General Information (Details)	12 Months Ended
	Dec. 31, 2018 segment vessel t
Property, Plant and Equipment [Line Items]
Number of operating segments | segment	1
Number of reportable segments | segment	1
Number of vessels	47
Carrying capacity (in dead weight tonnage) | t	2,705,764
Average age of operating fleet	9 years
Supramax Vessels
Property, Plant and Equipment [Line Items]
Vessels owned and operated	34
Ultramax Vessels
Property, Plant and Equipment [Line Items]
Vessels owned and operated	13
Vessels chartered in	3
Minimum | Ultramax Vessels
Property, Plant and Equipment [Line Items]
Term of charter agreement	1 year
Maximum | Ultramax Vessels
Property, Plant and Equipment [Line Items]
Term of charter agreement	4 years