Assets Held for Sale and Discontinued Operations - Operating Results of Discontinued Operations (Details) - Radio Segment - Disposed of by sale $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues	$ 13,299
Total costs and expenses	(11,516)
Impairment of goodwill and intangible assets	(20,000)
Other, net	(148)
Loss from discontinued operations before income taxes	(18,365)
Provision (benefit) for income taxes	139
Net loss from discontinued operations	$ (18,504)