Balance Sheet Components Additional Information (Details) - USD ($) $ in Thousands		Sep. 28, 2018	Dec. 31, 2017	Sep. 29, 2017
Restricted Cash for bank guarantee		$ 0	$ 1,203	$ 1,178
R&D tax credits receivable		18,104	22,322
French R&D tax credits receivable(1)	[1]	7,453	$ 6,609
TVN [Member] | Research Tax Credit Carryforward [Member]
R&D tax credits receivable		25,600
Prepaid Expenses and Other Current Assets [Member] | TVN [Member] | Research Tax Credit Carryforward [Member]
French R&D tax credits receivable(1)		7,500
Other Noncurrent Assets [Member] | TVN [Member] | Research Tax Credit Carryforward [Member]
French R&D tax credits receivable(1)		$ 18,100

[1] The Company’s TVN subsidiary in France (the “TVN French Subsidiary”) participates in the French Crédit d’Impôt Recherche program (the “R&D tax credits”) which allows companies to monetize eligible research expenses. The R&D tax credits can be used to offset against income tax payable to the French government in each of the four years after being incurred, or if not utilized, are recoverable in cash. The amount of R&D tax credits recoverable are subject to audit by the French government. The R&D tax credits receivable at September 28, 2018 were approximately $25.6 million and are expected to be recoverable from 2019 through 2022 with $7.5 million reported as a component of “Prepaid expenses and other current assets” and $18.1 million reported as a component of “Other long-term assets” on the Company’s Condensed Consolidated Balance Sheets.