EMPLOYEE BENEFIT PLANS - Narrative (Details) $ in Millions	12 Months Ended
	Oct. 31, 2024 USD ($) plan	Oct. 31, 2023 USD ($)	Oct. 31, 2022 USD ($)
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Expected return on assets	$ 0.0	$ 0.2	$ 0.4
Net periodic benefit cost	0.8	0.6	0.1
Expected future benefit payments	$ 11.2
Number of defined contribution plans | plan	2
Cost recognized	$ 30.6	29.8	27.7
Defined Contribution Plans
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Cost recognized	54.5	59.2	54.7
Multiemployer Plans, Postretirement Benefit Plans
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Contributions by ABM	434.1	441.8	426.6
Rabbi Trust
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Fair value deferred compensation plan assets	4.4	4.0
Deferred Compensation Plans
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Total liability of deferred compensation	26.7	27.0
Compensation expense	$ 0.6	$ 0.5	$ 0.3