Fair Value Measurements (Details) - Schedule of non-financial assets measured and recorded at fair value on a non-recurring basis - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Feb. 29, 2020	May 31, 2020	May 31, 2019	May 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset impairments and write downs	$ 40.0	$ 40.6	$ 0.9	$ 11.2
Additions		1.6	4.5
Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Author Advances, Fair Value Disclosure		0.0
Author Advances, Property, plant and equipment, net		1.6
Prepublication assets		0.0
Prepublication costs		0.8
Property, plant and equipment, net		0.0	0.0	0.0
Impairment of Long-Lived Assets to be Disposed of			0.9	11.2
Asset impairments and write downs		0.6
Investments, Fair Value Disclosure			6.0
Investments Impairment Loss			0.0
Intangible assets		1.5	4.9	3.1
Impairment, Intangible assets		0.0	0.0	0.0
Additions		0.0
Fair Value, Nonrecurring [Member] | Property, Plant and Equipment, Net [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additions		0.0	0.0	0.0
Fair Value, Nonrecurring [Member] | Intangible Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible assets acquired		1.6	5.1	3.3
Fair Value, Nonrecurring [Member] | Prepublication Costs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additions		0.0
Fair Value, Nonrecurring [Member] | Investments Acquired [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additions			6.0
Fair Value, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Author Advances, Fair Value Disclosure		0.0
Prepublication assets		0.0
Property, plant and equipment, net		0.0	0.0	0.0
Investments, Fair Value Disclosure			0.0
Intangible assets		0.0	0.0	0.0
Fair Value, Nonrecurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Author Advances, Fair Value Disclosure		0.0
Prepublication assets		0.0
Property, plant and equipment, net		0.0	0.0	0.0
Investments, Fair Value Disclosure			0.0
Intangible assets		0.0	0.0	0.0
Fair Value, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Author Advances, Fair Value Disclosure		1.6
Prepublication assets		0.8
Property, plant and equipment, net		0.6	0.0	0.0
Investments, Fair Value Disclosure			6.0
Intangible assets		$ 1.6	$ 5.1	$ 3.3