ACQUISITIONS AND DISPOSITIONS OF ASSETS - Narrative (Details) $ in Thousands		1 Months Ended			3 Months Ended	12 Months Ended			24 Months Ended
	Sep. 01, 2017 USD ($) station market	Mar. 31, 2017 USD ($)	Feb. 28, 2017 USD ($) station	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) station market	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)	Mar. 31, 2018 market
Acquisitions
Cash paid									$ 689,400
Working capital adjustment									$ 3,400
Number of television stations owned | station						191
Number of markets | market						89
Increase to goodwill						$ (131)	$ 307
Amortization period, weighted average useful life						14 years
Acquisition costs related to legal and other professioanl services							1,100	$ 1,400
Broadcast incentive auction proceeds							310,800
Deferred spectrum auction proceeds						$ 40,063	278,872	6,029
Number of stations assigned new channels | station			100
Total legislation funds to reimburse stations			$ 2,750,000
Total capital expenditure						31,100
Gain (loss) recognized on sale					$ 225,300	5,800
Bonten
Acquisitions
Cash paid	$ 240,000
Working capital adjustment	$ 2,200
Number of television stations owned | station	14
Number of markets | market	8
Number of stations to which sales services were provided | station	4
Increase to goodwill						1,500
Finite-lived intangible assets acquired	$ 161,900
Goodwill, expected tax deductible amount	5,600
Other Acquisitions
Acquisitions
Cash paid							27,400
Working capital adjustment							2,700
Tennis Channel
Acquisitions
Cash paid				$ 350,000
Working capital adjustment				4,100
Other Acquisitions In 2016
Acquisitions
Cash paid								72,000
Working capital adjustment								100
Tribune Media Company
Acquisitions
Acquisition costs related to legal and other professioanl services						99,800
Spectrum Auction
Acquisitions
Number of markets | market										3
Deferred spectrum auction proceeds						83,300	225,300
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Disposals in 2016
Acquisitions
Value of consideration given, non-cash								23,800
Gain on sale of broadcast assets								$ 4,400
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Alarm Funding Associates
Acquisitions
Sales agreement price		$ 200,000
Working capital and transaction costs from sale		5,000
Gain recognized on sale of broadcast assets		53,000					53,000
Gain (loss) on disposal, attributable to non-controlling interest		$ 12,300					$ 12,300
Network affiliations | Bonten
Acquisitions
Finite-lived intangible assets acquired	$ 53,300
Amortization period, weighted average useful life	15 years
Customer relationships | Bonten
Acquisitions
Finite-lived intangible assets acquired	$ 108,600
Amortization period, weighted average useful life	14 years
Customer relationships | Tennis Channel
Acquisitions
Finite-lived intangible assets acquired				$ 272,700
Amortization period, weighted average useful life				15 years
General and Administrative Expense | Tribune Media Company
Acquisitions
Acquisition costs related to legal and other professioanl services						21,300
Interest Expense | Tribune Media Company
Acquisitions
Acquisition costs related to legal and other professioanl services						$ 78,500