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Investment in Real Estate - Additional Information (Detail) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended 12 Months Ended
Mar. 31, 2015
Property
sqft
Land_Parcel
Mar. 31, 2014
Property
Dec. 31, 2014
Property
Real Estate [Abstract]      
Number of industrial properties held for sale 1fr_NumberofIndustrialPropertiesHeldforSale    
Gross leasable area (GLA) of industrial properties held for sale 200,000fr_SquareFootageofIndustrialPropertiesHeldforSale    
Number of land parcels held for sale 1fr_NumberofLandParcelsHeldforSale    
Number of industrial properties sold 9fr_NumberOfIndustrialPropertiesSold    
Gross leasable area (GLA) of industrial properties sold 500,000fr_SquareFootageOfIndustrialPropertiesSold    
Proceeds from the sale of industrial properties $ 26,626us-gaap_ProceedsFromSaleOfBuildings    
Gain on sale of real estate $ 7,930us-gaap_GainLossOnSaleOfProperties $ 735us-gaap_GainLossOnSaleOfProperties  
Number of sold industrial properties included in discontinued operations   3fr_NumberOfSoldIndustrialPropertiesIncludedInDiscontinuedOperations 29fr_NumberOfSoldIndustrialPropertiesIncludedInDiscontinuedOperations