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

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

No definition available.

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

Represents the period after latest vessel delivery date for first periodic repayment of the line of credit facility.

No definition available.

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

Represents the maximum delivered cost per vessel allowed under the credit facility.

No definition available.

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

Represents the maximum percentage of delivered cost per vessel allowed under the credit facility.

No definition available.

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

Represents the maximum percentage of fair market value per vessel at delivery allowed under the credit facility.

No definition available.

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

Represents the percentage of each facility amount due as balloon payment at final maturity.

No definition available.

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

Represents percentage of facility amount due per installment.

No definition available.

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

Represents the percentage of outstanding principal plus interest insured by China Export & Credit Insurance Corporation (Sinosure) to cover political and commercial risks.

No definition available.

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

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

No definition available.

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

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.

No definition available.

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

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.

No definition available.

Name:	us-gaap_LineOfCreditFacilityExpirationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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.

No definition available.

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

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.

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

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

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

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)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585

Name:	us-gaap_RepaymentsOfSecuredDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

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

Name:	us-gaap_DebtInstrumentAxis=gnk_BalticTradingTermLoanFacility2014Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

Name:	gnk_VesselsByNameAxis=gnk_BalticHornetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	gnk_VesselsByNameAxis=gnk_BalticWaspMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_StatementScenarioAxis=gnk_PeriodStartingFromDecember312017ToJune292018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_StatementScenarioAxis=gnk_PeriodStartingFromJune302018ToDecember302018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_StatementScenarioAxis=gnk_PeriodStartingFromDecember312018ToDecember302019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: