Earnings Per Share / Unit (EPS / EPU) - Computation of Basic and Diluted EPS / EPU (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator:
Net Income Available to Common Stockholders / Unitholders and Participating Securities	$ 43,198	$ 31,519	$ 103,469	$ 97,436
Net Income Allocable to Participating Securities	(145)	(110)	(327)	(329)
Net Income Available to Common Stockholders / Unitholders	$ 43,053	$ 31,409	$ 103,142	$ 97,107
Denominator:
Weighted Average Shares / Units - Basic	119,446	116,467	117,870	114,491
LTIP Unit Awards (As Defined in Note 9)	544	397	482	318
Weighted Average Shares / Units - Diluted	119,990	116,864	118,352	114,809
Basic Earnings Per Share / Unit:
Net Income Available to Common Stockholders / Unitholders	$ 0.36	$ 0.27	$ 0.88	$ 0.85
Diluted Earnings Per Share / Unit:
Net Income Available to Common Stockholders / Unitholders	$ 0.36	$ 0.27	$ 0.87	$ 0.85
First Industrial, L.P.
Numerator:
Net Income Available to Common Stockholders / Unitholders and Participating Securities	$ 44,613	$ 32,630	$ 106,904	$ 100,959
Net Income Allocable to Participating Securities	(145)	(110)	(327)	(328)
Net Income Available to Common Stockholders / Unitholders	$ 44,468	$ 32,520	$ 106,577	$ 100,631
Denominator:
Weighted Average Shares / Units - Basic	123,483	120,740	121,909	118,781
LTIP Unit Awards (As Defined in Note 9)	544	397	482	318
Weighted Average Shares / Units - Diluted	124,027	121,137	122,391	119,099
Basic Earnings Per Share / Unit:
Net Income Available to Common Stockholders / Unitholders	$ 0.36	$ 0.27	$ 0.87	$ 0.85
Diluted Earnings Per Share / Unit:
Net Income Available to Common Stockholders / Unitholders	$ 0.36	$ 0.27	$ 0.87	$ 0.84