Propert and Equipment (Property, Plant, Equipment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	$ 443,433	$ 438,784
Accumulated Depreciation And Amortization	(259,919)	(272,148)
Property and equipment, net	183,514	166,636
Program, Service and Test Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	212,357	223,847
Satellite Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	$ 46,315	51,423
Property, Plant and Equipment, Useful Life	13 years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	$ 21,067	21,471
Transmission Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	$ 56,035	51,954
Property, Plant and Equipment, Useful Life	5 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	$ 107,659	$ 90,089
Minimum [Member] | Program, Service and Test Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Minimum [Member] | Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Maximum [Member] | Program, Service and Test Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Maximum [Member] | Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	8 years