Debt (Grouping Of Debt Between Fixed And Variable As Well As Secured And Unsecured) (Details) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Schedule of Long-term Debt, By Type [Line Items]
Total	[1]	$ 2,081,152	$ 2,356,528
As To Interest Rate [Member]
Schedule of Long-term Debt, By Type [Line Items]
Fixed-rate debt		2,063,263	2,089,769
Variable-rate debt		17,889	266,759
As To Collateralization [Member]
Schedule of Long-term Debt, By Type [Line Items]
Unsecured debt		1,667,462	1,913,399
Secured debt		$ 413,690	$ 443,129

[1] * Consolidated variable interest entities' assets held as collateral and debt included in the above balances at December 31, 2017 and December 31, 2016 are Property, net of $207,969 and $476,117; Accrued Rent and Accounts Receivable, net of $12,011 and $11,066; Cash and Cash Equivalents of $9,025 and $9,560; Debt, net of $46,253 and $47,112.