EMPLOYEE BENEFIT PLANS - Schedule of Multiemployer Defined Benefit Pension Plans (Details) - Multiemployer Plans, Pension Plans - USD ($) $ in Millions	12 Months Ended
	Oct. 31, 2024	Oct. 31, 2023	Oct. 31, 2022
Multiemployer Plans [Line Items]
Total Contributions	$ 77.3	$ 73.6	$ 73.8
Building Service 32BJ Pension Fund
Multiemployer Plans [Line Items]
Contributions by ABM, significant	22.1	21.4	22.7
S.E.I.U National Industry Pension Fund
Multiemployer Plans [Line Items]
Contributions by ABM, significant	19.4	19.3	17.6
Central Pension Fund of the IUOE & Participating Employers
Multiemployer Plans [Line Items]
Contributions by ABM, significant	12.4	13.0	12.8
SEIU Local 1 & Participating Employers Pension Trust
Multiemployer Plans [Line Items]
Contributions by ABM, significant	4.3	4.8	5.8
Western Conference of Teamsters Pension Plan
Multiemployer Plans [Line Items]
Contributions by ABM, significant	2.7	2.4	2.2
IUOE Stationary Engineers Local 39 Pension Plan
Multiemployer Plans [Line Items]
Contributions by ABM, significant	2.5	4.6	4.4
All Other Plans
Multiemployer Plans [Line Items]
Contributions by ABM, insignificant	$ 13.9	$ 8.0	$ 8.2