Funds Held for Clients and Corporate Investments (Classification of Investments on Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	May 31, 2022	May 31, 2021
Funds Held for Clients and Corporate Investments [Abstract]
Funds held for clients	$ 3,682.9	$ 3,750.0
Corporate investments	853.9	36.7
Long-term corporate investments	5.0	7.1
Total funds held for clients and corporate investments, Fair value	$ 4,541.8	$ 3,793.8

Funds held for clients and corporate investments.

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- Definition

Funds held for clients and corporate investments, fair value.

+ References

No definition available.

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- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as noncurrent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

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-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124260329&loc=d3e26626-111562

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- Definition

Carrying amount as of the balance sheet date of the funds held on behalf of others and that are expected to be liquidated within one year or the normal operating cycle, if longer. This does not include funds held under reinsurance agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.8)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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Amount of investment in marketable security, classified as current.

+ References

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-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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