CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues [Abstract]
Rental Income	$ 76,372	$ 76,497	$ 227,232	$ 227,217
Tenant Recoveries and Other Income	23,884	22,813	71,640	67,055
Total Revenues	100,256	99,310	298,872	294,272
Expenses:
Property Expenses	28,466	28,452	86,430	83,835
General and Administrative	6,581	6,492	21,470	21,310
Impairment of Real Estate	0	0	2,756	0
Depreciation and Other Amortization	28,645	29,696	85,596	87,230
Total Expenses	63,692	64,640	196,252	192,375
Other Income (Expense):
Gain on Sale of Real Estate	8,135	23,271	53,291	52,140
Interest Expense	(12,424)	(14,376)	(37,818)	(43,660)
Amortization of Debt Issuance Costs	(850)	(778)	(2,550)	(2,336)
Mark-to-Market Gain on Interest Rate Protection Agreements	0	1,848	0	1,848
Loss from Retirement of Debt	0	0	(39)	(1,653)
Total Other Income (Expense)	(5,139)	9,965	12,884	6,339
Income from Operations Before Equity in Loss of Joint Venture and Income Tax Benefit (Provision)	31,425	44,635	115,504	108,236
Equity in Loss of Joint Venture	(197)	0	(199)	0
Income Tax Benefit (Provision)	302	21	93	(1,236)
Net Income	31,530	44,656	115,398	107,000
Less: Net Income Attributable to the Noncontrolling Interest	(619)	(1,458)	(2,986)	(3,531)
Net Income Available to Common Stockholders / Unitholders and Participating Securities	$ 30,911	$ 43,198	$ 112,412	$ 103,469
Basic Earnings Per Share / Unit:
Net Income Available to Common Stockholders / Unitholders	$ 0.24	$ 0.36	$ 0.91	$ 0.88
Diluted Earnings Per Share / Unit:
Net Income Available to Common Stockholders / Unitholders	0.24	0.36	0.91	0.87
Dividends/Distributions Per Share/Unit	$ 0.2175	$ 0.2100	$ 0.6525	$ 0.6300
Weighted Average Shares/Units Outstanding - Basic	125,768	119,446	123,098	117,870
Weighted Average Shares/Units Outstanding - Diluted	126,130	119,990	123,497	118,352
First Industrial, L.P.
Revenues [Abstract]
Rental Income	$ 76,372	$ 76,497	$ 227,232	$ 227,217
Tenant Recoveries and Other Income	23,884	22,813	71,640	67,055
Total Revenues	100,256	99,310	298,872	294,272
Expenses:
Property Expenses	28,466	28,452	86,430	83,835
General and Administrative	6,581	6,492	21,470	21,310
Impairment of Real Estate	0	0	2,756	0
Depreciation and Other Amortization	28,645	29,696	85,596	87,230
Total Expenses	63,692	64,640	196,252	192,375
Other Income (Expense):
Gain on Sale of Real Estate	8,135	23,271	53,291	52,140
Interest Expense	(12,424)	(14,376)	(37,818)	(43,660)
Amortization of Debt Issuance Costs	(850)	(778)	(2,550)	(2,336)
Mark-to-Market Gain on Interest Rate Protection Agreements	0	1,848	0	1,848
Loss from Retirement of Debt	0	0	(39)	(1,653)
Total Other Income (Expense)	(5,139)	9,965	12,884	6,339
Income from Operations Before Equity in Loss of Joint Venture and Income Tax Benefit (Provision)	31,425	44,635	115,504	108,236
Equity in Loss of Joint Venture	(197)	0	(199)	0
Income Tax Benefit (Provision)	302	21	93	(1,236)
Net Income	31,530	44,656	115,398	107,000
Less: Net Income Attributable to the Noncontrolling Interest	(22)	(43)	(65)	(96)
Net Income Available to Common Stockholders / Unitholders and Participating Securities	$ 31,508	$ 44,613	$ 115,333	$ 106,904
Basic Earnings Per Share / Unit:
Net Income Available to Common Stockholders / Unitholders	$ 0.24	$ 0.36	$ 0.91	$ 0.87
Diluted Earnings Per Share / Unit:
Net Income Available to Common Stockholders / Unitholders	0.24	0.36	0.91	0.87
Dividends/Distributions Per Share/Unit	$ 0.2175	$ 0.2100	$ 0.6525	$ 0.6300
Weighted Average Shares/Units Outstanding - Basic	128,526	123,483	126,380	121,909
Weighted Average Shares/Units Outstanding - Diluted	128,888	124,027	126,779	122,391