Schedule III: Real Estate and Accumulated Depreciation (Parenthetical) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Property		Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Real Estate and Accumulated Depreciation [Line Items]
Number of industrial properties | Property	458
Tenant improvements, useful life	Lease Term
Balance, Beginning of Year	$ 3,495,745		$ 3,388,611	$ 3,297,649
Acquisition of Real Estate Assets	162,769		168,517	108,538
Construction Costs and Improvements	190,383		137,361	167,342
Disposition of Real Estate Assets	(148,408)		(170,928)	(153,364)
Impairment of Real Estate	(2,756)		0	0
Write-off of Fully Depreciated and Other Assets	(24,089)		(27,816)	(31,554)
Balance, End of Year Including Real Estate Held for Sale	3,673,644		3,495,745	3,388,611
Real Estate Held for Sale	0	[1]	0	(3,697)
Balance, End of Year Excluding Real Estate Held for Sale	3,673,644		3,495,745	3,384,914
Balance, Beginning of Year	789,919		797,919	792,501
Depreciation for Year	94,626		94,078	95,514
Disposition of Assets	(49,144)		(78,844)	(62,634)
Write-off of Fully Depreciated and Other Assets	(23,617)		(23,234)	(27,462)
Balance, End of Year Including Real Estate Held for Sale	811,784		789,919	797,919
Real Estate Held for Sale	0	[2]	0	(1,427)
Balance, End of Year Excluding Real Estate Held for Sale	$ 811,784		$ 789,919	$ 796,492
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	5 years
Land Improvements | Maximum
Real Estate and Accumulated Depreciation [Line Items]
Property, plant and equipment, useful life	20 years

[1] The Real Estate Held for Sale at December 31, 2018 excludes $0 of other assets.

[2] The Real Estate Held for Sale at December 31, 2018 excludes $0 of accumulated amortization related to the other assets mentioned above.