Nature of operations and summary of significant accounting policies and going concern (Property and Equipment, Net) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	$ 10,383	$ 10,678
Less accumulated depreciation, amortization and impairment	3,716	3,459
Property and equipment, excluding land, net	6,667	7,219
Land	1,936	1,998
Property and equipment - at cost, net	8,603	9,217
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	3,477	3,543
Office and computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	3,556	3,363
Automobiles and trucks
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	2,678	3,071
Building and improvements
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	664	693
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	$ 8	$ 8