Revenues - Disaggregation of Revenue Data (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 1,487.1	$ 1,653.9	$ 1,628.4
Childrens Book Publishing And Distribution
Disaggregation of Revenue [Line Items]
Revenues	847.4	987.4	970.2
Childrens Book Publishing And Distribution | Book Clubs
Disaggregation of Revenue [Line Items]
Revenues	156.8	212.4	224.3
Childrens Book Publishing And Distribution | Book Fairs
Disaggregation of Revenue [Line Items]
Revenues	383.8	499.6	513.6
Childrens Book Publishing And Distribution | Trade
Disaggregation of Revenue [Line Items]
Revenues	306.8	275.4	232.3
Education
Disaggregation of Revenue [Line Items]
Revenues	287.1	297.3	288.6
International
Disaggregation of Revenue [Line Items]
Revenues	352.6	369.2	369.6
International | Major Markets
Disaggregation of Revenue [Line Items]
Revenues	256.6	257.9	258.3
International | Other Markets
Disaggregation of Revenue [Line Items]
Revenues	$ 96.0	$ 111.3	$ 111.3