Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2021	Aug. 31, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 259.8	$ 215.2
Children's Book Publishing and Distribution
Disaggregation of Revenue [Line Items]
Revenues	115.8	92.3
Children's Book Publishing and Distribution | Book Clubs - U.S.
Disaggregation of Revenue [Line Items]
Revenues	6.8	5.8
Children's Book Publishing and Distribution | Book Fairs - U.S.
Disaggregation of Revenue [Line Items]
Revenues	16.0	13.2
Children's Book Publishing and Distribution | Trade - U.S.
Disaggregation of Revenue [Line Items]
Revenues	80.1	65.8
Children's Book Publishing and Distribution | Trade - International
Disaggregation of Revenue [Line Items]
Revenues	12.9	7.5
Education
Disaggregation of Revenue [Line Items]
Revenues	80.1	53.6
International
Disaggregation of Revenue [Line Items]
Revenues	63.9	69.3
International | Major Markets
Disaggregation of Revenue [Line Items]
Revenues	47.5	50.0
International | Other Markets
Disaggregation of Revenue [Line Items]
Revenues	$ 16.4	$ 19.3