Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 373.3	$ 360.1	$ 1,203.1	$ 1,183.2
Children's Book Publishing and Distribution | U.S. Book Clubs
Disaggregation of Revenue [Line Items]
Revenues	43.4	55.0	137.3	165.4
Children's Book Publishing and Distribution | U.S. Book Fairs
Disaggregation of Revenue [Line Items]
Revenues	100.1	97.4	351.7	343.3
Children's Book Publishing and Distribution | U.S. Trade
Disaggregation of Revenue [Line Items]
Revenues	70.4	65.6	231.6	222.9
Education
Disaggregation of Revenue [Line Items]
Revenues	74.3		192.5	179.7
International | Major Markets
Disaggregation of Revenue [Line Items]
Revenues	59.2	54.0	210.1	192.2
International | Other Markets
Disaggregation of Revenue [Line Items]
Revenues	$ 25.9	$ 27.8	$ 79.9	$ 79.7