Property and equipment (Estimated Useful Lives of Asset) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Mar. 21, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	$ 10,678	$ 50,426
Less accumulated depreciation and amortization	3,459
Less accumulated depreciation and amortization		12,449
Property and equipment, excluding land, net	7,219	37,977
Land	1,998	5,119
Property and equipment - at cost, net	9,217
Property and equipment - at cost, net		43,096	$ 57,378
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	$ 8	520
Property and equipment, useful life	10 years
Automobiles and trucks
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	$ 3,071	3,548
Property and equipment, useful life	5 years
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	$ 3,543	21,482
Machinery and equipment | Low
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	10 years
Machinery and equipment | High
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	20 years
Office and computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	$ 3,363	6,183
Office and computer equipment | Low
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	5 years
Office and computer equipment | High
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	10 years
Building and improvements
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	$ 693	$ 18,693
Building and improvements | Low
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	10 years
Building and improvements | High
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	40 years