Commitments to Acquire/Dispose of Real Estate (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2011 Year Project Apartment Property Store Customers OptionPlan
Commitments to Acquire Real Estate
Properties Acquired-Total	6
Rental Units Acquired - Total	2,641
Purchase Price - Total	$ 552,887
Commitments to Dispose of Real Estate
Rental Units Disposed-Total	351
Properties Disposed - Total	4
Sales Price-Total	15,550
Rental Properties [Member]
Commitments to Acquire Real Estate
Properties Acquired-Total	6
Rental Units Acquired - Total	2,641
Purchase Price - Total	394,900
Commitments to Dispose of Real Estate
Rental Units Disposed-Total	351
Properties Disposed - Total	4
Sales Price-Total	15,550
Land Parcels (three) [Member]
Commitments to Acquire Real Estate
Properties Acquired-Total	0
Rental Units Acquired - Total	0
Purchase Price - Total	$ 157,987

Commitments to acquire real estate.

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- Definition

Commitments to Dispose of Real Estate Abstract.

+ Details

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- Definition

Total number of rental properties to be acquired subsequent to the balance sheet date per separate agreements entered into prior to the balance sheet date.

+ Details

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- Definition

Total number of rental properties to be disposed of subsequent to the balance sheet date per separate agreements entered into prior to the balance sheet date.

+ Details

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- Definition

The amount of the fixed and determinable portion of an unrecorded purchase commitment for the acquisition of a rental property or land parcel subsequent to the balance sheet date.

+ Details

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- Definition

The amount of the fixed and determinable portion of an unrecorded sales commitment for the disposition of a rental property or land parcel subsequent to the balance sheet date.

+ Details

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- Definition

Total number of rental units to be acquired subsequent to the balance sheet date per separate agreements entered into prior to the balance sheet date.

+ Details

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- Definition

Total number of rental units to be disposed of subsequent to the balance sheet date per separate agreements entered into prior to the balance sheet date.

+ Details

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