Represents the minimum prepayment amount to have the lien released on the vessel.

No definition available.

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

- Definition

Represents the minimum cash required per vessel mortgaged under this facility.

+ References

No definition available.

+ Details

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

- Definition

Represents the consolidated net worth threshold amount calculated as per the terms of the credit facilities' covenants.

+ References

No definition available.

+ Details

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Namespace Prefix:	gnk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the percentage of the value of any subsequent primary equity offerings that is used in the calculation of consolidated net worth threshold amount as per the terms of the credit facilities' covenants.

+ References

No definition available.

+ Details

Name:	gnk_LineOfCreditFacilityCovenantConsolidatedNetWorthThresholdPercentageOfValueOfAnySubsequentPrimaryEquityOfferings
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the aggregate fair value of the mortgaged vessels to be maintained as a percentage of aggregate outstanding principal amount as per the terms of the credit facilities' covenants.

+ References

No definition available.

+ Details

Name:	gnk_LineOfCreditFacilityCovenantFairMarketValueOfMortgagedVesselsAsPercentageOfAggregateOutstandingPrincipalAmount
Namespace Prefix:	gnk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents maximum ratio of financial indebtedness to total assets under the terms of the credit facility leverage covenant.

+ References

No definition available.

+ Details

Name:	gnk_LineOfCreditFacilityLeverageCovenantMaximumRatioOfFinancialIndebtednessToTotalAssets
Namespace Prefix:	gnk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the minimum cash balance per vessel in its fleet required to be maintained by the entity.

+ References

No definition available.

+ Details

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

- Definition

Represents the number of quarterly installments in which the line of credit facility shall be repaid.

+ References

No definition available.

+ Details

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

- Definition

Represents the required payment amount under the line of credit facility due on final maturity date.

+ References

No definition available.

+ Details

Name:	gnk_LineOfCreditFacilityPaymentAmountDueAtMaturity
Namespace Prefix:	gnk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the period after last drawdown date for first periodic repayment of the line of credit facility.

+ References

No definition available.

+ Details

Name:	gnk_LineOfCreditFacilityPeriodAfterLastDrawdownDateForFirstPeriodicRepayment
Namespace Prefix:	gnk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Amount of the required periodic payments of both interest and principal.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityPeriodicPayment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The cash inflow from amounts received from issuance of long-term debt that is wholly or partially secured by collateral. Excludes proceeds from tax exempt secured debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585

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Name:	us-gaap_ProceedsFromIssuanceOfSecuredDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow to repay long-term debt that is wholly or partially secured by collateral. Excludes repayments of tax exempt secured debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
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Name:	us-gaap_RepaymentsOfSecuredDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_SecuredDebtMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=gnk_BalticTradingTermLoanFacilityTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	gnk_VesselsByNameAxis=gnk_BalticTigerAndBalticLionMember
Namespace Prefix:
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DEBT - $44M Term Loan (Details) $ in Thousands			12 Months Ended
DEBT - $44M Term Loan (Details) $ in Thousands	Dec. 23, 2013 USD ($)	Dec. 03, 2013 USD ($) item	Dec. 31, 2016 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Apr. 30, 2015 USD ($)	Aug. 30, 2013 USD ($)
Line of Credit Facility
Minimum cash balance per vessel in the fleet		$ 750				$ 750	$ 750
Secured Debt \| $44 Million Term Loan Facility
Line of Credit Facility
Maximum borrowing capacity		$ 44,000	$ 44,000
Commitment fee on unused daily average unutilized commitment (as a percent)		0.75%
Number of quarterly installments \| item		23
Amount of periodic payment		$ 688
Period after last drawdown date for first periodic repayment		3 months
Final payment amount		$ 28,188
Amount of prepayments to have liens released		$ 18,000
Maximum ratio of financial indebtedness to total assets (as a percent)		70.00%
Consolidated net worth threshold, base amount		$ 786,360
Consolidated net worth threshold, percentage of the value of any subsequent primary equity offerings (as a percent)		50.00%
Collateral security maintenance test (as a percent)		125.00%
Drawdowns during the period	$ 44,000
Repayment of secured debt			$ 38,500
Long-term debt				$ 0	$ 0
Secured Debt \| $44 Million Term Loan Facility \| LIBOR
Line of Credit Facility
Reference rate		three-month LIBOR
Applicable margin over reference rate (as a percent)		3.35%
Secured Debt \| $44 Million Term Loan Facility \| Baltic Lion and Baltic Tiger
Line of Credit Facility
Minimum cash required to be maintained by each collateralized vessel		$ 1,000