NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition, Effects of Adoption (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues, net	$ 893,325	$ 766,261	$ 730,143	$ 665,352	$ 712,512	$ 644,532	$ 652,235	$ 626,936	$ 3,055,081	$ 2,636,215	$ 2,622,510
Media production expenses									1,191,016	1,064,144	955,604
Operating income (loss)	262,954	157,810	131,583	107,314	357,581	103,447	118,849	157,629	659,661	737,506	602,853
Net income	$ 206,201	$ 63,875	$ 28,042	$ 43,123	$ 443,529	$ 30,637	$ 44,645	$ 57,202	$ 341,241	$ 576,013	$ 245,301
Basic earnings per share (in dollars per share)	$ 2.12	$ 0.63	$ 0.27	$ 0.42	$ 4.36	$ 0.30	$ 0.43	$ 0.62	$ 3.38	$ 5.77	$ 2.62
Diluted earnings per share (in dollars per share)	$ 2.10	$ 0.62	$ 0.27	$ 0.42	$ 4.32	$ 0.30	$ 0.43	$ 0.61	$ 3.35	$ 5.72	$ 2.60
As Reported
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating income (loss)										$ 737,506	$ 602,853
Net income										$ 576,013	$ 245,301
Basic earnings per share (in dollars per share)										$ 5.77	$ 2.62
Diluted earnings per share (in dollars per share)										$ 5.72	$ 2.60
Adjustment (a) | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating income (loss)										$ 0	$ 0
Net income										$ 0	$ 0
Basic earnings per share (in dollars per share)										$ 0	$ 0
Diluted earnings per share (in dollars per share)										$ 0	$ 0
Station Barter Arrangements
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues, net										$ 23,060	$ 21,127
Media production expenses										1,070	2,515
Station Barter Arrangements | As Reported
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues, net										120,963	135,566
Media production expenses										98,973	116,954
Station Barter Arrangements | Adjustment (a) | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues, net										(97,903)	(114,439)
Media production expenses										$ (97,903)	$ (114,439)