Description of Business and Summary of Significant Accounting Policies - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 30, 2018	Jul. 01, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Cash and cash equivalents	$ 113,636	$ 63,170	$ 88,887
Restricted cash	182	151	207
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 113,818	$ 63,321	$ 89,094	$ 67,312