Quarterly report pursuant to Section 13 or 15(d)

Funds Held for Clients and Corporate Investments (Classification of Investments on Consolidated Balance Sheets) (Details)

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Funds Held for Clients and Corporate Investments (Classification of Investments on Consolidated Balance Sheets) (Details) - USD ($)
$ in Millions
Nov. 30, 2018
May 31, 2018
Funds Held for Clients and Corporate Investments [Abstract]    
Funds held for clients $ 3,672.3 $ 4,703.8 [1]
Corporate investments 248.4 66.0 [1]
Long-term corporate investments 10.0 295.5 [1]
Total funds held for clients and corporate investments, Fair value $ 3,930.7 $ 5,065.3
[1] Amounts have been adjusted to reflect the adoption of ASC Topic 606.