Summary of Significant Accounting Policies (Narrative) (Details) $ / shares in Units, $ in Thousands				1 Months Ended		3 Months Ended		9 Months Ended
	Mar. 04, 2020 $ / shares	Dec. 11, 2019 $ / shares	Sep. 12, 2019 $ / shares	May 30, 2019 $ / shares	Feb. 26, 2019 $ / shares	Sep. 30, 2020 USD ($) item $ / shares shares	Sep. 30, 2019 $ / shares shares	Sep. 30, 2020 USD ($) segment item $ / shares shares	Sep. 30, 2019 $ / shares shares	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number Of FM Radio Stations | item								79
Number Of AM Radio Stations								34
Number Of Metro Signals								78
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares						0	0	0	0
Number of Reportable Segments | item								27
Special cash dividend declared on Classes A and B Common Stock | $ / shares						$ 0	$ 0.30	$ 0.32	$ 0.90
Number Of Market Serving | item						27		27
Stock Repurchase Program, Remaining Authorized Repurchase Amount						$ 19,200		$ 19,200
Stock Repurchase Program, Authorized Amount						75,800		75,800
Operating Lease, Right-of-Use Asset						6,300		6,300		$ 6,900
Operating Lease, Liability						$ 6,595		$ 6,595		$ 7,000
Number of operating segments | segment								1
Customer relationships [Member]
Summary Of Significant Accounting Policies [Line Items]
Finite-Lived Intangible Asset, Useful Life								3 years
Class A Common Stock
Summary Of Significant Accounting Policies [Line Items]
Special cash dividend declared on Classes A and B Common Stock | $ / shares	$ 0.32	$ 0.30	$ 0.30	$ 0.30	$ 0.30