CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (8,280)	$ (5,105)	$ (24,370)	$ (16,121)
Other comprehensive income (loss):
Foreign currency translation adjustment	56	12	69	4
Unrealized gains on marketable securities, net of tax of $0	22		52	7
Total other comprehensive income (loss)	78	12	121	11
Comprehensive loss	$ (8,202)	$ (5,093)	$ (24,249)	$ (16,110)

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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