Goodwill and Other Intangible Assets - Intangible Assets and Goodwill (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill	$ 2,596,863	$ 2,579,417
Goodwill, Accumulated Amortization	0	0
Total indefinite-live and amortizable intangible assets	1,645,035	1,361,389
Total indefinite-live and amortizable intangible assets, accumulated amortization	(110,911)	(88,120)
Retransmission agreements
Goodwill and Intangible Assets Disclosure [Line Items]
Amortizable intangible assets	121,594	110,191
Amortizable intangible assets, accumulated amortization	(74,972)	(62,355)
Network affiliation agreements
Goodwill and Intangible Assets Disclosure [Line Items]
Amortizable intangible assets	110,390	43,485
Amortizable intangible assets, accumulated amortization	(27,712)	(19,371)
Other
Goodwill and Intangible Assets Disclosure [Line Items]
Amortizable intangible assets	28,865	15,763
Amortizable intangible assets, accumulated amortization	(8,227)	(6,394)
Television and radio station FCC licenses
Goodwill and Intangible Assets Disclosure [Line Items]
Indefinite-lived intangibles	1,384,186	1,191,950
Total indefinite-live and amortizable intangible assets, accumulated amortization	$ 0	$ 0