Accrued Liabilities (Details) - Accrued liabilities - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities (Details) - Accrued liabilities [Line Items]
Directors fees	$ 1,148	$ 1,007
Taxes payable	1,083	972
Deferred revenues	1,000	1,003
Interest payable	731	498
Compensation and employee benefits	636	596
Current portion of pension liability (see Note 14)	623	576
Warranty reserve	405	322
Audit fees	148	165
Other	558	642
Accrued Liabilities, Total	$ 6,332	$ 5,781