Schedule III: Real Estate and Accumulated Depreciation (Parenthetical) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) Property		Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Real Estate and Accumulated Depreciation [Line Items]
Number of industrial properties | Property	427
Tenant improvements, useful life	Lease Term
Balance, Beginning of Year	$ 3,830,209		$ 3,673,644	$ 3,495,745
Acquisition of Real Estate Assets	247,250		148,660	162,769
Construction Costs and Improvements	160,491		289,877	190,383
Disposition of Real Estate Assets	(109,070)		(258,639)	(148,408)
Impairment of Real Estate	0		0	(2,756)
Write-off of Fully Depreciated and Other Assets	(18,984)		(23,333)	(24,089)
Balance, End of Year Including Real Estate Held for Sale	4,109,896		3,830,209	3,673,644
Real Estate Held for Sale	22,263	[1]	0	0
Balance, End of Year Excluding Real Estate Held for Sale	4,087,633		3,830,209	3,673,644
Balance, Beginning of Year	804,780		811,784	789,919
Depreciation for Year	102,533		98,333	94,626
Disposition of Assets	(49,390)		(82,919)	(49,144)
Write-off of Fully Depreciated and Other Assets	(18,574)		(22,418)	(23,617)
Balance, End of Year Including Real Estate Held for Sale	839,349		804,780	811,784
Real Estate Held for Sale	(6,956)	[2]	0	0
Balance, End of Year Excluding Real Estate Held for Sale	832,393		$ 804,780	$ 811,784
Real Estate Held for Sale - Other Assets	454
Real Estate Held for Sale - Other Assets Accumulated Depreciation	$ 98
Buildings and Improvements | Minimum
Real Estate and Accumulated Depreciation [Line Items]
Property, plant and equipment, useful life	7 years
Buildings and Improvements | Maximum
Real Estate and Accumulated Depreciation [Line Items]
Property, plant and equipment, useful life	50 years
Land Improvements | Minimum
Real Estate and Accumulated Depreciation [Line Items]
Property, plant and equipment, useful life	3 years
Land Improvements | Maximum
Real Estate and Accumulated Depreciation [Line Items]
Property, plant and equipment, useful life	16 years

[1] The Real Estate Held for Sale at December 31, 2020 excludes $454 of other assets.

[2] The Real Estate Held for Sale at December 31, 2020 excludes $98 of accumulated amortization related to the other assets.