Other Current Liabilities (Schedule of Other Current Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Other Current Liabilities [Abstract]
Operating lease liability, current	$ 152	$ 345
Operating lease liability, current statement of financial position	Other current liabilities, total
Due to affiliate	$ 106	98
Accrued professional fees	1,850	1,287
Pension and other post-retirement liabilities	83	82
Accrued liabilities	343	190
Other current liabilities, total	$ 2,534	$ 2,002