Goodwill and Other Intangible Assets - Summary of other intangible assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Carrying amount:
Total carrying amount	$ 812,643	$ 437,337
Accumulated amortization:
Total accumulated amortization	(146,233)	(115,599)
Net amortizable intangible assets	666,410	321,738
Indefinite-lived intangible assets — FCC licenses	354,615	157,215
Total other intangible assets	1,021,025	478,953
Television network affiliation relationships
Carrying amount:
Total carrying amount	591,544	248,444
Accumulated amortization:
Total accumulated amortization	(75,472)	(62,020)
Customer lists and advertiser relationships
Carrying amount:
Total carrying amount	112,332	100,500
Accumulated amortization:
Total accumulated amortization	(45,195)	(36,380)
Other
Carrying amount:
Total carrying amount	108,767	88,393
Accumulated amortization:
Total accumulated amortization	$ (25,566)	$ (17,199)