Summary of Significant Accounting Policies - ASU Share-based payments to employees (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 28, 2020	Mar. 30, 2019	Dec. 28, 2019
Summary of Significant Accounting Policies
Income tax expense (benefit)	$ 6,542	$ 5,684
Operating lease right-of-use assets, net	38,313		$ 38,698
Total present value of future operating lease payments	$ 41,319		$ 41,810