Basis of Presentation and Significant Accounting Policies - Advance Hire, Prepaid Expenses and Other Current Assets (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Advance hire	$ 5,531,783	$ 3,985,826
Prepaid expenses	3,287,976	4,924,557
Accrued receivables	8,370,234	6,466,068
Margin deposit	2,053,309	269,379
Other current assets	3,178,833	3,124,995
Advance hire, prepaid expenses and other current assets	$ 22,422,135	$ 18,770,825