Rental Properties (Summary Of Carrying Amounts Of Rental Properties) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Real Estate Properties [Line Items]
Carrying amounts of rental properties	$ 6,208,685		$ 6,186,562
Accumulated depreciation	(1,023,993)		(989,254)
Total	5,184,692		5,197,308
Depreciation expense on rental properties	40,800	$ 34,500
Building and improvements [Member]
Real Estate Properties [Line Items]
Carrying amounts of rental properties	4,761,319		4,747,101
Furniture, fixtures & equipment [Member]
Real Estate Properties [Line Items]
Carrying amounts of rental properties	123,229		123,239
Land [Member]
Real Estate Properties [Line Items]
Carrying amounts of rental properties	1,298,096		1,290,181
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
-Topic 230
-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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