Revenues - Deferred Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2025	Feb. 29, 2024	Feb. 28, 2025	Feb. 29, 2024	May 31, 2024
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 210.3	$ 200.1	$ 210.3	$ 200.1	$ 167.6
Contract with customer, liability, revenue recognized	35.1	33.0	106.2	113.7
Book fairs incentive credits
Deferred Revenue Arrangement [Line Items]
Deferred revenue	116.8	109.9	116.8	109.9	114.2
Magazines+ subscriptions
Deferred Revenue Arrangement [Line Items]
Deferred revenue	28.1	30.5	28.1	30.5	4.6
U.S. digital subscriptions
Deferred Revenue Arrangement [Line Items]
Deferred revenue	15.3	16.8	15.3	16.8	15.6
U.S. Education-related
Deferred Revenue Arrangement [Line Items]
Deferred revenue	9.5	10.6	9.5	10.6	10.1
Media-related
Deferred Revenue Arrangement [Line Items]
Deferred revenue	7.3	0.1	7.3	0.1	0.0
Stored value cards
Deferred Revenue Arrangement [Line Items]
Deferred revenue	25.8	20.1	25.8	20.1	16.7
Other
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 7.5	$ 12.1	$ 7.5	$ 12.1	$ 6.4