INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Jan. 03, 2016	Dec. 28, 2014
Operating Loss Carryforwards [Line Items]
Deferred tax asset, valuation allowance, increase (decrease)	$ (26,900)
Undistributed earnings for certain foreign subsidiaries	742
Unrecognized tax benefits	2,107	$ 2,014	$ 696	$ 516
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	161,100
Federal | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research credit carryforward	4,200
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	53,900
State | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research credit carryforward	$ 4,200