Goodwill and Other Intangibles - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2024	May 31, 2023	May 31, 2022
Goodwill and Other Intangibles (Details) [Line Items]
Additions	$ 0.0	$ 7.6
Goodwill, impairment loss	0.0	0.0
Additions	$ 6.0	4.1
Useful life of intangible assets	6 years 1 month 6 days
Amortization of intangible assets	$ 2.6	2.2	$ 2.0
Amortizable Intangible Assets - Educational Programs
Goodwill and Other Intangibles (Details) [Line Items]
Additions	$ 5.8
Useful life of intangible assets	8 years
Amortizable Intangible Assets - Children's Book Publishing Business
Goodwill and Other Intangibles (Details) [Line Items]
Additions	$ 0.2
Useful life of intangible assets	5 years
Learning Ovations, Inc.
Goodwill and Other Intangibles (Details) [Line Items]
Additions		$ 4.1