Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued capital costs	$ 3,353	$ 33,105
Accrued operating expenses	7,329	12,149
Other accrued liabilities	2,172	4,956
Total accrued liabilities	$ 12,854	$ 50,210