Cover - shares	9 Months Ended
	Sep. 30, 2021	Nov. 04, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	000-26076
Entity Registrant Name	SINCLAIR BROADCAST GROUP, INC.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	52-1494660
Entity Address, Address Line One	10706 Beaver Dam Road
Entity Address, City or Town	Hunt Valley
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	21030
City Area Code	410
Local Phone Number	568-1500
Title of 12(b) Security	Class A Common Stock, par value $ 0.01 per share
Trading Symbol	SBGI
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0000912752
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false
Class A Common Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		51,763,251
Class B Common Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		23,775,056