Organization and Formation of Company (Details Textual)	3 Months Ended
Mar. 31, 2012 sqft Province State JointVentures IndustrialProperty
Organization and Formation of Company (Textual) [Abstract]
Ownership interest of sole general partner	94.40%
Noncontrolling interest percentage of partnership interest	5.60%
Number of Joint Ventures	2
Industrial property owned	738
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	66,100,000

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 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
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Percentage of ownership interest in operating partnership.

No definition available.

Name:	fr_PercentageOfOwnershipInterestInOperatingPartnership
Namespace Prefix:	fr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

No definition available.

Name:	us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

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