Property and equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Mar. 21, 2017
Property, Plant and Equipment [Line Items]
Furniture and fixtures	$ 520	$ 519
Automobiles and trucks	3,548	4,464
Machinery and equipment	21,482	22,467
Office and computer equipment	6,183	5,046
Building and improvements	18,693	19,728
Property and equipment, excluding land, gross	50,426	52,224
Less accumulated depreciation and amortization	12,449	6,158
Property and equipment, excluding land, net	37,977	46,066
Land	5,119	4,575
Property and equipment - at cost, net	$ 43,096	$ 50,641	$ 57,378
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	10 years
Automobiles and trucks
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	5 years
Machinery and equipment | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	10 years
Machinery and equipment | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	20 years
Office and computer equipment | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	5 years
Office and computer equipment | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	10 years
Building and improvements | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	10 years
Building and improvements | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	40 years