Acquisitions and Dispositions - CCA - Additional Information (Details) $ in Thousands			1 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2014 USD ($) TelevisionStation Market	Dec. 01, 2014 USD ($)	Apr. 30, 2013 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) TelevisionStation Market
Business Acquisition [Line Items]
Proceeds from disposal of a station												$ 481,946		$ 27,005
Proceeds from disposals of property and equipment												20,026	$ 718	3,624
Consolidation of remaining assets in non-controlling interests												7,600	108,694	2,900
Revenue included in consolidated statements of operations and comprehensive income				$ 653,664	$ 611,870	$ 626,115	$ 540,317	$ 309,879	$ 275,659	$ 261,994	$ 255,658	2,431,966	1,103,190	896,377
Operating income (loss)				$ 140,837	$ 129,072	$ 138,685	$ 110,151	$ 92,475	$ 72,897	$ 64,007	$ 57,929	518,745	287,308	206,107
Eliminations [Member]
Business Acquisition [Line Items]
Proceeds from disposal of a station														(43,300)
Revenue included in consolidated statements of operations and comprehensive income												$ (146,286)	$ (89,308)	(74,986)
CCA [Member]
Business Acquisition [Line Items]
Acquisition date	Jan. 01, 2015
Purchase price of entities acquired	$ 278,100
Number of television stations acquired | TelevisionStation	14														14
Number of television market of stations acquired | Market	10														10
Deposits and payments for acquisitions		$ 43,000	$ 27,000
Cash paid in business acquisition	$ 251,100
Acquisition related costs														500	$ 700
One time employment charges														600
Proceeds from disposal of a station	27,400
Proceeds from disposals of property and equipment	800
Loss on disposal of property and equipment	$ (500)
New television markets entered | Market	7														7
New market duopolies operated | Market	4														4
Consolidation of remaining assets in non-controlling interests	$ 2,900
Revenue included in consolidated statements of operations and comprehensive income														107,900
Operating income (loss)														$ 34,900
CCA [Member] | Eliminations [Member]
Business Acquisition [Line Items]
Purchase price of entities acquired	43,300
Proceeds from disposal of a station	$ 43,300