Other accrued liabilities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Other Accrued Liabilities [Line Items]
Other accrued liabilities	$ 28,996,836	$ 10,064,017
Vessel and voyage expenses
Other Accrued Liabilities [Line Items]
Other accrued liabilities	6,651,395	4,981,596
Scrubber, BWTS and drydocking costs
Other Accrued Liabilities [Line Items]
Other accrued liabilities	16,226,398	0
General and administrative expenses
Other Accrued Liabilities [Line Items]
Other accrued liabilities	6,119,043	4,768,244
Other expenses
Other Accrued Liabilities [Line Items]
Other accrued liabilities	$ 0	$ 314,177