Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 160,189		$ 160,189		$ 164,244
Less accumulated depreciation	(95,720)		(95,720)		(95,198)
Property and equipment, net	64,469		64,469		69,046
Total depreciation and amortization	4,859	$ 4,393	$ 13,610	$ 12,266
Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			2 years
Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			39 years
Assets not held under finance eases
Property, Plant and Equipment [Line Items]
Total depreciation and amortization	4,237	3,840	$ 11,882	11,012
Assets held under finance leases
Property, Plant and Equipment [Line Items]
Total depreciation and amortization	622	$ 553	1,728	$ 1,254
Tractors and trailers
Property, Plant and Equipment [Line Items]
Property and equipment, gross	115,809		$ 115,809		115,693
Tractors and trailers | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			5 years
Tractors and trailers | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			6 years
Tractors and trailers | Assets held under finance leases
Property, Plant and Equipment [Line Items]
Property and equipment, gross	7,200		$ 7,200		5,500
Less accumulated depreciation	(2,600)		(2,600)		(1,700)
Field equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	25,152		$ 25,152		25,094
Field equipment | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			2 years
Field equipment | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			5 years
Field equipment | Assets held under finance leases
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,300		$ 3,300		3,300
Less accumulated depreciation	(1,600)		(1,600)		(700)
Buildings
Property, Plant and Equipment [Line Items]
Property and equipment, gross	14,939		$ 14,939		16,055
Buildings | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			5 years
Buildings | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			39 years
Office equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,893		$ 1,893		1,951
Office equipment | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			2 years
Office equipment | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			5 years
Land
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,790		$ 1,790		1,790
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 606		$ 606		$ 3,661