Acquisitions - Narrative (Details) $ in Thousands						3 Months Ended		12 Months Ended
	Sep. 19, 2019 USD ($) affiliate station	Aug. 08, 2019 USD ($) radio_station station	Jun. 18, 2019 USD ($)	Jan. 02, 2019 USD ($)	Feb. 15, 2018 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 13, 2019 USD ($)	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Senior Notes issued						$ 4,203,000		$ 4,203,000	$ 2,960,000
Goodwill						2,950,587		2,950,587	2,596,863		$ 2,579,417
Goodwill acquired								$ 355,368	17,446
Network affiliation agreements
Business Acquisition [Line Items]
Weighted average useful life, intangible assets (in years)								15 years
Nexstar Media Group
Business Acquisition [Line Items]
Number of stations acquired | station	11
Number of affiliates acquired | affiliate	8
Initial purchase price	$ 769,100
Base purchase price	740,000
Working capital adjustment	$ 29,100
Weighted average useful life, intangible assets (in years)								11 years 1 month 6 days
Dispatch Stations
Business Acquisition [Line Items]
Number of stations acquired | station		2
Initial purchase price		$ 560,500
Base purchase price		535,000
Working capital adjustment		$ 25,500
Number of ratio stations acquired | radio_station		2
Weighted average useful life, intangible assets (in years)								11 years 2 months 12 days
Justice & Quest
Business Acquisition [Line Items]
Initial purchase price			$ 77,100
Working capital adjustment			$ 4,600
Ownership interest (as a percent)			85.00%
Gain recognized due to write-up of prior investment			$ 7,300
Weighted average useful life, intangible assets (in years)								6 years 9 months 18 days
Goodwill			23,558
Justice & Quest | Retransmission agreements
Business Acquisition [Line Items]
Definite-lived intangible assets			0
Justice & Quest | Network affiliation agreements
Business Acquisition [Line Items]
Definite-lived intangible assets			0
Justice & Quest | Distribution agreements
Business Acquisition [Line Items]
Weighted average useful life, intangible assets (in years)								7 years
Gray Stations
Business Acquisition [Line Items]
Initial purchase price				$ 109,900
Working capital adjustment				4,900
Weighted average useful life, intangible assets (in years)								10 years 4 months 24 days
Goodwill				18,756
Gray Stations | Retransmission agreements
Business Acquisition [Line Items]
Definite-lived intangible assets				12,957
Gray Stations | Network affiliation agreements
Business Acquisition [Line Items]
Definite-lived intangible assets				14,420
Recent Acquisitions
Business Acquisition [Line Items]
Increase in goodwill						78,200
Definite-lived intangible assets						386,600		$ 386,600
Goodwill						355,368		355,368
Acquisition related costs								30,800
Recent Acquisitions | Retransmission agreements
Business Acquisition [Line Items]
Reduction in intangible assets						9,600
Definite-lived intangible assets						134,939		134,939
Recent Acquisitions | Network affiliation agreements
Business Acquisition [Line Items]
Reduction in intangible assets						15,400
Definite-lived intangible assets						199,106		199,106
KFMB
Business Acquisition [Line Items]
Initial purchase price					$ 328,400
Working capital adjustment							$ 2,500
Weighted average amortization period					10 years
Goodwill acquired					$ 17,400
KFMB | Retransmission And Network Affiliation Agreements
Business Acquisition [Line Items]
Amortizable intangible assets					91,400
Unsecured notes bearing fixed rate interest at 5.00% due September 2029
Business Acquisition [Line Items]
Senior Notes issued						1,100,000		$ 1,100,000	$ 0	$ 1,100,000
Minimum | Retransmission agreements
Business Acquisition [Line Items]
Weighted average useful life, intangible assets (in years)								5 years
Maximum | Retransmission agreements
Business Acquisition [Line Items]
Weighted average useful life, intangible assets (in years)								6 years
FCC licenses | Justice & Quest
Business Acquisition [Line Items]
Definite-lived intangible assets			$ 0
FCC licenses | Gray Stations
Business Acquisition [Line Items]
Definite-lived intangible assets				$ 47,061
FCC licenses | Recent Acquisitions
Business Acquisition [Line Items]
Reduction in intangible assets						50,300
Definite-lived intangible assets						$ 717,313		$ 717,313
FCC licenses | KFMB
Business Acquisition [Line Items]
Indefinite lived intangible assets					$ 192,200