Recent Accounting Pronouncements - Operating Lease Assets and Liabilities (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets	$ 10,669,431			$ 10,669,431		$ 20,410,037	$ 20,410,037
Current portion of operating lease liabilities	10,848,313			10,848,313		13,255,978	13,255,978
Lease liabilities - long term	$ 793,917			$ 793,917		$ 8,301,793	8,301,793
Discount rate	5.48%			5.48%
Operating lease impairment	$ 0	$ 400,000	$ 0	$ 352,368	$ 0
Minimum
Lessee, Lease, Description [Line Items]
Discount rate	5.05%			5.05%
Maximum
Lessee, Lease, Description [Line Items]
Discount rate	6.08%			6.08%
Weighted Average
Lessee, Lease, Description [Line Items]
Discount rate	5.50%			5.50%
Chartered-in contracts greater than 12 months
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets	$ 9,171,817			$ 9,171,817			18,442,965
Current portion of operating lease liabilities	10,151,384			10,151,384			12,622,524
Lease liabilities - long term	$ 0			$ 0			6,974,943
Discount rate	5.37%			5.37%
Office leases
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets	$ 1,497,614			$ 1,497,614			1,967,072
Current portion of operating lease liabilities	696,929			696,929			633,454
Lease liabilities - long term	$ 793,917			$ 793,917			$ 1,326,850
Discount rate	5.80%			5.80%