Goodwill and Other Intangible Assets - Summary of other intangible assets (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Carrying amount:
Total carrying amount	$ 649,642	$ 437,337
Accumulated amortization:
Total accumulated amortization	(134,565)	(115,599)
Net amortizable intangible assets	515,077	321,738
Indefinite-lived intangible assets — FCC licenses	209,715	157,215
Total other intangible assets	724,792	478,953
Television network affiliation relationships
Carrying amount:
Total carrying amount	434,544	248,444
Accumulated amortization:
Total accumulated amortization	(69,950)	(62,020)
Customer lists and advertiser relationships
Carrying amount:
Total carrying amount	105,032	100,500
Accumulated amortization:
Total accumulated amortization	(42,028)	(36,380)
Other
Carrying amount:
Total carrying amount	110,066	88,393
Accumulated amortization:
Total accumulated amortization	$ (22,587)	$ (17,199)