Acquisitions - Summary of Estimated Preliminary Fair Values of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands					12 Months Ended
	Sep. 19, 2019	Aug. 08, 2019	Jun. 18, 2019	Jan. 02, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill					$ 2,950,587	$ 2,596,863	$ 2,579,417
Cash paid for acquisitions					1,514,183	$ 328,433	$ 0
Nexstar Stations
Business Acquisition [Line Items]
Cash	$ 0
Accounts receivable	34,680
Prepaid and other current assets	3,926
Property and equipment	40,821
Goodwill	115,225
Right-of-use assets for operating leases	0
Other noncurrent assets	237
Total assets acquired	799,205
Accounts payable	2,037
Accrued liabilities	7,294
Deferred income tax liability	0
Operating lease liabilities - noncurrent	20,346
Other noncurrent liabilities	426
Total liabilities assumed	30,103
Net assets acquired	769,102
Less: cash acquired	0
Less: fair value of existing ownership	0
Cash paid for acquisitions	769,102
Dispatch Stations
Business Acquisition [Line Items]
Cash		$ 2,363
Accounts receivable		26,568
Prepaid and other current assets		6,092
Property and equipment		40,418
Goodwill		197,829
Right-of-use assets for operating leases		0
Other noncurrent assets		0
Total assets acquired		668,951
Accounts payable		954
Accrued liabilities		9,011
Deferred income tax liability		98,287
Operating lease liabilities - noncurrent		226
Other noncurrent liabilities		0
Total liabilities assumed		108,478
Net assets acquired		560,473
Less: cash acquired		(2,363)
Less: fair value of existing ownership		0
Cash paid for acquisitions		558,110
Justice & Quest
Business Acquisition [Line Items]
Cash			$ 0
Accounts receivable			8,501
Prepaid and other current assets			6,987
Property and equipment			361
Goodwill			23,558
Right-of-use assets for operating leases			52,553
Other noncurrent assets			5,253
Total assets acquired			97,213
Accounts payable			725
Accrued liabilities			4,236
Deferred income tax liability			(471)
Operating lease liabilities - noncurrent			0
Other noncurrent liabilities			2,677
Total liabilities assumed			7,167
Net assets acquired			90,046
Less: cash acquired			0
Less: fair value of existing ownership			(12,995)		(8,000)
Cash paid for acquisitions			77,051
Gray Stations
Business Acquisition [Line Items]
Cash				$ 0
Accounts receivable				5,553
Prepaid and other current assets				987
Property and equipment				11,757
Goodwill				18,756
Right-of-use assets for operating leases				0
Other noncurrent assets				18
Total assets acquired				111,760
Accounts payable				1
Accrued liabilities				1,604
Deferred income tax liability				0
Operating lease liabilities - noncurrent				235
Other noncurrent liabilities				0
Total liabilities assumed				1,840
Net assets acquired				109,920
Less: cash acquired				0
Less: fair value of existing ownership				0
Cash paid for acquisitions				109,920
Recent Acquisitions
Business Acquisition [Line Items]
Cash					2,363
Accounts receivable					75,302
Prepaid and other current assets					17,992
Property and equipment					93,357
Goodwill					355,368
Intangible assets acquired					386,600
Right-of-use assets for operating leases					52,553
Other noncurrent assets					5,508
Total assets acquired					1,677,129
Accounts payable					3,717
Accrued liabilities					22,145
Deferred income tax liability					97,816
Operating lease liabilities - noncurrent					20,807
Other noncurrent liabilities					3,103
Total liabilities assumed					147,588
Net assets acquired					1,529,541
Less: cash acquired					(2,363)
Less: fair value of existing ownership					(12,995)
Cash paid for acquisitions					1,514,183
Network affiliation agreements | Nexstar Stations
Business Acquisition [Line Items]
Intangible assets acquired	123,919
Network affiliation agreements | Dispatch Stations
Business Acquisition [Line Items]
Intangible assets acquired		60,767
Network affiliation agreements | Justice & Quest
Business Acquisition [Line Items]
Intangible assets acquired			0
Network affiliation agreements | Gray Stations
Business Acquisition [Line Items]
Intangible assets acquired				14,420
Network affiliation agreements | Recent Acquisitions
Business Acquisition [Line Items]
Intangible assets acquired					199,106
Retransmission agreements | Nexstar Stations
Business Acquisition [Line Items]
Intangible assets acquired	83,413
Retransmission agreements | Dispatch Stations
Business Acquisition [Line Items]
Intangible assets acquired		38,569
Retransmission agreements | Justice & Quest
Business Acquisition [Line Items]
Intangible assets acquired			0
Retransmission agreements | Gray Stations
Business Acquisition [Line Items]
Intangible assets acquired				12,957
Retransmission agreements | Recent Acquisitions
Business Acquisition [Line Items]
Intangible assets acquired					134,939
Other intangible assets | Nexstar Stations
Business Acquisition [Line Items]
Intangible assets acquired	22,715
Other intangible assets | Dispatch Stations
Business Acquisition [Line Items]
Intangible assets acquired		362
Other intangible assets | Justice & Quest
Business Acquisition [Line Items]
Intangible assets acquired			0
Other intangible assets | Gray Stations
Business Acquisition [Line Items]
Intangible assets acquired				251
Other intangible assets | Recent Acquisitions
Business Acquisition [Line Items]
Intangible assets acquired					23,328
FCC licenses | Nexstar Stations
Business Acquisition [Line Items]
Intangible assets acquired	$ 374,269
FCC licenses | Dispatch Stations
Business Acquisition [Line Items]
Intangible assets acquired		$ 295,983
FCC licenses | Justice & Quest
Business Acquisition [Line Items]
Intangible assets acquired			$ 0
FCC licenses | Gray Stations
Business Acquisition [Line Items]
Intangible assets acquired				$ 47,061
FCC licenses | Recent Acquisitions
Business Acquisition [Line Items]
Intangible assets acquired					$ 717,313