Fair Value (Schedule Of Face And Fair Value Of Debt) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount	$ 6,400	$ 6,600
Face Value	2,818,800	2,758,800
Fair Value	3,314,439	3,370,588
Fixed Rate [Member]
Debt Instrument [Line Items]
Face Value	2,683,800	2,683,800
Fair Value	3,179,439	3,295,588
Variable Rate [Member]
Debt Instrument [Line Items]
Face Value	135,000	75,000
Fair Value	$ 135,000	$ 75,000