RESTRUCTURING AND ASSET IMPAIRMENT - Schedule of Other Restructuring Initiatives (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 1,856	$ 472	$ 2,494	$ 1,549
Cost of revenue
Restructuring Cost and Reserve [Line Items]
Restructuring costs	174	225	759	1,208
Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,682	247	1,735	341
Severance and Transition Costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,856	323	2,472	1,340
Severance and Transition Costs | Cost of revenue
Restructuring Cost and Reserve [Line Items]
Restructuring costs	174	76	737	999
Severance and Transition Costs | Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,682	247	1,735	341
Asset Impairments and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0	149	22	209
Asset Impairments and Other Costs | Cost of revenue
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0	149	22	209
Asset Impairments and Other Costs | Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 0	$ 0	$ 0	$ 0