Balance Sheet Components - Other Long Term 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(3)	[1]	$ 13,345	$ 15,899
Deferred tax assets		9,876	10,575
Equity investment		3,593	3,593
Other		9,438	11,238
Other Assets, Noncurrent		$ 36,252	$ 41,305

[1] See “Prepaid expenses and other current assets” for details related to French R&D tax credits receivable.