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		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Numerator:
Income from Continuing Operations	$ 14,465	$ 8,263	$ 31,499	$ 15,341
Noncontrolling Interest Allocable to Continuing Operations	(548)	(325)	(1,197)	(507)
Income from Continuing Operations Allocable to Participating Securities	(50)	(33)	(141)	(55)
Income from Continuing Operations Attributable to Common Stockholders / Unitholders	13,867	7,905	30,161	14,779
Preferred Dividends / Unit Distributions	0	0	0	(1,019)
Redemption of Preferred Stock / Units	0	0	0	(1,462)
Income from Continuing Operations Available to First Industrial Realty Trust, Inc.’s Common Stockholders	13,867	7,905	30,161	12,298
Income from Discontinued Operations	0	13,932	0	16,125
Noncontrolling Interest Allocable to Discontinued Operations	0	(543)	0	(630)
Income from Discontinued Operations Allocable to Participating Securities	0	(57)	0	(68)
Income from Discontinued Operations Attributable to Common Stockholders / Unitholders	0	13,332	0	15,427
Net Income Available to Common Stockholders / Unitholders and Participating Securities	13,917	21,327	30,302	27,848
Net Income Allocable to Participating Securities	(50)	(90)	(141)	(123)
Net Income Available to First Industrial Realty Trust, Inc.’s Common Stockholders	$ 13,867	$ 21,237	$ 30,161	$ 27,725
Denominator:
Weighted Average Shares / Units - Basic	110,356	110,072	110,338	109,856
LTIP performance units	492	199	397	442
Weighted Average Shares / Units - Diluted	110,848	110,271	110,735	110,298
Basic Earnings Per Share / Unit:
Income from Continuing Operations Available to Common Stockholders / Unitholders	$ 0.13	$ 0.07	$ 0.27	$ 0.11
Income from Discontinued Operations Attributable to Common Stockholders / Unitholders	0.00	0.12	0.00	0.14
Net Income Available to Common Stockholders / Unitholders	0.13	0.19	0.27	0.25
Diluted Earnings Per Share / Unit:
Income from Continuing Operations Available to Common Stockholders / Unitholders	0.13	0.07	0.27	0.11
Income from Discontinued Operations Attributable to Common Stockholders / Unitholders	0.00	0.12	0.00	0.14
Net Income Available to Common Stockholders / Unitholders	$ 0.13	$ 0.19	$ 0.27	$ 0.25
First Industrial, L.P.
Numerator:
Income from Continuing Operations	$ 14,465	$ 8,307	$ 31,614	$ 15,448
Noncontrolling Interest Allocable to Continuing Operations	(27)	(13)	(75)	(40)
Income from Continuing Operations Allocable to Participating Securities	(50)	(33)	(141)	(55)
Income from Continuing Operations Attributable to Common Stockholders / Unitholders	14,388	8,261	31,398	15,353
Preferred Dividends / Unit Distributions	0	0	0	(1,019)
Redemption of Preferred Stock / Units	0	0	0	(1,462)
Income from Continuing Operations Available to Unitholders	14,388	8,261	31,398	12,872
Income from Discontinued Operations	0	13,932	0	16,125
Noncontrolling Interest Allocable to Discontinued Operations	0	(8)	0	(10)
Income from Discontinued Operations Allocable to Participating Securities	0	(57)	0	(68)
Income from Discontinued Operations Attributable to Common Stockholders / Unitholders	0	13,867	0	16,047
Net Income Available to Common Stockholders / Unitholders and Participating Securities	14,438	22,218	31,539	29,042
Net Income Allocable to Participating Securities	(50)	(90)	(141)	(123)
Net Income Available to Unitholders	$ 14,388	$ 22,128	$ 31,398	$ 28,919
Denominator:
Weighted Average Shares / Units - Basic	114,720	114,512	114,705	114,346
LTIP performance units	492	199	397	442
Weighted Average Shares / Units - Diluted	115,212	114,711	115,102	114,788
Basic Earnings Per Share / Unit:
Income from Continuing Operations Available to Common Stockholders / Unitholders	$ 0.13	$ 0.07	$ 0.27	$ 0.11
Income from Discontinued Operations Attributable to Common Stockholders / Unitholders	0.00	0.12	0.00	0.14
Net Income Available to Common Stockholders / Unitholders	0.13	0.19	0.27	0.25
Diluted Earnings Per Share / Unit:
Income from Continuing Operations Available to Common Stockholders / Unitholders	0.12	0.07	0.27	0.11
Income from Discontinued Operations Attributable to Common Stockholders / Unitholders	0.00	0.12	0.00	0.14
Net Income Available to Common Stockholders / Unitholders	$ 0.12	$ 0.19	$ 0.27	$ 0.25