STOCK BASED COMPENSATION - Balances of stock-based compensation plans (Details) shares in Thousands	9 Months Ended
	Sep. 28, 2019 $ / shares shares
Stock Options
Number of Options
Balance at the beginning (in shares) | shares	2,889
Granted (in shares) | shares	601
Exercised/released (in shares) | shares	(1,570)
Forfeited/expired (in shares) | shares	(102)
Balance at the end (in shares) | shares	1,818
Weighted Average Exercise Price
Balance at the beginning (in dollars per share) | $ / shares	$ 6.56
Granted (in dollars per share) | $ / shares	23.59
Exercised/released (in dollars per share) | $ / shares	1.73
Forfeited/expired (in dollars per share) | $ / shares	20.10
Balance at the end (in dollars per share) | $ / shares	$ 15.62
Performance-Based Restricted Stock Units
Number of Shares
Balance at the beginning (in shares) | shares	1,411
Granted (in shares) | shares	0
Exercised/released (in shares) | shares	0
Forfeited/expired (in shares) | shares	(127)
Balance at the end (in shares) | shares	1,284
Weighted Average Grant Date Fair Value
Balance at the beginning (in dollars per share) | $ / shares	$ 31.74
Granted (in dollars per share) | $ / shares	0
Exercised/released (in dollars per share) | $ / shares	0
Forfeited/expired (in dollars per share) | $ / shares	31.74
Balance at the end (in dollars per share) | $ / shares	$ 31.74
Restricted Stock Units
Number of Shares
Balance at the beginning (in shares) | shares	7
Granted (in shares) | shares	338
Exercised/released (in shares) | shares	(10)
Forfeited/expired (in shares) | shares	(26)
Balance at the end (in shares) | shares	309
Weighted Average Grant Date Fair Value
Balance at the beginning (in dollars per share) | $ / shares	$ 17.00
Granted (in dollars per share) | $ / shares	23.69
Exercised/released (in dollars per share) | $ / shares	17.51
Forfeited/expired (in dollars per share) | $ / shares	22.84
Balance at the end (in dollars per share) | $ / shares	$ 23.81
Deferred Stock Units
Number of Shares
Balance at the beginning (in shares) | shares	13
Granted (in shares) | shares	10
Exercised/released (in shares) | shares	0
Forfeited/expired (in shares) | shares	0
Balance at the end (in shares) | shares	23
Weighted Average Grant Date Fair Value
Balance at the beginning (in dollars per share) | $ / shares	$ 17.00
Granted (in dollars per share) | $ / shares	24.80
Exercised/released (in dollars per share) | $ / shares	0
Forfeited/expired (in dollars per share) | $ / shares	0
Balance at the end (in dollars per share) | $ / shares	$ 20.34