THE COMPANY AND BASIS OF PRESENTATION (Details)			1 Months Ended		12 Months Ended
	Aug. 31, 2017 USD ($)	Mar. 28, 2017 USD ($) $ / shares shares	Mar. 31, 2017 USD ($) $ / shares shares	Mar. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares	Jan. 01, 2017 USD ($) $ / shares	Jan. 03, 2016 USD ($)	Sep. 25, 2015 USD ($)	Dec. 28, 2014 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents					$ 16,527,000	$ 14,870,000	$ 19,136,000		$ 30,050,000
Liquidity [Line Items]
Accumulated deficit					$ 254,035,000	$ 239,904,000
Share price (in dollars per share) | $ / shares		$ 1.50	$ 1.50	$ 1.00	$ 1.74
Common stock, par value (in dollars per share) | $ / shares		$ 0.001	$ 0.001		$ 0.001	$ 0.001
Proceeds from issuance of common stock		$ 15,200,000	$ 15,200,000	$ 8,800,000	$ 17,550,000	$ 10,603,000	$ 692,000
Silicon Valley Bank | Revolving Line of Credit
Liquidity [Line Items]
Available credit					$ 6,000,000
Extended period of line of credit	1 year
Unrestricted cash or cash equivalents (at least)	$ 6,000,000
Long-term portion of obligations (at least)	1.40
Revolving line of credit (up to)	$ 6,000,000							$ 6,000,000.0
Interest rate	4.31%
Common Stock at Par Value
Liquidity [Line Items]
Issuance of common stock (in shares) | shares		11,300,000.0	11,300,000.0	10,000,000.0
Customer G | Revenue
Liquidity [Line Items]
Percentage of total revenue					19.00%	33.00%	43.00%