Property and Equipment, net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Millions	6 Months Ended
Mar. 31, 2020	Sep. 30, 2019
Property Plant And Equipment [Line Items]
Property and equipment	$ 631.7	$ 602.0
Less: Accumulated depreciation	353.4	329.6
Property and equipment, net	278.3	272.4
Land
Property Plant And Equipment [Line Items]
Property and equipment	54.5	54.1
Building and Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment	42.2	40.1
Operating Equipment
Property Plant And Equipment [Line Items]
Property and equipment	204.3	199.8
Transportation Vehicles
Property Plant And Equipment [Line Items]
Property and equipment	259.1	236.5
Office Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment	62.4	63.3
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment	$ 9.2	$ 8.2
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

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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