Revenues - Summary of Revenues Disaggregated by Major Source (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation Of Revenue [Line Items]
Total Revenue	$ 66,838	$ 57,510
Broadcast Advertising
Disaggregation Of Revenue [Line Items]
Total Revenue	37,709	42,788
Digital Advertising
Disaggregation Of Revenue [Line Items]
Total Revenue	18,244	4,081
Spectrum Usage Rights
Disaggregation Of Revenue [Line Items]
Total Revenue	108
Retransmission Consent
Disaggregation Of Revenue [Line Items]
Total Revenue	8,853	7,960
Other
Disaggregation Of Revenue [Line Items]
Total Revenue	$ 1,924	$ 2,681