Nature of operations and summary of significant accounting policies (Property and Equipment, Net) (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 29, 2019	Jun. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Accounting Policies [Abstract]
Impairment of property and equipment		$ 6,407	$ 0	$ 0	$ 6,407	$ 0
Net proceeds from sale	$ 11,494
Loss on extinguishment of debt	$ (1,624)		(1,624)	$ 0	(1,624)	$ 0
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross			21,018		21,018		$ 50,426
Less accumulated depreciation, amortization and impairment			9,271		9,271		12,449
Property and equipment, excluding land, net			11,747		11,747		37,977
Land			2,518		2,518		5,119
Property and equipment - at cost, net			14,265		14,265		43,096
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross			7,249		7,249		21,482
Office and computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross			6,951		6,951		6,183
Automobiles and trucks
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross			4,911		4,911		3,548
Building and improvements
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross			1,899		1,899		18,693
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross			$ 8		$ 8		$ 520