Goodwill and Other Intangible Assets (Schedule Of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Beginning balance	$ 701,980	$ 798,037
Impairment charge	(25,062)	(97,996)
Purchase accounting adjustments		(2,414)
Amortization of "second component" goodwill	(1,343)	(1,328)
Foreign currency translation	10,832	5,681
Ending balance	686,407	701,980
National Networks [Member]
Goodwill [Roll Forward]
Beginning balance	237,103	238,431
Impairment charge	0	0
Purchase accounting adjustments		0
Amortization of "second component" goodwill	(1,343)	(1,328)
Foreign currency translation	0	0
Ending balance	235,760	237,103
International And Other [Member]
Goodwill [Roll Forward]
Beginning balance	464,877	559,606
Impairment charge	(25,062)	(97,996)
Purchase accounting adjustments		(2,414)
Amortization of "second component" goodwill	0	0
Foreign currency translation	10,832	5,681
Ending balance	$ 450,647	$ 464,877