Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Oct. 31, 2020	Jul. 31, 2020	Apr. 30, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2018
Revenue from External Customer [Line Items]
Revenues	$ 1,484.6	$ 1,394.1	$ 1,496.0	$ 1,612.9	$ 1,648.0	$ 1,647.9	$ 1,594.7	$ 1,607.9	$ 5,987.6	$ 6,498.6	$ 6,442.2
Operating Segments
Revenue from External Customer [Line Items]
Revenues									6,110.0	6,626.3
Operating Segments | Business & Industry
Revenue from External Customer [Line Items]
Revenues									3,157.8	3,251.4	3,268.4
Operating Segments | Technology & Manufacturing
Revenue from External Customer [Line Items]
Revenues									956.0	917.0	925.4
Operating Segments | Education
Revenue from External Customer [Line Items]
Revenues									808.8	847.4	856.7
Operating Segments | Aviation
Revenue from External Customer [Line Items]
Revenues									680.9	1,017.3	1,038.7
Operating Segments | Technical Solutions
Revenue from External Customer [Line Items]
Revenues									506.6	593.2	$ 500.1
Operating Segments | Janitorial
Revenue from External Customer [Line Items]
Revenues									4,029.0	3,937.9
Operating Segments | Janitorial | Business & Industry
Revenue from External Customer [Line Items]
Revenues									2,420.4	2,316.1
Operating Segments | Janitorial | Technology & Manufacturing
Revenue from External Customer [Line Items]
Revenues									770.9	739.7
Operating Segments | Janitorial | Education
Revenue from External Customer [Line Items]
Revenues									716.5	756.3
Operating Segments | Janitorial | Aviation
Revenue from External Customer [Line Items]
Revenues									121.2	125.8
Operating Segments | Janitorial | Technical Solutions
Revenue from External Customer [Line Items]
Revenues									0.0	0.0
Operating Segments | Parking
Revenue from External Customer [Line Items]
Revenues									654.0	875.8
Operating Segments | Parking | Business & Industry
Revenue from External Customer [Line Items]
Revenues									362.8	511.5
Operating Segments | Parking | Technology & Manufacturing
Revenue from External Customer [Line Items]
Revenues									33.5	25.9
Operating Segments | Parking | Education
Revenue from External Customer [Line Items]
Revenues									1.8	3.1
Operating Segments | Parking | Aviation
Revenue from External Customer [Line Items]
Revenues									255.9	335.3
Operating Segments | Parking | Technical Solutions
Revenue from External Customer [Line Items]
Revenues									0.0	0.0
Operating Segments | Facility Services
Revenue from External Customer [Line Items]
Revenues									647.9	734.6
Operating Segments | Facility Services | Business & Industry
Revenue from External Customer [Line Items]
Revenues									374.1	423.1
Operating Segments | Facility Services | Technology & Manufacturing
Revenue from External Customer [Line Items]
Revenues									151.6	151.4
Operating Segments | Facility Services | Education
Revenue from External Customer [Line Items]
Revenues									90.5	88.0
Operating Segments | Facility Services | Aviation
Revenue from External Customer [Line Items]
Revenues									31.6	72.1
Operating Segments | Facility Services | Technical Solutions
Revenue from External Customer [Line Items]
Revenues									0.0	0.0
Operating Segments | Building & Energy Solutions
Revenue from External Customer [Line Items]
Revenues									506.6	593.2
Operating Segments | Building & Energy Solutions | Business & Industry
Revenue from External Customer [Line Items]
Revenues									0.0	0.0
Operating Segments | Building & Energy Solutions | Technology & Manufacturing
Revenue from External Customer [Line Items]
Revenues									0.0	0.0
Operating Segments | Building & Energy Solutions | Education
Revenue from External Customer [Line Items]
Revenues									0.0	0.0
Operating Segments | Building & Energy Solutions | Aviation
Revenue from External Customer [Line Items]
Revenues									0.0	0.0
Operating Segments | Building & Energy Solutions | Technical Solutions
Revenue from External Customer [Line Items]
Revenues									506.6	593.2
Operating Segments | Airline Services
Revenue from External Customer [Line Items]
Revenues									272.6	484.8
Operating Segments | Airline Services | Business & Industry
Revenue from External Customer [Line Items]
Revenues									0.4	0.6
Operating Segments | Airline Services | Technology & Manufacturing
Revenue from External Customer [Line Items]
Revenues									0.0	0.1
Operating Segments | Airline Services | Education
Revenue from External Customer [Line Items]
Revenues									0.0	0.0
Operating Segments | Airline Services | Aviation
Revenue from External Customer [Line Items]
Revenues									272.2	484.1
Operating Segments | Airline Services | Technical Solutions
Revenue from External Customer [Line Items]
Revenues									0.0	0.0
Intersegment Eliminations
Revenue from External Customer [Line Items]
Revenues									$ (122.4)	$ (127.7)