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								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator:
Net Income Available to Common Stockholders / Unitholders and Participating Securities	$ 97,987	$ 43,198	$ 37,562	$ 22,709	$ 23,796	$ 31,519	$ 50,229	$ 15,688	$ 201,456	$ 121,232	$ 73,802
Net Income Allocable to Participating Securities	(331)	(145)	(129)	(67)	(82)	(110)	(180)	(63)	(646)	(411)	(248)
Net Income Available to Common Stockholders / Unitholders	$ 97,656	$ 43,053	$ 37,433	$ 22,642	$ 23,714	$ 31,409	$ 50,049	$ 15,625	$ 200,810	$ 120,821	$ 73,554
Denominator:
Weighted Average Shares/Units - Basic	119,462	119,446	117,299	116,837	116,636	116,467	116,191	110,793	118,272	115,030	110,352
LTIP Unit Awards (As Defined in Note 11)									515	340	429
Weighted Average Shares / Units - Diluted	120,076	119,990	117,779	117,261	117,042	116,864	116,558	110,985	118,787	115,370	110,781
Basic Earnings Per Share / Unit:
Net Income Available to Common Stockholders/Unitholders	$ 0.82	$ 0.36	$ 0.32	$ 0.19	$ 0.20	$ 0.27	$ 0.43	$ 0.14	$ 1.70	$ 1.05	$ 0.67
Diluted Earnings Per Share / Unit:
Net Income Available to Common Stockholders/Unitholders	$ 0.81	$ 0.36	$ 0.32	$ 0.19	$ 0.20	$ 0.27	$ 0.43	$ 0.14	$ 1.69	$ 1.05	$ 0.66
First Industrial, L.P.
Numerator:
Net Income Available to Common Stockholders / Unitholders and Participating Securities	$ 101,254	$ 44,613	$ 38,827	$ 23,464	$ 24,588	$ 32,630	$ 52,048	$ 16,281	$ 208,158	$ 125,547	$ 76,682
Net Income Allocable to Participating Securities	(331)	(145)	(129)	(66)	(83)	(110)	(180)	(63)	(646)	(410)	(248)
Net Income Available to Common Stockholders / Unitholders	$ 100,923	$ 44,468	$ 38,698	$ 23,398	$ 24,505	$ 32,520	$ 51,868	$ 16,218	$ 207,512	$ 125,137	$ 76,434
Denominator:
Weighted Average Shares/Units - Basic	123,483	123,483	121,339	120,877	120,740	120,740	120,486	115,096	122,306	119,274	114,709
LTIP Unit Awards (As Defined in Note 11)									515	340	429
Weighted Average Shares / Units - Diluted	124,097	124,027	121,819	121,301	121,146	121,137	120,853	115,288	122,821	119,614	115,138
Basic Earnings Per Share / Unit:
Net Income Available to Common Stockholders/Unitholders	$ 0.82	$ 0.36	$ 0.32	$ 0.19	$ 0.20	$ 0.27	$ 0.43	$ 0.14	$ 1.70	$ 1.05	$ 0.67
Diluted Earnings Per Share / Unit:
Net Income Available to Common Stockholders/Unitholders	$ 0.81	$ 0.36	$ 0.32	$ 0.19	$ 0.20	$ 0.27	$ 0.43	$ 0.14	$ 1.69	$ 1.05	$ 0.66