THE COMPANY AND BASIS OF PRESENTATION (Details)			1 Months Ended		12 Months Ended
	Sep. 28, 2018 USD ($)	May 29, 2018 $ / shares	May 31, 2018 USD ($) $ / shares shares	Mar. 31, 2017 USD ($) $ / shares shares	Dec. 30, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares	Jan. 01, 2017 USD ($)	Dec. 21, 2018 USD ($)
Liquidity [Line Items]
Cash and cash equivalents	$ 26,500,000				$ 26,363,000	$ 16,527,000
Revolving line of credit					15,000,000	6,000,000
Common stock, par value (in dollars per share) | $ / shares			$ 1.15	$ 1.50
Proceeds from issuance of common stock			$ 13,900,000	$ 15,200,000	16,215,000	17,550,000	$ 10,603,000
Underwriting discounts and other offering expenses					$ 1,638,000	$ 1,771,000	$ 1,197,000
Exercisable period of warrants		60 months			60 months
Strike price of warrants (in dollars per share) | $ / shares		$ 1.38			$ 1.38
Fair value assumptions of warrants, expected term		5 years			5 years
Common stock, par value (in dollars per share) | $ / shares				$ 0.001	$ 0.001	$ 0.001
Measurement Input, Share Price
Liquidity [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.57			0.57
Measurement Input, Risk Free Interest Rate
Liquidity [Line Items]
Warrants and Rights Outstanding, Measurement Input		2.58			0.0258
Measurement Input, Price Volatility
Liquidity [Line Items]
Warrants and Rights Outstanding, Measurement Input		52.75			0.5275
Measurement Input, Expected Dividend Rate
Liquidity [Line Items]
Warrants and Rights Outstanding, Measurement Input		0			0.00
Warrant
Liquidity [Line Items]
Issuance of common stock (in shares) | shares			5,405,404
Common stock, par value (in dollars per share) | $ / shares			$ 0.001
Number of warrant contain in each unit | shares			0.40
Common Stock at Par Value
Liquidity [Line Items]
Issuance of common stock (in shares) | shares			13,513,510	11,300,000
Common stock, par value (in dollars per share) | $ / shares			$ 0.001
Number of common stock contain in each unit | shares			1
Underwriting discounts and other offering expenses			$ 1,600,000
Heritage Bank | Revolving Line of Credit
Liquidity [Line Items]
Revolving line of credit	15,000,000				$ 15,000,000
Maximum borrowing capacity of the revolving line of credit at company's election	$ 9,000,000							$ 15,000,000
Line of credit facility, maturity date	Sep. 28, 2020
Line of credit base rate	0.50%
Line of credit facility, interest rate description					Loans under the Revolving Facility will bear interest at a rate equal to one half of one percentage point (0.50%) above the variable rate of interest, per annum, that appears in The Wall Street Journal from time to time, whether or not such announced rate is the lowest rate available from Heritage Bank.
Minimum cash required for covenant related to credit facility								3,000,000
Interest rate					6.00%
Heritage Bank | Revolving Line of Credit | Minimum
Liquidity [Line Items]
Minimum cash required for covenant related to credit facility								$ 3,000,000
Silicon Valley Bank | Revolving Line of Credit
Liquidity [Line Items]
Line of credit facility, maturity date	Sep. 24, 2018