COMMON STOCK - TRANSACTIONS (Details)
$ / shares in Units, $ in Thousands
 1 Months Ended 12 Months Ended
Apr. 08, 2015
shares
Jan. 31, 2017
shares
Mar. 31, 2016
USD ($)
$ / shares
shares
Jul. 31, 2015
USD ($)
Jan. 31, 2015
USD ($)
shares
Dec. 31, 2014
USD ($)
$ / shares
shares
Jan. 31, 2014
USD ($)
shares
Dec. 31, 2016
USD ($)
shares
Dec. 31, 2015
USD ($)
shares
Dec. 31, 2014
USD ($)
$ / shares
shares
Common stock disclosures                    
Proceeds from exercise of stock options | $               $ 191 $ 1,068 $ 212
Issuance of common stock to 401(k) plan | $               208 201 173
Proceeds from issuance of stock under ESPP | $               $ 91    
Proceeds from exercise of warrants | $                 $ 7,789 12
Reverse stock split ratio 0.25                  
Stock issued during period, shares, reverse stock splits 1,514                  
Common stock issued for services | $                   477
Fair value of stock issued for services | $                   $ 477
Sales Agreement                    
Common stock disclosures                    
Issuance of stock in public offering (in shares)                 388,245  
Net proceeds from issuance of equity (in dollars) | $                 $ 3,442  
Aggregate proceeds from sale agreement of shares of common stock | $       $ 50,000            
Percentage of Commission on the gross proceeds from sales agreement of shares of common stock       3.00%            
Employee Stock Purchase Plan                    
Common stock disclosures                    
Stock issued under ESPP (in shares)   7,986                
Common Stock                    
Common stock disclosures                    
Issuance of common stock upon exercise of stock options (in shares)               135,205 316,177 132,900
Proceeds from exercise of stock options | $               $ 191 $ 1,068 $ 212
Issuance of common stock upon cashless exercise of warrants (in shares)               4,979 25,052 6,903
Issuance of common stock to 401(k) plan (in shares)               37,528 17,437 41,753
Issuance of common stock to 401(k) plan | $               $ 208 $ 201 $ 173
Stock issued under ESPP (in shares)               16,729    
Proceeds from issuance of stock under ESPP | $               $ 91    
Issuance of stock in public offering (in shares)                 2,388,245 3,500,312
Number of shares for stock options in cashless exercise (in shares)                 52,224  
Issuance of stock for noncash exercise-stock options (in shares)                 14,961  
Issuance of stock for cash-stock options (in shares)                 301,216  
Issuance of common stock upon exercise of warrants (in shares)                 1,379,575 9,975
Number of warrants to purchase common stock (in shares)                 40,955 15,655
Shares issued through cashless exercise provision-warrants (in shares)               4,979 25,052 6,903
Issuance of stock for cash- warrants (in shares)                 1,354,523 3,072
Proceeds from exercise of warrants | $                 $ 7,789 $ 12
Issuance of common stock for services (in shares)               365   74,626
Common stock issued for services | $             $ 282      
Common Stock | Michael J. Astrue, Interim Chief Executive Officer                    
Common stock disclosures                    
Issuance of common stock for services (in shares)             27,212      
Common Stock | Gregory D. Perry, Interim Chief Financial Officer                    
Common stock disclosures                    
Issuance of common stock for services (in shares)             5,594      
Common Stock | Certain Employees                    
Common stock disclosures                    
Issuance of common stock for services (in shares)           41,821        
Fair value of stock issued for services | $           $ 195        
Common Stock | Public offering                    
Common stock disclosures                    
Issuance of stock in public offering (in shares)         2,000,000          
Net proceeds from issuance of equity (in dollars) | $         $ 11,038          
Common Stock | Public Offering, March 2016                    
Common stock disclosures                    
Warrants for purchase of common stock (in shares)     2,146,666              
Equity issuance (in price per unit) | $ / shares     $ 7.49              
Common Stock | Public Offering - Underwritten                    
Common stock disclosures                    
Warrants for purchase of common stock (in shares)           1,750,156       1,750,156
Equity issuance (in price per unit) | $ / shares           $ 4.60       $ 4.60
Warrants | Public Offering, March 2016                    
Common stock disclosures                    
Equity issuance (in price per unit) | $ / shares     0.01              
Exercise price (in dollars per unit) | $ / shares     $ 10.00              
Percentage of warrant exercises price over public offering price     133.00%              
Warrants | Public Offering - Underwritten                    
Common stock disclosures                    
Equity issuance (in price per unit) | $ / shares           0.00001       0.00001
Exercise price (in dollars per unit) | $ / shares           $ 5.75       $ 5.75
Percentage of warrant exercises price over public offering price                   125.00%
Common Stock And Warrants | Public Offering, March 2016                    
Common stock disclosures                    
Issuance of stock in public offering (in shares)     4,293,333              
Net proceeds from issuance of equity (in dollars) | $     $ 29,905              
Common Stock And Warrants | Public Offering - Underwritten                    
Common stock disclosures                    
Issuance of stock in public offering (in shares)                   3,500,312
Net proceeds from issuance of equity (in dollars) | $                   $ 14,600