Related-Party Transactions - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) Market Agreement shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Related Party Transaction [Line Items]
Number of Class A common stock shares converted | shares	1
Retransmission consent revenue	$ 35.1	$ 31.4
Fees paid for carriage of programming	$ 0.0
Univision
Related Party Transaction [Line Items]
Number of marketing and sales agreements | Agreement	2
Number of markets involved in sales and marketing | Market	6
Common stock percentage held by Univision	11.00%
Retransmission consent revenue	$ 28.2	30.0
Accounts receivable from third parties	$ 4.9	$ 3.9	$ 3.2
UniMas
Related Party Transaction [Line Items]
Affiliate advertising minutes per hour for which entity has right to sell	4 minutes 30 seconds
Minimum | Univision
Related Party Transaction [Line Items]
Affiliate advertising minutes per hour for which entity has right to sell	4 minutes