DEBT - $495 Million Credit Facility (Details) - Secured Debt $ in Thousands											3 Months Ended		9 Months Ended
	Sep. 23, 2019 USD ($)	Aug. 28, 2019 USD ($)	Jul. 05, 2019 USD ($)	Jun. 30, 2019 USD ($)	May 10, 2019 USD ($)	Apr. 15, 2019 USD ($)	Feb. 28, 2019 USD ($) item	Oct. 16, 2018 USD ($)	Jun. 05, 2018 USD ($)	May 31, 2018 USD ($) item	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) item	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
$495 Million Credit Facility
Line of Credit Facility
Maximum borrowing capacity						$ 495,000	$ 495,000				$ 495,000	$ 495,000	$ 495,000	$ 495,000	$ 495,000
Number of oldest vessels identified for sale for which debt will be paid down | item													7
Remaining borrowing capacity											13,128		$ 13,128
Drawdowns during the period													21,500	460,000
Repayment of secured debt											15,000	0	49,575	0
Long-term debt											404,424		$ 404,424		$ 430,577
Vessel sale proceeds utilized as a loan repayment						4,947
Prepayment of amortization payment before due date			$ 15,000		$ 15,000
Amount of periodic payment				$ 14,864
Percentage limit of consolidated net income for which dividends can be paid													50.00%
Collateral vessel replacement period													180 days
Key covenant - Unrestricted cash and cash equivalents minimum											30,000		$ 30,000
Key covenant – Percentage of unrestricted cash to total indebtedness													7.50%
Minimum restricted cash required											0		$ 0
Minimum working capital required											0		$ 0
Maximum total indebtedness to total capitalization (as a ratio)													0.70
Key covenant – Minimum time charters period													24 months
$495 Million Credit Facility | Genco Cavalier
Line of Credit Facility
Maximum borrowing capacity								$ 495,000
Vessel sale proceeds utilized as a loan repayment						4,947
Collateral vessel replacement period								180 days
$460 Million Credit Facility
Line of Credit Facility
Term of facilities										5 years
Maximum borrowing capacity										$ 460,000		$ 460,000		$ 460,000
Number of oldest vessels identified for sale for which debt will be paid down | item										7
Drawdowns during the period									$ 460,000
Amount of periodic payment				14,864
Final payment amount				$ 187,601
Repaid value of loan when certain debt terms are met										$ 0
Average age of collateral vessels for repayment of loan										17 years
$460 Million Credit Facility | Period after December 31, 2018
Line of Credit Facility
Amount of periodic payment										$ 15,000
$460 Million Credit Facility | Period upon final maturity on May 31, 2023
Line of Credit Facility
Final payment amount										$ 190,000
$460 Million Credit Facility | LIBOR | Through December 31, 2018
Line of Credit Facility
Applicable margin over reference rate (as a percent)										3.25%
$35,000 Scrubber Tranche
Line of Credit Facility
Maximum borrowing capacity						34,628	$ 35,000				$ 35,000		$ 35,000
Drawdowns during the period	$ 12,200	$ 9,300
Number of Capesize vessels for which the scrubber installation will be financed | item							17
Percentage of scrubber costs to be financed							90.00%
$35,000 Scrubber Tranche | Period To March 30, 2020
Line of Credit Facility
Minimum amount required per borrowing							$ 5,000
$35,000 Scrubber Tranche | Through September 30, 2019
Line of Credit Facility
Applicable margin over reference rate (as a percent)							2.50%
$35,000 Scrubber Tranche | Period After March 31, 2020
Line of Credit Facility
Term of facilities							4 years
Amount of periodic payment						$ 2,473	$ 2,500
Minimum | $495 Million Credit Facility
Line of Credit Facility
Collateral security maintenance test (as a percent)											135.00%		135.00%
Minimum | $460 Million Credit Facility | LIBOR | Period after December 31, 2018
Line of Credit Facility
Applicable margin over reference rate (as a percent)										3.00%
Minimum | $35,000 Scrubber Tranche | Period After September 30, 2019
Line of Credit Facility
Applicable margin over reference rate (as a percent)							2.25%
Maximum | $495 Million Credit Facility
Line of Credit Facility
Collateral security maintenance test (as a percent)											200.00%		200.00%
Maximum | $460 Million Credit Facility | LIBOR | Period after December 31, 2018
Line of Credit Facility
Applicable margin over reference rate (as a percent)										3.50%
Maximum | $35,000 Scrubber Tranche | Period After September 30, 2019
Line of Credit Facility
Applicable margin over reference rate (as a percent)							2.75%