Represents the amount of promissory note receivable by the entity on the first due date.

No definition available.

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

- Definition

Represents the amount of promissory note receivable by the entity on the second due date.

+ References

No definition available.

+ Details

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

- Definition

Represents the amount of annual lease rent receivable by the entity for each of the first five years.

+ References

No definition available.

+ Details

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

- Definition

Represents the amount of non-interest bearing note receivable on the sale of a portion of the entity's business.

+ References

No definition available.

+ Details

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

- Definition

Represents the carrying value of assets sold of the disposal group, including a component of the entity's (discontinued operation).

+ References

No definition available.

+ Details

Name:	grif_DisposalGroupIncludingDiscontinuedOperationCarryingValueOfAssetsSold
Namespace Prefix:	grif_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the aggregate consideration received from the disposal group, including a component of the entity's (discontinued operation).

+ References

No definition available.

+ Details

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

- Definition

Represents the amount of gain (loss) recognized on curtailment of employee benefit plan attributable to disposal group.

+ References

No definition available.

+ Details

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

- Definition

Represents the fair value of non-interest bearing note receivable, for the disposal group, including a component of the entity's discontinued operations.

+ References

No definition available.

+ Details

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

- Definition

Amount of difference between the carrying amount and the sales price of assets sold as part of discontinued.

+ References

No definition available.

+ Details

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

- Definition

Represents the period of lease entered into by the entity.

+ References

No definition available.

+ Details

Name:	grif_LeasePeriod
Namespace Prefix:	grif_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the lease period during which a purchase option is available to the lessee.

+ References

No definition available.

+ Details

Name:	grif_LeasePeriodDuringWhichPurchaseOptionAvailableToLessee
Namespace Prefix:	grif_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the optional extension period of lease entered into by the entity.

+ References

No definition available.

+ Details

Name:	grif_OptionalExtensionPeriodOfLease
Namespace Prefix:	grif_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the period during which non-competition restrictions are applicable.

+ References

No definition available.

+ Details

Name:	grif_PeriodOfNonCompetitionRestrictions
Namespace Prefix:	grif_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the price of land, land improvements and other operating assets under the purchase option available to the lessee.

+ References

No definition available.

+ Details

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

- Definition

Represents the price of a portion of land under the purchase option available to the lessee.

+ References

No definition available.

+ Details

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

- Definition

Amount of cash inflow from the sale of nursery inventory.

+ References

No definition available.

+ Details

Name:	grif_ProceedsFromSaleOfInventory
Namespace Prefix:	grif_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the discount rate applied to non-interest bearing note receivable.

+ References

No definition available.

+ Details

Name:	grif_PromissoryNoteReceivableDiscountRate
Namespace Prefix:	grif_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of installments in which the promissory note receivable by the entity will become due.

+ References

No definition available.

+ Details

Name:	grif_PromissoryNoteReceivableNumberOfInstallments
Namespace Prefix:	grif_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.14)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Amount of operating income (loss) attributable to disposal group, including, but not limited to, discontinued operation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721673-107760

+ Details

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

- Definition

Amount of other expense attributable to disposal group, including, but not limited to, discontinued operation.

+ References

+ Details

Name:	us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of revenue attributable to disposal group, including, but not limited to, discontinued operation.

+ References

+ Details

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

- References

No definition available.

+ Details

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

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

Amount before tax of reclassification adjustment from accumulated other comprehensive income (loss) for actuarial gain (loss) related to pension and other postretirement benefit plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e637-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e689-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (j)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

+ Details

Name:	us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3179-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

+ Details

Name:	us-gaap_ProceedsFromDivestitureOfBusinesses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DiscontinuedOperationsDisposedOfBySaleMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=grif_LandscapeNurseryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=grif_InventoryAndCertainAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=grif_ProductionNurseryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Discontinued Operations (Details) $ in Thousands		12 Months Ended
Discontinued Operations (Details) $ in Thousands	Jan. 08, 2014 USD ($)	Nov. 30, 2016 USD ($)	Nov. 30, 2014 USD ($) item	Nov. 30, 2015 USD ($)	Jun. 01, 2015 USD ($)	Jun. 01, 2014 USD ($)
Discontinued operation
Property and equipment accumulated depreciation		$ 844		$ 996
Pretax loss from the sale of assets
Proceeds from sale of real estate assets			$ 169
Discontinued operations
Discontinued operation
Proceeds from sale of nursery inventory			732
Pretax loss from the sale of assets
Proceeds from sale of real estate assets			732
Imperial's landscape nursery business \| Inventory and certain assets
Discontinued operation
Present value			4,036
Imperial's landscape nursery business \| Discontinued operations
Discontinued operation
Discount rate (as a percent)	7.00%
Present value	$ 4,036
Period of non-competition restrictions	4 years
Net annual rent receivable for each of the first five years		$ 500
Income statement disclosure
Reclassification of actuarial gains related to entity's postretirement benefits program			451
Pretax loss from the sale of assets
Consideration received			4,768
Carrying value of assets sold, principally inventory			(4,561)
Curtailment of employee benefit program			309
Severance and other expenses			(563)
Pretax loss			$ (47)
Imperial's landscape nursery business \| Discontinued operations \| Inventory and certain assets
Discontinued operation
Proceeds from sale of nursery inventory	$ 732
Non-interest bearing note receivable	$ 4,250
Number of installments in which promissory note will become due \| item			2
Amount of promissory note receivable due on June 1, 2014						$ 2,750
Amount of promissory note receivable due on June 1, 2015					$ 1,500
Income statement disclosure
Sales revenue			$ 159
Pre tax income			$ 259
Imperial's landscape nursery business \| Discontinued operations \| Connecticut production nursery
Discontinued operation
Lease period		10 years
Optional extension period of lease		15 years
Period during which purchase option is available		13 years
Price of land, land improvements and other operating assets under option to purchase		$ 9,500
Price of a portion of land under option to purchase		$ 7,000