Quarterly report pursuant to Section 13 or 15(d)

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

v3.5.0.2
Goodwill and Intangible Assets, Net of Accumulated Amortization (Components of Intangible Assets, at Cost) (Details) - USD ($)
$ in Millions
Aug. 31, 2016
May 31, 2016
Finite-Lived Intangible Assets [Line Items]    
Total intangible assets, gross $ 294.1 $ 294.6
Less: Accumulated amortization 229.1 225.1
Intangible assets, net of accumulated amortization 65.0 69.5
Client Lists [Member]    
Finite-Lived Intangible Assets [Line Items]    
Total intangible assets, gross 288.7 289.2
Other Intangible Assets [Member]    
Finite-Lived Intangible Assets [Line Items]    
Total intangible assets, gross $ 5.4 $ 5.4