Supplemental Financial Statement Information (Detailss) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Feb. 28, 2015	Nov. 30, 2014
Real estate assets
Deferred leasing costs	4,171us-gaap_DeferredCostsLeasingNet	$ 3,945us-gaap_DeferredCostsLeasingNet
Deferred rent receivable	3,535us-gaap_DeferredRentReceivablesNet	3,454us-gaap_DeferredRentReceivablesNet
Prepaid expenses	1,544	2,133
Lease receivables	1,225us-gaap_AccountsReceivableNet	1,343us-gaap_AccountsReceivableNet
Mortgage escrows	1,203grif_MortgageEscrows	1,073grif_MortgageEscrows
Deferred financing costs	805us-gaap_DeferredFinanceCostsNet	727us-gaap_DeferredFinanceCostsNet
Intangible assets	461us-gaap_FiniteLivedIntangibleAssetsNet	506us-gaap_FiniteLivedIntangibleAssetsNet
Other	755us-gaap_OtherAssetsMiscellaneous	1,035us-gaap_OtherAssetsMiscellaneous
Total other assets	13,699us-gaap_OtherAssets	14,216us-gaap_OtherAssets
Property and equipment
Accumulated depreciation	(1,012)	(988)
Property and Equipment, net	211us-gaap_PropertyPlantAndEquipmentNet	230us-gaap_PropertyPlantAndEquipmentNet
Machinery and equipment
Property and equipment
Property and Equipment, gross	1,223	$ 1,218
Machinery and equipment \| Minimum
Property and equipment
Estimated Useful Lives	3 years
Machinery and equipment \| Maximum
Property and equipment
Estimated Useful Lives	20 years

This element represents the mortgage escrows.

No definition available.

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Namespace Prefix:	grif_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

For an unclassified balance sheet, the amount due from customers or clients for goods or services that have been delivered or sold in the normal course of business, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

+ References

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

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-Paragraph 1

-Subparagraph (SX 210.9-03.9)

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-Paragraph 1

-Subparagraph (SX 210.7-03.5)

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

- Definition

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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-Paragraph 1

-Subparagraph (c)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 14

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+ Details

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

- Definition

This element represents costs incurred by the lessor that are (a) costs to originate a lease incurred in transactions with independent third parties that (i) result directly from and are essential to acquire that lease and (ii) would not have been incurred had that leasing transaction not occurred and (b) certain costs directly related to specified activities performed by the lessor for that lease. Those activities are: evaluating the prospective lessee's financial condition; evaluating and recording guarantees, collateral, and other security arrangements; negotiating lease terms; preparing and processing lease documents; and closing the transaction. This element is net of accumulated amortization.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 25

-Paragraph 17

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-Paragraph 16

-URI http://asc.fasb.org/extlink&oid=6748888&loc=d3e40588-112709

+ Details

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

- Definition

For an unclassified balance sheet, the carrying amount (net of accumulated amortization) as of the balance sheet date of capitalized costs associated with the issuance of debt instruments (for example, legal, accounting, underwriting, printing, and registration costs) that will be charged against earnings over the life of the debt instruments to which such costs pertain.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28555-108399

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-Publisher FASB

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-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.17)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 17

-Article 5

+ Details

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

- Definition

The cumulative difference between the rental payments required by a lease agreement and the rental income or expense recognized on a straight-line basis, or other systematic and rational basis more representative of the time pattern in which use or benefit is granted or derived from the leased property, expected to be recognized in income or expense over the term of the leased property, by the lessor or lessee, respectively. Such receivable is reduced by allowances attributable to, for instance, credit risk associated with a lessee.

+ References

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 210.5-02.8)

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-URI http://asc.fasb.org/extlink&oid=7501430&loc=d3e39896-112707

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

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-Paragraph 2

-Subparagraph (a)(1)

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

- Definition

The aggregate carrying amounts, as of the balance sheet date, of assets not separately disclosed in the balance sheet.

+ References

+ Details

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

- Definition

Amount of other miscellaneous assets.

+ References

No definition available.

+ Details

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

- Definition

Carrying amount as of the balance sheet date of expenditures made in advance of when the economic benefit of the cost will be realized, and which will be expensed in future periods with the passage of time or when a triggering event occurs.

+ References

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-Publisher FASB

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-Subparagraph (SX 210.9-03.10)

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-Subparagraph (SX 210.7-03.10)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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Balance Type:	debit
Period Type:	instant

- Details

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

- Definition

Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

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-Subparagraph (SX 210.5-02.13)

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+ Details

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

- Definition

Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

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-Number 210

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+ Details

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

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

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Data Type:	xbrli:stringItemType
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Period Type:	duration

- Details

Name:	us-gaap_MajorPropertyClassAxis=us-gaap_MachineryAndEquipmentMember
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Period Type: