Goodwill and Other Intangible Assets - Composition of Company's Acquired Intangible Assets and Associated Accumulated Amortization (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2020
Schedule Of Intangible Assets [Line Items]
Gross Carrying Amount	$ 116,591	$ 153,164
Accumulated Amortization	99,819	103,752
Net Carrying Amount	16,772	49,412
Intangible assets not subject to amortization:
Total intangible assets	269,316	266,065
FCC Licenses and Spectrum Usage Rights
Intangible assets not subject to amortization:
Licenses	$ 252,544	216,653
Television network affiliation agreements
Schedule Of Intangible Assets [Line Items]
Weighted average remaining life in years	7 years
Gross Carrying Amount	$ 67,489	67,488
Accumulated Amortization	58,338	59,726
Net Carrying Amount	$ 9,151	7,762
Customer base
Schedule Of Intangible Assets [Line Items]
Weighted average remaining life in years	4 years
Gross Carrying Amount	$ 10,045	47,052
Accumulated Amortization	6,414	7,874
Net Carrying Amount	$ 3,631	39,178
Pre-sold advertising contracts and other
Schedule Of Intangible Assets [Line Items]
Weighted average remaining life in years	5 years
Gross Carrying Amount	$ 39,057	38,624
Accumulated Amortization	35,067	36,152
Net Carrying Amount	$ 3,990	$ 2,472