Revenues - Deferred Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2023	Feb. 28, 2022	Feb. 28, 2023	Feb. 28, 2022	May 31, 2022
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 203.0	$ 176.8	$ 203.0	$ 176.8	$ 172.8
Contract with Customer, Liability, Revenue Recognized	45.9	21.2	126.2	64.4
Book fairs incentive credits
Deferred Revenue Arrangement [Line Items]
Deferred revenue	105.2	82.7	105.2	82.7	100.1
Magazines+ subscriptions
Deferred Revenue Arrangement [Line Items]
Deferred revenue	30.7	30.4	30.7	30.4	4.5
U.S. digital subscriptions
Deferred Revenue Arrangement [Line Items]
Deferred revenue	25.2	18.2	25.2	18.2	19.5
U.S. Education-related
Deferred Revenue Arrangement [Line Items]
Deferred revenue	13.5	12.5	13.5	12.5	13.6
Media-related
Deferred Revenue Arrangement [Line Items]
Deferred revenue	4.4	11.6	4.4	11.6	15.8
Stored value cards
Deferred Revenue Arrangement [Line Items]
Deferred revenue	14.8	8.8	14.8	8.8	9.4
Other
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 9.2	$ 12.6	$ 9.2	$ 12.6	$ 9.9