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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator:
Net Income Available to Common Stockholders/Unitholders and Participating Securities	$ 37,562	$ 50,229	$ 60,271	$ 65,917
Net Income Allocable to Participating Securities	(129)	(180)	(154)	(217)
Net Income Available to Common Stockholders / Unitholders	$ 37,433	$ 50,049	$ 60,117	$ 65,700
Denominator:
Weighted Average Shares / Units - Basic	117,299	116,191	117,070	113,492
LTIP Unit Awards (As Defined in Note 9)	480	367	452	279
Weighted Average Shares / Units - Diluted	117,779	116,558	117,522	113,771
Basic and Diluted EPS / EPU
Net Income Available to Common Stockholders/Unitholders	$ 0.32	$ 0.43	$ 0.51	$ 0.58
First Industrial, L.P.
Numerator:
Net Income Available to Common Stockholders/Unitholders and Participating Securities	$ 38,827	$ 52,048	$ 62,291	$ 68,329
Net Income Allocable to Participating Securities	(129)	(180)	(154)	(217)
Net Income Available to Common Stockholders / Unitholders	$ 38,698	$ 51,868	$ 62,137	$ 68,112
Denominator:
Weighted Average Shares / Units - Basic	121,339	120,486	121,109	117,791
LTIP Unit Awards (As Defined in Note 9)	480	367	452	279
Weighted Average Shares / Units - Diluted	121,819	120,853	121,561	118,070
Basic and Diluted EPS / EPU
Net Income Available to Common Stockholders/Unitholders	$ 0.32	$ 0.43	$ 0.51	$ 0.58