Represents the loss contingency (as a percent) for monitoring and oversight costs.

No definition available.

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- Definition

Represents the number of vessels directly admitted into pool by the entity.

+ References

No definition available.

+ Details

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Namespace Prefix:	gnrt_
Data Type:	xbrli:integerItemType
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- Definition

Represents the amount of working capital reserve recorded by the entity under the time charter.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.3-4)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 3

-Subparagraph a(1)

-Article 5

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 4

-Article 5

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The designation of funds furnished by a borrower to a lender to assure future payments of the borrower's real estate taxes and insurance obligations with respect to a mortgaged property. Escrow deposits may be made for a variety of other purposes such as earnest money and contingent payments. This element excludes replacement reserves which are an escrow separately provided for within the US GAAP taxonomy.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.10)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

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Balance Type:	na
Period Type:	duration

- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 9

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=gnrt_AtlasCharterDisputeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=gnrt_GmrAtlasLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	gnrt_VesselsByNameAxis=gnrt_GenmarProgressMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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- Details

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- Details

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- Details

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- Details

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COMMITMENTS AND CONTINGENCIES (Details) $ in Thousands				1 Months Ended
COMMITMENTS AND CONTINGENCIES (Details) $ in Thousands	Jul. 07, 2014 USD ($)	Mar. 07, 2014 USD ($)	Aug. 02, 2013 USD ($) item	Apr. 30, 2013 USD ($)	Oct. 31, 2010 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)	Apr. 22, 2013 USD ($)
Commitments and Contingencies
Receivables from pool						$ 58,553	$ 50,007
2011 VLCC Pool Dispute
Commitments and Contingencies
Vessel owning subsidiaries in the pool \| item			5
Working capital reserve fund for each vessel			$ 1,900
Receivables from pool						$ 3,446	$ 3,446
Atlas Charter Dispute \| GMR Atlas LLC
Commitments and Contingencies
Security provided by entity pursuant to the escrow agreement								$ 3,498
Amount of damages sought		$ 3,951
Genmar Progress
Commitments and Contingencies
Settlement amount					$ 6,273
Genmar Progress \| Alleged injury to Natural resources
Commitments and Contingencies
Amount of damages sought	$ 7,851			$ 4,940
Genmar Progress \| Loss of beach use
Commitments and Contingencies
Amount of damages sought	848
Genmar Progress \| Injury to Mangroves, Sea Grass and Coral
Commitments and Contingencies
Amount of damages sought	4,906
Genmar Progress \| Uncompensated Damage Assessment Costs
Commitments and Contingencies
Amount of damages sought	83
Genmar Progress \| Monitoring and Oversight
Commitments and Contingencies
Amount of damages sought	$ 2,014
Contingency for monitoring and oversight (as a percent)	35.00%