Assets Held for Sale and Discontinued Operations - Operating Results of Discontinued Operations and Net Assets Distributed (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
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of goodwill and intangible assets						$ (29,400)
(Loss) income from discontinued operations, net of tax	$ (13,974)	$ (908)	$ (2,942)	$ (18,504)	$ (5,999)	$ 920	$ 1,690	$ 794	$ (36,328)	$ (2,595)	$ 7,313
Radio | Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues									49,243	68,630	73,069
Total costs and expenses									(42,694)	(57,061)	(56,852)
Depreciation and amortization of intangibles									0	(2,910)	(3,377)
Impairment of goodwill and intangible assets					(8,000)				(25,900)	(8,000)	0
Other, net									(179)	(258)	(63)
Income (loss) from operations of discontinued operations									(19,530)	401	12,777
Pretax loss on disposal of discontinued operations									(18,558)	0	0
(Loss) income on discontinued operations before income taxes									(38,088)	401	12,777
Benefit (provision) for income taxes									1,760	(2,996)	(5,464)
(Loss) income from discontinued operations, net of tax									$ (36,328)	(2,595)	$ 7,313
Assets:
Total current assets					12,891					12,891
Property, plant and equipment					35,470					35,470
Goodwill and intangible assets					87,462					87,462
Other assets					181					181
Total assets included in the disposal group					136,004					136,004
Liabilities:
Total current liabilities					3,248					3,248
Deferred income taxes					16,288					16,288
Other liabilities					0					0
Total liabilities included in the disposal group					19,536					19,536
Net assets included in the disposal group					$ 116,468					$ 116,468