ACQUISITIONS (Details) (USD $)	0 Months Ended	3 Months Ended								12 Months Ended								0 Months Ended		0 Months Ended	12 Months Ended		1 Months Ended		1 Months Ended		1 Months Ended		1 Months Ended		3 Months Ended	12 Months Ended			1 Months Ended		1 Months Ended		1 Months Ended		1 Months Ended		0 Months Ended	12 Months Ended			0 Months Ended		0 Months Ended		0 Months Ended					12 Months Ended
	Oct. 02, 2012 item	Dec. 31, 2012 item	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 WLWC-TV	Dec. 31, 2011 WLWC-TV	Dec. 31, 2012 WSTR and KMYS Deerfield item	Dec. 31, 2012 WLAJ-TV	Dec. 31, 2011 WLAJ-TV	Oct. 12, 2012 6.125% Notes	Dec. 31, 2012 6.125% Notes	Jan. 02, 2012 Four Points item	Dec. 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, 2012 Freedom	Dec. 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. 03, 2012 Newport item	Dec. 31, 2012 Newport	Dec. 01, 2012 Newport item	Dec. 01, 2012 Newport LMA item	Dec. 03, 2012 Newport Network affiliations	Dec. 01, 2012 Newport Network affiliations	Dec. 03, 2012 Newport Decaying advertiser base	Dec. 01, 2012 Newport Decaying advertiser base	Dec. 03, 2012 Newport Other intangible assets	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 WLYH in Harrisburg, PA	Dec. 31, 2012 Other acquisitions item	Dec. 31, 2012 WTTA-TV
Acquisitions
Number of television stations		87								87										7													8												7	2										5
Number of markets	3									47										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												1,000,000											1,200,000
Noncontrolling interests related to the license assets																																																								4,400,000
Amount of draw under incremental loan commitment used to finance acquisition																		500,000,000											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%																																		6.125%
Price of assets acquired/sold															10,700,000																																							6,000,000	6,200,000
Allocated fair value of acquired assets and assumed liabilities
Prepaid expenses and other current assets																				456,000													373,000												1,377,000											98,000
Program contract costs																				3,731,000													3,520,000												9,309,000											2,487,000
Property and equipment																				34,578,000													54,109,000												61,253,000											17,309,000
Broadcast licenses																				10,658,000													10,424,000												15,017,000											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					226,516,000			167,700,000		21,300,000		37,500,000				17,990,000
Other assets																				548,000													278,000												994,000
Accrued liabilities																				(381,000)													(589,000)												(3,498,000)											(1,590,000)
Program contracts payable																				(5,157,000)													(3,404,000)												(10,539,000)											(4,900,000)
Fair value of identifiable net assets acquired																				138,233,000													205,674,000												300,429,000											34,219,000
Goodwill																				60,843,000													179,609,000												171,298,000											14,093,000
Total																				199,076,000													385,283,000												471,727,000											48,312,000
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
Legal and professional services cost incurred																																																								700,000
Net broadcast revenues										920,593,000	648,002,000	655,836,000	5,500,000			3,800,000					70,000,000										10,000,000	91,000,000												11,700,000
Operating income		119,097,000	78,399,000	71,887,000	59,895,000	63,500,000	52,410,000	58,238,000	51,472,000	329,278,000	225,620,000	240,815,000									17,300,000											32,500,000												2,900,000
Operating losses													200,000			900,000
Revenue from discontinued operations excluded from pro forma revenues													6,300,000	6,500,000		4,900,000	3,300,000
Costs incurred in corporate, general and administrative expenses										1,800,000
Number of stations whose license assets were sold															2
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										1,210,257,000	1,028,168,000
Net Income										151,751,000	77,899,000
Net Income attributable to Sinclair Broadcast Group										$ 151,352,000	$ 77,370,000
Basic and diluted earnings per share attributable to Sinclair Broadcast Group (in dollars per share)										$ 1.86	$ 0.96