Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 157,617		$ 157,617		$ 139,441
Less accumulated depreciation	(94,884)		(94,884)		(94,818)
Property and equipment, net	62,733		62,733		44,623
Total depreciation and amortization	4,393	$ 2,340	$ 12,266	$ 7,014
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 capital leases
Property, Plant and Equipment [Line Items]
Total depreciation and amortization	3,840	2,210	$ 11,012	6,703
Assets held under finance leases
Property, Plant and Equipment [Line Items]
Total depreciation and amortization	553	$ 130	1,254	$ 311
Tractors and trailers
Property, Plant and Equipment [Line Items]
Property and equipment, gross	109,595		$ 109,595		96,523
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	5,500		$ 5,500		4,700
Less accumulated depreciation	(1,500)		(1,500)		(700)
Field equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	24,851		$ 24,851		20,725
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			20 years
Field equipment | Assets held under finance leases
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,300		$ 3,300
Less accumulated depreciation	(500)		(500)
Buildings
Property, Plant and Equipment [Line Items]
Property and equipment, gross	16,003		$ 16,003		15,746
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	1,951		$ 1,951		1,863
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	$ 3,427		$ 3,427		$ 2,794