Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2022	Feb. 28, 2021	Feb. 28, 2022	Feb. 28, 2021
Disaggregation of Revenue [Line Items]
Revenues	$ 344.5	$ 277.5	$ 1,128.5	$ 898.9
Children's Book Publishing and Distribution
Disaggregation of Revenue [Line Items]
Revenues	201.0	142.9	669.3	479.2
Children's Book Publishing and Distribution | Book Clubs - U.S.
Disaggregation of Revenue [Line Items]
Revenues	40.5	35.1	99.2	107.9
Children's Book Publishing and Distribution | Book Fairs - U.S.
Disaggregation of Revenue [Line Items]
Revenues	76.0	27.0	268.2	87.9
Children's Book Publishing and Distribution | Trade - U.S.
Disaggregation of Revenue [Line Items]
Revenues	77.1	74.7	266.6	256.9
Children's Book Publishing and Distribution | Trade - International
Disaggregation of Revenue [Line Items]
Revenues	7.4	6.1	35.3	26.5
Education
Disaggregation of Revenue [Line Items]
Revenues	77.2	66.3	236.8	187.4
International
Disaggregation of Revenue [Line Items]
Revenues	66.3	68.3	222.4	232.3
International | Major Markets
Disaggregation of Revenue [Line Items]
Revenues	48.8	46.2	175.1	169.3
International | Other Markets
Disaggregation of Revenue [Line Items]
Revenues	$ 17.5	$ 22.1	$ 47.3	$ 63.0