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
Nov. 30, 2017
May 31, 2017
Finite-Lived Intangible Assets [Line Items]    
Total intangible assets, gross $ 283.3 $ 298.9
Less: Accumulated amortization 205.9 241.3
Intangible assets, net of accumulated amortization 77.4 57.6
Client Lists [Member]    
Finite-Lived Intangible Assets [Line Items]    
Total intangible assets, gross 277.9 293.5
Other Intangible Assets [Member]    
Finite-Lived Intangible Assets [Line Items]    
Total intangible assets, gross $ 5.4 $ 5.4