Represents the number customers of the entity from which revenue was earned.

No definition available.

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

- Definition

Represents the number of financial institutions with which the entity maintains its cash and cash equivalents.

+ References

No definition available.

+ Details

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

- Definition

Percentage of revenue earned from customers.

+ References

No definition available.

+ Details

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

- Definition

Represents the number of external customers from which the entity generated 10 percent or more of revenues.

+ References

No definition available.

+ Details

Name:	gnk_EntityWideRevenueMajorCustomerNumber
Namespace Prefix:	gnk_
Data Type:	xbrli:integerItemType
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_ConcentrationRiskLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 18

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13531-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 21

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13537-108611

+ Details

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of interest rate derivative instruments held by the entity at the reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5580258-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5579245-113959

+ Details

Name:	us-gaap_NumberOfInterestRateDerivativesHeld
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=gnk_VoyageRevenuesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorCustomersAxis=gnk_CargillInternationalSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorCustomersAxis=gnk_SwissmarineServicesSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_MajorCustomersAxis=gnk_PacificBasinCharteringLtdMember
Namespace Prefix:
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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 4)	6 Months Ended		12 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 4)	Dec. 31, 2014 customer item	Jul. 09, 2014 customer	Dec. 31, 2013 derivative customer item	Dec. 31, 2012 customer
Concentration Risk [Line Items]
Percentage of revenue earned (as a percent)	100.00%
Number of customers	44
Number of financial institutions with which the entity maintains its cash and cash equivalents \| item	3
Number of interest rate swaps \| item	0
Voyage Revenues
Concentration Risk [Line Items]
Major Customers	2
Concentration risk percentage (as a percent)	10.00%
Voyage Revenues \| Cargill International S.A.
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)	17.06%
Voyage Revenues \| Swissmarine Services S.A.
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)	22.52%
Predecessor
Concentration Risk [Line Items]
Percentage of revenue earned (as a percent)		100.00%	100.00%	100.00%
Number of customers		33	48	43
Number of financial institutions with which the entity maintains its cash and cash equivalents \| item			4
Number of interest rate swaps \| derivative			4
Predecessor \| Voyage Revenues
Concentration Risk [Line Items]
Major Customers		2	3	1
Concentration risk percentage (as a percent)		10.00%	10.00%	10.00%
Predecessor \| Voyage Revenues \| Cargill International S.A.
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)		19.37%	21.45%	31.27%
Predecessor \| Voyage Revenues \| Swissmarine Services S.A.
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)		20.67%	18.73%
Predecessor \| Voyage Revenues \| Pacific Basin Chartering Ltd.
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)			10.30%