ACQUISITIONS (Details) (USD $)	3 Months Ended		15 Months Ended		3 Months Ended		0 Months Ended	3 Months Ended			0 Months Ended	3 Months Ended			1 Months Ended		1 Months Ended		1 Months Ended		1 Months Ended		3 Months Ended				1 Months Ended		1 Months Ended		1 Months Ended		1 Months Ended		0 Months Ended	3 Months Ended	0 Months Ended						3 Months Ended	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Dec. 01, 2012 WLYH in Harrisburg, PA	Mar. 31, 2013 WLWC-TV	Mar. 31, 2012 WLWC-TV	Dec. 01, 2012 WSTR and KMYS Deerfield item	Mar. 31, 2013 WLAJ-TV	Mar. 31, 2012 WLAJ-TV	Mar. 31, 2013 6.125% Notes	Jan. 02, 2012 Four Points item	Mar. 31, 2013 Four Points	Mar. 31, 2012 Four Points	Dec. 31, 2011 Four Points	Jan. 31, 2012 Four Points Network affiliations	Jan. 02, 2012 Four Points Network affiliations	Jan. 31, 2012 Four Points Decaying advertiser base	Jan. 02, 2012 Four Points Decaying advertiser base	Jan. 31, 2012 Four Points Other intangible assets	Jan. 02, 2012 Four Points Other intangible assets	Jan. 31, 2012 Four Points Term Loan B	Apr. 30, 2012 Freedom item	Mar. 31, 2013 Freedom	Mar. 31, 2012 Freedom	Apr. 02, 2012 Freedom item	Dec. 31, 2011 Freedom	Apr. 30, 2012 Freedom Network affiliations	Apr. 02, 2012 Freedom Network affiliations	Apr. 30, 2012 Freedom Decaying advertiser base	Apr. 02, 2012 Freedom Decaying advertiser base	Apr. 30, 2012 Freedom Other intangible assets	Apr. 02, 2012 Freedom Other intangible assets	Apr. 30, 2012 Freedom Term Loan A	Apr. 30, 2012 Freedom Term Loan B	Dec. 01, 2012 Newport item	Mar. 31, 2013 Newport	Dec. 01, 2012 Newport Network affiliations	Dec. 01, 2012 Newport Decaying advertiser base	Dec. 01, 2012 Newport Other intangible assets	Dec. 01, 2012 Newport 6.125% Notes	Dec. 01, 2012 WPMI and WJTC Deerfield	Dec. 01, 2012 WHAM Deerfield	Mar. 31, 2013 Other acquisitions	Dec. 31, 2012 Other acquisitions item	Dec. 31, 2012 WTTA-TV
Acquisitions
Number of television stations											7														8										7									5
Number of markets											4											7													6									3
Cash paid											$ 200,000,000														$ 385,000,000										$ 460,500,000									$ 45,100,000
Working capital adjustment											900,000														(300,000)										1,300,000									700,000
Noncontrolling interests related to the license assets																																												4,400,000
Amount of draw under incremental loan commitment used to finance acquisition																					180,000,000												157,500,000	192,500,000
Escrow deposit used to fund acquisition											20,000,000														38,500,000										41,300,000
Interest rate (as a percent)										6.125%																														6.125%
Number of stations whose license assets were sold							2
Price of assets acquired/sold				200,000			10,700,000																																		6,000,000	6,000,000
Allocated fair value of acquired assets and assumed liabilities
Prepaid expenses and other current assets											456,000														373,000										1,390,000									160,000
Program contract costs											3,731,000														3,520,000										10,378,000									2,487,000
Property and equipment											34,578,000														54,109,000										53,883,000									17,309,000
Broadcast licenses											10,658,000														10,424,000										15,581,000									2,825,000
Definite-lived intangible assets											93,800,000					66,900,000		9,800,000		17,100,000					140,963,000			93,100,000		25,100,000		22,800,000			240,013,000		176,000,000	23,700,000	40,300,000					17,990,000
Other assets											548,000														278,000										1,097,000
Accrued liabilities											(381,000)														(589,000)										(3,928,000)									(1,178,000)
Program contracts payable											(5,157,000)														(3,404,000)										(11,634,000)									(4,900,000)
Fair value of identifiable net assets acquired											138,233,000														205,674,000										306,780,000									34,693,000
Goodwill											60,843,000														179,609,000										164,621,000									14,106,000
Total											199,076,000														385,283,000										471,401,000									48,799,000
Amortization period															15 years		10 years										15 years		10 years								15 years	10 years
Weighted average life																			14 years												16 years								14 years
Amount paid for funding working capital needs														8,100,000										9,600,000		1,500,000
Transaction costs																																											0	600,000
Net broadcast revenues	252,925,000	190,888,000										17,700,000	16,500,000										26,300,000	10,000,000												34,900,000							6,600,000
Operating income	63,656,000	59,894,000										4,300,000	4,500,000										5,900,000													8,300,000							1,600,000
Net broadcast revenues					1,300,000	1,300,000		600,000
Operating income (losses)					400,000	30,000		(200,000)
Revenue from discontinued operations excluded from pro forma revenues									1,000,000
Costs incurred in corporate, general and administrative expenses	200,000	400,000	1,900,000
Difference between the purchase price and the historical cost basis recorded as a reduction in additional paid-in capital																																													23,600,000
Difference between the purchase price and the historical cost basis recorded as a reduction in additional paid-in capital, tax amount																																													15,600,000
Pro Forma Information
Total revenues		267,076,000
Net Income		27,366,000
Net Income attributable to Sinclair Broadcast Group		$ 27,613,000
Basic and diluted earnings per share attributable to Sinclair Broadcast Group (in dollars per share)		$ 0.34