Balance Sheet Components - Prepaid Expenses And Other Current Assets (Details) - USD ($) $ in Thousands		Sep. 28, 2018		Dec. 31, 2017		Sep. 29, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
French R&D tax credits receivable(1)	[1]	$ 7,453		$ 6,609
Deferred cost of revenue		4,700		4,440
Contract assets(2)	[2]	3,656		0
Prepaid maintenance, royalty, rent, property taxes and value added tax		3,609		3,867
Capitalized commission		1,259
Restricted cash(3)		222	[3]	530	[3]	$ 803
Other		3,327		3,485
Prepaid Expense and Other Assets, Current		$ 24,226		$ 18,931

[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.

[2] Contract assets reflect the satisfied performance obligations for which the Company does not yet have an unconditional right to consideration.

[3] Amounts represent cash collateral security for certain bank guarantees. These restricted funds are invested in bank deposits and cannot be withdrawn from the Company’s accounts without the prior written consent of the applicable secured party.