Basis Of Presentation And Summary Of Significant Accounting Policies (Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable, net	$ 2,972,052	$ 2,979,281
Unsecured senior notes, net	7,251,578	7,247,330
Unsecured line of credit	0	45,000
Unsecured term loan, net	498,248	0
Carrying Amount [Member]
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable, net	2,972,052	2,979,281
Unsecured senior notes, net	7,251,578	7,247,330
Unsecured line of credit	0	45,000
Unsecured term loan, net	498,248	0
Total	10,721,878	10,271,611
Estimated Fair Value [Member]
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable, net	2,938,167	3,042,920
Unsecured senior notes, net	7,188,261	7,461,615
Unsecured line of credit	0	45,000
Unsecured term loan, net	500,181	0
Total	$ 10,626,609	$ 10,549,535