Accumulated Other Comprehensive Income (Changes in AOCI) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021 USD ($)
Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	$ 1,947,320
Ending Balance	2,002,048
Derivative Instruments
Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(17,308)
Other Comprehensive Gain Before Reclassifications	3,593
Amounts Reclassified from Accumulated Other Comprehensive Loss	3,454
Net Current Period Other Comprehensive Gain	7,047
Ending Balance	(10,261)
Comprehensive Loss Attributable to Noncontrolling Interest of the Company
Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	355
Other Comprehensive Gain Before Reclassifications	(120)
Amounts Reclassified from Accumulated Other Comprehensive Loss	0
Net Current Period Other Comprehensive Gain	(120)
Ending Balance	235
Accumulated Other Comprehensive Loss of the Company
Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(16,953)
Other Comprehensive Gain Before Reclassifications	3,473
Amounts Reclassified from Accumulated Other Comprehensive Loss	3,454
Net Current Period Other Comprehensive Gain	6,927
Ending Balance	(10,026)
First Industrial, L.P. | Accumulated Other Comprehensive Loss of the Operating Partnership
Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(17,308)
Other Comprehensive Gain Before Reclassifications	3,593
Amounts Reclassified from Accumulated Other Comprehensive Loss	3,454
Net Current Period Other Comprehensive Gain	7,047
Ending Balance	$ (10,261)