Property and Equipment, net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	9 Months Ended
Jun. 30, 2018	Sep. 30, 2017
Property Plant And Equipment [Line Items]
Property and equipment	$ 534,644	$ 473,712
Less: Accumulated depreciation	274,108	228,178
Property and equipment, net	260,536	245,534
Land
Property Plant And Equipment [Line Items]
Property and equipment	51,310	37,225
Building and Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment	35,577	27,652
Operating Equipment
Property Plant And Equipment [Line Items]
Property and equipment	184,102	182,720
Transportation Vehicles
Property Plant And Equipment [Line Items]
Property and equipment	197,687	174,434
Office Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment	60,554	47,042
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment	$ 5,414	$ 4,639
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	3 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	7 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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