Segment Information - Schedule of segment reporting information (Details) $ in Millions	12 Months Ended
	May 31, 2022 USD ($) segment	May 31, 2021 USD ($)	May 31, 2020 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	3
Accounts Receivable, Credit Loss Expense (Reversal)	$ 15.2	$ 5.2	$ 15.6
Depreciation and amortization	91.3	90.3	90.2
Operating Income (Loss)	97.4	(22.7)	(88.5)
Segment assets	1,940.8	2,008.3	2,033.6
Long-lived assets	456.7	497.5
Revenues	1,642.9	1,300.3	1,487.1
Children's Book Publishing and Distribution
Segment Reporting Information [Line Items]
Revenues	946.5	675.0	881.7
Education Solutions
Segment Reporting Information [Line Items]
Revenues	393.6	312.3	287.3
International Segment
Segment Reporting Information [Line Items]
Revenues	$ 302.8	313.0	318.1
Operating Segments | Children's Book Publishing and Distribution
Segment Reporting Information [Line Items]
Number of Operating Segments | segment	3
Depreciation and amortization	$ 24.9	25.6	26.5
Operating Income (Loss)	115.3	8.9	17.1
Segment assets	559.4	518.0	528.0
Long-lived assets	32.3	44.2
Revenues	$ 946.5	675.0	881.7
Operating Segments | Education Solutions
Segment Reporting Information [Line Items]
Number of Operating Segments | segment	1
Depreciation and amortization	$ 15.1	12.7	13.0
Operating Income (Loss)	81.8	57.7	24.7
Segment assets	289.4	239.8	223.4
Long-lived assets	2.7	6.8
Revenues	$ 393.6	312.3	287.3
Operating Segments | International Segment
Segment Reporting Information [Line Items]
Number of Operating Segments | segment	3
Depreciation and amortization	$ 6.2	6.6	7.3
Operating Income (Loss)	3.3	21.2	(8.0)
Segment assets	258.3	302.1	270.3
Long-lived assets	25.0	29.4
Revenues	302.8	313.0	318.1
Corporate, Non-Segment | Overhead
Segment Reporting Information [Line Items]
Depreciation and amortization	45.1	45.4	43.4
Operating Income (Loss)	(103.0)	(110.5)	(122.3)
Segment assets	833.7	948.4	$ 1,011.9
Long-lived assets	$ 396.7	$ 417.1