Acquisitions - Other Acquisitions Narrative (Details) - USD ($) $ in Millions	Dec. 01, 2016	Sep. 30, 2016	Dec. 01, 2015	May 01, 2015	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2015
Business Acquisition [Line Items]
Goodwill					$ 1,864.2	$ 912.8	$ 867.5
Mechanical Solutions Inc (MSI)
Business Acquisition [Line Items]
Purchase price	$ 12.6
Contingent consideration liability	1.0
OFJ Connections Ltd (OFJ)
Business Acquisition [Line Items]
Purchase price	$ 6.3
8 Solutions Ltd (8 Solutions)
Business Acquisition [Line Items]
Purchase price		$ 16.1
Westway Services Holdings (Westway)
Business Acquisition [Line Items]
Purchase price			$ 81.0
Goodwill			53.8
Intangible assets			$ 22.5
CTS Services/Facility Support Services (CTS)
Business Acquisition [Line Items]
Purchase price				$ 18.8
Contingent consideration liability				$ 3.8