Summary of Significant Accounting Policies - Reconciliation of Changes in Deferred Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 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	559	223
Revenue recognized	(516)	(498)
Balance, end of period	2,268	2,245
Non-current portion of deferred revenue	526	663	$ 586
Current portion of deferred revenue	$ 1,742	$ 1,582	$ 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.