Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Product Information [Line Items]
Contract with customer liability	$ 7,625
Advertising expense	$ 939	$ 1,019	$ 1,048
Revenue benchmark \| Government contracts concentration risk
Product Information [Line Items]
Concentration risk, percentage	68.00%	67.00%	68.00%
Revenue benchmark \| Geographic concentration risk \| CALIFORNIA
Product Information [Line Items]
Concentration risk, percentage	27.00%	30.00%	32.00%
Transferred at point in time
Product Information [Line Items]
Concentration risk, percentage	10.00%	8.00%

Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

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