Real Estate (Details) (USD $)	12 Months Ended
Dec. 31, 2010 Year Apartmentunit Hector Property LandParcels Project RealEstate	Dec. 31, 2009 Apartmentunit LandParcels Year Property Hector Project	Dec. 31, 2008
Table of Real Estate Owned
Land	$ 4,110,275,000	$ 3,650,324,000
Depreciable property:
Buildings and improvements	13,995,121,000	12,781,543,000
Furniture and Fixtures, Gross	1,231,391,000	1,111,978,000
Land - Projects under development	28,260,000	106,716,000
Construction-in-progress	130,337,000	668,979,000
Land - Land held for development	235,247,000	252,320,000
Investment in real estate	19,702,371,000	18,465,144,000
Accumulated depreciation	(4,337,357,000)	(3,877,564,000)
Investment in real estate, net	15,365,014,000	14,587,580,000
Significant Acquisitions and Disposals [Line Items]
Properties - acquired	16	2
Units - acquired	4,445	566
Net (loss) on sales of land parcels	(1,395,000)		2,976,000
Acquired Properties
Properties - acquired	16	2
Units - acquired	4,445	566
Purchase Price - acquired	1,554,570,000	156,536,000
Total Properties:
Properties - disposed	63	61
Units - disposed	13,448	12,551
Sales Price - disposed	1,140,491,000	1,013,258,000
Equity interest in Acquired property	75.00%
Interest in unconsolidated rental properties	25.00%	25.00%
Real Estate (Textuals) [Abstract]
Gain on sale of discontinued operations	298,000,000	335,300,000
Land parcels acquired	6
Land Parcels Disposed		1
Projects under development [Member]
Depreciable property:
Construction-in-progress	102,077,000	562,263,000
Land held for development [Member]
Depreciable property:
Construction-in-progress	36,782,000	70,890,000
Land - Land held for development	198,465,000	181,430,000
Consolidated Rental Properties [Member]
Total Properties:
Properties - disposed	35	54
Units - disposed	7,171	11,055
Sales Price - disposed	718,352,000	905,219,000
Unconsolidated Rental Properties [Member]
Significant Acquisitions and Disposals [Line Items]
Properties - acquired	7	1
Cost of acquiring properties	105,100,000	18,500,000
Units - acquired	1,811	250
Net (loss) on sales of land parcels	28,100,000	10,700,000
Acquired Properties
Properties - acquired	7	1
Units - acquired	1,811	250
Total Properties:
Properties - disposed	27	6
Units - disposed	6,275	1,434
Sales Price - disposed	417,779,000	96,018,000
Equity interest in Acquired property		75.00%
Interest in unconsolidated rental properties	25.00%
Land Parcel (one) [Member]
Significant Acquisitions and Disposals [Line Items]
Net (loss) on sales of land parcels	1,400,000
Acquired Properties
Purchase Price - acquired		11,500,000
Total Properties:
Sales Price - disposed	4,000,000
Condominium Conversion Properties [Member]
Total Properties:
Properties - disposed	1	1
Units - disposed	2	62
Sales Price - disposed	360,000	12,021,000
Unaffiliated Parties [Member]
Significant Acquisitions and Disposals [Line Items]
Properties - acquired	16	2
Units - acquired	4,445	566
Acquired Properties
Properties - acquired	16	2
Units - acquired	4,445	566
Purchase Price - acquired	1,485,701,000	145,036,000
Land Parcel Six [Member]
Acquired Properties
Purchase Price - acquired	$ 68,869,000

Total number of rental property or properties acquired from unaffiliated third parties during the period.

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Depreciable property.

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Gain (loss) after tax expense (benefit), not previously recognized and resulting from the sale of a business component, which is recognized at the date of sale. A gain (loss) reflects the amount by which the consideration received exceeds (is exceeded by) the net carrying amount (reflecting previous provisions for loss on disposal, if any) of the disposal group.

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The total number of rental properties that the Company disposed of to unaffiliated parties during the period.

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Total number of rental units associated with rental properties that the company disposed of to unaffiliated third parties during the period.

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The difference between the book value and the sale price of land parcels sold within the period.

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Total number of land parcel or parcels acquired from unaffiliated third parties during the period.

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Total number of land parcel or parcels that the Company disposed of to unaffiliated third parties during the period.

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Carrying amount of land for a real estate project that has not yet been completed.

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The cash inflow from the sale of investment property.

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Total number of units associated with the property or properties acquired from unaffiliated third parties during the period.

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Real Estate Textuals Abstract.

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Rental Properties Abstract.

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Amount of cash paid to acquire the entity.

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-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 51

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The total cost of the acquired entity including the cash paid to shareholders of acquired entities, fair value of debt and equity securities issued to shareholders of acquired entities, the fair value of the liabilities assumed, and direct costs of the acquisition.

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

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-Name Statement of Financial Accounting Standard (FAS)

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Percentage of voting equity interests acquired in the business combination.

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

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-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

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The current amount of expenditures for a real estate project that has not yet been completed.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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

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Carrying amount at the balance sheet date for long-lived, depreciable asset commonly used in offices and stores. Examples include desks, chairs, and store fixtures.

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-Publisher AICPA

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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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Carrying amount as of the balance sheet date of real estate held for productive use. This excludes land held for sale.

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Carrying amount of land available for development.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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Represents a total 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.

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The net book value of real estate property held for investment purposes.

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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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