QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 02, 2021	Sep. 26, 2020	Jun. 27, 2020	Mar. 28, 2020	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Jan. 02, 2021	Dec. 28, 2019	Dec. 29, 2018
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 375,768	$ 294,603	$ 246,938	$ 174,412	$ 297,602	$ 229,125	$ 231,654	$ 155,353	$ 1,091,721	$ 913,734	$ 778,833
Gross profit	224,844	173,976	137,525	92,458	162,334	120,076	116,277	76,627	628,803	475,314	383,128
Net income	$ 62,394	$ 51,445	$ 33,482	$ 8,480	$ 4,742	$ 21,302	$ 22,223	$ 2,167	$ 155,801	$ 50,434	$ 57,763
Net income per share - basic (in dollars per share)	$ 0.72	$ 0.59	$ 0.39	$ 0.10	$ 0.05	$ 0.25	$ 0.26	$ 0.03	$ 1.79	$ 0.59	$ 0.71
Net income per share - diluted (in dollars per share)	$ 0.71	$ 0.58	$ 0.38	$ 0.10	$ 0.05	$ 0.25	$ 0.26	$ 0.03	$ 1.77	$ 0.58	$ 0.69