Debt (Grouping Of Debt Between Fixed And Variable As Well As Secured And Unsecured) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Total	$ 1,786,962	$ 1,838,419
As To Interest Rate [Member]
Debt Instrument [Line Items]
Fixed-rate debt	1,782,960	1,798,419
Variable-rate debt	4,002	40,000
Total	1,786,962	1,838,419
As To Collateralization [Member]
Debt Instrument [Line Items]
Unsecured debt	1,453,858	1,488,909
Secured debt	333,104	349,510
Total	$ 1,786,962	$ 1,838,419