Goodwill and Other Intangible Assets - Summary of other intangible assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Carrying amount:
Total carrying amount	$ 837,100	$ 437,337
Accumulated amortization:
Total accumulated amortization	(161,224)	(115,599)
Net amortizable intangible assets	675,876	321,738
Total other intangible assets	1,061,791	478,953
FCC licenses
Accumulated amortization:
Other indefinite-lived intangible assets - FCC licenses	385,915	157,215
Television network affiliation relationships
Carrying amount:
Total carrying amount	616,244	248,444
Accumulated amortization:
Total accumulated amortization	(82,917)	(62,020)
Customer lists and advertiser relationships
Carrying amount:
Total carrying amount	111,700	100,500
Accumulated amortization:
Total accumulated amortization	(48,586)	(36,380)
Other intangible assets
Carrying amount:
Total carrying amount	109,156	88,393
Accumulated amortization:
Total accumulated amortization	$ (29,721)	$ (17,199)