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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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Area of leased space in a building.

No definition available.

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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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The amount of fee to be received on a terminated lease.

No definition available.

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Area of land sold.

No definition available.

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Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

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

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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Amount of real estate property that has been reclassed as held for sale during the period.

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 to reduction of previously recognized revenue.

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
-Paragraph 1
-Subparagraph (SX 210.4-10(c)(7)(ii))
-URI http://asc.fasb.org/extlink&oid=82851474&loc=d3e511914-122862

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Area of land held.

No definition available.

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Amount of deferred revenue as of balance sheet date. Deferred revenue represents collections of cash or other assets related to a revenue producing activity for which revenue has not yet been recognized. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

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

Name:	us-gaap_LandImprovements
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The total amount of revenue recognized for the period from operating leases, including minimum lease revenue, contingent revenue, percentage revenue and sublease revenue.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
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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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 10
-Section S99
-Paragraph 6
-Subparagraph (SX 210.5-04.(c) Schedule III)
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 970
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-28)
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Name:	us-gaap_RealEstateAndAccumulatedDepreciationLifeUsedForDepreciation1
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Data Type:	xbrli:durationItemType
Balance Type:	na
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- References

No definition available.

Name:	us-gaap_RealEstateAssetsHeldForDevelopmentAndSaleAbstract
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Data Type:	xbrli:stringItemType
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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
-Paragraph 1
-Subparagraph (SX 210.7-03.1(3))
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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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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Revenue from the sale of commercial, industrial, or residential property during the period. This element is more likely than not relevant to an entity for which real estate operations are a principal activity. If real estate operations are not a principal activity, the reporting entity would likely use a gain (loss) on sale of property, plant, or equipment type element.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(e))
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Name:	us-gaap_SalesOfRealEstate
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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
-Paragraph 1
-Subparagraph (SX 210.7-03.1(f))
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Name:	us-gaap_TenantImprovements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Name:	us-gaap_StatementScenarioAxis=grif_TenantBankruptcyMember
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Name:	us-gaap_LongLivedAssetsHeldForSaleByAssetTypeAxis=grif_RealEstateAssetsHeldForSaleMember
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Data Type:	na
Balance Type:
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Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=grif_InternationalDriveConcordNorthCarolianMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=grif_UpperMacungieTownshipLehighCountyPaSiteMember
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Data Type:	na
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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
Balance Type:
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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
Balance Type:
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Name:	us-gaap_MajorPropertyClassAxis=us-gaap_BuildingAndBuildingImprovementsMember
Namespace Prefix:
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