LEASES - Lease expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 03, 2020	Jun. 28, 2019	Jul. 03, 2020	Jun. 28, 2019
Lease cost
Operating lease cost	$ 1,766	$ 1,181	$ 3,508	$ 2,270
Amortization of assets	155	124	310	231
Interest on lease liabilities	8	9	17	18
Total net lease cost	$ 1,929	$ 1,314	$ 3,835	$ 2,519