Goodwill and Identified Intangible Assets - Allocation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization expense for identified intangibles	$ 3,139	$ 3,187	$ 3,142
Amortization	8,319	8,367	8,322	[1]
Cost of revenue [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense for identified intangibles	5,180	5,180	5,180
Operating expense [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense for identified intangibles	$ 3,139	$ 3,187	$ 3,142

[1] For the year ended December 31, 2017, the unallocated corporate expenses included acquisition- and integration-related costs, French VDP costs (see Note 11, “Restructuring and Related charges,” for more information on French VDP) and Cable Access product line inventory obsolescence costs, totaling $7.9 million. In addition, in fiscal 2017, the unallocated corporate expenses included $8.0 million of Avid litigation settlement cost and associated legal fees (see Note 20, “Legal Proceedings,” for more information). The remaining unallocated corporate expenses for all years presented above include primarily other restructuring charges and excess facilities charges.