Goodwill and Other Intangible Assets - Goodwill Rollforward (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)
Changes in the Company's net goodwill
Goodwill before accumulated impairment losses beginning balance	$ 4,067,529
Accumulated impairment losses beginning balance	0
Ending balance	4,067,529
Activity during the period:
Goodwill before accumulated impairment losses ending balance	4,070,039
Accumulated impairment losses ending balance	0
Ending balance	4,070,039
Operating Segments
Changes in the Company's net goodwill
Goodwill before accumulated impairment losses beginning balance	4,257,718
Accumulated impairment losses beginning balance	(190,189)
Ending balance	4,067,529
Activity during the period:
Acquisitions	0
Impairment	0
Foreign currency exchange rate changes	2,510
Total	2,510
Goodwill before accumulated impairment losses ending balance	4,260,228
Accumulated impairment losses ending balance	(190,189)
Ending balance	4,070,039
Operating Segments | Media
Changes in the Company's net goodwill
Goodwill before accumulated impairment losses beginning balance	2,579,418
Accumulated impairment losses beginning balance	0
Ending balance	2,579,418
Activity during the period:
Acquisitions	0
Impairment	0
Foreign currency exchange rate changes	0
Total	0
Goodwill before accumulated impairment losses ending balance	2,579,418
Accumulated impairment losses ending balance	0
Ending balance	2,579,418
Operating Segments | Digital
Changes in the Company's net goodwill
Goodwill before accumulated impairment losses beginning balance	1,678,300
Accumulated impairment losses beginning balance	(190,189)
Ending balance	1,488,111
Activity during the period:
Acquisitions	0
Impairment	0
Foreign currency exchange rate changes	2,510
Total	2,510
Goodwill before accumulated impairment losses ending balance	1,680,810
Accumulated impairment losses ending balance	(190,189)
Ending balance	$ 1,490,621