Revenues - Deferred Revenue (Details) - USD ($) $ in Millions	Aug. 31, 2022	May 31, 2022	Aug. 31, 2021
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 182.6	$ 172.8	$ 125.5
Book fairs incentive credits
Deferred Revenue Arrangement [Line Items]
Deferred revenue	84.4	100.1	52.4
Magazines+ subscriptions
Deferred Revenue Arrangement [Line Items]
Deferred revenue	24.7	4.5	21.7
U.S. digital subscriptions
Deferred Revenue Arrangement [Line Items]
Deferred revenue	23.8	19.5	21.8
U.S. Education-related
Deferred Revenue Arrangement [Line Items]
Deferred revenue	16.5	13.6	10.6
Media-related
Deferred Revenue Arrangement [Line Items]
Deferred revenue	15.6	15.8	5.6
Stored value cards
Deferred Revenue Arrangement [Line Items]
Deferred revenue	9.3	9.4	3.9
Other
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 8.3	$ 9.9	$ 9.5