Basis Of Presentation And Summary Of Significant Accounting Policies (Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable	$ 4,328,464,000	$ 4,449,734,000
Mezzanine notes payable	310,114,000	311,040,000
Unsecured senior notes	5,837,172,000	5,835,854,000
Unsecured exchangeable senior notes	0	744,880,000
Estimated Fair Value [Member]
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable	4,460,353,000	4,545,283,000
Mezzanine notes payable	310,141,000	311,064,000
Unsecured senior notes	6,173,499,000	6,050,517,000
Unsecured exchangeable senior notes	0	750,266,000
Total	10,943,993,000	11,657,130,000
Carrying Amount [Member]
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable	4,328,464,000	4,449,734,000
Mezzanine notes payable	310,114,000	311,040,000
Unsecured senior notes	5,837,172,000	5,835,854,000
Unsecured exchangeable senior notes	0	744,880,000	[1]
Total	10,475,750,000	11,341,508,000
ASC 470-20 Adjustment [Member]
Summary Of Significant Accounting Policies [Line Items]
Impact of accounting pronouncement		$ 2,400,000

[1] Includes the net adjustment for the equity component allocation totaling approximately $2.4 million at December 31, 2013.