Broadcast Licenses, Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Indefinite-lived Intangible Assets [Line Items]
Balance				$ 93,259				$ 96,229		$ 93,259	$ 96,229
Acquisitions										1,991	8,086
Dispositions											(9,607)
Impairment charge	$ 0	$ 0	$ 0	0	$ (1,449)	$ 0	$ 0	0	[1]	0	(1,449)	$ 0
Balance	95,250				93,259					95,250	93,259	96,229
Discontinued Operations [Member]
Indefinite-lived Intangible Assets [Line Items]
Balance				0				9,607		0	9,607
Acquisitions										0	0
Dispositions											(9,607)
Impairment charge											0
Balance	0				0					0	0	9,607
Continuing Operations [Member]
Indefinite-lived Intangible Assets [Line Items]
Balance				$ 93,259				$ 86,622		93,259	86,622
Acquisitions										1,991	8,086
Dispositions											0
Impairment charge											(1,449)
Balance	$ 95,250				$ 93,259					$ 95,250	$ 93,259	$ 86,622

[1] March 31, 2017 quarterly data have been reclassified to conform with current presentation.