EMPLOYEE BENEFIT PLANS - Schedule of Multiemployer Defined Benefit Pension Plans (Details) - Multiemployer Plans, Pension Plans - USD ($) $ in Millions	12 Months Ended
	Oct. 31, 2023	Oct. 31, 2022	Oct. 31, 2021
Multiemployer Plans [Line Items]
Total Contributions	$ 73.6	$ 73.8	$ 56.8
Building Service 32BJ Pension Fund
Multiemployer Plans [Line Items]
Contributions by ABM, significant	21.4	22.7	18.8
S.E.I.U National Industry Pension Fund
Multiemployer Plans [Line Items]
Contributions by ABM, significant	19.3	17.6	10.9
Central Pension Fund of the IUOE & Participating Employers
Multiemployer Plans [Line Items]
Contributions by ABM, significant	13.0	12.8	5.3
SEIU Local 1 & Participating Employers Pension Trust
Multiemployer Plans [Line Items]
Contributions by ABM, significant	4.8	5.8	3.9
IUOE Stationary Engineers Local 39 Pension Plan
Multiemployer Plans [Line Items]
Contributions by ABM, significant	4.6	4.4	6.6
Western Conference of Teamsters Pension Plan
Multiemployer Plans [Line Items]
Contributions by ABM, significant	2.4	2.2	2.0
All Other Plans
Multiemployer Plans [Line Items]
Contributions by ABM, insignificant	$ 8.0	$ 8.2	$ 9.3