Subsequent Events	9 Months Ended
	Jul. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTSOn August 25, 2021, we entered into a purchase agreement (the “Agreement”) with Crown Building Maintenance Co. and Crown Energy Services, Inc. (collectively, “Able”) and their owners. Under the terms of the Agreement, ABM will acquire Able for $830 million in cash, subject to customary adjustments for working capital and net debt. ABM will finance the acquisition with cash on hand and borrowings from our revolver under the Amended Credit Facility. The parties’ obligations to consummate the acquisition are subject to customary closing conditions, including conditions relating to the expiration or termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976.