Investments in Real Estate - Schedule of Net Real Estate (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Real Estate [Line Items]
Buildings and building improvements	$ 2,962,982	$ 2,746,446
Land, land estates and land improvements	355,697	341,848
Construction in progress	1,895	1,840
Real estate - intangible assets	409,756	419,612
Investments in real estate under construction	13,313	0
Real estate, gross	3,743,643	3,509,746
Accumulated depreciation and amortization	(887,629)	(954,087)
Real estate, net	2,856,014	2,555,659
Accumulated amortization	212,033	231,443
Amortization expense, next 12 months	28,634
Amortization expense, year 2	26,647
Amortization expense, year 3	24,640
Amortization expense, year 4	23,487
Amortization expense, year 5	18,270
In-place lease values
Real Estate [Line Items]
Real estate - intangible assets	339,154	331,607
Tenant relationships
Real Estate [Line Items]
Real estate - intangible assets	42,396	54,662
Above-market leases
Real Estate [Line Items]
Real estate - intangible assets	$ 28,206	$ 33,343

Real Estate Investment Property, Finite-Lived Intangible Assets and Construction in Progress, Gross

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The current amount of expenditures for a real estate project that has not yet been completed.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Aggregate of the carrying amounts as of the balance sheet date of investments in building and building improvements.

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Amount before accumulated deprecation and depletion of real estate held for productive use and additions or improvements to real estate held for productive use, examples include, but are not limited to, walkways, driveways, fences, and parking lots. Excludes land held for sale.

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Carrying amount as of the balance sheet date of unprocessed goods that will be used in the course of a construction project which will become a part of the finished inventory.

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The cumulative amount of depreciation for real estate property held for investment purposes.

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Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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