Earnings Per Share / Unit (EPS / EPU) - Computation of Basic and Diluted EPS / EPU (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerator:
Net Income Available to Common Stockholders / Unitholders and Participating Securities	$ 50,229	$ 14,012	$ 65,917	$ 16,385
Net Income Allocable to Participating Securities	(180)	(50)	(217)	(91)
Net Income Available to First Industrial Realty Trust, Inc.’s Common Stockholders	$ 50,049	$ 13,962	$ 65,700	$ 16,294
Denominator:
Weighted Average Shares / Units - Basic	116,191	110,348	113,492	110,329
LTIP Unit Awards (As Defined in Note 9)	367	335	279	350
Weighted Average Shares / Units - Diluted	116,558	110,683	113,771	110,679
Basic and Diluted EPS / EPU:
Net Income Available to Common Stockholders / Unitholders	$ 0.43	$ 0.13	$ 0.58	$ 0.15
First Industrial, L.P.
Numerator:
Net Income Available to Common Stockholders / Unitholders and Participating Securities	$ 52,048	$ 14,644	$ 68,329	$ 17,101
Net Income Allocable to Participating Securities	(180)	(50)	(217)	(91)
Net Income Available to Unitholders	$ 51,868	$ 14,594	$ 68,112	$ 17,010
Denominator:
Weighted Average Shares / Units - Basic	120,486	114,712	117,791	114,697
LTIP Unit Awards (As Defined in Note 9)	367	335	279	350
Weighted Average Shares / Units - Diluted	120,853	115,047	118,070	115,047
Basic and Diluted EPS / EPU:
Net Income Available to Common Stockholders / Unitholders	$ 0.43	$ 0.13	$ 0.58	$ 0.15