Represents the area of fully leased building acquired.

No definition available.

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

- Definition

Represents the area of land acquired.

+ References

No definition available.

+ Details

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

- Definition

Represents the area of land on which building is constructed.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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- Definition

Represents the percentage of total net sales made through one buying cooperative.

+ References

No definition available.

+ Details

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

- Details

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Balance Type:	na
Period Type:	duration

- Definition

Represents the length of each fiscal year.

+ References

No definition available.

+ Details

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

- Definition

Represents the number of buildings expected to be built by the entity.

+ References

No definition available.

+ Details

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

- Definition

Represents the number of major customers of the entity.

+ References

No definition available.

+ Details

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

- Definition

Represents the conditional period defined with a significant accounting policy to classify an asset as held for sale.

+ References

No definition available.

+ Details

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Namespace Prefix:	grif_
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- Details

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- Details

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Balance Type:	na
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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 18

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

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-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 21

-Subparagraph (a)

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

-Paragraph 20

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-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13531-108611

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Data Type:	num:percentItemType
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- Details

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- Definition

Investment in short-term money-market instruments (such as commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and so forth) which are highly liquid (that is, readily convertible to known amounts of cash) and so near their maturity that they present an insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify as cash equivalents by definition. Original maturity means an original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash Equivalents

-URI http://asc.fasb.org/extlink&oid=6507016

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 8, 9

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

- Definition

Number of interest rate derivative instruments held by the entity at the reporting date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

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Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 01, 2012 acre item	Dec. 03, 2011	Nov. 27, 2010 acre sqft
Fiscal Year
Length of fiscal year	364 days	371 days	364 days
Cash and Cash Equivalents
Money market funds invested in U.S. Treasury obligations	$ 175	$ 175
Real Estate Assets
Period within which sale of property is probable and is expected to be completed	1 year
Interest Rate Swap Agreements
Number of Interest Rate Derivatives Held	3
Risks and uncertainties
Area of leased building acquired (in square feet)			120,000
Area of land acquired (in acres)			51
Number of buildings expected to be built	2
Area of land on which building is constructed (in acres)	228,000
Imperial Nurseries, Inc. \| Net sales \| Customer concentration risk \| Group of largest customers
Concentrations
Number of major customers	10
Concentrations risk (as a percent)	18.00%	20.00%	25.00%
Imperial Nurseries, Inc. \| Net sales \| Customer concentration risk \| Buying cooperatives
Concentrations
Number of major customers	1
Concentrations risk (as a percent)	23.00%
Total net sales made through one buying cooperative (as a percent)	15.00%
Imperial Nurseries, Inc. \| Accounts receivable \| Customer concentration risk \| Buying cooperatives
Concentrations
Number of major customers	1