Basis of Presentation and Significant Accounting Policies Narrative (Details) $ / shares in Units, $ in Thousands							3 Months Ended								12 Months Ended
	Feb. 11, 2018	Oct. 18, 2017	Sep. 15, 2017	Aug. 02, 2017	Jul. 06, 2017	May 08, 2017 USD ($) $ / shares	Dec. 31, 2017 USD ($) television_station	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) television_station		Dec. 31, 2016 USD ($)		Dec. 31, 2015 USD ($)		Feb. 20, 2018
Summary of Significant Account Policies [Line Items]
Number of Television Stations | television_station							42								42
FCC Transaction Review Period					180 days
FCC Transaction Review Period, Pause		15 days
Hart-Scott-Rodino Antitrust Improvement Act of 1976 Waiting Period				30 days
Department of Justice Merger Waiting Period			60 days
Department of Justice, Days Notice			10 days
Fiscal Year Less Days																	2 days
Restricted cash and cash equivalents							$ 17,566				$ 17,566				$ 17,566		$ 17,566
Broadcast rights impairment charge															80,000		37,000		$ 74,000
Advertising Expense															34,000		42,000		39,000
Self-insurance deductible, per occurrence							1,000								1,000
Liabilities for self-insured risks							24,000				26,000				24,000		26,000
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification															23,000		25,000		29,000
Total operating revenues							488,999	$ 450,533	$ 469,517	$ 439,910	529,624	$ 470,038	$ 479,796	$ 468,472	1,848,959	[1]	1,947,930	[1]	1,801,967	[1]
Costs and Expenses															$ 1,740,491		1,514,356		2,071,302
Document Fiscal Year Focus															2017
Barter
Summary of Significant Account Policies [Line Items]
Total operating revenues															$ 28,000		30,000		29,000
Program rights							$ 45,000				$ 37,000				45,000		37,000
Costs and Expenses															$ 28,000		$ 30,000		$ 29,000
Buildings | Minimum
Summary of Significant Account Policies [Line Items]
Useful life of property, plant and equipment, years															3 years
Buildings | Maximum
Summary of Significant Account Policies [Line Items]
Useful life of property, plant and equipment, years															44 years
Equipment | Minimum
Summary of Significant Account Policies [Line Items]
Useful life of property, plant and equipment, years															1 year
Equipment | Maximum
Summary of Significant Account Policies [Line Items]
Useful life of property, plant and equipment, years															30 years
Sinclair Merger
Summary of Significant Account Policies [Line Items]
Business Combination, Common Stock Cash Value Per Share Conversion | $ / shares						$ 35.00
Business Combination, Consideration Transferred, Common Stock Exchange Ratio						0.2300
Contract Termination Fee						$ 135,500
Grace Period After Contact Termination, Not Terminated by Company, Before Obtaining New Bid Without Termination Fee						12 months
Sinclair | Sinclair Merger
Summary of Significant Account Policies [Line Items]
Common stock par value (usd per share) | $ / shares						$ 0.01
Subsequent Event
Summary of Significant Account Policies [Line Items]
Department of Justice Merger Waiting Period	60 days
Department of Justice, Days Notice	10 days
Television Markets, Sinclair Proposes to Own Duopoly																					3
Television Markets, Sinclair Proposes to Divest																					11

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