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Additional area of leased space in a building.

No definition available.

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The area of the building.

No definition available.

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Balance Type:	na
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Funds placed in escrow for the acquisition of a replacement property, as a part of the Section 1031 like-kind exchange.

No definition available.

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Fair value as of the balance sheet date of intangible assets.

No definition available.

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Area of land sold.

No definition available.

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Fair value as of the balance sheet date of real estate assets.

No definition available.

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The amount of real estate assets that are moved out of held for sale.

No definition available.

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Amount of real estate depreciation expense for the period.

No definition available.

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The total gross cost at balance sheet date of construction on real estate projects that are not yet completed.

No definition available.

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Amount of real estate investment property not held for sale, which may include the following: (1) land available-for-development; (2) investments in building and building improvements; (3) tenant allowances; (4) developments in-process; (5) rental properties; and (6) other real estate investments.

No definition available.

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Amount of real estate investment property not including that held for sale, net of accumulated depreciation, which may include the following: (1) land available-for-development; (2) investments in building and building improvements; (3) tenant allowances; (4) developments in-process; (5) rental properties; and (6) other real estate investments.

No definition available.

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Reduction amount of real estate property classified as held for sale due to sale during the period.

No definition available.

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Represents the sale price of land and related assets.

No definition available.

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The capitalized costs incurred during the period (excluded from amortization) to purchase, lease or otherwise acquire an unproved property, including costs of lease bonuses and options to purchase or lease properties, the portion of costs applicable to minerals when land including mineral rights is purchased in fee, brokers' fees, recording fees, legal costs, and other costs incurred in acquiring properties.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 10
-Section S99
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-Subparagraph (SX 210.4-10(c)(7)(ii))
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Area of land held.

No definition available.

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The current amount of expenditures for a real estate project that has not yet been completed.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Amount before accumulated depreciation of fixtures and equipment. Includes, but is not limited to, machinery, equipment, and engines.

No definition available.

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Amount of gain (loss) on sale or disposal of property, plant and equipment assets, excluding oil and gas property and timber property.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of interest capitalized during the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Aggregate of the carrying amounts as of the balance sheet date of investments in building and building improvements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Amount before accumulated depletion of real estate held for productive use, excluding land held for sale.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount before accumulated deprecation and depletion of additions or improvements to real estate held for productive use. Examples include, but are not limited to, walkways, driveways, fences, and parking lots.

No definition available.

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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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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The cash inflow from the sale of land held for investment; excludes sales of land held as inventory or productive use.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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Useful life on which depreciation was computed for entities with a substantial portion of business acquiring and holding investment real estate, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

No definition available.

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Carrying amount as of the balance sheet date of investments in land and buildings held for sale, excluding real estate considered to be inventory of the entity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
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Name:	us-gaap_RealEstateHeldforsale
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The cumulative amount of depreciation for real estate property held for investment purposes.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
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Name:	us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation
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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.

No definition available.

Name:	us-gaap_RealEstatePropertiesLineItems
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Carrying amount as of the balance sheet date of improvements having a life longer than one year that were made for the benefit of one or more tenants.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
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-Section S99
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-Subparagraph (SX 210.7-03.1(f))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Name:	us-gaap_TenantImprovements
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Name:	us-gaap_LongLivedAssetsHeldForSaleByAssetTypeAxis=grif_RealEstateAssetsHeldForSaleMember
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Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=grif_InternationalDriveConcordNorthCarolianMember
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Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=grif_UpperMacungieTownshipLehighCountyPaSiteMember
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Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=grif_SouthwickMaSiteMember
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Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=grif_WindsorMember
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Name:	us-gaap_MajorPropertyClassAxis=us-gaap_LandImprovementsMember
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Data Type:	na
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Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_MajorPropertyClassAxis=us-gaap_BuildingAndBuildingImprovementsMember
Namespace Prefix:
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