Summary Of Significant Accounting Policies (Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable	$ 3,438,714	$ 4,309,484
Mezzanine notes payable	308,482	309,796
Unsecured senior notes	5,289,317	5,287,704
Total	3,358,479
Carrying Amount [Member]
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable	3,438,714	4,309,484
Mezzanine notes payable	308,482	309,796
Unsecured senior notes	5,289,317	5,287,704
Total	9,036,513	9,906,984
Estimated Fair Value [Member]
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable	3,503,746	4,449,541
Mezzanine notes payable	306,103	306,156
Unsecured senior notes	5,547,738	5,645,819
Total	$ 9,357,587	$ 10,401,516