COMMITMENTS AND CONTINGENCIES (Details) $ in Thousands		1 Months Ended	3 Months Ended		12 Months Ended
	Jul. 29, 2016	Feb. 28, 2017 USD ($) station	Mar. 31, 2017 USD ($) station	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)	Sep. 06, 2016 station
COMMITMENTS AND CONTINGENCIES
Period subject to ongoing compliance monitoring by the FCC	36 months
Net revenue | $			$ 649,935	$ 578,889
FCC national ownership cap, percentage of domestic households reached						39.00%
Number of television stations owned and operated			173
Number of stations assigned new channels		93
Broadcast incentive auction, total legislation funds to reimburse stations | $		$ 1,750,000
FCC Consent Decree Settlement
COMMITMENTS AND CONTINGENCIES
Number of television stations owned and operated						28
Percentage of U.S. households reached (over)						39.00%
Percentage of domestic households reached, UHF discount applied						25.00%
LMA
COMMITMENTS AND CONTINGENCIES
Number of separately owned television stations having programming agreement			2
Number of stations that programs substantial portions of broadcast day and sells advertising time			1
Joint Sales Agreements
COMMITMENTS AND CONTINGENCIES
Net revenue | $			$ 13,100	$ 12,200
Forecast
COMMITMENTS AND CONTINGENCIES
Broadcast incentive auction, proceeds | $					$ 313,000