Revenue Recognition (Schedule Of Breakout Of The Company's Derived Revenue And Other Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue Recognition [Abstract]
Revenue from contracts with customers	$ 95,706	$ 52,935	$ 219,466	$ 150,990
Interest income		11	6	20
Cost recovery income			158	417
Dividend income				18
Total revenue	$ 95,706	$ 52,946	$ 219,630	$ 151,445