Revenues - Summary of Revenues Disaggregated by Major Source (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation Of Revenue [Line Items]
Total revenue	$ 64,680	$ 66,838
Broadcast Advertising
Disaggregation Of Revenue [Line Items]
Total revenue	34,708	37,709
Digital Advertising
Disaggregation Of Revenue [Line Items]
Total revenue	14,472	18,244
Spectrum Usage Rights
Disaggregation Of Revenue [Line Items]
Total revenue	5,084	108
Retransmission Consent
Disaggregation Of Revenue [Line Items]
Total revenue	8,760	8,853
Other
Disaggregation Of Revenue [Line Items]
Total revenue	$ 1,656	$ 1,924