Property and Equipment - Cost of Property and Equipment and Related Accumulated Depreciaiton, Depletion, and Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 139,441	$ 126,276
Less accumulated depreciation, depletion and amortization	(94,818)	(96,914)
Property and equipment, net	44,623	29,362
Depreciation, depletion and amortization	$ 10,654	13,599	$ 18,792
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
Tractors and trailers
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 96,523	88,065
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
Field equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 20,725	18,490
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
Buildings
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 15,746	15,727
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	$ 1,863	1,929
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
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,794	275
Assets held under capital leases
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4,700	1,800
Less accumulated depreciation, depletion and amortization	(700)	(100)
Depreciation, depletion and amortization	542	121	0
Assets not held under capital leases
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	$ 10,112	$ 13,478	$ 18,792