Other Current Liabilities (Schedule of Other Current Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Other Current Liabilities [Abstract]
Operating lease liability, current	$ 470	$ 345
Operating lease liability, current statement of financial position	Other current liabilities, total	Other current liabilities, total
Due to affiliate	$ 198	$ 98
Accrued professional fees	1,163	1,287
Pension and other post-retirement liabilities	83	82
Income taxes payable	34	0
Accrued liabilities	232	190
Other current liabilities, total	$ 2,180	$ 2,002