Acquisitions - Narrative (Details) $ in Millions					9 Months Ended
	Sep. 19, 2019 USD ($) affiliate market station	Aug. 08, 2019 USD ($) radio_station	Jun. 18, 2019 USD ($)	Jan. 02, 2019 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2019 station
Business Acquisition [Line Items]
Number of stations acquired | station						15
Goodwill, increase in carrying amount					$ 18.1
Amortization expense related to intangibles					68.0
Retransmission agreements
Business Acquisition [Line Items]
Reduction in intangible assets					$ 21.3
Nexstar Media Group
Business Acquisition [Line Items]
Number of stations acquired | station	11
Number of markets | market	8
Number of affiliates acquired | affiliate	8
Initial purchase price	$ 769.9
Base purchase price	740.0
Working capital adjustment	$ 29.9
Dispatch Stations
Business Acquisition [Line Items]
Initial purchase price		$ 560.5
Base purchase price		535.0
Working capital adjustment		$ 25.5
Number of ratio stations acquired | radio_station		2
Justice & Quest
Business Acquisition [Line Items]
Initial purchase price			$ 77.1
Working capital adjustment			$ 4.6
Ownership interest (as a percent)			85.00%
Gray Stations
Business Acquisition [Line Items]
Initial purchase price				$ 109.9
Working capital adjustment				$ 4.9