Recent Accounting Pronouncements - Lease Expense (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Lessee, Lease, Description [Line Items]
Sublease income from chartered-in contracts greater than 12 months *	$ 7,550,105	$ 1,308,833	$ 14,303,242	$ 6,598,871
Charter hire expenses
Lessee, Lease, Description [Line Items]
Lease expense for chartered-in contracts less than 12 months	5,856,694	2,560,224	13,511,509	6,348,081
Operating lease, expense	4,867,043	2,500,279	11,861,992	9,472,728
Lease cost	10,723,737	5,060,503	25,373,501	15,820,809
General and administrative expenses
Lessee, Lease, Description [Line Items]
Operating lease, expense	$ 188,880	$ 185,525	$ 465,269	$ 548,349