Fair Value Measurements - Schedule of non-financial assets measured and recorded at fair value on a non-recurring basis (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2022	May 31, 2021	May 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non cash write off related to assets held for sale	$ 11.6	$ 0.0	$ 0.0
Additions	0.0	0.0
Intangible assets acquired	0.0	0.0
Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, plant and equipment, net		0.0	0.0
Non cash write off related to assets held for sale		1.5	0.6
Author advances			0.0
Author Advances, Property, plant and equipment, net			1.6
Prepublication assets			0.5
Prepublication costs			0.8
Intangible assets			1.5
Impairment, Intangible assets			0.0
Operating Lease, Right-Of-Use Asset, Fair Value Disclosure	0.0	8.1
Fair Value, Nonrecurring | Inventories
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non cash write off related to assets held for sale	1.6
Assets Held-for-sale, Long Lived, Fair Value Disclosure	2.3
Fair Value, Nonrecurring | Other Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non cash write off related to assets held for sale	0.7
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0.0
Fair Value, Nonrecurring | Accounts Receivable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non cash write off related to assets held for sale	9.3
Assets Held-for-sale, Long Lived, Fair Value Disclosure	1.4
Fair Value, Nonrecurring | Operating lease right-of-use assets, net
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges	0.4	9.6
Additions	0.0	0.0
Intangible assets acquired	0.0	0.0
Fair Value, Nonrecurring | Property, plant and equipment, net
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additions		0.0	0.0
Intangible assets acquired		0.0	0.0
Fair Value, Nonrecurring | Prepublication assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additions			0.0
Intangible assets acquired			0.0
Fair Value, Nonrecurring | Intangible assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible assets acquired			1.6
Fair Value, Nonrecurring | Other Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additions	0.0
Intangible assets acquired	0.0
Fair Value, Nonrecurring | Accounts Receivable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additions	0.0
Intangible assets acquired	0.0
Fair Value, Nonrecurring | Inventories
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additions	0.0
Intangible assets acquired	0.0
Fair Value, Nonrecurring | Author Advance
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additions			0.0
Intangible assets acquired			0.0
Fair Value, Nonrecurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, plant and equipment, net		0.0	0.0
Author advances			0.0
Prepublication assets			0.0
Intangible assets			0.0
Operating Lease, Right-Of-Use Asset, Fair Value Disclosure	0.0	0.0
Fair Value, Nonrecurring | Level 1 | Inventories
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0.0
Fair Value, Nonrecurring | Level 1 | Other Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0.0
Fair Value, Nonrecurring | Level 1 | Accounts Receivable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0.0
Fair Value, Nonrecurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, plant and equipment, net		0.0	0.0
Author advances			0.0
Prepublication assets			0.0
Intangible assets			0.0
Operating Lease, Right-Of-Use Asset, Fair Value Disclosure	0.0	0.0
Fair Value, Nonrecurring | Level 2 | Inventories
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0.0
Fair Value, Nonrecurring | Level 2 | Other Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0.0
Fair Value, Nonrecurring | Level 2 | Accounts Receivable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0.0
Fair Value, Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, plant and equipment, net		0.0	0.0
Author advances			0.0
Prepublication assets			0.5
Intangible assets			$ 1.6
Operating Lease, Right-Of-Use Asset, Fair Value Disclosure	0.0	$ 9.1
Fair Value, Nonrecurring | Level 3 | Inventories
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	2.3
Fair Value, Nonrecurring | Level 3 | Other Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0.0
Fair Value, Nonrecurring | Level 3 | Accounts Receivable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	$ 1.4