Recently Adopted Accounting Pronouncements - Additional Information (Details) - USD ($)	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Mar. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit	$ (427,899,178)	$ (427,951,923)	$ (427,164,813)
Other current assets	1,577,556	1,581,535	785,027
Unearned charter hire revenue	6,231,209	7,262,291	$ 5,678,673
Restricted cash	74,917			$ 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	522,485	796,508
Unearned charter hire revenue	$ 718,907	$ 1,583,618