LEASES - Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 27, 2020	Dec. 28, 2019
ASSETS
Operating lease assets	$ 34,963	$ 37,768
Finance lease assets	1,015
Total lease assets	35,978
Current liabilities
Operating lease liabilities	8,086	7,768
Finance lease liabilities	191
Liabilities, Noncurrent [Abstract]
Operating lease liabilities, non-current	38,589	$ 42,200
Finance lease liabilities	853
Total lease liabilities	$ 47,719
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtCurrent
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtNoncurrent