Organization and Formation of Company (Details Textual)	2 Months Ended	12 Months Ended
Feb. 28, 2012 sqft IndustrialProperty State Province	Dec. 31, 2011 sqft JointVentures IndustrialProperty State Province
Organization and Formation of Company (Textual) [Abstract]
Industrial property owned		740
Number of states in which industrial properties are located		26
Number of provinces in which industrial properties are located		1
Gross Leasable Area (GLA) of industrial property owned	400,000	66,300,000
Number of Joint Ventures		2
Number of joint ventures in which company disposed off their equity interests		5

The number of joint ventures that the entity owns a non-controlling interest in as of the balance sheet date.

No definition available.

The number of joint ventures that the entity has sold their interest in during the period.

No definition available.

Name:	fr_NumberOfJointVenturesInWhichCompanyDisposedOffTheirEquityInterests
Namespace Prefix:	fr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The number of provinces in Canada in which the entity operates as of the balance sheet date.

No definition available.

Name:	fr_NumberOfProvincesInWhichEntityOperates
Namespace Prefix:	fr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Name:	fr_OrganizationAndFormationOfCompanyTextualAbstract
Namespace Prefix:	fr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The number of real estate properties owned as of the balance sheet date.

No definition available.

Name:	us-gaap_NumberOfRealEstateProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

The number of states the entity operates in as of the balance sheet date.

No definition available.

Name:	us-gaap_NumberOfStatesInWhichEntityOperates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

The amount of square footage related to a real estate property.

No definition available.

Name:	us-gaap_SquareFootageOfRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration