Goodwill and Identified Intangible Assets - Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Balance at beginning of period	$ 242,827	$ 237,279
Foreign currency translation adjustment	(2,209)	5,548
Balance at end of period	240,618	242,827
Video [Member]
Goodwill [Line Items]
Balance at beginning of period	182,012	176,519
Foreign currency translation adjustment	(2,173)	5,493
Balance at end of period	179,839	182,012
Cable Edge [Member]
Goodwill [Line Items]
Balance at beginning of period	60,815	60,760
Foreign currency translation adjustment	(36)	55
Balance at end of period	$ 60,779	$ 60,815