Assets Held for Sale and Discontinued Operations - Operating Results of Discontinued Operations (Details) - Radio Segment - Disposed of by sale - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues	$ 13,456	$ 44,141
Total costs and expenses	(14,511)	(39,448)
Impairment of goodwill and intangible assets	0	(25,900)
Other, net	0	(157)
Loss from discontinued operations before income taxes	(1,055)	(21,364)
Provision (benefit) for income taxes	(147)	990
Net loss from discontinued operations	$ (908)	$ (22,354)