Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Current portion of environmental remediation obligations	$ 400	$ 600
Current portion of lease liabilities	100	100
Accrued interest payable - related parties	1,600	4,200
Accrued liabilities	3,100	1,700
Other current liabilities	$ 5,200	$ 6,600