Supplemental Financial Statement Information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Nov. 30, 2014	Nov. 30, 2013	Dec. 01, 2012
Supplemental Cash Flow Information
Accumulated amortization	$ 1,251	$ 1,073
Amortization expense	178us-gaap_AmortizationOfIntangibleAssets	171us-gaap_AmortizationOfIntangibleAssets	200us-gaap_AmortizationOfIntangibleAssets
Estimated amortization expense
2015	166
2016	77
2017	44
2018	27
2019	27
Deferred leasing costs	3,945us-gaap_DeferredCostsLeasingNet	3,598us-gaap_DeferredCostsLeasingNet
Deferred rent receivable	3,454us-gaap_DeferredRentReceivablesNet	3,553us-gaap_DeferredRentReceivablesNet
Prepaid real estate assets	2,133grif_PrepaidRealEstateAssets	2,065grif_PrepaidRealEstateAssets
Accounts receivable	1,343us-gaap_AccountsReceivableNet	258us-gaap_AccountsReceivableNet
Mortgage escrows	1,073grif_MortgageEscrows	1,032grif_MortgageEscrows
Deferred financing costs	727us-gaap_DeferredFinanceCostsNet	903us-gaap_DeferredFinanceCostsNet
Intangible assets, net of amortization	506us-gaap_FiniteLivedIntangibleAssetsNet	684us-gaap_FiniteLivedIntangibleAssetsNet
Other	1,035us-gaap_OtherAssetsMiscellaneous	1,541us-gaap_OtherAssetsMiscellaneous
Total other assets	$ 14,216us-gaap_OtherAssets	$ 13,634us-gaap_OtherAssets

This element represents the mortgage escrows.

No definition available.

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

- Definition

This element represents the prepaid real estate assets.

+ References

No definition available.

+ Details

Name:	grif_PrepaidRealEstateAssets
Namespace Prefix:	grif_
Data Type:	xbrli:monetaryItemType
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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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 3

-Article 5

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-Publisher FASB

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-Topic 942

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-Paragraph 1

-Subparagraph (SX 210.9-03.9)

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-Subparagraph (SX 210.7-03.5)

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- Definition

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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- 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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+ Details

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- 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.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

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-Paragraph 3

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 17

-Article 5

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- 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

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+ Details

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- Definition

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

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

-Paragraph 2

-Subparagraph (a)(1)

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+ Details

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Period Type:	instant

- Definition

Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References