Basis Of Presentation And Significant Accounting Policies (Details) $ / shares in Units, $ in Thousands									3 Months Ended		12 Months Ended
		May 15, 2018	Feb. 11, 2018	Oct. 18, 2017	Sep. 15, 2017	Aug. 02, 2017	Jul. 06, 2017	May 08, 2017 USD ($) $ / shares	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	May 08, 2018 USD ($) television_station	Apr. 24, 2018 television_station	Feb. 20, 2018 television_station	Dec. 31, 2016 USD ($)
Investment Holdings [Line Items]
Operating revenues	[1]								$ 443,635	$ 439,910
Costs and Expenses									256,350	460,877
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification										6,000	$ 23,000
Restricted cash and cash equivalents									$ 16,607	17,566	17,566				$ 17,566
Deferred Revenue and Other LT Liability, Useful Lives, Spectrum									30 years
Operating profit	[1],[2]								$ 187,285	(20,967)
Federal Communications Commission Regulation, Proceeds Received From Auction											191,000
Corporate and Other
Investment Holdings [Line Items]
Operating revenues	[1]								2,933	3,877
Operating profit	[1],[2]								(24,567)	(40,980)
Barter
Investment Holdings [Line Items]
Operating revenues									7,000	7,000
Costs and Expenses									7,000	7,000
Program rights									40,000		45,000
Program Rights Obligations									40,000		45,000
Dreamcatcher Stations
Investment Holdings [Line Items]
Federal Communications Commission Regulation, Proceeds Received From Auction											$ 26,000
Dreamcatcher Stations | Variable Interest Entity, Primary Beneficiary
Investment Holdings [Line Items]
Operating revenues									18,000	17,000
Operating profit									$ 3,000	$ 2,000
Sinclair Merger
Investment Holdings [Line Items]
Business Combination, Common Stock Cash Value Per Share Conversion | $ / shares								$ 35.00
Business Combination, Consideration Transferred, Common Stock Exchange Ratio								0.2300
FCC Transaction Review Period							180 days
FCC Transaction Review Period, Pause				15 days
Television Markets, Sinclair Proposes to Own Duopoly | television_station														3
Television Markets, Sinclair Proposes to Divest | television_station														11
Hart-Scott-Rodino Antitrust Improvement Act of 1976 Waiting Period						30 days
Department of Justice Merger Waiting Period			60 days		60 days
Department of Justice, Days Notice			10 days		10 days
Grace Period After Contact Termination, Not Terminated by Company, Before Obtaining New Bid Without Termination Fee								12 months
Contract Termination Fee								$ 135,500
Sinclair Merger | Subsequent Event
Investment Holdings [Line Items]
Television Markets, Sinclair Proposes to Divest | television_station													15
Television Stations, Sinclair proposes assignment of license or transfer of control | television_station													11
Sinclair Merger | Subsequent Event | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Investment Holdings [Line Items]
Television stations, Tribune to sell upon close of merger | television_station												7
Disposal Group, Including Discontinued Operation, Consideration												$ 910,000
Days to File Request from the FCC for the Assignment of FCC Licenses, Fox		5 days
Sinclair Merger | Sinclair
Investment Holdings [Line Items]
Common Stock, Par or Stated Value Per Share | $ / shares								$ 0.01

[1] (1)See Note 2 for the disclosures of operating revenues and operating loss included in discontinued operations for the historical periods.

[2] (2)Operating profit (loss) for each segment excludes income and loss on equity investments, interest and dividend income, interest expense, non-operating items, reorganization costs and income taxes.