EMPLOPYEE BENEFIT PLANS - Narrative (Details) $ in Millions	12 Months Ended
	Oct. 31, 2022 USD ($) plan	Oct. 31, 2021 USD ($)	Oct. 31, 2020 USD ($)
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Expected return on assets	$ 0.4	$ 0.3	$ 0.4
Net periodic benefit cost	0.1	0.3	0.2
Expected future benefit payments	$ 11.2
Number of defined contribution plans | plan	4
Cost recognized	$ 27.7	21.6	18.2
Multiemployer Plans, Pension Plans | Defined Contribution Plans
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Cost recognized	54.7	21.2	15.5
Multiemployer Plans, Postretirement Benefit Plans
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Contributions by ABM	426.6	270.8	264.8
Rabbi Trust
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Fair value deferred compensation plan assets	4.1	4.9
Deferred Compensation Plans
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Total liability of deferred compensation	27.5	32.1
Compensation expense	0.3	0.2	$ 0.2
Deferred Compensation Plans | Able
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Total liability of deferred compensation	$ 14.2	$ 18.0
Equity Securities
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Target plan asset allocations	31.00%
Fixed Income Funds
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Target plan asset allocations	69.00%