscriptions
Deferred Revenue Arrangement [Line Items]
Deferred revenue	12.3	19.2	11.1
U.S. Education-related
Deferred Revenue Arrangement [Line Items]
Deferred revenue	7.0	10.3	7.5
Entertainment-related (2)
Deferred Revenue Arrangement [Line Items]
Deferred revenue	12.8	6.8	8.2
Stored value programs
Deferred Revenue Arrangement [Line Items]
Deferred revenue	22.8	17.3	22.4
Other
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 6.5	$ 5.0	$ 7.8