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Property and Equipment - Narrative (Details) $ in Millions | 1 Months Ended | 3 Months Ended | 9 Months Ended
--- | --- | --- | ---
Jun. 29, 2018 USD ($) | Sep. 28, 2018 USD ($) ft² | Sep. 29, 2017 USD ($) | Sep. 28, 2018 USD ($) ft² | Sep. 29, 2017 USD ($)
Property, Plant and Equipment [Line Items] |  |  |  |  |
Depreciation expense |  | $ 1.7 | $ 0.3 | $ 2.9 | $ 0.8
Leasehold Improvements, Buildings, Furniture and Fixtures, Computer Equipment and Software |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Construction in progress capitalized | $ 46.3 |  |  |  |
Operating Leases and Other Financing Leases | Alameda, California |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Area of lease property (in square feet) | ft² |  | 134,765 |  | 134,765 |

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- Definition The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 + Details
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