Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Millions	Dec. 31, 2023	Sep. 30, 2023
Property Plant And Equipment [Line Items]
Property and equipment	$ 858.9	$ 857.4
Less: Accumulated depreciation	556.1	542.2
Property and equipment, net	302.8	315.2
Land
Property Plant And Equipment [Line Items]
Property and equipment	44.7	44.7
Building and Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment	46.1	45.6
Operating Equipment
Property Plant And Equipment [Line Items]
Property and equipment	341.7	338.8
Transportation Vehicles
Property Plant And Equipment [Line Items]
Property and equipment	347.5	351.9
Office Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment	71.0	68.7
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment	$ 7.9	$ 7.7
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