Accumulated Other Comprehensive Income (Changes in AOCI) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 1,679,911	$ 1,475,877
Ending Balance	1,798,263	1,679,911
Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	3,574	1,382
Other Comprehensive Income Before Reclassifications	(9,603)	1,987
Amounts Reclassified from Accumulated Other Comprehensive Income	(984)	205
Net Current Period Other Comprehensive Income	(10,587)	2,192
Ending Balance	(7,013)	3,574
Comprehensive (Loss) Income Attributable to Noncontrolling Interest of the Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(72)	(44)
Other Comprehensive Income Before Reclassifications	202	(28)
Amounts Reclassified from Accumulated Other Comprehensive Income	0	0
Net Current Period Other Comprehensive Income	202	(28)
Ending Balance	130	(72)
Accumulated Other Comprehensive (Loss) Income of the Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	3,502	1,338
Other Comprehensive Income Before Reclassifications	(9,401)	1,959
Amounts Reclassified from Accumulated Other Comprehensive Income	(984)	205
Net Current Period Other Comprehensive Income	(10,385)	2,164
Ending Balance	(6,883)	3,502
First Industrial, L.P. | Accumulated Other Comprehensive Income of the Operating Partnership
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	3,574	1,382
Other Comprehensive Income Before Reclassifications	(9,603)	1,987
Amounts Reclassified from Accumulated Other Comprehensive Income	(984)	205
Net Current Period Other Comprehensive Income	(10,587)	2,192
Ending Balance	$ (7,013)	$ 3,574