Summary of Significant Accounting Policies - Reconciliation of Changes in Deferred Revenue (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Dec. 29, 2018	[1]
Reconciliation of the changes in the Company's deferred revenue balance
Balance, beginning of period	$ 2,225	$ 2,520
Additions to deferral	1,575	1,426
Revenue recognized	(1,906)	(1,729)
Balance, end of period	1,894	2,217
Non-current portion of deferred revenue	366	608	$ 586
Current portion of deferred revenue	$ 1,528	$ 1,609	$ 1,639

[1] Derived from the audited consolidated financial statements included in the Annual Report on Form 10-K filed with the SEC for the year ended December 29, 2018.