Summary of Significant Accounting Policies - Impact of Adoption (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 28, 2020	Mar. 30, 2019	Dec. 28, 2019
Summary of Significant Accounting Policies
Net sales	$ 449,370	$ 412,734
Cost of goods sold	344,454	324,655
Gross profit	104,916	88,079
Selling, general and administrative expenses	39,973	38,297
Operating income	60,220	45,291
Other income	(453)	(258)
Net income	28,092	$ 16,791
Unamortized deferred financing costs	$ 20,102		$ 20,869
Earnings per share:
Basic (in dollars per share)	$ 0.44	$ 0.26
Diluted (in dollars per share)	$ 0.44	$ 0.26

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