Segment Information - Summary Financial Infomation by reportable segments (Details) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 29, 2018 USD ($)		Jun. 30, 2017 USD ($)	Jun. 29, 2018 USD ($) segment	Jun. 30, 2017 USD ($)
Segment Reporting Information [Line Items]
Revenue	$ 99,160		$ 82,315	$ 189,287	$ 165,258
Gross Profit	51,603		33,815	98,786	74,223
Operating Income (Loss)	642		(27,422)	$ (8,685)	(48,580)
Number of Reportable Segments | segment				2
Video [Member]
Segment Reporting Information [Line Items]
Revenue	79,208	[1]	73,379	$ 150,956	147,721
Gross Profit	43,558	[1]	37,720	84,784	78,493
Operating Income (Loss)	6,239	[1]	(8,947)	8,234	(14,783)
Cable Access [Member]
Segment Reporting Information [Line Items]
Revenue	20,236	[1]	8,936	38,726	17,537
Gross Profit	10,187	[1]	1,699	18,827	3,909
Operating Income (Loss)	540	[1]	(7,411)	(973)	(13,491)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	99,444	[1]	82,315	189,682	165,258
Gross Profit	53,745	[1]	39,419	103,611	82,402
Operating Income (Loss)	$ 6,779	[1]	(16,358)	$ 7,261	(28,274)
Operating Income (Loss) [Member]
Segment Reporting Information [Line Items]
Prior period reclassification adjustment			$ 2,100		$ 3,200

[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 has 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 six months ended June 30, 2017 compared to the Company’s historical approach was an increase in operating loss of $2.1 million and $3.2 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.