Goodwill - Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Balance at beginning of period	$ 239,780	$ 240,618
Foreign currency translation adjustment	3,894	(838)
Balance at end of period	243,674	239,780
Video [Member]
Goodwill [Line Items]
Balance at beginning of period	178,982	179,839
Foreign currency translation adjustment	3,873	(857)
Balance at end of period	182,855	178,982
Cable Access [Member]
Goodwill [Line Items]
Balance at beginning of period	60,798	60,779
Foreign currency translation adjustment	21	19
Balance at end of period	$ 60,819	$ 60,798