CONDENSED CONSOLIDATING FINANCIAL STATEMENTS - Statement of Cash Flows (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME
NET CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES	$ 278,411	$ 330,260
CASH FLOWS FROM (USED IN) INVESTING ACTIVITIES:
Acquisition of property and equipment	(55,463)	(68,601)
Acquisition of businesses, net of cash acquired	(269,799)	(425,856)
Purchase of alarm monitoring contracts	(5,682)	(29,143)
Proceeds from sale of non-media business	192,634	16,396
Investments in equity and cost method investees	(22,302)	(34,224)
Loans to affiliates	0	(19,500)
Other, net	550	(3,401)
Net cash flows used in investing activities	(161,162)	(557,527)
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES:
Proceeds from notes payable and commercial bank financing	166,041	1,011,312
Repayments of notes payable, commercial bank financing and capital leases	(318,309)	(653,987)
Net proceeds from the sale of Class A Common Stock	487,883	0
Dividends paid on Class A and Class B Common Stock	(53,049)	(49,667)
Repurchase of outstanding Class A Common Stock	(30,287)	(101,164)
Distributions to noncontrolling interests	(20,469)	(8,363)
Increase (decrease) in intercompany payables	0	0
Other, net	(6,850)	(16,291)
Net cash flows from financing activities	224,960	181,840
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	342,209	(45,427)
CASH AND CASH EQUIVALENTS, beginning of period	259,984	149,972
CASH AND CASH EQUIVALENTS, end of period	602,193	104,545
Reportable legal entities | Sinclair Broadcast Group, Inc.
CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME
NET CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES	(5,605)	(4,060)
CASH FLOWS FROM (USED IN) INVESTING ACTIVITIES:
Acquisition of property and equipment	(131)	(7)
Acquisition of businesses, net of cash acquired	0	0
Purchase of alarm monitoring contracts	0	0
Proceeds from sale of non-media business	0	0
Investments in equity and cost method investees	(945)	(2,945)
Loans to affiliates		0
Other, net	(3,903)	(1,714)
Net cash flows used in investing activities	2,827	(1,238)
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES:
Proceeds from notes payable and commercial bank financing	0	0
Repayments of notes payable, commercial bank financing and capital leases	0	0
Net proceeds from the sale of Class A Common Stock	487,883
Dividends paid on Class A and Class B Common Stock	(53,049)	(49,667)
Repurchase of outstanding Class A Common Stock	(30,287)	(101,164)
Distributions to noncontrolling interests	0	0
Increase (decrease) in intercompany payables	(400,451)	158,574
Other, net	(1,318)	(2,445)
Net cash flows from financing activities	2,778	5,298
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	0	0
CASH AND CASH EQUIVALENTS, beginning of period	0	0
CASH AND CASH EQUIVALENTS, end of period	0	0
Reportable legal entities | Sinclair Television Group, Inc.
CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME
NET CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES	(141,239)	(152,724)
CASH FLOWS FROM (USED IN) INVESTING ACTIVITIES:
Acquisition of property and equipment	(6,088)	(3,626)
Acquisition of businesses, net of cash acquired	(8,308)	0
Purchase of alarm monitoring contracts	0	0
Proceeds from sale of non-media business	0	0
Investments in equity and cost method investees	(1,101)	(10,840)
Loans to affiliates		(19,500)
Other, net	7,733	1,828
Net cash flows used in investing activities	(23,230)	(35,794)
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES:
Proceeds from notes payable and commercial bank financing	159,669	995,000
Repayments of notes payable, commercial bank financing and capital leases	(200,119)	(636,547)
Net proceeds from the sale of Class A Common Stock	0
Dividends paid on Class A and Class B Common Stock	0	0
Repurchase of outstanding Class A Common Stock	0	0
Distributions to noncontrolling interests	0	0
Increase (decrease) in intercompany payables	524,016	(189,022)
Other, net	(45)	(15,013)
Net cash flows from financing activities	483,521	154,418
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	319,052	(34,100)
CASH AND CASH EQUIVALENTS, beginning of period	232,297	115,771
CASH AND CASH EQUIVALENTS, end of period	551,349	81,671
Reportable legal entities | Guarantor Subsidiaries and KDSM, LLC
CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME
NET CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES	433,435	451,804
CASH FLOWS FROM (USED IN) INVESTING ACTIVITIES:
Acquisition of property and equipment	(47,564)	(61,758)
Acquisition of businesses, net of cash acquired	(261,491)	(415,481)
Purchase of alarm monitoring contracts	0	0
Proceeds from sale of non-media business	0	7,263
Investments in equity and cost method investees	(15,469)	(34)
Loans to affiliates		0
Other, net	(541)	86
Net cash flows used in investing activities	(323,983)	(470,096)
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES:
Proceeds from notes payable and commercial bank financing	0	0
Repayments of notes payable, commercial bank financing and capital leases	(1,367)	(1,171)
Net proceeds from the sale of Class A Common Stock	0
Dividends paid on Class A and Class B Common Stock	0	0
Repurchase of outstanding Class A Common Stock	0	0
Distributions to noncontrolling interests	0	0
Increase (decrease) in intercompany payables	(92,993)	22,603
Other, net	(3,606)	1,175
Net cash flows from financing activities	(97,966)	22,607
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	11,486	4,315
CASH AND CASH EQUIVALENTS, beginning of period	10,675	235
CASH AND CASH EQUIVALENTS, end of period	22,161	4,550
Reportable legal entities | Non- Guarantor Subsidiaries
CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME
NET CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES	(12,959)	17,138
CASH FLOWS FROM (USED IN) INVESTING ACTIVITIES:
Acquisition of property and equipment	(2,677)	(3,842)
Acquisition of businesses, net of cash acquired	0	(10,375)
Purchase of alarm monitoring contracts	(5,682)	(29,143)
Proceeds from sale of non-media business	192,634	9,133
Investments in equity and cost method investees	(4,787)	(20,405)
Loans to affiliates		0
Other, net	(2,739)	(3,601)
Net cash flows used in investing activities	182,227	(51,031)
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES:
Proceeds from notes payable and commercial bank financing	6,372	16,312
Repayments of notes payable, commercial bank financing and capital leases	(116,823)	(16,269)
Net proceeds from the sale of Class A Common Stock	0
Dividends paid on Class A and Class B Common Stock	0	0
Repurchase of outstanding Class A Common Stock	0	0
Distributions to noncontrolling interests	(20,469)	(8,363)
Increase (decrease) in intercompany payables	(24,750)	26,764
Other, net	(1,927)	(193)
Net cash flows from financing activities	(157,597)	18,251
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	11,671	(15,642)
CASH AND CASH EQUIVALENTS, beginning of period	17,012	33,966
CASH AND CASH EQUIVALENTS, end of period	28,683	18,324
Eliminations
CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME
NET CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES	4,779	18,102
CASH FLOWS FROM (USED IN) INVESTING ACTIVITIES:
Acquisition of property and equipment	997	632
Acquisition of businesses, net of cash acquired	0	0
Purchase of alarm monitoring contracts	0	0
Proceeds from sale of non-media business	0	0
Investments in equity and cost method investees	0	0
Loans to affiliates		0
Other, net	0	0
Net cash flows used in investing activities	997	632
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES:
Proceeds from notes payable and commercial bank financing	0	0
Repayments of notes payable, commercial bank financing and capital leases	0	0
Net proceeds from the sale of Class A Common Stock	0
Dividends paid on Class A and Class B Common Stock	0	0
Repurchase of outstanding Class A Common Stock	0	0
Distributions to noncontrolling interests	0	0
Increase (decrease) in intercompany payables	(5,822)	(18,919)
Other, net	46	185
Net cash flows from financing activities	(5,776)	(18,734)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	0	0
CASH AND CASH EQUIVALENTS, beginning of period	0	0
CASH AND CASH EQUIVALENTS, end of period	$ 0	$ 0