Rental Properties (Summary Of Carrying Amounts Of Rental Properties) (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Real Estate Properties [Line Items]
Carrying amounts of rental properties	$ 6,558,790		$ 5,907,231
Accumulated depreciation	(989,480)		(883,174)
Total	5,569,310		5,024,057
Depreciation expense on rental properties	123,000	$ 110,400
Building and improvements [Member]
Real Estate Properties [Line Items]
Carrying amounts of rental properties	5,074,504		4,593,159
Furniture, fixtures & equipment [Member]
Real Estate Properties [Line Items]
Carrying amounts of rental properties	126,659		97,463
Land [Member]
Real Estate Properties [Line Items]
Carrying amounts of rental properties	1,331,586		1,190,568
Leaseholds and Leasehold Improvements [Member]
Real Estate Properties [Line Items]
Carrying amounts of rental properties	$ 26,041		$ 26,041

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(3))
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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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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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

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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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