Apartment homes sold.

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Communities held for sale.

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Number of properties purchased.

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Real estate owned.

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Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination.

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The cash inflow associated with the acquisition of business during the period (for example, cash that was held by the acquired business).

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Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.

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The net gain (loss) resulting from sales and other disposals of real estate owned for investment purposes.

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Amount of interest capitalized, including amount of allowance for funds used during construction.

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The number of real estate properties owned as of the balance sheet date.

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Real Estate Owned (Details Textual) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) ft² Communities Apartment_Homes States $ / shares	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) ft² Communities Apartment_Homes States $ / shares	Jun. 30, 2014 USD ($)	Jun. 30, 2013 USD ($)
Real Estate Properties [Line Items]
Communities Held For Sale		1		1
Real Estate Owned (Textual) [Abstract]
Number of states in which there are owned and consolidated communities	10		10
Number of apartment homes owned and consolidated by the Company \| Apartment_Homes	39,404		39,404
Number of Real Estate Properties \| Communities	136		136
Development costs excluding direct costs and capitlized interest	$ 1,600	$ 2,100	$ 3,800	$ 5,500
Interest capitalized during period	3,800	4,900	8,600	10,200
Other Cost and Expense, Operating	1,769	2,162	3,535	4,088
Proceeds from Sale of Property, Plant, and Equipment			109,900
Payments for (Proceeds from) Investments			90,543	47,922
Gains/(loss) on sales of real estate, net of tax	79,042	26,709	79,042	51,003
Acquisition of real estate			24,067	0
Casualty-related (recoveries)/charges, net	(843)	0	(1,839)	(500)
Casualty (Recoveries)/Charges	$ (843)	0	$ (1,839)	(500)
Communities Sold \| Communities			3
Apartment Homes Sold \| Apartment_Homes			812
Home Acquisition [Member]
Real Estate Owned (Textual) [Abstract]
Number of Properties Purchased	6
Fair Value of Assets Acquired	$ 908,000
Business Acquisition, Share Price \| $ / shares	$ 35		$ 35
Acquisition of real estate	$ 90,000
Cash Acquired from Acquisition	$ 65,000
Unconsolidated Joint Venture Four Texas [Member]
Real Estate Owned (Textual) [Abstract]
Proceeds from Sale of Property, Plant, and Equipment			$ 43,500
Gain (Loss) on Disposition of Property Plant Equipment			$ 59,100
1745 Shea [Member]
Real Estate Owned (Textual) [Abstract]
Square Footage \| ft²	120,000		120,000
UDR, Inc. [Member]
Real Estate Owned (Textual) [Abstract]
Square Footage \| ft²	44,000		44,000
United Dominion Reality L.P. [Member]
Real Estate Owned (Textual) [Abstract]
Number of states in which there are owned and consolidated communities \| States	9		9
Number of apartment homes owned and consolidated by the Company \| Apartment_Homes	20,569		20,569
Number of Real Estate Properties \| Communities	67		67
Development costs excluding direct costs and capitlized interest	$ 195	542	$ 328	1,300
Interest capitalized during period	0	1,000	100	2,000
Other Cost and Expense, Operating	1,496	1,451	2,986	2,887
Proceeds from Sale of Property, Plant, and Equipment			45,300
Payments for (Proceeds from) Investments			27,700
Gains/(loss) on sales of real estate, net of tax	32,375	16,285	56,998	40,687
Casualty-related (recoveries)/charges, net	280	0	873		$ 500
Casualty (Recoveries)/Charges	$ (280)	0	$ (873)	(500)
Communities Sold \| Communities			1
Apartment Homes Sold \| Apartment_Homes			240
Operating Community [Member]
Real Estate Owned (Textual) [Abstract]
Gain (Loss) on Disposition of Property Plant Equipment		$ 26,700		49,900
Operating Community [Member] \| Unconsolidated Joint Venture Vitruvian Park [Member]
Real Estate Owned (Textual) [Abstract]
Number of Real Estate Properties	3		3
Operating Community [Member] \| Unconsolidated Joint Venture Four Texas [Member]
Real Estate Owned (Textual) [Abstract]
Number of Real Estate Properties \| Communities	8		8
Development Community [Member] \| Unconsolidated Joint Venture Four Texas [Member]
Real Estate Owned (Textual) [Abstract]
Number of Real Estate Properties	0		0
Land [Member]
Real Estate Owned (Textual) [Abstract]
Gain (Loss) on Disposition of Property Plant Equipment				$ 1,100
Office Building [Member] \| 1745 Shea [Member]
Real Estate Owned (Textual) [Abstract]
Property, Plant and Equipment, Additions			$ 24,000
UDR DownREIT Unit [Member] \| Home Acquisition [Member]
Real Estate Owned (Textual) [Abstract]
Stock Issued During Period, Value, Acquisitions	$ 753,000