XML 38 R28.htm IDEA: XBRL DOCUMENT v3.7.0.1
Organization - Additional Information (Detail) - USD ($)
$ in Thousands
1 Months Ended 3 Months Ended
Apr. 01, 2017
Feb. 28, 2017
Mar. 31, 2017
Dec. 31, 2016
Mar. 31, 2016
Dec. 31, 2015
Organization And Basis Of Presentation [Line Items]            
Unrestricted cash and cash equivalents     $ 10,541 $ 4,182 $ 14,753 $ 18,902
Accumulated deficit     (159,429) $ (155,946)    
Working capital     $ 6,619      
Subsequent Event [Member] | BTIG LLC [Member]            
Organization And Basis Of Presentation [Line Items]            
Sale of stock, number of shares sold in transaction 645,271          
Proceeds from sale of common stock $ 2,211          
Registered Direct Offering [Member]            
Organization And Basis Of Presentation [Line Items]            
Proceeds from sale of common stock   $ 7,598        
At the Market Offering [Member] | BTIG LLC [Member]            
Organization And Basis Of Presentation [Line Items]            
Sale of stock, number of shares sold in transaction     538,427      
Proceeds from sale of common stock     $ 2,104      
Second Purchase Agreement [Member] | Registered Direct Offering [Member]            
Organization And Basis Of Presentation [Line Items]            
Sale of stock, number of shares sold in transaction   2,950,000        
Proceeds from sale of common stock   $ 7,598