Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2020	Aug. 31, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 215.2	$ 232.6
Children's Book Publishing and Distribution | U.S. Book Clubs
Disaggregation of Revenue [Line Items]
Revenues	5.8	8.0
Children's Book Publishing and Distribution | U.S. Book Fairs
Disaggregation of Revenue [Line Items]
Revenues	13.2	27.5
Children's Book Publishing and Distribution | U.S. Trade
Disaggregation of Revenue [Line Items]
Revenues	65.8	67.7
Education
Disaggregation of Revenue [Line Items]
Revenues	53.5	48.4
International | Major Markets
Disaggregation of Revenue [Line Items]
Revenues	56.6	56.3
International | Other Markets
Disaggregation of Revenue [Line Items]
Revenues	$ 20.3	$ 24.7