QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 1,512	$ 1,539	$ 1,283	$ 1,609	$ 1,622	$ 1,125	$ 771	$ 722	$ 5,943	$ 4,240	$ 3,055
Operating income (loss)	625	(4,216)	492	327	277	(6)	106	93	(2,772)	470	660
Net income (loss)	514	(3,367)	273	151	88	(49)	43	23	(2,429)	105	346
Net income (loss) attributable to Sinclair Broadcast Group	$ 467	$ (3,256)	$ 252	$ 123	$ 44	$ (60)	$ 42	$ 21	$ (2,414)	$ 47	$ 341
Basic earnings per share common shares (in dollars per share)	$ 6.32	$ (43.53)	$ 3.13	$ 1.36	$ 0.47	$ (0.65)	$ 0.46	$ 0.23	$ (30.20)	$ 0.52	$ 3.38
Diluted earnings per share common shares (in dollars per share)	$ 6.27	$ (43.53)	$ 3.12	$ 1.35	$ 0.47	$ (0.65)	$ 0.45	$ 0.23	$ (30.20)	$ 0.51	$ 3.35