Basis Of Presentation And Summary Of Significant Accounting Policies (Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable	$ 4,289,120	$ 4,309,484
Mezzanine notes payable	309,475	309,796
Unsecured senior notes	5,288,101	5,287,704
Estimated Fair Value [Member]
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable	4,428,519	4,449,541
Mezzanine notes payable	306,143	306,156
Unsecured senior notes	5,749,666	5,645,819
Total	10,484,328	10,401,516
Carrying Amount [Member]
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable	4,289,120	4,309,484
Mezzanine notes payable	309,475	309,796
Unsecured senior notes	5,288,101	5,287,704
Total	$ 9,886,696	$ 9,906,984