Revenues - Deferred Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 29, 2024	Feb. 28, 2023	Feb. 29, 2024	Feb. 28, 2023	May 31, 2023
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 200.1	$ 203.0	$ 200.1	$ 203.0	$ 169.1
Contract with Customer, Liability, Revenue Recognized	33.0	45.9	113.7	126.2
Book fairs incentive credits
Deferred Revenue Arrangement [Line Items]
Deferred revenue	109.9	105.2	109.9	105.2	110.8
Magazines+ subscriptions
Deferred Revenue Arrangement [Line Items]
Deferred revenue	30.5	30.7	30.5	30.7	5.0
U.S. digital subscriptions
Deferred Revenue Arrangement [Line Items]
Deferred revenue	16.8	25.2	16.8	25.2	22.8
U.S. Education-related
Deferred Revenue Arrangement [Line Items]
Deferred revenue	10.6	13.5	10.6	13.5	9.8
Media-related
Deferred Revenue Arrangement [Line Items]
Deferred revenue	0.1	4.4	0.1	4.4	0.0
Stored value programs
Deferred Revenue Arrangement [Line Items]
Deferred revenue	20.1	14.8	20.1	14.8	12.4
Other
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 12.1	$ 9.2	$ 12.1	$ 9.2	$ 8.3