The Company and Significant Accounting Policies - Additional Information (Detail)			3 Months Ended						9 Months Ended		12 Months Ended	27 Months Ended
	May 01, 2019 USD ($)	Nov. 30, 2017 USD ($)	Sep. 30, 2019 USD ($) Location $ / shares shares	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2018 USD ($) shares	Jun. 30, 2018 USD ($) Station	Mar. 31, 2018 USD ($)	Sep. 30, 2019 USD ($) Segment Station Location Market shares	Sep. 30, 2018 USD ($) shares	Dec. 31, 2018 USD ($)	Sep. 30, 2019 USD ($) Location $ / shares shares	Aug. 27, 2019 USD ($)	Jan. 01, 2019 USD ($)	Apr. 11, 2018 USD ($)	Jul. 13, 2017 USD ($)
Accounting Policies [Line Items]
Number of reportable segments | Segment									3
Restricted cash			$ 734,000						$ 734,000		$ 732,000	$ 734,000
Retransmission consent revenue			$ 8,800,000			$ 8,800,000			$ 26,600,000	$ 26,400,000
Number of Class A common stock shares converted | shares									1
Shares of dilutive securities not included in computation of diluted income per share | shares			1,242,354			0			1,081,875	92,979
Impairment to goodwill									$ 27,714,000		0
Impairment to indefinite life intangibles									3,500,000		0
Amount approved under share purchase													$ 45,000,000		$ 30,000,000	$ 15,000,000
Aggregate purchase price of repurchased shares			$ 1,349,000	$ 1,302,000	$ 7,706,000		$ 5,258,000	$ 2,402,000
Unamortized debt issuance costs			2,600,000						2,600,000		2,709,000	2,600,000
Interest income related to available-for-sale securities			825,000			$ 933,000			2,601,000	$ 2,885,000
Agreement amount to sell building			1,000,000
Impairment charges of assets held for sale			200,000
Operating leases right of use asset			45,058,000						45,058,000			45,058,000		$ 45,800,000
Lease liabilities			51,515,000						51,515,000			51,515,000		$ 52,400,000
Available-for-Sale Securities
Accounting Policies [Line Items]
Interest income related to available-for-sale securities			800,000						$ 2,400,000
2017 Credit Facility
Accounting Policies [Line Items]
Agreement date		Nov. 30, 2017
Additional borrowing capacity		$ 100,000,000
First lien net leverage ratio		4.00%
Certain customary events of default, number of business days to default in the payment of interest on borrowings									3 days
Certain customary events of default, number of days default continue for compliance with other agreement									30 days
Certain customary events of default, number of days default continue for financial statement delivery obligations									10 days
Certain customary events of default, indebtedness aggregate amount									$ 15,000,000
Certain customary events of default, failure in payment of final judgments aggregate amount									$ 15,000,000
Certain customary events of default, failure in payment of final judgments aggregate amount period									30 days
Percentage of fee equal to amount of outstanding loan	0.10%
Total fee amount	$ 200,000
2017 Credit Facility | Eurodollar Rate
Accounting Policies [Line Items]
Variable interest rate basis spread on debt		2.75%
2017 Credit Facility | Base Rate Margin
Accounting Policies [Line Items]
Variable interest rate basis spread on debt		1.75%
2017 Credit Facility | Term Loan B Facility
Accounting Policies [Line Items]
Senior Secured debt		$ 300,000,000
Maturity date of revolving credit facility		Nov. 30, 2024
2013 Credit Facility | Term Loan B Facility
Accounting Policies [Line Items]
Carrying value of term loan			241,400,000						$ 241,400,000			241,400,000
Unamortized debt issuance costs			2,600,000						2,600,000			2,600,000
Estimated fair value of term loan			$ 239,100,000						239,100,000			$ 239,100,000
Class A common stock
Accounting Policies [Line Items]
Amount approved under share purchase													$ 15,000,000		$ 15,000,000
Number of shares repurchased | shares			500,000									7,500,000
Average price of repurchased shares | $ / shares			$ 2.84									$ 3.91
Aggregate purchase price of repurchased shares			$ 1,300,000									$ 29,500,000
MEXICO
Accounting Policies [Line Items]
Broadcast license fees prepayment period			20 years
Broadcast license term expiry date			Dec. 31, 2021
Stock Options And Restricted Stock Units
Accounting Policies [Line Items]
Share-based compensation expenses			$ 800,000			1,300,000			2,500,000	3,700,000
Employee Stock Options
Accounting Policies [Line Items]
Share-based compensation expenses										0
Restricted Stock Units
Accounting Policies [Line Items]
Total unrecognized compensation expense related to grants of restricted stock units			2,300,000						$ 2,300,000			2,300,000
Weighted average period for unrecognized compensation expense related to grants of restricted stock units									1 year 2 months 12 days
Univision
Accounting Policies [Line Items]
Payment of sales representation fees to television stations			2,000,000			2,200,000			$ 6,000,000	6,400,000
Amount due from television stations for carriage			4,500,000						4,500,000			$ 4,500,000
Retransmission consent revenue			$ 7,000,000			$ 6,500,000			$ 20,700,000	$ 21,500,000
Common stock percentage held by Univision			11.00%						11.00%			11.00%
UniMas
Accounting Policies [Line Items]
Affiliate advertising minutes per hour for which entity has right to sell									4 minutes 30 seconds
Accounting Standards Update 2016-18
Accounting Policies [Line Items]
Restricted cash			$ 700,000						$ 700,000		$ 700,000	$ 700,000
Minimum | Employee Stock Options
Accounting Policies [Line Items]
Vesting period									1 year
Minimum | Restricted Stock Units
Accounting Policies [Line Items]
Vesting period									1 year
Minimum | Univision
Accounting Policies [Line Items]
Affiliate advertising minutes per hour for which entity has right to sell									4 minutes
Maximum | Employee Stock Options
Accounting Policies [Line Items]
Vesting period									4 years
Maximum | Restricted Stock Units
Accounting Policies [Line Items]
Vesting period									4 years
Television
Accounting Policies [Line Items]
Number of stations owned | Station									55
Impairment to indefinite life intangibles			$ 3,500,000						$ 3,500,000
Number of stations relocated | Station | Station							2
Radio
Accounting Policies [Line Items]
Number of stations owned | Station									49
Radio operations stations, number of location | Location			16						16			16
Advertisements and Syndicate Radio Programming | Minimum
Accounting Policies [Line Items]
Number of markets owned | Market									100
Digital
Accounting Policies [Line Items]
Impairment to goodwill			$ 5,300,000						$ 27,714,000