Recent Accounting Pronouncements - Additional Information (Details) - USD ($)	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017	Sep. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit	$ 421,863,589	$ 427,951,923	$ 427,164,813
Other current assets	2,693,532	1,581,535	785,027
Unearned charter hire revenue	5,974,568	7,262,291	$ 5,678,673
Restricted cash	10,907,592			$ 74,917
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit		787,110
Other current assets	404,059	796,508
Unearned charter hire revenue	$ 223,073	$ 1,583,618