NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition, Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Total revenues	$ 770,719	$ 730,143	$ 1,492,822	$ 1,395,496
Broadcast
Disaggregation of Revenue [Line Items]
Total revenues	659,624	642,279	1,278,125	1,238,172
Other
Disaggregation of Revenue [Line Items]
Total revenues	111,095	87,864	214,697	157,324
Advertising revenue
Disaggregation of Revenue [Line Items]
Total revenues	339,104	359,122	647,156	675,450
Advertising revenue | Broadcast
Disaggregation of Revenue [Line Items]
Total revenues	314,520	338,204	602,370	637,116
Advertising revenue | Other
Disaggregation of Revenue [Line Items]
Total revenues	24,584	20,918	44,786	38,334
Distribution revenue
Disaggregation of Revenue [Line Items]
Total revenues	366,657	319,458	718,822	633,818
Distribution revenue | Broadcast
Disaggregation of Revenue [Line Items]
Total revenues	334,746	291,931	654,744	579,056
Distribution revenue | Other
Disaggregation of Revenue [Line Items]
Total revenues	31,911	27,527	64,078	54,762
Other media and non-media revenues
Disaggregation of Revenue [Line Items]
Total revenues	64,958	51,563	126,844	86,228
Other media and non-media revenues | Broadcast
Disaggregation of Revenue [Line Items]
Total revenues	10,358	12,144	21,011	22,000
Other media and non-media revenues | Other
Disaggregation of Revenue [Line Items]
Total revenues	$ 54,600	$ 39,419	$ 105,833	$ 64,228