Revenues - Deferred Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2022	Nov. 30, 2021	Nov. 30, 2022	Nov. 30, 2021	May 31, 2022
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 232.7	$ 192.3	$ 232.7	$ 192.3	$ 172.8
Contract with Customer, Liability, Revenue Recognized	49.5	27.9	80.3	43.2
Book fairs incentive credits
Deferred Revenue Arrangement [Line Items]
Deferred revenue	107.6	77.4	107.6	77.4	100.1
Magazines+ subscriptions
Deferred Revenue Arrangement [Line Items]
Deferred revenue	55.5	54.8	55.5	54.8	4.5
U.S. digital subscriptions
Deferred Revenue Arrangement [Line Items]
Deferred revenue	22.3	20.9	22.3	20.9	19.5
U.S. Education-related
Deferred Revenue Arrangement [Line Items]
Deferred revenue	13.4	9.8	13.4	9.8	13.6
Media-related
Deferred Revenue Arrangement [Line Items]
Deferred revenue	10.6	8.5	10.6	8.5	15.8
Stored value cards
Deferred Revenue Arrangement [Line Items]
Deferred revenue	13.8	9.2	13.8	9.2	9.4
Other
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 9.5	$ 11.7	$ 9.5	$ 11.7	$ 9.9