Annual report pursuant to Section 13 and 15(d)

Property and Equipment, Net of Accumulated Depreciation (Components of Property and Equipment, at Cost) (Details)

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Property and Equipment, Net of Accumulated Depreciation (Components of Property and Equipment, at Cost) (Details) - USD ($)
$ in Millions
May 31, 2018
May 31, 2017
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross $ 1,182.7 $ 1,051.0
Less: Accumulated depreciation 789.2 713.8
Property and equipment, net of accumulated depreciation 393.5 337.2
Land and Improvements [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross 10.6 8.3
Buildings and Improvements [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross 126.4 103.5
Data Processing Equipment [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross 211.3 199.7
Software [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross [1] 545.5 496.1
Furniture, Fixtures, and Equipment [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross 114.5 115.2
Leasehold Improvements [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross 111.4 109.5
Construction in Progress [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross [1] $ 63.0 $ 18.7
[1] Software includes both purchased software and costs capitalized related to internally developed software placed in service. Capitalized costs related to internally developed software that has not yet been placed in service is included in construction in progress.