Summary Of Significant Accounting Policies (Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable, net	$ 2,979,281	$ 2,063,087
Mezzanine notes payable	0	307,093
Unsecured senior notes, net	7,247,330	7,245,953
Unsecured line of credit	45,000	0
Total	3,013,961
Carrying Amount [Member]
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable, net	2,979,281	2,063,087
Mezzanine notes payable	0	307,093
Unsecured senior notes, net	7,247,330	7,245,953
Unsecured line of credit	45,000
Total	10,271,611	9,616,133
Estimated Fair Value [Member]
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable, net	3,042,920	2,092,237
Mezzanine notes payable	0	308,344
Unsecured senior notes, net	7,461,615	7,428,077
Unsecured line of credit	45,000
Total	$ 10,549,535	$ 9,828,658