Goodwill and Other Intangible Assets - Summary of other intangible assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Carrying amount:
Total carrying amount	$ 823,180	$ 823,500
Accumulated amortization:
Total accumulated amortization	(190,729)	(148,740)
Net amortizable intangible assets	632,451	674,760
Indefinite-lived intangible assets — FCC licenses	349,915	385,915
Total other intangible assets	982,366	1,060,675
Television network affiliation relationships
Carrying amount:
Total carrying amount	616,244	616,244
Accumulated amortization:
Total accumulated amortization	(106,258)	(82,917)
Customer lists and advertiser relationships
Carrying amount:
Total carrying amount	102,900	104,300
Accumulated amortization:
Total accumulated amortization	(50,305)	(42,012)
Other
Carrying amount:
Total carrying amount	104,036	102,956
Accumulated amortization:
Total accumulated amortization	$ (34,166)	$ (23,811)