STOCK-BASED COMPENSATION - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Jan. 03, 2016	Mar. 31, 2017	Mar. 28, 2017	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity award vesting period	4 years
Maximum contractual term	10 years
Closing stock price (in dollars per share)	$ 1.74			$ 1.50	$ 1.50	$ 1.00
The total intrinsic value of options exercised	$ 31,000	$ 0	$ 83,000
Total cash received from employees as a result of employee stock option exercises	85,000	0	117,000
Stock-based compensation	1,441,000	$ 1,584,000	$ 2,028,000
Weighted average estimated fair value (in dollars per share)		$ 0.46	$ 0.87
Fair value of unvested stock options, net of forfeitures	260,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 239,000	$ 486,000	$ 861,000
Weighted average period	2 years 5 months 1 day
RSUs & PRSUs Outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1,000,000	$ 953,000	$ 834,000
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period	4 years 6 months
Weighted average estimated fair value as defined by amended authoritative guidance (in dollars per share)	$ 0.43	$ 0.62	$ 0.42
Sales under ESPP (in shares)	538,000	732,000	458,000
Average price of sales under ESPP (in dollars per share)	$ 0.86	$ 0.81	$ 1.26
Shares available for issuance (in shares)	1,600,000
Compensation expenses related to ESPP	$ 153,000	$ 258,000	$ 232,000
Unrecognized stock-based compensation expense	$ 80,000