Goodwill and Other Intangible Assets - Carrying Amount of Goodwill (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Goodwill, Beginning balance		$ 46,511,000	$ 46,511,000	$ 74,292,000
Acquisition			12,332,000
Currency				(67,000)
Impairment			(800,000)	(27,714,000)
Goodwill, Ending balance	$ 58,043,000		58,043,000	46,511,000
Television
Goodwill [Line Items]
Goodwill, Beginning balance		40,549,000	40,549,000	40,549,000
Impairment			0
Goodwill, Ending balance	40,549,000		40,549,000	40,549,000
Radio
Goodwill [Line Items]
Goodwill, Beginning balance		0	0
Goodwill, Ending balance	0		0	0
Digital
Goodwill [Line Items]
Goodwill, Beginning balance		5,962,000	5,962,000	33,743,000
Acquisition			12,332,000
Currency				(67,000)
Impairment	0	$ (800,000)	(800,000)	(27,714,000)
Goodwill, Ending balance	$ 17,494,000		$ 17,494,000	$ 5,962,000