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
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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=51801978&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=49121117&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=51801978&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=49121117&loc=d3e13537-108611

+ Details

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

- Definition

Aggregate revenue during the period from services rendered in the normal course of business, after deducting allowances and discounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(d))
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

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

- Details

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

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_CustomerConcentrationRiskMember
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_MajorCustomersAxis=gnk_ClipperGroupMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_PredecessorMember
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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Concentration Risk (Details) $ in Thousands	6 Months Ended		12 Months Ended
	Dec. 31, 2014 USD ($) customer	Jul. 09, 2014 USD ($) customer	Dec. 31, 2016 USD ($) customer item	Dec. 31, 2015 USD ($) customer item
Concentration Risk
Total revenue earned \| $	$ 1,584		$ 2,340	$ 3,175
Number of financial institutions with which the entity maintains its cash and cash equivalents \| item			4	3
Voyage Revenues \| Customer Concentration Risk
Concentration Risk
Percentage of revenue earned (as a percent)			100.00%
Number of customers	44		52	52
Major Customers	2		3	3
Concentration risk percentage (as a percent)	10.00%		10.00%	10.00%
Voyage Revenues \| Customer Concentration Risk \| Cargill International S.A.
Concentration Risk
Concentration risk percentage (as a percent)	17.06%
Voyage Revenues \| Customer Concentration Risk \| Swissmarine Services S.A.
Concentration Risk
Concentration risk percentage (as a percent)	22.52%		25.31%	24.37%
Voyage Revenues \| Customer Concentration Risk \| Clipper Group
Concentration Risk
Concentration risk percentage (as a percent)			22.96%	19.09%
Voyage Revenues \| Customer Concentration Risk \| Pioneer Navigation Ltd
Concentration Risk
Concentration risk percentage (as a percent)			11.11%	13.03%
Predecessor
Concentration Risk
Total revenue earned \| $		$ 1,701
Predecessor \| Voyage Revenues \| Customer Concentration Risk
Concentration Risk
Percentage of revenue earned (as a percent)		100.00%
Number of customers		33
Major Customers		2
Concentration risk percentage (as a percent)		10.00%
Predecessor \| Voyage Revenues \| Customer Concentration Risk \| Cargill International S.A.
Concentration Risk
Concentration risk percentage (as a percent)		19.37%
Predecessor \| Voyage Revenues \| Customer Concentration Risk \| Swissmarine Services S.A.
Concentration Risk
Concentration risk percentage (as a percent)		20.67%