EMPLOYEE BENEFIT PLANS - Schedule of Multiemployer Defined Benefit Pension Plans (Details) - Multiemployer Plans, Pension Plans - USD ($) $ in Millions	12 Months Ended
	Oct. 31, 2025	Oct. 31, 2024	Oct. 31, 2023
Multiemployer Plans [Line Items]
Total Contributions	$ 82.3	$ 77.3	$ 73.6
Building Service 32BJ Pension Fund
Multiemployer Plans [Line Items]
Contributions by ABM, significant	23.7	22.1	21.4
S.E.I.U National Industry Pension Fund
Multiemployer Plans [Line Items]
Contributions by ABM, significant	20.5	19.4	19.3
Central Pension Fund of the IUOE & Participating Employers
Multiemployer Plans [Line Items]
Contributions by ABM, significant	14.0	12.4	13.0
SEIU Local 1 & Participating Employers Pension Trust
Multiemployer Plans [Line Items]
Contributions by ABM, significant	4.2	4.3	4.8
Western Conference of Teamsters Pension Plan
Multiemployer Plans [Line Items]
Contributions by ABM, significant	2.6	2.7	2.4
IUOE Stationary Engineers Local 39 Pension Plan
Multiemployer Plans [Line Items]
Contributions by ABM, significant	2.9	2.5	4.6
All Other Plans
Multiemployer Plans [Line Items]
Contributions by ABM, insignificant	$ 14.5	$ 13.9	$ 8.0