Document and Entity Information (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Jun. 29, 2012	Mar. 01, 2013 Class A Common Stock	Mar. 01, 2013 Class B Common Stock
Entity Listings
Entity Registrant Name	SINCLAIR BROADCAST GROUP INC
Entity Central Index Key	0000912752
Document Type	10-K
Document Period End Date	Dec. 31, 2012
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float		$ 465.8
Entity Common Stock, Shares Outstanding			52,783,301	28,846,259
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY