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

Represents the obligation of sublessor towards the cost of alterations to the assets under the lease agreement.

No definition available.

Name:	gnk_OperatingLeasesObligationOfSublessorTowardsCostOfAlterationsOfAssetUnderLease
Namespace Prefix:	gnk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of lease cost recognized by lessee for lease contract.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=77888399&loc=SL77918982-209971

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

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980

Name:	us-gaap_LesseeOperatingLeaseTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

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

Name:	us-gaap_TypeOfArrangementAxis=gnk_LeaseAgreementForOfficeSpaceEnteredApril2011Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	gnk_OperatingLeaseRentExpensePeriodAxis=gnk_OperatingLeaseRentExpensePeriodFrom1October2018To30April2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	gnk_OperatingLeaseRentExpensePeriodAxis=gnk_OperatingLeaseRentExpensePeriodFrom1May2023To30September2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_TypeOfArrangementAxis=gnk_SubSubleaseAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	gnk_OperatingLeaseRentExpensePeriodAxis=gnk_OperatingLeaseRentExpensePeriodUntil31May2015Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: