Revenues - Deferred Revenue (Details) - USD ($) $ in Millions	Feb. 28, 2022	May 31, 2021	Feb. 28, 2021
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 176.8	$ 99.1	$ 121.9
Book fairs incentive credits
Deferred Revenue Arrangement [Line Items]
Deferred revenue	82.7	59.4	57.9
Magazines+ subscriptions
Deferred Revenue Arrangement [Line Items]
Deferred revenue	30.4	4.6	28.4
U.S. digital subscriptions
Deferred Revenue Arrangement [Line Items]
Deferred revenue	18.2	11.9	13.6
U.S. Education-related
Deferred Revenue Arrangement [Line Items]
Deferred revenue	12.5	6.2	6.4
Media-related
Deferred Revenue Arrangement [Line Items]
Deferred revenue	11.6	2.5	0.4
Stored value cards
Deferred Revenue Arrangement [Line Items]
Deferred revenue	8.8	2.9	2.2
Other
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 12.6	$ 11.6	$ 13.0