Intangible Assets and Goodwill - Additional Information (Details)		3 Months Ended		12 Months Ended
	Jan. 17, 2017 ReportingUnit	Dec. 31, 2017 USD ($) ReportingUnit	Mar. 31, 2017 USD ($) ReportingUnit	Dec. 31, 2017 USD ($) ReportingUnit	Dec. 31, 2016 USD ($) ReportingUnit	Dec. 31, 2015 USD ($)
Finite-Lived Intangible Assets [Line Items]
Assets impairment charge				$ 8,500,000
Goodwill impairment charges				11,517,000	$ 15,262,000
Goodwill		$ 2,142,846,000		$ 2,142,846,000	$ 473,304,000	$ 451,662,000
FCC licenses [Member] | Quantitative Impairment Test Passed [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment charges		$ 0
Broadcasting [Member]
Finite-Lived Intangible Assets [Line Items]
Number of business reporting units | ReportingUnit	100		1	1	60
Broadcasting [Member] | Quantitative Impairment Test Passed [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment charges			$ 0	$ 0
All Other Segments [Member]
Finite-Lived Intangible Assets [Line Items]
Number of business reporting units | ReportingUnit	4	3			2
Goodwill		$ 19,900,000		$ 19,900,000	$ 23,600,000
Discount rate				15.50%
Terminal growth rate				2.50%
All Other Segments [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Compound annual growth rate				5.00%
Initial year operating profit margin				(2.00%)
Operating profit margin				4.70%
Income tax rate				21.00%
All Other Segments [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Compound annual growth rate				11.30%
Initial year operating profit margin				10.00%
Operating profit margin				20.00%
Income tax rate				28.70%
All Other Segments [Member] | Quantitative Impairment Test Failed [Member]
Finite-Lived Intangible Assets [Line Items]
Number of business reporting units | ReportingUnit	4	3			2
Goodwill impairment charges		$ 11,500,000			$ 15,300,000