Segment Information - Schedule of segment reporting information (Details) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2023 USD ($)	Nov. 30, 2022 USD ($)	Nov. 30, 2023 USD ($) segment	Nov. 30, 2022 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			3
Revenues	$ 562.6	$ 587.9	$ 791.1	$ 850.8
Total Revenues excluding rental income	560.3	587.9	786.3	850.8
Segment operating income (loss)	101.3	100.1	$ 2.2	42.0
Children's Book Publishing & Distribution
Segment Reporting Information [Line Items]
Number of operating segments | segment			2
Revenues	392.8	418.3	$ 495.6	543.0
Education
Segment Reporting Information [Line Items]
Number of operating segments | segment			1
Revenues	81.0	80.0	$ 147.0	153.2
International
Segment Reporting Information [Line Items]
Number of operating segments | segment			3
Revenues	86.5	89.6	$ 143.7	154.6
Operating Segments | Children's Book Publishing & Distribution
Segment Reporting Information [Line Items]
Revenues	392.8	418.3	495.6	543.0
Segment operating income (loss)	110.8	113.2	69.3	83.1
Operating Segments | Education
Segment Reporting Information [Line Items]
Revenues	81.0	80.0	147.0	153.2
Segment operating income (loss)	5.8	7.0	(12.9)	2.7
Operating Segments | International
Segment Reporting Information [Line Items]
Revenues	86.5	89.6	143.7	154.6
Segment operating income (loss)	8.0	6.7	(0.2)	3.2
Operating Segments | Overhead
Segment Reporting Information [Line Items]
Segment operating income (loss)	$ (23.3)	$ (26.8)	$ (54.0)	$ (47.0)