CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	$ 36,707	$ 80,002	$ 114,662	$ 145,055
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Depreciation			76,580	73,054
Amortization of Debt Issuance Costs	905	805	2,477	2,430
Other Amortization, including Stock Based Compensation			26,776	21,226
Equity in Loss (Income) of Joint Ventures	162	72	236	(16,288)
Distributions from Joint Ventures			0	16,012
Gain on Sale of Real Estate	(6,525)	(52,489)	(29,594)	(53,378)
Gain on Involuntary Conversion			(6,476)	0
Payments to Settle Derivative Instruments	0	0	0	(3,149)
Straight-line Rental Income and Expense, Net			(6,481)	(7,321)
Decrease (Increase) in Tenant Accounts Receivable, Prepaid Expenses and Other Assets, Net			3,149	(8,325)
Increase in Accounts Payable, Accrued Expenses, Other Liabilities, Rents Received in Advance and Security Deposits			8,810	20,863
Net Cash Provided by Operating Activities			190,139	190,179
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions of Real Estate			(184,883)	(108,468)
Additions to Investment in Real Estate and Non-Acquisition Tenant Improvements and Lease Costs			(150,908)	(211,424)
Net Proceeds from Sales of Investments in Real Estate, Including Sales-Type Lease Receivable			110,049	102,758
Contributions to and Investments in Joint Ventures			(42,744)	0
Distributions from Joint Ventures			0	8,658
Proceeds from Involuntary Conversion			6,476	0
Deposits on Future Acquisitions and Other Investing Activity			(12,345)	(6,459)
Net Cash Used in Investing Activities			(274,355)	(214,935)
CASH FLOWS FROM FINANCING ACTIVITIES:
Financing and Equity Issuance Costs			(3,329)	(953)
Proceeds from the Issuance of Common Stock, Net of Underwriter's Discount			78,718	0
Tax Paid on Shares Withheld			(5,944)	(4,384)
Common Stock Dividends and Unit Distributions Paid			(94,493)	(87,490)
Contributions from Noncontrolling Interests			4,321	0
Repayments on Mortgage Loans Payable			(18,654)	(116,518)
Proceeds from Issuance of Unsecured Debt			300,000	150,000
Proceeds from Unsecured Credit Facility			247,000	295,000
Repayments on Unsecured Credit Facility			(405,000)	(217,000)
Net Cash Provided by Financing Activities			102,619	18,655
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash			18,403	(6,101)
Cash, Cash Equivalents and Restricted Cash, Beginning of Year			152,718	50,373
Cash, Cash Equivalents and Restricted Cash, End of Period	171,121	44,272	171,121	44,272
SUPPLEMENTAL INFORMATION TO STATEMENTS OF CASH FLOWS:
Interest Expense Capitalized in Connection with Development Activity			5,029	4,161
Cash Paid for Operating Lease Liabilities			2,175	1,273
Supplemental Schedule of Non-Cash Operating Activities:
Operating Lease Liabilities Arising from Obtaining Right-of-Use Assets			1,208	22,871
Supplemental Schedule of Non-Cash Investing and Financing Activities:
Dividends and Distributions Payable	33,577	30,386	33,577	30,386
Exchange of Limited Partnership Units for Common Stock/General Partnership Units:
Conversion of Limited Partner Units to Common Stock / General Partner Units	0	0	0	0
Lease Reclassification from Operating Lease to Sales Type Lease:
Land	(1,092,966)		(1,092,966)
Deferred Rent Receivable	(83,010)		(83,010)
Assumption of Liabilities in Connection with the Acquisition of Real Estate			6,542	692
Accounts Payable Related to Construction in Progress and Additions to Investment in Real Estate			24,385	57,872
Write-off of Fully Depreciated Assets			(30,935)	(26,115)
Sales Type Lease
Lease Reclassification from Operating Lease to Sales Type Lease:
Lease Receivable	0	54,521	0	54,521
Land	0	(24,803)	0	(24,803)
Building Net Of Accumulated Depreciation			0	(17,845)
Deferred Rent Receivable	0	(2,073)	0	(2,073)
Other Assets Net Of Accumulated Amortization			0	(1,194)
Sales-type Lease, Selling Profit (Loss)			0	8,606
Noncontrolling Interest
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	748	1,691
Exchange of Limited Partnership Units for Common Stock/General Partnership Units:
Conversion of Limited Partner Units to Common Stock / General Partner Units	(4)	(6,861)	(2,069)	(6,861)
Common Stock
Exchange of Limited Partnership Units for Common Stock/General Partnership Units:
Conversion of Limited Partner Units to Common Stock / General Partner Units	0	5	2	5
Additional Paid-in- Capital
Exchange of Limited Partnership Units for Common Stock/General Partnership Units:
Conversion of Limited Partner Units to Common Stock / General Partner Units	4	6,856	2,067	6,856
First Industrial, L.P.
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	36,707	80,002	114,662	145,055
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Depreciation			76,580	73,054
Amortization of Debt Issuance Costs	905	805	2,477	2,430
Other Amortization, including Stock Based Compensation			26,776	21,226
Equity in Loss (Income) of Joint Ventures	162	72	236	(16,288)
Distributions from Joint Ventures			0	16,012
Gain on Sale of Real Estate	(6,525)	(52,489)	(29,594)	(53,378)
Gain on Involuntary Conversion			(6,476)	0
Payments to Settle Derivative Instruments	0	0	0	(3,149)
Straight-line Rental Income and Expense, Net			(6,481)	(7,321)
Decrease (Increase) in Tenant Accounts Receivable, Prepaid Expenses and Other Assets, Net			3,709	(8,240)
Increase in Accounts Payable, Accrued Expenses, Other Liabilities, Rents Received in Advance and Security Deposits			8,810	20,863
Net Cash Provided by Operating Activities			190,699	190,264
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions of Real Estate			(184,883)	(108,468)
Additions to Investment in Real Estate and Non-Acquisition Tenant Improvements and Lease Costs			(150,908)	(211,424)
Net Proceeds from Sales of Investments in Real Estate, Including Sales-Type Lease Receivable			110,049	102,758
Contributions to and Investments in Joint Ventures			(42,744)	0
Distributions from Joint Ventures			0	8,658
Proceeds from Involuntary Conversion			6,476	0
Deposits on Future Acquisitions and Other Investing Activity			(12,345)	(6,459)
Net Cash Used in Investing Activities			(274,355)	(214,935)
CASH FLOWS FROM FINANCING ACTIVITIES:
Financing and Equity Issuance Costs			(3,329)	(953)
Proceeds from the Issuance of Common Stock, Net of Underwriter's Discount			78,718	0
Tax Paid on Shares Withheld			(5,944)	(4,384)
Common Stock Dividends and Unit Distributions Paid			(94,493)	(87,490)
Contributions from Noncontrolling Interests			4,388	10
Distributions to Noncontrolling Interests			(627)	(95)
Repayments on Mortgage Loans Payable			(18,654)	(116,518)
Proceeds from Issuance of Unsecured Debt			300,000	150,000
Proceeds from Unsecured Credit Facility			247,000	295,000
Repayments on Unsecured Credit Facility			(405,000)	(217,000)
Net Cash Provided by Financing Activities			102,059	18,570
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash			18,403	(6,101)
Cash, Cash Equivalents and Restricted Cash, Beginning of Year			152,718	50,373
Cash, Cash Equivalents and Restricted Cash, End of Period	171,121	44,272	171,121	44,272
SUPPLEMENTAL INFORMATION TO STATEMENTS OF CASH FLOWS:
Interest Expense Capitalized in Connection with Development Activity			5,029	4,161
Cash Paid for Operating Lease Liabilities			2,175	1,273
Supplemental Schedule of Non-Cash Operating Activities:
Operating Lease Liabilities Arising from Obtaining Right-of-Use Assets			1,208	22,871
Supplemental Schedule of Non-Cash Investing and Financing Activities:
Dividends and Distributions Payable	33,577	30,386	33,577	30,386
Exchange of Limited Partnership Units for Common Stock/General Partnership Units:
Conversion of Limited Partner Units to Common Stock / General Partner Units	0	0	0	0
Lease Reclassification from Operating Lease to Sales Type Lease:
Land	(1,092,966)		(1,092,966)
Deferred Rent Receivable	(83,010)		(83,010)
Assumption of Liabilities in Connection with the Acquisition of Real Estate			6,542	692
Accounts Payable Related to Construction in Progress and Additions to Investment in Real Estate			24,385	57,872
Write-off of Fully Depreciated Assets			(30,935)	(26,115)
First Industrial, L.P. | Sales Type Lease
Lease Reclassification from Operating Lease to Sales Type Lease:
Lease Receivable	0	54,521	0	54,521
Land	0	(24,803)	0	(24,803)
Building Net Of Accumulated Depreciation			0	(17,845)
Deferred Rent Receivable	0	(2,073)	0	(2,073)
Other Assets Net Of Accumulated Amortization			0	(1,194)
Sales-type Lease, Selling Profit (Loss)			0	8,606
First Industrial, L.P. | Limited Partner Units
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	760	1,691
Exchange of Limited Partnership Units for Common Stock/General Partnership Units:
Conversion of Limited Partner Units to Common Stock / General Partner Units	(4)	(6,861)	(2,069)	(6,861)
First Industrial, L.P. | General Partner Units
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	35,879	78,278
Exchange of Limited Partnership Units for Common Stock/General Partnership Units:
Conversion of Limited Partner Units to Common Stock / General Partner Units	$ 4	$ 6,861	$ 2,069	$ 6,861