Other matters (Details)					1 Months Ended			3 Months Ended		6 Months Ended		12 Months Ended	18 Months Ended	23 Months Ended
	Jul. 03, 2020 station	Mar. 02, 2020 USD ($) market	Jun. 17, 2019 defendant	Jul. 30, 2018 defendant	Jun. 30, 2019 defendant	Dec. 13, 2018 defendant	Apr. 30, 2017 USD ($) market	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) station	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) station	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Mar. 23, 2018 USD ($)
Business Acquisition [Line Items]
Number of markets where stations were repacked | market							18
Broadcast spectrum program, number of station acquired | station										1		4
Authorized reimbursement amount							$ 1,750,000,000
Authorized reimbursement amount, repacking fund															$ 1,000,000,000
Authorized reimbursement amount, repacking fund, full power, class a stations and multichannel distributors															$ 750,000,000
Capital expenditures incurred													$ 40,600,000
Broadcast Spectrum Program, Amount Purchased										$ 4,900,000
FCC reimbursements received														$ 34,100,000
Payments for acquisition of minority interest		$ 14,000,000.0								14,000,000	$ 0
Settled litigation
Business Acquisition [Line Items]
Number of other broadcasters settling DOJ complaint (defendant) | defendant			4			7
Equity And Debt Investment | Affiliated Entity
Business Acquisition [Line Items]
Expenses incurred with related party								$ 13,700,000	$ 9,300,000
Accounts payable and accrued liabilities with related party								$ 4,200,000		$ 4,200,000		$ 4,300,000	$ 4,200,000
Clay, Massey & Associates, P.C. v. Gray Television
Business Acquisition [Line Items]
Number of other broadcasters settling DOJ complaint (defendant) | defendant				16	4
Gray Television
Business Acquisition [Line Items]
Number of television markets | market		93
Subsequent Event
Business Acquisition [Line Items]
Number of stations broadcasting on interim antennas | station	1