Nature of operations and summary of significant accounting policies and going concern (Property and Equipment, Net) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	$ 9,976	$ 10,678
Less accumulated depreciation, amortization and impairment	3,963	3,459
Property and equipment, excluding land, net	6,013	7,219
Land	1,935	1,998
Property and equipment, net	7,948	9,217
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	3,229	3,543
Office and computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	3,606	3,363
Automobiles and trucks
Property, Plant and Equipment [Line Items]
Property and equipment, excluding land, gross	2,469	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