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The net book value of real estate held for investment and real estate under development.

+ References

No definition available.

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- Definition

Real Estate Owned Gross.

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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)

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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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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))

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

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- Definition

Amount of accumulated depreciation pertaining to real estate investments for entities with a substantial portion of business acquiring and holding investment real estate.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 970

-SubTopic 360

-Section S99

-Paragraph 1

-Subparagraph (SX 210.12-28.FN4)

-URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024

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-Name Accounting Standards Codification

-Topic 205

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-Section S99

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-Subparagraph (SX 210.5-04.(c) Schedule III)

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-Name Regulation S-X (SX)

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-Paragraph c

-Subparagraph Schedule III

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- Definition

Carrying amount as of the balance sheet date of investments in land and buildings held for sale, excluding real estate considered to be inventory of the entity.

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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(f))

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

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Real Estate Owned (UNITED DOMINION REALTY, L.P.) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Summary of carrying amounts for real estate owned (at cost)
Land	$ 1,980,221us-gaap_LandAndLandImprovements	$ 1,847,127us-gaap_LandAndLandImprovements
Under development:
Real estate under development (net of accumulated depreciation of $0)	177,632us-gaap_DevelopmentInProcess	466,002us-gaap_DevelopmentInProcess
Real estate owned	8,383,259udr_RealEstateOwnedGross	8,207,977udr_RealEstateOwnedGross
Accumulated depreciation	(2,434,772)	(2,208,794)	(1,924,682)	(1,831,727)
Total real estate owned, net of accumulated depreciation	5,948,487udr_RealEstateNet	5,999,183udr_RealEstateNet
Land
Held for sale:
Sold or held for sale	0	10,751
Under development:
Real estate under development (net of accumulated depreciation of $0)	24,584	110,769
Building and improvements
Held for sale:
Sold or held for sale	0	5,969
Construction in progress
Under development:
Real estate under development (net of accumulated depreciation of $0)	153,048	356,644
United Dominion Reality L.P.
Summary of carrying amounts for real estate owned (at cost)
Land	1,008,014	1,004,447
Depreciable property - held and used:
Building and improvements	3,230,756	3,103,970
Under development:
Real estate under development (net of accumulated depreciation of $0)	0	80,063
Real estate owned	4,238,770	4,188,480
Accumulated depreciation	(1,403,303)	(1,241,574)	(1,097,133)	(976,358)
Total real estate owned, net of accumulated depreciation	2,835,467	2,946,906
United Dominion Reality L.P. \| Land
Under development:
Real estate under development (net of accumulated depreciation of $0)	0	9,447
United Dominion Reality L.P. \| Construction in progress
Under development:
Real estate under development (net of accumulated depreciation of $0)	$ 0	$ 70,616