Quarterly report pursuant to Section 13 or 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
Nov. 30, 2017
May 31, 2017
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross $ 1,121.8 $ 1,051.0
Less: Accumulated depreciation 744.7 713.8
Property and equipment, net of accumulated depreciation 377.1 337.2
Land and Improvements [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross 9.7 8.3
Buildings and Improvements [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross 123.7 103.5
Data Processing Equipment [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross 207.5 199.7
Software [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross [1] 507.1 496.1
Furniture, Fixtures, and Equipment [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross 113.4 115.2
Leasehold Improvements [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross 108.2 109.5
Construction in Progress [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross [1] $ 52.2 $ 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.