Basis of Presentation and General Information (Details)		6 Months Ended
	May 10, 2017 t	Jun. 30, 2018 USD ($) segment vessel t	Jan. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)
Property, Plant and Equipment [Line Items]
Number of business segments | segment		1
Vessels in operation | vessel		47
Dead weight tonnage of operating fleet | t		2,693,430
Average age of operating fleet (in years)		8 years 210 days
Accumulated deficit | $		$ 424,448,411	$ 427,951,923	$ 427,164,813
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Property, Plant and Equipment [Line Items]
Accumulated deficit | $			787,110
Unearned revenue and other current assets | $			$ 800,000
2013 Built Japanese Vessel
Property, Plant and Equipment [Line Items]
Dead weight tonnage of operating fleet | t	61,400	61,400
Charters agreement term	3 years	3 years
Supramax Vessels
Property, Plant and Equipment [Line Items]
Vessels in operation | vessel		35
Ultramax Vessels
Property, Plant and Equipment [Line Items]
Vessels in operation | vessel		12