STOCK BASED COMPENSATION - Summary of stock options (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Jan. 02, 2021	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Number of Options
Options granted (in shares)	0
Stock Options
Number of Options
Options outstanding at beginning (in shares)	1,618	2,889	2,884
Options granted (in shares)	0	601	761
Options exercised (in shares)	(247)	(1,730)	(560)
Options forfeited, cancelled (in shares)	(117)	(142)	(172)
Options expired (in shares)			(24)
Options outstanding at ending (in shares)	1,254	1,618	2,889	2,884
Options exercisable (in shares)	715
Weighted Average Exercise Price
Weighted average exercise price at beginning (in dollars per share)	$ 16.44	$ 6.56	$ 5.22
Options granted (in dollars per share)		23.59	18.00
Options exercised (in dollars per share)	12.23	2.06	0.47
Options forfeited, cancelled (in dollars per share)	21.56	20.88	47.91
Options expired (in dollars per share)			53.55
Weighted average exercise price at ending (in dollars per share)	16.79	$ 16.44	$ 6.56	$ 5.22
Options exercisable (in dollars per share)	$ 14.07
Weighted average remaining contractual term (Years)	7 years 2 months 19 days	8 years 1 month 13 days	6 years 5 months 23 days	6 years 1 month 6 days
Weighted average remaining contractual term of options exercisable (years)	6 years 7 months 28 days
Aggregate intrinsic value of options outstanding options	$ 64,781
Aggregate intrinsic value of options exercisable options	$ 38,917