Aggregate Area of undeveloped Land.

No definition available.

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Balance Type:	na
Period Type:	instant

- Definition

Represents the estimated pretax gain on sale that would be recognized after all costs are incurred and total revenue is recognized.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Funds held in escrow for the acquisition of a replacement property, as a part of the Section 1031 like-kind exchange.

+ References

No definition available.

+ Details

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- Definition

Area of land sold.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Represents the percentage of total cost incurred, related to the sale of real estate property.

+ References

No definition available.

+ Details

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

- Definition

Amount of real estate depreciation expense for the period.

+ References

No definition available.

+ Details

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Balance Type:	debit
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- Definition

Represents the percentage of revenue and pretax gain from sale of real estate property recognized based on the percentage of total costs incurred related to sale.

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

This element represents the amount of deposit received in a land sale transaction.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Represents the sale price of land and related assets.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 605

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 13.A.4(a).Q1 Response)

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-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 13

-Section A

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- Definition

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

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6391110&loc=d3e2941-110230

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Balance Type:	credit
Period Type:	duration

- Definition

Amount of interest capitalized during the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Allowance for Funds Used during Construction

-URI http://asc.fasb.org/extlink&oid=6504829

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

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Balance Type:	debit
Period Type:	duration

- Definition

Revenue from the sale of land in the reporting period.

+ References

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))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

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

- Definition

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.

+ References

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)

-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

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)

-URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph c

-Subparagraph Schedule III

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 28

-Article 12

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

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

- Definition

The cumulative amount of depreciation for real estate property held for investment purposes.

+ References

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))

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 7

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of real estate investment property which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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

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- Details

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Namespace Prefix:
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Period Type:

- Details

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Namespace Prefix:
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- Details

Name:	us-gaap_PropertySubjectToOrAvailableForOperatingLeaseAxis=us-gaap_AssetsHeldForSaleMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertySubjectToOrAvailableForOperatingLeaseAxis=grif_ImperialsFloridaFarmMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorPropertyClassAxis=us-gaap_LandMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorPropertyClassAxis=us-gaap_LandImprovementsMember
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- Details

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Real Estate Assets (Details) $ in Thousands		3 Months Ended			6 Months Ended		12 Months Ended
Real Estate Assets (Details) $ in Thousands	Jun. 01, 2015 USD ($)	May. 31, 2015 USD ($)	Feb. 28, 2015 USD ($)	May. 31, 2014 USD ($)	May. 31, 2015 USD ($)	May. 31, 2014 USD ($)	Nov. 30, 2014 USD ($)	Nov. 30, 2013 USD ($) a
Real Estate Assets
Real estate assets, gross		$ 215,575			$ 215,575		$ 209,284
Accumulated depreciation		(69,146)			(69,146)		(74,762)
Real estate assets, net		146,429			146,429		134,522
Depreciation expense		1,596		$ 1,374	3,146	$ 2,798
Capitalized interest		204		251	367	375
Sales
Deferred revenue		11,763			11,763		8,349
Imperial's landscape nursery business
Sales
Sale price		4,100			4,100
Windsor undeveloped land sale
Sales
Revenue from sale of land					6,844
Pretax gain on land sale					5,097
Held for Sale
Real Estate Assets
Real estate assets, gross		19,726			19,726		9,943
Accumulated depreciation		(8,312)			(8,312)
Real estate assets, net		11,414			11,414		9,943
Imperial's Florida farm
Real Estate Assets
Real estate assets, net		1,451			1,451
Imperial's Florida farm \| Imperial's landscape nursery business
Sales
Deposit received in real estate sale	$ 400
Land
Real Estate Assets
Real estate assets, gross		$ 17,676			$ 17,676		17,955
Land \| Windsor undeveloped land sale
Sales
Number of acres sold \| a								90
Sale price								$ 9,000
Number of acres of undeveloped land \| a								253
Proceeds from land sale deposited in escrow								$ 8,860
Percentage of cost incurred on sale of land		76.00%			76.00%
Percentage of total revenue and pretax gain on sale have been recognized		76.00%
Revenue from sale of land		$ 245		277	$ 1,071	370
Pretax gain on land sale		127		$ 207	749	$ 276
Deferred revenue		2,124			2,124
Estimated pretax gain on sale that would be recognized after incurring total costs and recognizing total revenue		6,678	$ 6,678				6,678	$ 6,678
Land \| Held for Sale
Real Estate Assets
Real estate assets, gross		565			565		286
Land improvements
Real Estate Assets
Real estate assets, gross		14,500			$ 14,500		18,527
Land improvements \| Minimum
Real Estate Assets
Estimated Useful Lives					10 years
Land improvements \| Maximum
Real Estate Assets
Estimated Useful Lives					30 years
Land improvements \| Held for Sale
Real Estate Assets
Real estate assets, gross		4,089			$ 4,089
Buildings and improvements
Real Estate Assets
Real estate assets, gross		136,556			$ 136,556		135,857
Buildings and improvements \| Minimum
Real Estate Assets
Estimated Useful Lives					10 years
Buildings and improvements \| Maximum
Real Estate Assets
Estimated Useful Lives					40 years
Buildings and improvements \| Held for Sale
Real Estate Assets
Real estate assets, gross		1,207			$ 1,207
Tenant improvements
Real Estate Assets
Real estate assets, gross		17,804			17,804		14,820
Machinery and equipment
Real Estate Assets
Real estate assets, gross		7,622			$ 7,622		11,810
Machinery and equipment \| Minimum
Real Estate Assets
Estimated Useful Lives					3 years
Machinery and equipment \| Maximum
Real Estate Assets
Estimated Useful Lives					20 years
Machinery and equipment \| Held for Sale
Real Estate Assets
Real estate assets, gross		4,188			$ 4,188
Construction in progress
Real Estate Assets
Real estate assets, gross		14,418			14,418		3,829
Development costs
Real Estate Assets
Real estate assets, gross		6,999			6,999		6,486
Development costs \| Held for Sale
Real Estate Assets
Real estate assets, gross		$ 9,677			$ 9,677		$ 9,657