Debt and lease liabilities (Schedule of Notes Payable) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Current portion of notes payable	$ (1,815)	$ (1,750)
Net long-term notes payable	6,261	7,629
Notes Payable
Debt Instrument [Line Items]
Notes payable	8,076	9,379
Current portion of notes payable	(1,815)	(1,750)
Net long-term notes payable	$ 6,261	$ 7,629