Goodwill and Identified Intangible Assets - Allocation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Amortization expense for identified intangibles	$ 3,187	$ 3,142		$ 10,402
Amortization	8,367	8,322	[1]	14,836	[1]
Cost of revenue [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense for identified intangibles	5,180	5,180		4,434
Operating expense [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense for identified intangibles	$ 3,187	$ 3,142		$ 10,402

[1] For the years ended December 31, 2017 and 2016, the unallocated corporate expenses included TVN acquisition- and integration-related costs, TVN VDP costs (see Note 10, “Restructuring and Related charges-TVN VDP,” for more information on TVN VDP ) and Cable Access product line inventory obsolescence costs, totaling $7.9 million and $32.2 million, respectively. In addition, in fiscal 2017, the unallocated corporate expenses included $8.0 million of Avid litigation settlement cost and associated legal fees (see Note 19, “Legal Proceedings,” for more information). The remaining unallocated corporate expenses for all years presented above include primarily other restructuring charges and excess facilities charges.