XML 43 R30.htm IDEA: XBRL DOCUMENT
v3.23.1

Investment in Real Estate - Additional Information (Details) ft² in Thousands | Mar. 31, 2023 ft² Property
--- | ---
Real Estate Properties [Line Items] |
Number of industrial properties | Property | 431
Gross leasable area (GLA) of industrial properties | ft² | 65,700
Acquisition Activity |
Real Estate Properties [Line Items] |
Number of industrial properties | Property | 1
Gross leasable area (GLA) of industrial properties | ft² | 20

X
- Definition Area of a real estate property. + References No definition available. + Details
Name: | us-gaap_AreaOfRealEstateProperty
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:areaItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of real estate properties owned as of the balance sheet date. + References No definition available. + Details
Name: | us-gaap_NumberOfRealEstateProperties
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_RealEstatePropertiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | fr_InvestmentinRealEstateActivityAxis=fr_AcquisitionActivityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |