Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Millions		3 Months Ended
		Aug. 31, 2019	Aug. 31, 2018
Disaggregation of Revenue [Line Items]
Revenues		$ 232.6	$ 218.4
Children's Book Publishing and Distribution | U.S. Book Clubs
Disaggregation of Revenue [Line Items]
Revenues		8.0	9.1
Children's Book Publishing and Distribution | U.S. Book Fairs
Disaggregation of Revenue [Line Items]
Revenues		27.5	25.2
Children's Book Publishing and Distribution | U.S. Trade
Disaggregation of Revenue [Line Items]
Revenues		67.7	61.4
Education
Disaggregation of Revenue [Line Items]
Revenues		48.4	47.9
International | Major Markets
Disaggregation of Revenue [Line Items]
Revenues	[1]	56.3	50.3
International | Other Markets
Disaggregation of Revenue [Line Items]
Revenues	[2]	$ 24.7	$ 24.5

[1] Includes Canada, UK, Australia and New Zealand.

[2] Primarily includes markets in Asia.