Segment Information - Schedule of segment reporting information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2025 USD ($)	Feb. 29, 2024 USD ($)	Feb. 28, 2025 USD ($) segment	Feb. 29, 2024 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			4
Revenues	$ 335.4	$ 323.7	$ 1,117.2	$ 1,114.8
Segment operating income (loss)	(23.9)	(34.9)	$ (37.7)	(32.7)
Total Children's Book Publishing and Distribution
Segment Reporting Information [Line Items]
Number of operating segments | segment			2
Total Education Solutions
Segment Reporting Information [Line Items]
Number of operating segments | segment			1
Total Entertainment
Segment Reporting Information [Line Items]
Number of operating segments | segment			1
Total International
Segment Reporting Information [Line Items]
Number of operating segments | segment			3
Operating Segments | Total Children's Book Publishing and Distribution
Segment Reporting Information [Line Items]
Revenues	203.3	193.1	$ 675.7	687.9
Segment operating income (loss)	7.6	2.3	73.1	72.9
Operating Segments | Total Education Solutions
Segment Reporting Information [Line Items]
Revenues	57.2	68.5	184.1	215.5
Segment operating income (loss)	(6.9)	(0.8)	(24.4)	(13.7)
Operating Segments | Total Entertainment
Segment Reporting Information [Line Items]
Revenues	12.8	0.5	46.2	1.3
Segment operating income (loss)	(3.9)	(3.1)	(9.1)	(4.4)
Operating Segments | Total International
Segment Reporting Information [Line Items]
Revenues	59.3	59.1	202.8	202.8
Segment operating income (loss)	(2.1)	(5.9)	(4.7)	(6.1)
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Revenues	2.8	2.5	8.4	7.3
Corporate, Non-Segment | Overhead
Segment Reporting Information [Line Items]
Revenues	2.8	2.5	8.4	7.3
Segment operating income (loss)	$ (18.6)	$ (27.4)	$ (72.6)	$ (81.4)