Summary of Significant Accounting Policies - Revenue from Contracts with Customers, Financial Statement Impact (Details) - USD ($) $ in Thousands		3 Months Ended																12 Months Ended
		Dec. 31, 2018		Sep. 28, 2018		Jun. 29, 2018		Mar. 30, 2018		Dec. 31, 2017		Sep. 29, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016		Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenue		$ 113,655		$ 100,616		$ 99,160		$ 90,127		$ 100,974		$ 92,014		$ 82,315		$ 82,943		$ 403,558	[1]	$ 358,246	[1]	$ 405,911	[1]
Cost of revenue																		194,349		188,426		205,161
Gross profit		60,321	[2]	50,102	[2]	51,603	[2]	47,183	[2]	48,572	[2]	47,025	[2]	33,815	[2]	40,408	[2]	209,209		169,820		200,750
Selling, general and administrative																		118,952		136,270		144,381
Operating Income (Loss)																		(5,011)		(70,877)	[3]	(67,036)	[3]
Loss before income taxes																		(16,948)		(84,707)	[3]	(80,430)	[3]
Net loss		3,330	[4],[5],[6]	$ (7,758)	[4],[5],[6]	$ (2,913)	[4],[5],[6]	$ (13,694)	[4],[5],[6]	(11,516)	[5],[6]	$ (15,583)	[5],[6]	$ (31,500)	[5],[6]	$ (24,027)	[5],[6]	(21,035)		(82,955)		(72,314)
Accounts receivable, net		81,795								69,844								81,795		69,844
Prepaid expenses and other current assets		23,280								18,931								23,280		18,931
Other long-term assets		38,377								42,913								38,377		42,913
Deferred revenue		41,592								52,429								41,592		52,429
Other non-current liabilities		18,228								22,626								18,228		22,626
Accumulated deficit		(2,067,416)								(2,057,812)								(2,067,416)		(2,057,812)
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable, net																								$ 71,625
Prepaid expenses and other current assets																								22,509
Other long-term assets																								43,686
Deferred revenue																								47,603
Other non-current liabilities																								22,153
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenue																		402,550
Cost of revenue																		194,101
Gross profit																		208,449
Selling, general and administrative																		119,151
Operating Income (Loss)																		(5,970)
Loss before income taxes																		(17,907)
Net loss																		(21,994)
Accounts receivable, net		79,954																79,954
Prepaid expenses and other current assets		19,067																19,067
Other long-term assets		37,872																37,872
Deferred revenue		47,117																47,117
Other non-current liabilities		18,534																18,534
Accumulated deficit		(2,079,806)																(2,079,806)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total net revenue																		1,008
Cost of revenue																		248
Gross profit																		760
Selling, general and administrative																		(199)
Operating Income (Loss)																		959
Loss before income taxes																		959
Net loss																		959
Accounts receivable, net		1,841																1,841						1,781
Prepaid expenses and other current assets		4,213																4,213						3,578
Other long-term assets		505																505						773
Deferred revenue		(5,525)																(5,525)						(4,826)
Other non-current liabilities		(306)																(306)						(473)
Accumulated deficit		12,390																12,390
Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss																		(21,035)		(82,955)		$ (72,314)
Accumulated deficit		$ (2,067,416)								$ (2,057,812)								$ (2,067,416)		$ (2,057,812)
Retained Earnings [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit																								(2,046,381)
Retained Earnings [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit	[7]																							$ 11,431

[1] Revenue is attributed to countries based on the location of the customer.

[2] Gross margin decreased to 49.8% during the third quarter of 2018 compared to 52.0% during the second quarter of 2018 and increased to 53.1% during the fourth quarter primarily as a result of product mix. Gross margin decreased to 41.1% during the second quarter of 2017 compared to 48.7% during the first quarter of 2017, primarily due to lower service margins and higher inventory obsolescence charges for the Company’s legacy broadcast video inventory due to reduced demand, as well as higher inventory obsolescence charge for our older Cable Edge product lines. The factors negatively impacting the gross margin during the second quarter of 2017 were mostly absent during the third quarter of 2017, and together with a more favorable product mix, the gross margin increased to 51.1% during the third quarter of 2017 compared to 41.1% during the second quarter of 2017.

[3] 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.

[4] During the fourth quarter of 2018, the Company recorded net income primarily due to higher revenues with stronger gross margins of 53.1% coupled with reduced operating expenses as a result of our vigilant cost management.

[5] During the fourth quarter of 2018, the Company released $1.0 million of valuation allowance associated with one of Company’s foreign subsidiaries. During the third and fourth quarter of 2017, the Company recorded $2.4 million of tax benefit associated with the release of tax reserves for uncertain tax positions as a result of the expiration of statute of limitations and $2.5 million of tax benefits associated with the alternative minimum tax refund related to the TCJA, respectively. These tax benefits were offset by $3.0 million tax expense recorded during the fourth quarter of 2017, related to tax law changes in one of the Company’s foreign subsidiaries.

[6] In 2017, the Company incurred TVN acquisition- and integration-related expenses of $2.2 million, $0.5 million, $0.1 million and $0.1 million during the first through fourth quarter of 2017. These costs consisted of acquisition-related costs which include outside legal, accounting and other professional services as well as integration-related costs which include incremental costs resulting from the TVN acquisition that are not expected to generate future benefits once the integration is fully consummated. These costs are expensed as incurred and the Company did not incur any TVN acquisition- and integration-related expenses in 2018.

[7] See Note 2, “Summary of Significant Accounting Policies-Recently Adopted Accounting Pronouncements,” for more information on the adoption of ASC 606, Revenue from Contracts with Customers (“Topic 606”) issued by the Financial Accounting Standards Board.