Name:	gnrt_BusinessCombinationShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsFairValueAssumed
Namespace Prefix:	gnrt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Exercise price per warrant of warrants or rights outstanding.

No definition available.

Name:	gnrt_ClassOfWarrantOrRightExercisePricePerWarrantOfWarrantsOrRights
Namespace Prefix:	gnrt_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

The multiplier used for converting the number of shares issuable under equity-based compensation plan of acquiree to shares issuable under plan of reporting entity.

No definition available.

Name:	gnrt_ShareBasedCompensationArrangementByShareBasedPaymentAwardMultiplierForConvertingNumberOfSharesIssuableUnderPlanOfAcquiree
Namespace Prefix:	gnrt_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

The denominator used for converting the exercise price of outstanding awards issued under plan of acquiree to exercise price under plan of reporting entity.

No definition available.

Name:	gnrt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsDenominatorForConvertingExercisePriceOfOutstandingAwardsUnderPlanOfAcquiree
Namespace Prefix:	gnrt_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

Represents gross number of shares per option after modification.

No definition available.

Name:	gnrt_ShareBasedCompensationArrangementByShareBasedPaymentAwardsNumberOfSharesPerOptionAfterModification
Namespace Prefix:	gnrt_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Represents gross number of shares per option prior to modification.

No definition available.

Name:	gnrt_ShareBasedCompensationArrangementByShareBasedPaymentAwardsNumberOfSharesPerOptionPriorToModification
Namespace Prefix:	gnrt_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Represents the number of stock options modified.

No definition available.

Name:	gnrt_ShareBasedCompensationArrangementByShareBasedPaymentsAwardsNumberOfStockOptionsModified
Namespace Prefix:	gnrt_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Warrant agreement abstract.

No definition available.

Name:	gnrt_WarrantAgreementAbstract
Namespace Prefix:	gnrt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Rollforward for warrants.

No definition available.

Name:	gnrt_WarrantsOutstandingRollforward
Namespace Prefix:	gnrt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Exercise price per share or per unit of warrants or rights outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(2))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Name:	us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Number of warrants or rights outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Name:	us-gaap_ClassOfWarrantOrRightOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Weighted average price at which option holders acquired shares when converting their stock options into shares.

No definition available.

Name:	us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_CounterpartyNameAxis=gnrt_Navig8Warrantholder2015Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	dei_LegalEntityAxis=gnrt_Navig8CrudeTankersIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: