Quarterly Financial Information (unaudited) - Net Income Available and Basic and Diluted EPS/EPU (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Total Revenues	$ 110,758	$ 106,590	$ 104,095	$ 104,541	$ 105,082	$ 100,256	$ 98,845	$ 99,771	$ 425,984	$ 403,954	$ 396,402
Net Income Available to Common Stockholders / Unitholders and Participating Securities	96,861	78,311	39,800	23,803	50,827	30,911	45,209	36,292	238,775	163,239	201,456
Net Income Allocable to Participating Securities	(199)	(170)	(89)	(60)	(164)	(101)	(151)	(97)	(518)	(513)	(646)
Net Income Available to Common Stockholders / Unitholders	$ 96,662	$ 78,141	$ 39,711	$ 23,743	$ 50,663	$ 30,810	$ 45,058	$ 36,195	$ 238,257	$ 162,726	$ 200,810
Basic Earnings Per Share / Unit:
Net Income Available to Common Stockholders/Unitholders	$ 0.76	$ 0.62	$ 0.31	$ 0.19	$ 0.40	$ 0.24	$ 0.36	$ 0.30	$ 1.89	$ 1.31	$ 1.70
Diluted Earnings Per Share / Unit:
Net Income Available to Common Stockholders/Unitholders	$ 0.76	$ 0.62	$ 0.31	$ 0.19	$ 0.40	$ 0.24	$ 0.36	$ 0.30	$ 1.88	$ 1.31	$ 1.69
Weighted Average Shares/Units - Basic	126,682	126,480	126,206	126,194	125,897	125,768	123,616	119,846	126,392	123,804	118,272
Weighted Average Shares / Units - Diluted	127,030	126,783	126,489	126,456	126,249	126,130	124,085	120,211	126,691	124,191	118,787
First Industrial, L.P.
Total Revenues	$ 110,758	$ 106,590	$ 104,095	$ 104,541	$ 105,082	$ 100,256	$ 98,845	$ 99,771	$ 425,984	$ 403,954	$ 396,402
Net Income Available to Common Stockholders / Unitholders and Participating Securities	98,656	79,969	40,689	24,314	51,913	31,508	46,382	37,443	243,628	167,246	208,158
Net Income Allocable to Participating Securities	(279)	(249)	(128)	(76)	(164)	(101)	(151)	(97)	(732)	(513)	(646)
Net Income Available to Common Stockholders / Unitholders	$ 98,377	$ 79,720	$ 40,561	$ 24,238	$ 51,749	$ 31,407	$ 46,231	$ 37,346	$ 242,896	$ 166,733	$ 207,512
Basic Earnings Per Share / Unit:
Net Income Available to Common Stockholders/Unitholders	$ 0.76	$ 0.62	$ 0.31	$ 0.19	$ 0.40	$ 0.24	$ 0.36	$ 0.30	$ 1.89	$ 1.31	$ 1.70
Diluted Earnings Per Share / Unit:
Net Income Available to Common Stockholders/Unitholders	$ 0.76	$ 0.62	$ 0.31	$ 0.19	$ 0.40	$ 0.24	$ 0.36	$ 0.30	$ 1.88	$ 1.31	$ 1.69
Weighted Average Shares/Units - Basic	128,837	128,837	128,831	128,818	128,526	128,526	126,832	123,729	128,831	126,921	122,306
Weighted Average Shares / Units - Diluted	129,308	129,256	129,221	129,178	128,878	128,888	127,301	124,094	129,241	127,308	122,821