LOAN PAYABLE (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	May 01, 2015	Oct. 31, 2012	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Aug. 11, 2017	Mar. 31, 2016
Loans Payable
Interest expense			$ 74	$ 155	$ 172
Common Stock
Loans Payable
Number of shares into which a warrant may be converted			577,548		1,354,523	48,507
Common Stock | Public Offering, March 2016
Loans Payable
Number of shares into which a warrant may be converted							2,146,666
Warrants | Public Offering, March 2016
Loans Payable
Exercise price of warrant (in dollars per share)							$ 10.00
Fair value of warrants							$ 11,726
MassDev
Loans Payable
Line of credit, maximum		$ 2,000
Line of credit for working capital purpose		$ 200
Fixed interest rate (as a percent)		6.50%
Period for interest-only payments		30 months
Period for charging equal installments of interest and principal		54 months
Maturity date		Oct. 05, 2019
Commencement date of monthly installments	May 01, 2015
Amount of monthly payment	$ 41
Future Principal payment due: 2018			$ 452
Future Principal payment due : 2019			400
MassDev | Common Stock
Loans Payable
Number of shares into which a warrant may be converted		9,037
MassDev | Warrants
Loans Payable
Warrant period		7 years
Exercise price of warrant (in dollars per share)		$ 6.64
Fair value of warrants		$ 32
MassDev | Warrants | Interest Expense
Loans Payable
Amortization of deferred financing costs			5	5	$ 5
MassDev | Equipment Line of Credit
Loans Payable
Interest expense			$ 71	$ 99	$ 126