Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill, Subsequent Recognition of Deferred Tax Asset	$ 2,544	$ 2,546
Amortization of Intangible Assets	$ 47,100	38,600	$ 42,000
Percentage Of Hypothetical Decrease	20.00%
National Networks [Member]
Goodwill [Line Items]
Goodwill, Subsequent Recognition of Deferred Tax Asset	$ 2,544	2,546
International And Other [Member]
Goodwill [Line Items]
Goodwill, Subsequent Recognition of Deferred Tax Asset	$ 0	$ 0
Hypothetical Decrease, Fair Value of Reporting Unit	2.00%
Accelerated Amortization of Intangible Assets	$ 9,000