DEBT - $108 Million Credit Facility (Details) - Secured Debt - $108 Million Credit Facility $ in Thousands			3 Months Ended
	Nov. 05, 2019 USD ($)	Aug. 14, 2018 USD ($) item	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)
Line of Credit Facility
Term of facilities		5 years
Maximum borrowing capacity		$ 108,000	$ 108,000	$ 108,000		$ 108,000
Proceeds from credit facility					$ 108,000
Number of vessels to serve as collateral under debt agreement | item		6
Maximum facility amount of fair market value of aggregate vessels at delivery (as a percent)					45.00%
Remaining borrowing capacity			0
Repayment of secured debt			$ 1,580	$ 1,580
Repaid value of loan when certain debt terms are met		$ 0
Average age of collateral vessels for repayment of loan		20 years
Amount of repayment per quarter		$ 1,580
Percentage limit of consolidated net income for which dividends can be paid	50.00%
Debt covenant to pay dividends or repurchase stock - Total cash and cash equivalents to total indebtedness (as a percent)	18.75%
Key covenant - Unrestricted cash and cash equivalents minimum		$ 30,000
Key covenant – Percentage of unrestricted cash to total indebtedness		7.50%
Minimum working capital required		$ 0
Maximum total indebtedness to total capitalization (as a ratio)		70
LIBOR | Through September 30, 2019
Line of Credit Facility
Applicable margin over reference rate (as a percent)		2.50%
Agreement To Purchase Ultramax And Capesize Vessels
Line of Credit Facility
Number of vessels committed to be acquired under purchase agreement | item		6
Agreement to Purchase Capesize Drybulk Vessels
Line of Credit Facility
Number of vessels committed to be acquired under purchase agreement | item		4
Agreement To Purchase Ultramax Drybulk Vessels
Line of Credit Facility
Number of vessels committed to be acquired under purchase agreement | item		2
Minimum
Line of Credit Facility
Debt covenant to pay dividends or repurchase stock - Total cash and cash equivalents	$ 100,000
Collateral security maintenance test (as a percent)	200.00%	135.00%
Minimum | LIBOR | Period After September 30, 2019
Line of Credit Facility
Applicable margin over reference rate (as a percent)		2.25%
Maximum | LIBOR | Period After September 30, 2019
Line of Credit Facility
Applicable margin over reference rate (as a percent)		2.75%