Goodwill and Other Intangible Assets - Goodwill Activity by Business Segment (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Beginning of period			$ 1,642,169	$ 1,804,748
Purchase price allocation adjustments				(46,124)
Additions - business acquisitions			10,320	450
Write-down/impairment	$ (505)	$ (57,878)	(505)	(57,878)
Foreign currency translation			167,709	(59,027)
End of period	1,819,693	1,642,169	1,819,693	1,642,169
U.S. Networks [Member]
Goodwill [Line Items]
Beginning of period			510,484	510,484
Additions - business acquisitions			10,320
End of period	520,804	510,484	520,804	510,484
International Networks [Member]
Goodwill [Line Items]
Beginning of period			1,131,685	1,294,264
Purchase price allocation adjustments				(46,124)
Additions - business acquisitions				450
Write-down/impairment			(505)	(57,878)
Foreign currency translation			167,709	(59,027)
End of period	$ 1,298,889	$ 1,131,685	$ 1,298,889	$ 1,131,685