Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2021	Feb. 29, 2020	Feb. 28, 2021	Feb. 29, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 277.5	$ 373.3	$ 898.9	$ 1,203.1
Children's Book Publishing and Distribution | U.S. Book Clubs
Disaggregation of Revenue [Line Items]
Revenues	35.0	43.4	107.7	137.3
Children's Book Publishing and Distribution | U.S. Book Fairs
Disaggregation of Revenue [Line Items]
Revenues	27.0	100.1	87.9	351.7
Children's Book Publishing and Distribution | U.S. Trade
Disaggregation of Revenue [Line Items]
Revenues	74.7	70.4	256.9	231.6
Education
Disaggregation of Revenue [Line Items]
Revenues	66.2	74.3	187.0	192.5
International | Major Markets
Disaggregation of Revenue [Line Items]
Revenues	51.6	59.2	191.3	210.1
International | Other Markets
Disaggregation of Revenue [Line Items]
Revenues	$ 23.0	$ 25.9	$ 68.1	$ 79.9