INCOME TAXES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 30, 2018	Dec. 31, 2017	Jan. 01, 2017	Jan. 03, 2016
Operating Loss Carryforwards [Line Items]
Corporate income tax rate	35.00%	21.00%
Unrecognized tax benefits	$ 2,161,000	$ 2,107,000	$ 2,014,000	$ 696,000
Unrecognized tax benefits that would affect effective tax rate	0
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	157,400,000
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	63,600,000
State | Research
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	4,600,000
Federal | Research
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	$ 4,100,000