Debt covenant minimum period for the collateral time charters.

No definition available.

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- Definition

The debt covenant period for replacement of new vessel having an equal or greater appraised value if in compliance with collateral maintenance test.

+ References

No definition available.

+ Details

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- Definition

Amount of minimum restricted cash required per terms of the credit facility.

+ References

No definition available.

+ Details

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

- Definition

Debt covenant unrestricted cash and cash equivalents minimum.

+ References

No definition available.

+ Details

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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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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

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

- Definition

Amount of line of credit facility future amortization payments per quarter per facility agreement. Upon payment of excess cash flow to lenders, these amortization payments shall be adjusted.

+ References

No definition available.

+ Details

Name:	gnk_LineOfCreditFacilityFutureAmortizationPaymentsPerQuarter
Namespace Prefix:	gnk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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 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

Number of oldest vessels identified for sale, for which debt will be paid down.

+ References

No definition available.

+ Details

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

- 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://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 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/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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-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

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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://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

+ Details

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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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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- Details

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DEBT - $460 Million Credit Facility (Details) $ in Thousands			3 Months Ended	6 Months Ended
	Jun. 05, 2018 USD ($)	May 31, 2018 USD ($) item	Jun. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Line of Credit Facility
Minimum restricted cash required		$ 0
Secured Debt \| $460 Million Credit Facility
Line of Credit Facility
Term of facilities		5 years
Maximum borrowing capacity		$ 460,000	$ 460,000	$ 460,000
Proceeds from credit facility	$ 460,000			460,000
Number of oldest vessels identified for sale for which debt will be paid down \| item		7
Remaining borrowing capacity			0	0
Repayment of secured debt			0	0
Long-term debt			$ 443,937	$ 443,937	$ 0
Amortization payments per quarter		$ 15,000
Repaid value of loan when certain debt terms are met		$ 0
Average age of collateral vessels for repayment of loan		17 years
Percentage limit of consolidated net income for which dividends can be paid		50.00%
Collateral vessel replacement period		120 days
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		0.70
Key covenant – Minimum time charters period		24 months
Secured Debt \| $460 Million Credit Facility \| Period upon final maturity on May 31, 2023
Line of Credit Facility
Final payment amount		$ 190,000
Secured Debt \| $460 Million Credit Facility \| LIBOR \| Through December 31, 2018
Line of Credit Facility
Applicable margin over reference rate (as a percent)		3.25%
Secured Debt \| Minimum \| $460 Million Credit Facility
Line of Credit Facility
Collateral security maintenance test (as a percent)		135.00%
Secured Debt \| 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%
Secured Debt \| Maximum \| $460 Million Credit Facility
Line of Credit Facility
Collateral security maintenance test (as a percent)		200.00%
Secured Debt \| 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%