Property and Equipment, net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	6 Months Ended
Mar. 31, 2019	Sep. 30, 2018
Property Plant And Equipment [Line Items]
Property and equipment	$ 578,344	$ 544,813
Less: Accumulated depreciation	311,676	288,007
Property and equipment, net	266,668	256,806
Land
Property Plant And Equipment [Line Items]
Property and equipment	52,696	51,490
Building and Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment	36,873	36,275
Operating Equipment
Property Plant And Equipment [Line Items]
Property and equipment	198,948	186,499
Transportation Vehicles
Property Plant And Equipment [Line Items]
Property and equipment	222,006	208,371
Office Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment	57,928	57,976
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment	$ 9,893	$ 4,202
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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