Revenues - Summary of Disaggregation of Broadcast Advertising Revenue by Sales Channel (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation Of Revenue [Line Items]
Total revenue	$ 760,192	$ 344,026	$ 273,575
Advertising
Disaggregation Of Revenue [Line Items]
Total revenue	154,297	152,677	148,082
Advertising | Local Direct
Disaggregation Of Revenue [Line Items]
Total revenue	23,070	21,334	25,972
Advertising | Local Agency
Disaggregation Of Revenue [Line Items]
Total revenue	59,865	48,702	58,425
Advertising | National Agency
Disaggregation Of Revenue [Line Items]
Total revenue	$ 71,362	$ 82,641	$ 63,685