Nature of Business, Basis of Presentation and Summary of Significant Accounting Policies (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) segment station market	Dec. 31, 2019 USD ($) station
Accounting Policies [Abstract]
Number of owned and operated stations | station	415
Number of markets | market	86
Number of radio stations | station	7,300
Number of reportable segments | segment	1
Advertising expense	$ 4,000	$ 6,000
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Stock-based compensation expense	3,337	5,301
Trade revenue	34,203	45,308
Trade expense	$ 33,604	$ 44,378
Marketing Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of radio stations under local marketing agreement | station	1	2
Revenue	$ 2,500	$ 3,500