Summary of Significant Accounting Policies - Reconciliation of Changes in Deferred Revenue (Details) - USD ($) $ in Thousands	6 Months Ended
	Jul. 01, 2017		Jul. 02, 2016
Reconciliation of the changes in the Company's deferred revenue balance
Balance, beginning of period	$ 1,383	[1]	$ 1,311
Additions to deferral	590		640
Revenue recognized	(628)		(680)
Balance, end of period	$ 1,345		$ 1,271

[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 31, 2016.