Revenues - Summary of Revenues Disaggregated by Major Source (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation Of Revenue [Line Items]
Total revenue	$ 199,008	$ 62,978	$ 526,298	$ 172,343
Digital Advertising
Disaggregation Of Revenue [Line Items]
Total revenue	146,121	13,655	377,826	38,359
Broadcast Advertising
Disaggregation Of Revenue [Line Items]
Total revenue	40,495	37,596	110,608	98,913
Spectrum Usage Rights
Disaggregation Of Revenue [Line Items]
Total revenue	1,104	1,358	5,057	4,070
Retransmission Consent
Disaggregation Of Revenue [Line Items]
Total revenue	9,128	9,056	28,061	27,998
Other
Disaggregation Of Revenue [Line Items]
Total revenue	$ 2,160	$ 1,313	$ 4,746	$ 3,003