Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 166,680		$ 166,680		$ 164,244
Less accumulated depreciation	(97,400)		(97,400)		(95,198)
Property and equipment, net	69,280		69,280		69,046
Total depreciation and amortization	4,278	$ 4,284	$ 8,751	$ 7,873
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	3,725	3,828	$ 7,645	7,172
Assets held under finance leases
Property, Plant and Equipment [Line Items]
Total depreciation and amortization	553	$ 456	1,106	$ 701
Tractors and trailers
Property, Plant and Equipment [Line Items]
Property and equipment, gross	122,892		$ 122,892		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	(2,300)		(2,300)		(1,700)
Field equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	24,960		$ 24,960		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	(1,300)		(1,300)		(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	1,387		$ 1,387		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	$ 712		$ 712		$ 3,661