Income Taxes - Schedule of Effective Income Tax Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Computed “expected” tax provision (benefit)		$ (2,400)	$ 4,500
Change in income tax resulting from:
State taxes, net of federal benefit	$ 700	1,000	1,500
Change in fair value of earnout		(1,600)	400
Non-deductible executive compensation	400	300	300
Non-deductible expenses	200	300	300
Foreign income	100	200
State tax impact of previously deferred gain from FCC auction for broadcast spectrum	(2,500)	2,700
Transaction costs	100		100
Change in valuation allowance	1,700
Change in state tax rate	500	400	500
Stock compensation	200	400	500
Change in unrecognized tax benefits	100	700	(300)
Impairment	200	6,300
Other	(200)	(100)	100
Total provision (benefit) for taxes	$ 1,506	$ 8,158	$ 7,877