Trade accounts receivable - net - Reserves for doubtful accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Trade accounts receivable - net
Beginning Balance	$ 1,597	$ 710
Allowance for doubtful accounts	44	880
Deductions and Other	(57)	7
Ending Balance	$ 1,584	$ 1,597