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

Carrying amount due after one year of the balance sheet date (or one operating cycle, if longer) of amounts due under fresh start lease asset.

No definition available.

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

Carrying amount due after one year of the balance sheet date (or one operating cycle, if longer) of amounts due under long-term due from charterers.

No definition available.

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

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

No definition available.

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

Carrying amount due after one year of the balance sheet date (or one operating cycle, if longer) of amount due in settlement of a claim for reimbursement from an insurance company when the Company has suffered a loss covered under an insurance policy.

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 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

Aggregate carrying amount, as of the balance sheet date, of noncurrent assets not separately disclosed in the balance sheet. Noncurrent assets are expected to be realized or consumed after one year (or the normal operating cycle, if longer).

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

- References

No definition available.