Goodwill and Other Intangible Assets - Intangible Assets and Goodwill (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill	$ 2,602,849	$ 2,579,417
Goodwill, Accumulated Amortization	0	0
Total indefinite-live and amortizable intangible assets	1,635,205	1,361,389
Total indefinite-live and amortizable intangible assets, accumulated amortization	(94,902)	(88,120)
Retransmission agreements
Goodwill and Intangible Assets Disclosure [Line Items]
Amortizable intangible assets	121,184	110,191
Amortizable intangible assets, accumulated amortization	(66,360)	(62,355)
Network affiliation agreements
Goodwill and Intangible Assets Disclosure [Line Items]
Amortizable intangible assets	99,511	43,485
Amortizable intangible assets, accumulated amortization	(21,603)	(19,371)
Other
Goodwill and Intangible Assets Disclosure [Line Items]
Amortizable intangible assets	27,137	15,763
Amortizable intangible assets, accumulated amortization	(6,939)	(6,394)
Television and radio station FCC licenses
Goodwill and Intangible Assets Disclosure [Line Items]
Indefinite-lived intangibles	1,387,373	1,191,950
Total indefinite-live and amortizable intangible assets, accumulated amortization	$ 0	$ 0