LEASES - Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 26, 2020	Dec. 28, 2019
Assets:
Operating lease assets	$ 34,652	$ 37,768
Finance lease assets	962
Total lease assets	35,614
Current liabilities
Operating lease liabilities	8,425	7,768
Finance lease liabilities	194
Non-current
Operating lease liabilities, non-current	37,679	$ 42,200
Finance lease liabilities	804
Total lease liabilities	$ 47,102
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