CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues [Abstract]
Lease Revenue	$ 437,543	$ 422,236	$ 398,822
Other Revenue	10,485	3,748	5,132
Total Revenues	448,028	425,984	403,954
Expenses:
Property Expenses	119,195	116,585	116,854
General and Administrative	32,848	28,569	27,749
Depreciation and Other Amortization	129,638	121,229	116,459
Impairment of Real Estate	0	0	2,756
Total Expenses	281,681	266,383	263,818
Other Income (Expense):
Gain on Sale of Real Estate	86,751	124,942	81,600
Interest Expense	(51,293)	(50,273)	(50,775)
Amortization of Debt Issuance Costs	(3,428)	(3,218)	(3,404)
Loss from Retirement of Debt	0	0	(39)
Total Other Income (Expense)	32,030	71,451	27,382
Income from Operations Before Equity in Income (Loss) of Joint Ventures and Income Tax (Provision) Benefit	198,377	231,052	167,518
Equity in Income (Loss) of Joint Ventures	4,200	16,235	(276)
Income Tax (Provision) Benefit	(2,408)	(3,406)	92
Net Income	200,169	243,881	167,334
Less: Net Income Attributable to the Noncontrolling Interests	(4,180)	(5,106)	(4,095)
Net Income Available to Common Stockholders / Unitholders and Participating Securities	$ 195,989	$ 238,775	$ 163,239
Basic Earnings Per Share / Unit:
Net Income Available to Common Stockholders/Unitholders	$ 1.53	$ 1.89	$ 1.31
Diluted Earnings Per Share / Unit:
Net Income Available to Common Stockholders/Unitholders	$ 1.53	$ 1.88	$ 1.31
Weighted Average Shares/Units Outstanding - Basic	127,711	126,392	123,804
Weighted Average Shares / Units Outstanding - Diluted	127,904	126,691	124,191
First Industrial, L.P.
Revenues [Abstract]
Lease Revenue	$ 437,543	$ 422,236	$ 398,822
Other Revenue	10,485	3,748	5,132
Total Revenues	448,028	425,984	403,954
Expenses:
Property Expenses	119,195	116,585	116,854
General and Administrative	32,848	28,569	27,749
Depreciation and Other Amortization	129,638	121,229	116,459
Impairment of Real Estate	0	0	2,756
Total Expenses	281,681	266,383	263,818
Other Income (Expense):
Gain on Sale of Real Estate	86,751	124,942	81,600
Interest Expense	(51,293)	(50,273)	(50,775)
Amortization of Debt Issuance Costs	(3,428)	(3,218)	(3,404)
Loss from Retirement of Debt	0	0	(39)
Total Other Income (Expense)	32,030	71,451	27,382
Income from Operations Before Equity in Income (Loss) of Joint Ventures and Income Tax (Provision) Benefit	198,377	231,052	167,518
Equity in Income (Loss) of Joint Ventures	4,200	16,235	(276)
Income Tax (Provision) Benefit	(2,408)	(3,406)	92
Net Income	200,169	243,881	167,334
Less: Net Income Attributable to the Noncontrolling Interests	(235)	(253)	(88)
Net Income Available to Common Stockholders / Unitholders and Participating Securities	$ 199,934	$ 243,628	$ 167,246
Basic Earnings Per Share / Unit:
Net Income Available to Common Stockholders/Unitholders	$ 1.54	$ 1.89	$ 1.31
Diluted Earnings Per Share / Unit:
Net Income Available to Common Stockholders/Unitholders	$ 1.53	$ 1.88	$ 1.31
Weighted Average Shares/Units Outstanding - Basic	129,752	128,831	126,921
Weighted Average Shares / Units Outstanding - Diluted	130,127	129,241	127,308