Commitments and Contingencies (Details) $ in Thousands				1 Months Ended	3 Months Ended			12 Months Ended	49 Months Ended
	Mar. 23, 2018 USD ($)	Aug. 16, 2017	Dec. 08, 2008 subsidiary	Feb. 29, 2012 USD ($)	Mar. 31, 2018 USD ($) claim	Sep. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) case	Dec. 31, 2012 claim	May 10, 2018 radio_station television_station	Apr. 13, 2017 station	Dec. 31, 2016 USD ($)	Aug. 12, 2016 case
Loss Contingencies [Line Items]
Number of direct and indirect wholly-owned subsidiaries included in bankruptcy filing | subsidiary			110
Number of proofs of claim settled or satisfied pursuant to the terms of the plan | case													106
Number of complaints filed | claim									7,400
Restricted cash and cash equivalents					$ 16,607		$ 17,566	$ 17,566				$ 17,566
Number of proofs of claim subject to further evaluation and adjustments | claim					403
Reorganization Items					$ (893)		(250)
Federal Communications Commission Regulation, Television Station Ownership Cap, Percent					39.00%
The UHF Discount, Percent					50.00%
FCC regulation, maximum reimbursement amount for required product modifications				$ 1,750,000
FCC regulation, additional reimbursement amount for required product modifications	$ 1,000,000
Proceeds Received From FCC Spectrum Auction								191,000
Repayments of long-term debt					$ 0		$ 584,245
Proceeds from FCC spectrum auction								172,000
Proceeds from Spectrum, Sharing Arrangement, Pretax								84,000
Payments for Spectrum, Sharing Arrangements, Pretax								$ 66,000
Number of Stations Subject to Spectrum Frequency Transition | station											22
Loss Contingency, Number of Filed Complaints | case								4
Third Party Involved in Claim, Participated in the Sale		4
Third Party Involved in Claim, Confidentiality Agreement		23
Deferred Revenue and Other LT Liability, Useful Lives, Spectrum					30 years
Prepaid and Other LT Asset, Useful Lives, Spectrum					30 years
FCC Licenses
Loss Contingencies [Line Items]
(Gain) Loss on Disposition of Intangible Assets					$ (133,000)
Amended Secured Credit Facility | Term Loan Facility
Loss Contingencies [Line Items]
Repayments of long-term debt						$ 102,000		$ 102,000
Dreamcatcher Credit Facility Due 2018
Loss Contingencies [Line Items]
Repayments of long-term debt								12,600
Dreamcatcher Stations
Loss Contingencies [Line Items]
Proceeds Received From FCC Spectrum Auction								$ 26,000
Subsequent Event
Loss Contingencies [Line Items]
FCC regulation, number of television stations authorized | television_station										39
FCC regulation, number of radio stations authorized | radio_station										1