Balance Sheet Components - Prepaid Expenses And Other Current Assets (Details) - USD ($) $ in Thousands		Sep. 25, 2020	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
French R&D tax credits receivable(1)	[1]	$ 6,170	$ 7,343
Contract assets(2)	[2]	4,067	13,969
Deferred cost of revenue		2,062	2,631
Prepaid maintenance, royalty and property taxes		2,718	1,594
Capitalized sales commissions		1,502	1,309
Other		8,552	13,916
Prepaid Expense and Other Assets, Current		$ 25,071	$ 40,762

[1] The Company’s 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 total R&D tax credits receivable at September 25, 2020 were approximately $19.5 million and are expected to be recoverable from 2021 through 2024. See “Other long-term assets” for the long-term portion of the French R&D tax credits receivable.

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