Debt covenant unrestricted cash and cash equivalents minimum.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Debt covenant pertaining to unrestricted cash and cash equivalents to total indebtedness.

+ References

No definition available.

+ Details

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

- Definition

Represents the average age of collateral vessels for repayment of loan.

+ References

No definition available.

+ Details

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

- 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 the maximum percentage of fair market value of aggregate vessels at delivery allowed under the credit facility.

+ References

No definition available.

+ Details

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

- Definition

Represents the maximum ratio of total debt outstanding to total capitalization.

+ References

No definition available.

+ Details

Name:	gnk_MaximumTotalDebtToTotalCapitalizationRatio
Namespace Prefix:	gnk_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum working capital required per terms of the credit facility.

+ References

No definition available.

+ Details

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

- Definition

Represents the number of vessels committed to be acquired by the entity under purchase agreement.

+ References

No definition available.

+ Details

Name:	gnk_NumberOfVesselsCommittedToBeAcquiredUnderPurchaseAgreement
Namespace Prefix:	gnk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage limit of consolidated net income for dividends to be paid if collateral maintenance test is met.

+ References

No definition available.

+ Details

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

- Definition

The value of loan when the average age of the vessels serving as collateral from time to time reaches a specified period, following an initial non-amortization period and all additional debt covenants are met.

+ References

No definition available.

+ Details

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

- 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

Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
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://fasb.org/us-gaap/role/ref/legacyRef
-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

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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

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

- 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/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585

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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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Name:	us-gaap_CreditFacilityAxis=us-gaap_SecuredDebtMember
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DEBT - $108 Million Credit Facility (Details) $ in Thousands		3 Months Ended			6 Months Ended
	Aug. 14, 2018 USD ($) item	Jun. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)	Jul. 12, 2018 item	Jun. 06, 2018 item
Agreement To Purchase Ultramax And Capesize Vessels
Line of Credit Facility
Number of vessels committed to be acquired under purchase agreement \| item									4
Agreement to Purchase Capesize Drybulk Vessels
Line of Credit Facility
Number of vessels committed to be acquired under purchase agreement \| item								2	2
Agreement To Purchase Ultramax Drybulk Vessels
Line of Credit Facility
Number of vessels committed to be acquired under purchase agreement \| item									2
Secured Debt \| $108 Million Credit Facility
Line of Credit Facility
Term of facilities	5 years
Maximum borrowing capacity	$ 108,000	$ 108,000	$ 108,000		$ 108,000		$ 108,000
Proceeds from credit facility			$ 108,000
Maximum facility amount of fair market value of aggregate vessels at delivery (as a percent)			45.00%
Remaining borrowing capacity		0			0
Repayment of secured debt		1,580		$ 0	3,160	$ 0
Long-term debt		$ 101,606			$ 101,606		$ 104,571
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%
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)	0.70
Secured Debt \| $108 Million Credit Facility \| LIBOR \| Through September 30, 2019
Line of Credit Facility
Applicable margin over reference rate (as a percent)	2.50%
Secured Debt \| $108 Million Credit Facility \| Agreement To Purchase Ultramax And Capesize Vessels
Line of Credit Facility
Number of vessels committed to be acquired under purchase agreement \| item	6
Secured Debt \| $108 Million Credit Facility \| Agreement to Purchase Capesize Drybulk Vessels
Line of Credit Facility
Number of vessels committed to be acquired under purchase agreement \| item	4
Secured Debt \| $108 Million Credit Facility \| Agreement To Purchase Ultramax Drybulk Vessels
Line of Credit Facility
Number of vessels committed to be acquired under purchase agreement \| item	2
Secured Debt \| Minimum \| $108 Million Credit Facility
Line of Credit Facility
Collateral security maintenance test (as a percent)	135.00%
Secured Debt \| Minimum \| $108 Million Credit Facility \| LIBOR \| Period After September 30, 2019
Line of Credit Facility
Applicable margin over reference rate (as a percent)	2.25%
Secured Debt \| Maximum \| $108 Million Credit Facility
Line of Credit Facility
Collateral security maintenance test (as a percent)	200.00%
Secured Debt \| Maximum \| $108 Million Credit Facility \| LIBOR \| Period After September 30, 2019
Line of Credit Facility
Applicable margin over reference rate (as a percent)	2.75%