Quarterly report pursuant to Section 13 or 15(d)

Goodwill and Intangible Assets, Net of Accumulated Amortization (Components of Intangible Assets, at Cost) (Details)

v3.8.0.1
Goodwill and Intangible Assets, Net of Accumulated Amortization (Components of Intangible Assets, at Cost) (Details) - USD ($)
$ in Millions
Aug. 31, 2017
May 31, 2017
Finite-Lived Intangible Assets [Line Items]    
Total intangible assets, gross $ 324.1 $ 298.9
Less: Accumulated amortization 244.9 241.3
Intangible assets, net of accumulated amortization 79.2 57.6
Client Lists [Member]    
Finite-Lived Intangible Assets [Line Items]    
Total intangible assets, gross 318.7 293.5
Other Intangible Assets [Member]    
Finite-Lived Intangible Assets [Line Items]    
Total intangible assets, gross $ 5.4 $ 5.4