Real Estate and Lease Intangibles - Summary of Carrying Amounts of Investment in Real Estate (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Land	$ 5,960,804	$ 5,996,024
Depreciable property:
Buildings and improvements	17,748,897	17,743,042
Furniture, fixtures and equipment	1,575,934	1,548,961
In-Place lease intangibles	473,522	476,359
Projects under development:
Construction-in-progress	96,609	163,547
Land held for development:
Land	102,851	98,963
Construction-in-progress	96,609	163,547
Investment in real estate	25,958,617	26,026,896
Accumulated depreciation	(6,173,047)	(6,040,378)
Investment in real estate, net	19,785,570	19,986,518
Projects under development [Member]
Projects under development:
Land	30,605	43,226
Construction-in-progress	66,004	120,321
Land held for development:
Construction-in-progress	66,004	120,321
Land held for development [Member]
Projects under development:
Construction-in-progress	40,313	36,425
Land held for development:
Land	62,538	62,538
Construction-in-progress	$ 40,313	$ 36,425

Carrying amount of land for a real estate project that has not yet been completed.

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Land held for development [Abstract]

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Projects under development [Abstract]

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.10)
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- Definition

This element represents the amount of value allocated by a lessor (acquirer) to lease agreements which exist at acquisition of a leased property. Such amount may include the value assigned to existing tenant relationships and excludes the market adjustment component of the value assigned for above or below-market leases acquired.

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No definition available.

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- Definition

Amount before accumulated depreciation of fixtures and equipment. Includes, but is not limited to, machinery, equipment, and engines.

+ References

No definition available.

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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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
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Amount before accumulated depletion of real estate held for productive use, excluding land held for sale.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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Carrying amount of land available for development.

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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 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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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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