Commitments and Contingencies (Details) $ in Thousands			1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended	49 Months Ended
	Mar. 23, 2018 USD ($)	Dec. 08, 2008 subsidiary	Feb. 29, 2012 USD ($)	Sep. 30, 2018 USD ($) claim	Mar. 31, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) claim	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2012 claim	Nov. 09, 2018 television_station radio_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	$ 16,607	$ 17,566	$ 17,566				$ 17,566
Number of proofs of claim subject to further evaluation and adjustments | claim				403			403
Reorganization Items				$ 244		753	$ 1,822	1,452
Federal Communications Commission Regulation, Television Station Ownership Cap, Percent				39.00%			39.00%
The UHF Discount, Percent				50.00%			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	703,527
Proceeds from FCC spectrum auction							$ 0	$ 172,102	172,000
Proceeds from Spectrum, Sharing Arrangement, Pretax						79,000			84,000
Payments for Spectrum, Sharing Arrangements, Pretax									66,000
Deferred Revenue and Other LT Liability, Useful Lives, Spectrum							30 years
Prepaid and Other LT Asset, Useful Lives, Spectrum							30 years
Number of Stations Subject to Spectrum Frequency Transition | station												22
Capital expenditures incurred related to spectrum repack							$ 16,000
FCC reimbursements received				$ 5,000			$ 7,000
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						21,000			$ 26,000
Repayments of long-term debt						$ 12,600
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