Leases - Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 05, 2020	Jun. 30, 2019	Jul. 05, 2020	Jun. 30, 2019	Dec. 29, 2019
Leases [Abstract]
Finance lease cost: Amortization of right-of-use assets	$ 335	$ 278	$ 635	$ 424
Finance lease cost: Interest on lease liabilities	16	11	34	19
Operating lease cost	6,759	5,930	12,981	11,601
Short-term lease cost	166	408	341	1,146
Variable lease cost	924	613	1,570	758
Total lease cost	8,200	7,240	15,561	13,948
Operating cash flows from finance leases	16	11	34	19
Operating cash flows from operating leases	5,569	5,395	11,450	10,505
Financing cash flows from finance leases	411	271	810	517
Right-of-use assets obtained in exchange for new finance lease liabilities	340	551	553	551
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 3,088	$ 4,069	$ 4,065	$ 6,536
Weighted-average remaining lease term – finance leases (in years)	2 years 8 months 12 days		2 years 8 months 12 days		2 years 9 months 3 days
Weighted-average remaining lease term – operating leases (in years)	10 years 7 months 13 days		10 years 7 months 13 days		10 years 7 months 6 days
Weighted-average discount rate – finance leases (percentage)	2.37%		2.37%		2.06%
Weighted-average discount rate – operating leases (percentage)	5.93%		5.93%		5.86%