Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2023	Sep. 30, 2022
Property Plant And Equipment [Line Items]
Property and equipment	$ 854.2	$ 812.6
Less: Accumulated depreciation	522.1	484.3
Property and equipment, net	332.1	328.3
Land
Property Plant And Equipment [Line Items]
Property and equipment	43.3	43.3
Building and Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment	47.9	46.3
Operating Equipment
Property Plant And Equipment [Line Items]
Property and equipment	332.2	302.4
Transportation Vehicles
Property Plant And Equipment [Line Items]
Property and equipment	348.2	339.8
Office Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment	76.8	75.1
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment	$ 5.8	$ 5.7
Minimum | Building and Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	2 years
Minimum | Operating Equipment
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	2 years
Minimum | Transportation Vehicles
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	3 years
Minimum | Office Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	3 years
Maximum | Building and Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	40 years
Maximum | Operating Equipment
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	7 years
Maximum | Transportation Vehicles
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	7 years
Maximum | Office Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment, Useful Life	10 years