Goodwill and Other Intangibles - Schedule of activity in goodwill (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
Nov. 30, 2023	Nov. 30, 2022	May 31, 2023	May 31, 2022
Goodwill [Roll Forward]
Gross goodwill			$ 172.3	$ 164.9
Goodwill, Impaired, Accumulated Impairment Loss			(39.6)	(39.6)
Goodwill	$ 132.8	$ 132.0	132.7	$ 125.3
Additions	0.0	7.0	7.6
Foreign currency translation	$ 0.1	$ (0.3)	$ (0.2)

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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