STOCKHOLDERS' EQUITY - Issuance of Common Stock and Warrants (Details) $ / shares in Units, $ in Thousands		1 Months Ended		12 Months Ended
	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 ($)	Jun. 30, 2017 $ / shares shares
Class Of Stock [Line Items]
Common stock, par value (in dollars per share)		$ 1.15	$ 1.50
Net proceeds from issuance of common stock | $		$ 13,900	$ 15,200	$ 16,215	$ 17,550	$ 10,603
Underwriting discounts and other offering expenses | $				$ 1,638	$ 1,771	$ 1,197
Exercisable period of warrants	60 months			60 months
Strike price of warrants (in dollars per share)	$ 1.38			$ 1.38
Fair value assumptions of warrants, expected term	5 years			5 years
Common stock, par value (in dollars per share)			$ 0.001	$ 0.001	$ 0.001
June 2012 financing
Class Of Stock [Line Items]
Strike price of warrants (in dollars per share)							$ 2.98
Warrants outstanding (in shares) | shares							2,300,000
Measurement Input, Share Price
Class Of Stock [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.57			0.57
Measurement Input, Risk Free Interest Rate
Class Of Stock [Line Items]
Warrants and Rights Outstanding, Measurement Input	2.58			0.0258
Measurement Input, Price Volatility
Class Of Stock [Line Items]
Warrants and Rights Outstanding, Measurement Input	52.75			0.5275
Measurement Input, Expected Dividend Rate
Class Of Stock [Line Items]
Warrants and Rights Outstanding, Measurement Input	0			0.00
Warrant
Class Of Stock [Line Items]
Issuance of common stock (in shares) | shares		5,405,404
Common stock, par value (in dollars per share)		$ 0.001
Number of warrant contain in each unit | shares		0.40
Common stock
Class Of Stock [Line Items]
Issuance of common stock (in shares) | shares		13,513,510	11,300,000
Common stock, par value (in dollars per share)		$ 0.001
Number of common stock contain in each unit | shares		1
Underwriting discounts and other offering expenses | $		$ 1,600