The Company and Significant Accounting Policies - Carrying Amount of Intangible Assets Not Subject to Amortization (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($)
Indefinite Lived Intangible Assets By Major Class [Line Items]
Intangible assets, Beginning balance	$ 216,653
Impairment	(1,326)
Transfer to Assets Held for Sale	(6,174)
Intangible assets, Ending balance	209,153
Television
Indefinite Lived Intangible Assets By Major Class [Line Items]
Intangible assets, Beginning balance	130,274
Intangible assets, Ending balance	130,274
Radio
Indefinite Lived Intangible Assets By Major Class [Line Items]
Intangible assets, Beginning balance	86,379
Impairment	(1,326)
Transfer to Assets Held for Sale	(6,174)
Intangible assets, Ending balance	$ 78,879