Other Current Liabilities (Schedule of Other Current Liabilities) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Other Current Liabilities [Abstract]
Operating lease liability, current	$ 677	$ 652
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other current liabilities, total
Due to affiliate	$ 0	5
Accrued professional fees	1,595	1,419
Pension and other postretirement liabilities	77	77
Income taxes payable	0	673
Accrued liabilities	125	57
Other current liabilities, total	$ 2,474	$ 2,883