Real Estate (Summary of Real Estate Subject to Operating Leases) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Property Subject to or Available for Operating Lease [Line Items]
Real estate subject to operating leases, gross	$ 6,988,406	$ 6,596,957
Less accumulated depreciation and amortization	(810,460)	(739,362)
Real estate subject to operating leases before work in process	6,177,946	5,857,595
Accounted for using the operating method, net of accumulated depreciation and amortization	6,198,346	5,881,652
Land and improvements
Property Subject to or Available for Operating Lease [Line Items]
Land and improvements	2,197,287	2,103,233
Buildings and improvements
Property Subject to or Available for Operating Lease [Line Items]
Buildings and improvements	4,785,858	4,489,159
Leasehold interests
Property Subject to or Available for Operating Lease [Line Items]
Leasehold interests	5,261	4,565
Work in progress
Property Subject to or Available for Operating Lease [Line Items]
Work in progress	$ 20,400	$ 24,057

Aggregate carrying amounts as of the balance sheet date of investments in leasehold interests

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- Definition

Real Estate Subject To Operating Leases Before Work In Process

+ References

No definition available.

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- Definition

Real Estate Subject to Operating Leases, Gross

+ References

No definition available.

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- Definition

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)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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- Definition

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

+ 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 210.7-03.1(d))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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- Definition

Amount before accumulated depletion of real estate held for productive use, excluding land held for sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 4
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6812-107765

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- Definition

The amount of accumulated depreciation, by major property class, recorded on property subject to or available for lease as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84164653&loc=d3e41551-112718

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-Name Accounting Standards Codification
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- Definition

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.

+ References

No definition available.

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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