Goodwill and Identified Intangible Assets - Changes in Carrying Amount of Goodwill (Detail) $ in Thousands	9 Months Ended
	Sep. 25, 2020 USD ($)
Goodwill [Line Items]
Balance at beginning of period	$ 239,780
Foreign currency translation adjustment, net	1,645
Balance at end of period	241,425
Video [Member]
Goodwill [Line Items]
Balance at beginning of period	178,982
Foreign currency translation adjustment, net	1,662
Balance at end of period	180,644
Cable Access [Member]
Goodwill [Line Items]
Balance at beginning of period	60,798
Foreign currency translation adjustment, net	(17)
Balance at end of period	$ 60,781