Debt (Grouping Of Debt Between Fixed And Variable As Well As Secured And Unsecured) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total	$ 1,838,419	$ 1,732,338
As To Interest Rate [Member]
Debt Instrument [Line Items]
Fixed-rate debt	1,798,419	1,714,890
Variable-rate debt	40,000	17,448
Total	1,838,419	1,732,338
As To Collateralization [Member]
Debt Instrument [Line Items]
Unsecured debt	1,488,909	1,450,762
Secured debt	349,510	281,576
Total	$ 1,838,419	$ 1,732,338