CONDENSED CONSOLIDATED FINANCIAL STATEMENTS - Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Revenue	$ 893,325	$ 766,261	$ 730,143	$ 665,352	$ 712,512	$ 644,532	$ 652,235	$ 626,936	$ 3,055,081	$ 2,636,215		$ 2,622,510
Media production expenses									1,191,016	1,064,144		955,604
Selling, general and administrative									740,989	646,790		575,145
Depreciation, amortization and other operating expenses									463,415	187,775		488,908
Total operating expenses									2,395,420	1,898,709		2,019,657
Operating income	262,954	157,810	131,583	107,314	357,581	103,447	118,849	157,629	659,661	737,506		602,853
Equity in earnings of consolidated subsidiaries									0	0		0
Interest expense									(291,976)	(212,315)		(211,143)
Other income (expense)									(57,462)	(6,447)		(18,820)
Total other expense									(349,438)	(218,762)		(229,963)
Income tax benefit (provision)									35,775	75,360		(122,128)
NET INCOME									345,998	594,104	[1]	250,762	[1]
Net income attributable to the noncontrolling interests									(4,757)	(18,091)		(5,461)
Net income attributable to Sinclair Broadcast Group	$ 206,201	$ 63,875	$ 28,042	$ 43,123	$ 443,529	$ 30,637	$ 44,645	$ 57,202	341,241	576,013		245,301
Comprehensive income (loss)									346,637	593,488		250,789
Reportable legal entities | Sinclair Broadcast Group, Inc.
Condensed Financial Statements, Captions [Line Items]
Revenue									0	0		0
Media production expenses									0	0		0
Selling, general and administrative									9,916	9,204		4,062
Depreciation, amortization and other operating expenses									483	984		1,064
Total operating expenses									10,399	10,188		5,126
Operating income									(10,399)	(10,188)		(5,126)
Equity in earnings of consolidated subsidiaries									348,090	579,954		244,580
Interest expense									(1)	(88)		(238)
Other income (expense)									1,856	1,678		3,613
Total other expense									349,945	581,544		247,955
Income tax benefit (provision)									1,695	4,657		2,472
NET INCOME									341,241	576,013		245,301
Net income attributable to the noncontrolling interests									0	0		0
Net income attributable to Sinclair Broadcast Group									341,241	576,013		245,301
Comprehensive income (loss)									346,637	593,488		250,789
Reportable legal entities | Sinclair Television Group, Inc.
Condensed Financial Statements, Captions [Line Items]
Revenue									7	0		0
Media production expenses									2	0		0
Selling, general and administrative									100,251	102,930		70,503
Depreciation, amortization and other operating expenses									4,951	6,250		7,331
Total operating expenses									105,204	109,180		77,834
Operating income									(105,197)	(109,180)		(77,834)
Equity in earnings of consolidated subsidiaries									724,476	793,620		463,598
Interest expense									(285,438)	(205,107)		(198,893)
Other income (expense)									(1,852)	5,077		(22,867)
Total other expense									437,186	593,590		241,838
Income tax benefit (provision)									89,852	100,473		99,148
NET INCOME									421,841	584,883		263,152
Net income attributable to the noncontrolling interests									0	0		0
Net income attributable to Sinclair Broadcast Group									421,841	584,883		263,152
Comprehensive income (loss)									422,480	584,267		263,179
Reportable legal entities | Guarantor Subsidiaries and KDSM, LLC
Condensed Financial Statements, Captions [Line Items]
Revenue									2,855,586	2,507,183		2,476,669
Media production expenses									1,130,278	1,013,035		920,715
Selling, general and administrative									613,074	522,039		489,882
Depreciation, amortization and other operating expenses									257,877	131,880		360,550
Total operating expenses									2,001,229	1,666,954		1,771,147
Operating income									854,357	840,229		705,522
Equity in earnings of consolidated subsidiaries									(457)	(16)		220
Interest expense									(3,961)	(4,586)		(4,481)
Other income (expense)									(57,288)	(5,790)		715
Total other expense									(61,706)	(10,392)		(3,546)
Income tax benefit (provision)									(62,252)	(30,171)		(231,504)
NET INCOME									730,399	799,666		470,472
Net income attributable to the noncontrolling interests									0	0		0
Net income attributable to Sinclair Broadcast Group									730,399	799,666		470,472
Comprehensive income (loss)									730,399	799,666		470,472
Reportable legal entities | Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Revenue									293,108	209,914		254,031
Media production expenses									141,622	124,044		135,511
Selling, general and administrative									19,740	14,800		10,804
Depreciation, amortization and other operating expenses									206,980	51,461		121,986
Total operating expenses									368,342	190,305		268,301
Operating income									(75,234)	19,609		(14,270)
Equity in earnings of consolidated subsidiaries									0	0		0
Interest expense									(18,482)	(21,643)		(32,521)
Other income (expense)									(178)	(7,412)		(281)
Total other expense									(18,660)	(29,055)		(32,802)
Income tax benefit (provision)									6,480	401		7,756
NET INCOME									(87,414)	(9,045)		(39,316)
Net income attributable to the noncontrolling interests									(4,959)	(17,738)		(4,937)
Net income attributable to Sinclair Broadcast Group									(92,373)	(26,783)		(44,253)
Comprehensive income (loss)									(87,414)	(9,045)		(39,316)
Eliminations
Condensed Financial Statements, Captions [Line Items]
Revenue									(93,620)	(80,882)		(108,190)
Media production expenses									(80,886)	(72,935)		(100,622)
Selling, general and administrative									(1,992)	(2,183)		(106)
Depreciation, amortization and other operating expenses									(6,876)	(2,800)		(2,023)
Total operating expenses									(89,754)	(77,918)		(102,751)
Operating income									(3,866)	(2,964)		(5,439)
Equity in earnings of consolidated subsidiaries									(1,072,109)	(1,373,558)		(708,398)
Interest expense									15,906	19,109		24,990
Other income (expense)									0	0		0
Total other expense									(1,056,203)	(1,354,449)		(683,408)
Income tax benefit (provision)									0	0		0
NET INCOME									(1,060,069)	(1,357,413)		(688,847)
Net income attributable to the noncontrolling interests									202	(353)		(524)
Net income attributable to Sinclair Broadcast Group									(1,059,867)	(1,357,766)		(689,371)
Comprehensive income (loss)									$ (1,065,465)	$ (1,374,888)		$ (694,335)

[1] See Recent Accounting Pronouncements within Note 1. Nature of Operations and Summary of Significant Accounting Policies for a discussion of the adoption of new accounting principles related to the classification of certain cash receipts and cash payments.