Goodwill and Other Intangible Assets (Schedule Of Goodwill) (Details) $ in Thousands	9 Months Ended
Sep. 30, 2018 USD ($)
Goodwill [Roll Forward]
December 31, 2017	$ 695,158
Additions	24,214
Amortization of second component goodwill	(984)
Foreign currency translation	(13,006)
September 30, 2018	705,382
National Networks [Member]
Goodwill [Roll Forward]
December 31, 2017	239,759
Additions	0
Amortization of second component goodwill	(984)
Foreign currency translation	0
September 30, 2018	238,775
International And Other [Member]
Goodwill [Roll Forward]
December 31, 2017	455,399
Additions	24,214
Amortization of second component goodwill	0
Foreign currency translation	(13,006)
September 30, 2018	$ 466,607

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of (increase) decrease to an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from the subsequent recognition of deferred tax assets.

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