Summary of Significant Accounting Policies (Narrative) (Details)	3 Months Ended
	Mar. 31, 2021 USD ($) segment item shares	Mar. 31, 2020 shares	Dec. 31, 2020 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number Of FM Radio Stations | item	79
Number Of AM Radio Stations	35
Number Of Metro Signals	79
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares	0	0
Number of Reportable Segments | item	27
Number Of Market Serving | item	27
Operating Lease, Right-of-Use Asset | $	$ 6,300,000		$ 6,600,000
Operating Lease, Liability | $	$ 6,587,000		6,900,000
Number of operating segments | segment	1
Allowance for doubtful accounts receivable | $	$ 528,000		$ 648,000
Customer relationships [Member]
Summary Of Significant Accounting Policies [Line Items]
Finite-Lived Intangible Asset, Useful Life	3 years