Represents the commitment purchase price of convertible preferred stock.

No definition available.

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

- Definition

Represents the commitment of convertible preferred stock shares to be purchased.

+ References

No definition available.

+ Details

Name:	gnk_CommitmentOfSharesToBePurchased
Namespace Prefix:	gnk_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the maximum amount permitted to withdraw for expenses and additional conditions under the debt covenants.

+ References

No definition available.

+ Details

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

- Definition

Amount per vessel maintained under its minimum cash covenants

+ References

No definition available.

+ Details

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

- Definition

Represents the amount of equity financing to be provided by each equity commitment.

+ References

No definition available.

+ Details

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

- Definition

Represents conditions to be fulfilled by proceeds to the company from Equity financing to lenders including equity commitments.

+ References

No definition available.

+ Details

Name:	gnk_EquityFinancingToLendersGross
Namespace Prefix:	gnk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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 the minimum cash requirement through the end of the waiver period.

+ References

No definition available.

+ Details

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

- Definition

Represents the number of credit facilities required to be in compliance with covenants on a quarterly basis.

+ References

No definition available.

+ Details

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

- Definition

Represents the number of credit facilities with a waiver through a specified period.

+ References

No definition available.

+ Details

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

- Definition

Amount of reduction in the commitment to purchase Preferred stock on a pro-rata basis if there is a private placement of Preferred stock to third parties.

+ References

No definition available.

+ Details

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

- Definition

Face amount or stated value per share of common stock.

+ 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 210.5-02.29)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 30
-Article 5

+ Details

Name:	us-gaap_CommonStockParOrStatedValuePerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
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_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

+ Details

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

- Definition

Price of a single share of a number of saleable stocks of a company.

+ References

No definition available.

+ Details

Name:	us-gaap_SharePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_StatementClassOfStockAxis=us-gaap_SeriesAPreferredStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TitleOfIndividualAxis=us-gaap_PresidentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_PrivatePlacementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxis=gnk_CenterbridgePartnersL.pMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxis=gnk_StrategicValuePartnersLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentsInAndAdvancesToAffiliatesCategorizationAxis=gnk_ApolloGlobalManagementLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Commitments (Details) $ / shares in Units, $ in Thousands			9 Months Ended
	Oct. 06, 2016 USD ($) $ / shares shares	Jun. 08, 2016 USD ($)	Sep. 30, 2016 USD ($) item $ / shares	Oct. 27, 2016 USD ($) $ / shares	Jun. 29, 2016 USD ($)	Jun. 28, 2016	Dec. 31, 2015 $ / shares
Line of Credit Facility
Number of credit facilities \| item			9
Number of credit facilities with waiver \| item			9
Common Stock, Par or Stated Value Per Share \| $ / shares			$ 0.01				$ 0.01
Series A Convertible preferred stock \| John C. Wobensmith
Line of Credit Facility
Purchase price (in dollars per share) \| $ / shares				$ 4.85
Commitment to purchase convertible preferred stock				$ 38,600
$98 Million Credit Facility Commitment Letter
Line of Credit Facility
Maximum borrowing capacity			$ 98,000
Collateral security maintenance test (as a percent)					120.00%	140.00%
Second Amended Commitment Letter
Line of Credit Facility
Common Stock, Par or Stated Value Per Share \| $ / shares	$ 0.01
Second Amended Commitment Letter \| Series A Convertible preferred stock
Line of Credit Facility
Purchase price (in dollars per share) \| $ / shares	$ 4.85
Commitment of shares to be purchased \| shares	1,288,660
Commitment Letter
Line of Credit Facility
Maximum borrowing capacity		$ 400,000
Minimum \| $98 Million Credit Facility Commitment Letter
Line of Credit Facility
Minimum cash requirement through the end of the waiver period					$ 25,000
Minimum \| Amended Commitment Letter
Line of Credit Facility
Minimum cash requirement through the end of the waiver period			25,000
Minimum \| Commitment Letter
Line of Credit Facility
Equity Financing		125,000
Maximum \| Amended Commitment Letter
Line of Credit Facility
Maximum cash withdrawal under covenant			10,000
Reduction of cash under covenants (per vessel)			250
Maximum \| Second Amended Commitment Letter \| Series A Convertible preferred stock
Line of Credit Facility
Equity Financing	$ 125,000
Maximum \| Second Amended Commitment Letter \| Series A Convertible preferred stock \| Private placement
Line of Credit Facility
Reduction in amount purchase by pro rate	$ 38,600
Centerbridge Partners L.P \| Firm Commitment \| Series A Convertible preferred stock
Line of Credit Facility
Commitment of shares to be purchased \| shares	6,597,938
Commitment to purchase convertible preferred stock	$ 32,000
Centerbridge Partners L.P \| Backstop Commitment \| Series A Convertible preferred stock
Line of Credit Facility
Commitment of shares to be purchased \| shares	3,402,062
Centerbridge Partners L.P \| Commitment Letter
Line of Credit Facility
Equity financing to be provided by each equity commitment		31,200
Strategic Value Partners LLC \| Firm Commitment \| Series A Convertible preferred stock
Line of Credit Facility
Commitment of shares to be purchased \| shares	7,628,866
Commitment to purchase convertible preferred stock	$ 37,000
Strategic Value Partners LLC \| Backstop Commitment \| Series A Convertible preferred stock
Line of Credit Facility
Commitment of shares to be purchased \| shares	2,371,134
Strategic Value Partners LLC \| Commitment Letter
Line of Credit Facility
Equity financing to be provided by each equity commitment		17,300
Apollo Global Management LLC \| Firm Commitment \| Series A Convertible preferred stock
Line of Credit Facility
Commitment of shares to be purchased \| shares	3,587,629
Commitment to purchase convertible preferred stock	$ 17,400
Apollo Global Management LLC \| Backstop Commitment \| Series A Convertible preferred stock
Line of Credit Facility
Commitment of shares to be purchased \| shares	2,185,568
Apollo Global Management LLC \| Commitment Letter
Line of Credit Facility
Equity financing to be provided by each equity commitment		$ 14,000
Line of Credit Facility \| $98 Million Credit Facility Commitment Letter
Line of Credit Facility
Maximum borrowing capacity			$ 98,000		$ 98,000