Revenues - Summary of Revenues Disaggregated by Major Source (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation Of Revenue [Line Items]
Total revenue	$ 70,838	$ 68,816	$ 69,241	$ 64,680	$ 82,073	$ 74,575	$ 74,329	$ 66,838	$ 273,575	$ 297,815	$ 536,034
Broadcast Advertising
Disaggregation Of Revenue [Line Items]
Total revenue									148,082	169,009	171,715
Digital Advertising
Disaggregation Of Revenue [Line Items]
Total revenue									68,908	80,982	57,098
Spectrum Usage Rights
Disaggregation Of Revenue [Line Items]
Total revenue									13,061	2,976	263,943
Retransmission Consent
Disaggregation Of Revenue [Line Items]
Total revenue									35,362	35,066	31,413
Other
Disaggregation Of Revenue [Line Items]
Total revenue									$ 8,162	$ 9,782	$ 11,865