Segment Information - Summary Financial Infomation by reportable segments (Details) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 28, 2018 USD ($)		Sep. 29, 2017 USD ($)	Sep. 28, 2018 USD ($) segment	Sep. 29, 2017 USD ($)
Segment Reporting Information [Line Items]
Revenue	$ 100,616		$ 92,014	$ 289,903	$ 257,272
Gross Profit	50,102		47,025	148,888	121,248
Operating Income (Loss)	(3,651)		(14,206)	$ (12,336)	(62,786)
Number of Reportable Segments | segment				2
Video [Member]
Segment Reporting Information [Line Items]
Revenue	73,344	[1]	84,155	$ 224,300	231,876
Gross Profit	41,937	[1]	48,283	126,721	126,776
Operating Income (Loss)	5,258	[1]	7,009	13,492	(7,774)
Cable Access [Member]
Segment Reporting Information [Line Items]
Revenue	28,062	[1]	7,859	66,788	25,396
Gross Profit	10,871	[1]	1,064	29,698	4,973
Operating Income (Loss)	395	[1]	(5,357)	(578)	(18,848)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	101,406	[1]	92,014	291,088	257,272
Gross Profit	52,808	[1]	49,347	156,419	131,749
Operating Income (Loss)	$ 5,653	[1]	1,652	$ 12,914	(26,622)
Operating Income (Loss) [Member]
Segment Reporting Information [Line Items]
Prior period reclassification adjustment			$ 2,700		$ 5,900

[1] The Company has historically employed an aggregate allocation methodology based on total revenues to attribute professional services revenue and sales expenses between its Video and Cable Access segments. Beginning in the fourth quarter of 2017, the Company prospectively changed to a more precise attribution methodology as the activities of selling and supporting the CableOS solution have become increasingly distinct from those of Video solutions. The impact of making this change in the three and nine months ended September 29, 2017 compared to the Company’s historical approach was a decrease in operating income of $2.7 million and an increase in operating loss of $5.9 million, respectively, from the Video segment and a corresponding decrease in operating loss of the Cable Access segment. The Company believes that the updated allocation methodology will provide greater clarity regarding the operating metrics of the Video and Cable Access business segments.