Quarterly report pursuant to Section 13 or 15(d)

Common Stock - Additional Information (Detail)

v3.3.0.814
Common Stock - Additional Information (Detail) - USD ($)
 3 Months Ended 9 Months Ended
Apr. 30, 2015
Aug. 13, 2015
Sep. 30, 2015
Sep. 30, 2014
May. 21, 2015
May. 20, 2015
Dec. 31, 2014
May. 29, 2014
May. 28, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Common stock, shares authorized     75,000,000   75,000,000 50,000,000 75,000,000    
Common stock, par value     $ 0.001       $ 0.001    
Preferred stock, shares authorized     5,000,000            
Preferred stock, par value     $ 0.001            
Initial purchase of units consisting of common stock and warrants issued     $ 17,629,000            
Common stock, shares issued     29,832,907       22,630,652    
Proceeds from issuance of common shares, net of issuance costs       $ 22,372,000          
Common stock available for sale under offering   $ 0              
Stock option exercises, shares     0 10,000          
Restricted stock unit settlements     260,676 199,849          
Stock Options [Member] | Employees and consultants [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Award vesting period     4 years            
Stock Options [Member] | Minimum [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Award expiration period     7 years            
Stock Options [Member] | Minimum [Member] | Board of Directors [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Award vesting period     1 year            
Stock Options [Member] | Maximum [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Award expiration period     10 years            
Stock Options [Member] | Maximum [Member] | Board of Directors [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Award vesting period     3 years            
Restricted Stock Unit [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Award vesting period     4 years            
2010 Performance Incentive Plan [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock available for issuance under performance incentive plan         4,300,000 2,800,000   2,800,000 2,050,000
Common shares reserved for issuance under various plans     4,138,001            
Common shares available for future equity grants     1,769,296            
2010 Performance Incentive Plan [Member] | Stock Options [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Common shares reserved for issuance under various plans     1,723,596            
2010 Performance Incentive Plan [Member] | Restricted Stock Unit [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Common shares reserved for issuance under various plans     645,109            
Series A-1 Units [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Exercise price per unit of warrant     $ 2.40            
LPC [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Common stock, par value $ 0.001                
Common stock value right to sell, maximum $ 18,000,000                
Common stock, purchase price $ 1.50                
Additional common stock value right to sell, maximum $ 16,000,000                
Additional purchase of common stock, maximum 125,000                
Common stock, shares issued 126,582 6,814,980              
Proceeds from issuance of common shares, net of issuance costs $ 0                
Gross proceeds   $ 18,000,000              
Offering expenses   $ 400,000              
LPC [Member] | Series A-1 Units [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Initial purchase of common stock 956,938                
Common stock, purchase price $ 2.09                
Purchase agreement, description     Series A-1 Unit consisting of (a) one share of Common Stock and (b) one warrant to purchase one-quarter of a share of Common Stock at an exercise price of $2.40 per share, or Series A-1 Warrant. Each Series A-1 Warrant is exercisable six months following the issuance date until the date that is five years and six months after the issuance date and is subject to customary adjustments.            
Exercise price per unit of warrant $ 2.40                
Initial purchase of units consisting of common stock and warrants issued $ 2,000,000                
LPC [Member] | Other Than Series A-1 Units [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Number of warrants issued 0