The Company and Significant Accounting Policies - Carrying Amount of Intangible Assets Not Subject to Amortization (Detail) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Indefinite Lived Intangible Assets By Major Class [Line Items]
Intangible assets, Beginning balance		$ 254,598,000
Impairment		(3,500,000)	$ 0
Intangible assets, Ending balance	$ 251,098,000	251,098,000	254,598,000
Television
Indefinite Lived Intangible Assets By Major Class [Line Items]
Intangible assets, Beginning balance		159,019,000
Impairment	(3,500,000)	(3,500,000)
Intangible assets, Ending balance	155,519,000	155,519,000	159,019,000
Radio
Indefinite Lived Intangible Assets By Major Class [Line Items]
Intangible assets, Beginning balance		95,579,000
Intangible assets, Ending balance	$ 95,579,000	$ 95,579,000	$ 95,579,000