Property and Equipment - Components of property and equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property, Plant And Equipment [Line Items]
Property and equipment, gross	$ 677,682	$ 661,619
Less accumulated depreciation and amortization	(235,590)	(212,818)
Property and equipment, net	442,092	448,801
Finance Lease, Assets And Liabilities, Lessee [Abstract]
Property and equipment, at cost	81,012
Property and equipment, at cost		102,852
Less accumulated depreciation	(22,513)
Less accumulated depreciation		(31,954)
Property and equipment under finance lease, net	58,499
Property and equipment under finance lease, net		70,898
Land
Property, Plant And Equipment [Line Items]
Property and equipment, gross	20,827	21,431
Buildings and improvements
Property, Plant And Equipment [Line Items]
Property and equipment, gross	41,212	40,524
Well service units and equipment
Property, Plant And Equipment [Line Items]
Property and equipment, gross	128,960	122,694
Finance Lease, Assets And Liabilities, Lessee [Abstract]
Property and equipment, at cost	0
Property and equipment, at cost		199
Fracturing/test tanks
Property, Plant And Equipment [Line Items]
Property and equipment, gross	121,206	123,550
Pumping equipment
Property, Plant And Equipment [Line Items]
Property and equipment, gross	103,532	103,689
Finance Lease, Assets And Liabilities, Lessee [Abstract]
Property and equipment, at cost	24,393
Property and equipment, at cost		48,929
Fluid services equipment
Property, Plant And Equipment [Line Items]
Property and equipment, gross	80,061	78,524
Finance Lease, Assets And Liabilities, Lessee [Abstract]
Property and equipment, at cost	35,437
Property and equipment, at cost		35,034
Disposal facilities
Property, Plant And Equipment [Line Items]
Property and equipment, gross	66,995	63,229
Rental equipment
Property, Plant And Equipment [Line Items]
Property and equipment, gross	67,735	62,642
Light vehicles
Property, Plant And Equipment [Line Items]
Property and equipment, gross	29,828	27,080
Finance Lease, Assets And Liabilities, Lessee [Abstract]
Property and equipment, at cost	21,182
Property and equipment, at cost		18,376
Contract drilling equipment
Property, Plant And Equipment [Line Items]
Property and equipment, gross	9,039	9,846
Finance Lease, Assets And Liabilities, Lessee [Abstract]
Property and equipment, at cost	0
Property and equipment, at cost		314
Other
Property, Plant And Equipment [Line Items]
Property and equipment, gross	4,262	4,257
Brine and fresh water stations
Property, Plant And Equipment [Line Items]
Property and equipment, gross	3,192	3,296
Software
Property, Plant And Equipment [Line Items]
Property and equipment, gross	$ 833	$ 857