Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid expenses	$ 1,013	$ 1,234
Deposits	111	364
Tradable equity securities	0	5,069
Derivative asset (Note 6)	0	3,121
Other current assets	58	1,510
Total prepaid expenses and other current assets	$ 1,182	$ 11,298