Vessels - Additional Information (Details)				3 Months Ended				9 Months Ended
	Jul. 27, 2017 USD ($)	Apr. 06, 2017 USD ($)	Jan. 06, 2017 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($) vessel t	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) vessel t	Sep. 30, 2016 USD ($)	Feb. 28, 2017 USD ($) vessel	Nov. 14, 2016 USD ($) t
Property, Plant and Equipment [Line Items]
Number of vessels | vessel						48		48
Dead weight tonnage of operating fleet | t						2,737,100		2,737,100
Proceeds from sale of vessels								$ 18,400,000	$ 13,001,000
Gain on sale of vessels						$ 202,487	$ 299,350	$ 2,100,386	$ (101,860)
SDARI-64 Ultramax Dry Bulk Vessel
Property, Plant and Equipment [Line Items]
Dead weight tonnage of operating fleet | t											64,000
Vessel purchase price											$ 17,900,000
Vessel Redwing
Property, Plant and Equipment [Line Items]
Proceeds from sale of vessels			$ 5,800,000
Gain on disposition of property, plant and equipment			$ 100,000
Greenship Vessels | Eagle Bulk Ultraco LLC
Property, Plant and Equipment [Line Items]
Number of vessels to be purchased | vessel										9
Vessel aggregate purchase price										$ 153,000,000
Vessel purchase agreement, price per vessel										$ 17,000,000
Number of vessels delivered | vessel								9
Vessel Sparrow
Property, Plant and Equipment [Line Items]
Proceeds from sale of vessels		$ 4,800,000
Gain on sale of vessels		$ 1,800,000
Vessel Woodstar
Property, Plant and Equipment [Line Items]
Proceeds from sale of vessels	$ 7,800,000
Gain on sale of vessels	$ 200,000
Vessel Wren | Forecast
Property, Plant and Equipment [Line Items]
Proceeds from sale of vessels					$ 7,600,000
Gain on sale of vessels					$ 50,000
Vessel Avocet | Forecast
Property, Plant and Equipment [Line Items]
Proceeds from sale of vessels				$ 9,600,000
Gain on sale of vessels				$ 300,000