Represents the period of trailing industry average charter rates for each vessel class for testing goodwill impairment.

No definition available.

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

- Definition

Percentage considered to method of discounted cash flows that were used for calculating the fair value of each reporting unit.

+ References

No definition available.

+ Details

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

- Definition

Percentage considered to method of fair value of assets that were used for calculating the fair value of each reporting unit.

+ References

No definition available.

+ Details

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

- Definition

Percentage considered to method of public trading price that were used for calculating the fair value of each reporting unit.

+ References

No definition available.

+ Details

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

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

+ Details

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13854-109267

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13777-109266

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_GoodwillLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfOperatingSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of reporting units tested for impairment of goodwill. A reporting unit is an operating segment or one level below an operating segment.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Reporting Unit

-URI http://asc.fasb.org/extlink&oid=6523643

+ Details

Name:	us-gaap_NumberOfReportingUnits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

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

GOODWILL IMPAIRMENT (Details) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
GOODWILL IMPAIRMENT (Details) $ in Thousands	Dec. 31, 2014 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2014 segment item	Jul. 09, 2014 USD ($)
Goodwill
Number of operating segments \| segment			2
Number of Reporting Units \| item			2
Period of industry average charter rates for each vessel class			10 years
Goodwill, Impairment Loss	$ 166,067	$ 166,067
Percentage of fair value assets used method			75.00%
Percentage of public trading price method			25.00%
Percentage of discounted cash flow method			0.00%
Predecessor
Goodwill
Goodwill				$ 166,067