Represents the purchase price of the ballast water treatments systems.

No definition available.

Name:	gnk_BallastWaterTreatmentsSystemsPurchasePrice
Namespace Prefix:	gnk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of vessels to receive ballast water treatments systems.

+ References

No definition available.

+ Details

Name:	gnk_NumberOfVesselsToReceiveBallastWaterTreatmentsSystems
Namespace Prefix:	gnk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Long lived, depreciable assets used for the primary purpose of water transportation, net of accumulated depreciation.

+ References

No definition available.

+ Details

Name:	gnk_VesselsNet
Namespace Prefix:	gnk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_PurchaseCommitmentExcludingLongtermCommitmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of purchase arrangement to be paid in next fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

Name:	us-gaap_PurchaseObligationDueInNextTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of purchase arrangement to be paid in remainder of current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment.

+ References

No definition available.

+ Details

Name:	us-gaap_PurchaseObligationFutureMinimumPaymentsRemainderOfFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_TypeOfArrangementAxis=gnk_PurchaseAgreementsForBallastWaterTreatmentsSystemsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=gnk_PurchaseAgreementOfBWTSForCapesizeVesselsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=gnk_PurchaseAgreementOfBWTSForSupramaxVesselsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

COMMITMENTS AND CONTINGENCIES (Details) $ in Thousands	6 Months Ended
COMMITMENTS AND CONTINGENCIES (Details) $ in Thousands	Dec. 31, 2018 USD ($) item	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Purchase commitment
Vessel assets		$ 991,471	$ 919,114
Remainder of 2021 purchase obligation		345
2022 purchase obligation		3,909
Purchase Agreements for BWTS
Purchase commitment
Number of vessels to receive ballast water treatments systems \| item	36
Vessel assets		$ 18,724	$ 17,009
Purchase Agreement of BWTS for Capesize Vessels
Purchase commitment
BWTS purchase price	$ 900
Purchase Agreement of BWTS for Supramax Vessels
Purchase commitment
BWTS purchase price	$ 600