Description of Business and Summary of Significant Accounting Policies - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jul. 01, 2018	Dec. 31, 2017	Jul. 02, 2017	Jan. 01, 2017
Accounting Policies [Abstract]
Cash and cash equivalents	$ 88,887	$ 67,200	$ 89,462	$ 61,023
Restricted cash	207	112	115	268
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 89,094	$ 67,312	$ 89,577	$ 61,291