Acquisitions - Summary of Estimated Preliminary Fair Values of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands					3 Months Ended
	Sep. 19, 2019	Aug. 08, 2019	Jun. 18, 2019	Jan. 02, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Business Acquisition [Line Items]
Goodwill					$ 2,967,383		$ 2,950,587
Cash paid for acquisitions					15,000	$ 108,872
Nexstar Stations
Business Acquisition [Line Items]
Cash	$ 0
Accounts receivable	34,680
Prepaid and other current assets	3,776
Property and equipment	45,186
Goodwill	126,928
Right-of-use assets for operating leases	22,715
Other noncurrent assets	237
Total assets acquired	800,033
Accounts Payable	2,037
Accrued liabilities	8,122
Deferred income tax liability	0
Operating lease liabilities - noncurrent	20,346
Other noncurrent liabilities	426
Total liabilities assumed	30,931
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		26,344
Prepaid and other current assets		6,092
Property and equipment		40,418
Goodwill		202,274
Right-of-use assets for operating leases		362
Other noncurrent assets		0
Total assets acquired		667,708
Accounts Payable		954
Accrued liabilities		9,011
Deferred income tax liability		97,044
Operating lease liabilities - noncurrent		226
Other noncurrent liabilities		0
Total liabilities assumed		107,235
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			0
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)
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				19,405
Right-of-use assets for operating leases				251
Other noncurrent assets				18
Total assets acquired				111,650
Accounts Payable				1
Accrued liabilities				1,494
Deferred income tax liability				0
Operating lease liabilities - noncurrent				235
Other noncurrent liabilities				0
Total liabilities assumed				1,730
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					75,078
Prepaid and other current assets					17,842
Property and equipment					97,722
Goodwill					372,165
Right-of-use assets for operating leases					23,328
Other noncurrent assets					5,508
Total assets acquired					1,676,604
Accounts Payable					3,717
Accrued liabilities					22,863
Deferred income tax liability					96,573
Operating lease liabilities - noncurrent					20,807
Other noncurrent liabilities					3,103
Total liabilities assumed					147,063
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	123,926
Network affiliation agreements | Dispatch Stations
Business Acquisition [Line Items]
Intangible assets acquired		60,765
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					199,111
Retransmission agreements | Nexstar Stations
Business Acquisition [Line Items]
Intangible assets acquired	68,316
Retransmission agreements | Dispatch Stations
Business Acquisition [Line Items]
Intangible assets acquired		33,107
Retransmission agreements | Justice & Quest
Business Acquisition [Line Items]
Intangible assets acquired			0
Retransmission agreements | Gray Stations
Business Acquisition [Line Items]
Intangible assets acquired				12,198
Retransmission agreements | Recent Acquisitions
Business Acquisition [Line Items]
Intangible assets acquired					113,621
Other intangible assets | Nexstar Stations
Business Acquisition [Line Items]
Intangible assets acquired	0
Other intangible assets | Dispatch Stations
Business Acquisition [Line Items]
Intangible assets acquired		0
Other intangible assets | Justice & Quest
Business Acquisition [Line Items]
Intangible assets acquired			52,553
Other intangible assets | Gray Stations
Business Acquisition [Line Items]
Intangible assets acquired				0
Other intangible assets | Recent Acquisitions
Business Acquisition [Line Items]
Intangible assets acquired					52,553
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