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
	Mar. 31, 2017	Mar. 31, 2016
Numerator:
Net Income Available to Common Stockholders/Unitholders and Participating Securities	$ 22,709	$ 15,688
Net Income Allocable to Participating Securities	(67)	(63)
Net Income Available to Common Stockholders / Unitholders	$ 22,642	$ 15,625
Denominator:
Weighted Average Shares / Units - Basic	116,837	110,793
LTIP Unit Awards (As Defined in Note 9)	424	192
Weighted Average Shares / Units - Diluted	117,261	110,985
Basic and Diluted EPS / EPU
Net Income Available to Common Stockholders/Unitholders	$ 0.19	$ 0.14
First Industrial, L.P.
Numerator:
Net Income Available to Common Stockholders/Unitholders and Participating Securities	$ 23,464	$ 16,281
Net Income Allocable to Participating Securities	(66)	(63)
Net Income Available to Common Stockholders / Unitholders	$ 23,398	$ 16,218
Denominator:
Weighted Average Shares / Units - Basic	120,877	115,096
LTIP Unit Awards (As Defined in Note 9)	424	192
Weighted Average Shares / Units - Diluted	121,301	115,288
Basic and Diluted EPS / EPU
Net Income Available to Common Stockholders/Unitholders	$ 0.19	$ 0.14