Broadcast Licenses, Goodwill and Other Intangible Assets (Changes to broadcast licenses) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Broadcast License, Goodwill and Other Intangible Assets
Balance			$ 95,311,000	$ 95,250,000
Acquisitions			46,000	61,000
Impairment charge	$ (1,392,000)	$ (3,757,000)	(5,149,000)	0	$ 0
Balance			$ 90,208,000	$ 95,311,000	$ 95,250,000