Summary of Significant Accounting Policies - Reconciliation of Changes in Deferred Revenue (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 29, 2018		Sep. 30, 2017
Reconciliation of the changes in the Company's deferred revenue balance
Balance, beginning of period	$ 2,520	[1]	$ 1,383
Additions to deferral	1,426		981
Revenue recognized	(1,729)		(961)
Balance, end of period	$ 2,217		$ 1,403

[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 30, 2017.