Name:	grif_LineOfCreditFacilityContingentIncreaseAggregateMaximumBorrowingCapacity
Namespace Prefix:	grif_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Represents the sale price of land and related assets.

No definition available.

Name:	grif_SalePriceOfLand
Namespace Prefix:	grif_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Area of land held.

No definition available.

Name:	us-gaap_AreaOfLand
Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The cash outflow from the acquisition of a piece of land and anything permanently fixed to it, including buildings, structures on it and so forth, and payments to develop real estate assets by adding improvements on or to a parcel of land. Such improvements may include drainage, utilities, subdividing, access, buildings, and any combination of these elements. Including real estate intended to generate income for the owner; excluding real estate acquired for use by the owner.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585

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

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

No definition available.

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=grif_WindsorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=grif_RestaurantBuildingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=grif_FloridaFarmUsedByImperialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=grif_OrlandoBuildingFloridaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: