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Real Estate Assets (Details 2) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Nov. 30, 2013
acre
Nov. 30, 2014
sqft
Acquisitions    
Area, square feet   280,000us-gaap_AreaOfRealEstateProperty
Undeveloped land in the Lehigh Valley of Pennsylvania | Land    
Acquisitions    
Number of acres purchased 49us-gaap_AreaOfLand
/ us-gaap_BusinessAcquisitionAxis
= grif_LehighValleyPennsylvaniaLandMember
/ us-gaap_MajorPropertyClassAxis
= us-gaap_LandMember		  
Cash paid $ 7,119us-gaap_PaymentsToAcquireCommercialRealEstate
/ us-gaap_BusinessAcquisitionAxis
= grif_LehighValleyPennsylvaniaLandMember
/ us-gaap_MajorPropertyClassAxis
= us-gaap_LandMember