Goodwill, Other Intangible Assets and Intangible Liabilities - Narrative (Details)		3 Months Ended	12 Months Ended
		Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 27, 2013 USD ($)	Dec. 31, 2012 USD ($)
Finite-Lived Intangible Assets [Line Items]
Contract intangible liability, net							$ 227,000,000
Amortizable Intangible Assets, weighted average remaining useful life			7 years
Amortization expense of amortizable intangible assets, excluding lease contract intangible assets, Next Twelve Months			$ 167,000,000
Amortization expense of amortizable intangible assets, excluding lease contract intangible assets, 2019			140,000,000
Amortization expense of amortizable intangible assets, excluding lease contract intangible assets, 2020			134,000,000
Amortization expense of amortizable intangible assets, excluding lease contract intangible assets, 2021			103,000,000
Amortization expense of amortizable intangible assets, excluding lease contract intangible assets, 2022			84,000,000
Impairment charge, goodwill			0	$ 0
Goodwill			3,228,988,000	3,227,930,000	$ 3,228,224,000
Proceeds from FCC spectrum auction (Note 6)			172,102,000	0	$ 0
Amortization of Intangible Assets	[1],[2]		167,560,000	$ 167,717,000
FCC licenses
Finite-Lived Intangible Assets [Line Items]
FCC License Impairments, number of licenses impaired				2	1
Impairment charge. FCC licenses			$ 0	$ 3,400,000	$ 4,000,000
Fair value inputs, average revenue share period (years)			4 years
Level 3 | Goodwill
Finite-Lived Intangible Assets [Line Items]
Fair value input, Projected cash flows					10 years
Discount rate, percent					10.50%
Terminal growth range, percent					2.00%
Level 3 | FCC licenses
Finite-Lived Intangible Assets [Line Items]
Discount rate, percent			9.50%
Terminal growth range, percent			2.00%
Television and Entertainment
Finite-Lived Intangible Assets [Line Items]
Impairment charge, goodwill					$ (381,000,000)
Local TV
Finite-Lived Intangible Assets [Line Items]
Broadcast rights intangible liabilities						$ 9,000,000
Broadcast rights intangible liabilities
Finite-Lived Intangible Assets [Line Items]
Contract intangible liability, net							$ 226,000,000
Lease Contract Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets			$ 1,000,000	$ 1,000,000
Subsequent Event | FCC licenses
Finite-Lived Intangible Assets [Line Items]
Gain (Loss) on Disposition of Intangible Assets		$ 133,000,000
Cable Reporting Unit [Member] | Television and Entertainment
Finite-Lived Intangible Assets [Line Items]
Impairment charge, goodwill					(381,000,000)
Goodwill					$ 723,000,000

[1] Amortization of intangible assets includes $1 million related to lease contract intangible assets and is recorded in cost of sales or SG&A expense, if applicable, in the Consolidated Statements of Operations.

[2] Beginning in the fourth quarter of 2016, the Television and Entertainment reportable segment includes the operations of Covers, including the goodwill and other intangible assets subject to amortization allocated in accordance with ASC Topic 350 guidance, which was previously included in the Digital and Data reportable segment.