Earnings Per Share / Unit (EPS / EPU) - Additional Information (Details) - shares	Sep. 30, 2026	Sep. 30, 2025
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Unvested Restricted Stock / Unit Awards	58,893	69,105
First Industrial, L.P.
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Unvested Restricted Stock / Unit Awards	188,903	189,493

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
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-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
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-URI https://asc.fasb.org/1943274/2147482689/260-10-45-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
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-URI https://asc.fasb.org/1943274/2147482689/260-10-45-60B

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