Quarterly report pursuant to Section 13 or 15(d)

Common Stock - Additional Information (Detail)

v2.4.0.8
Common Stock - Additional Information (Detail) (USD $)
In Millions, except Share data, unless otherwise specified
9 Months Ended 12 Months Ended 9 Months Ended 3 Months Ended 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Dec. 31, 2012
Sep. 30, 2013
Stock Option [Member]
Sep. 30, 2013
Stock Option [Member]
Minimum [Member]
Sep. 30, 2013
Stock Option [Member]
Maximum [Member]
Sep. 30, 2013
Stock Option [Member]
Employees And Consultants [Member]
Sep. 30, 2013
Stock Option [Member]
Board Of Directors [Member]
Minimum [Member]
Sep. 30, 2013
Stock Option [Member]
Board Of Directors [Member]
Maximum [Member]
Sep. 30, 2013
Restricted stock units [Member]
Sep. 30, 2012
Restricted stock units [Member]
Sep. 30, 2013
Restricted stock units [Member]
Sep. 30, 2012
Restricted stock units [Member]
Jun. 18, 2013
MLV [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                            
Common stock, shares authorized 50,000,000   25,000,000                      
Common stock, par value $ 0.001   $ 0.001                      
Preferred stock, shares authorized 5,000,000                          
Preferred stock, par value $ 0.001                          
Common stock sales agreement aggregate offering amount                           $ 25
Common stock sales agreement commission in percentage                           3.00%
Number of shares issued for stock option exercises 3,475 116,834                        
Number of shares issued for Restricted stock unit settlements 45,869                          
Common shares reserved for issuance under various plans 2,381,607                          
Common shares reserved for options currently outstanding       985,616           352,313   352,313    
Common shares available for future equity grants 1,043,678                          
Award vesting period             4 years 1 year 3 years     4 years    
Award expiration period         7 years 10 years                
Unrecognized compensation expense related to stock options granted 3.0   2.7                      
Weighted-average period, restricted stock awards       2 years 4 months 24 days               2 years 9 months 18 days    
Effect on diluted per share on options, restricted stock units and warrants 2,900,000   2,600,000                      
Stock-based compensation expense                   0.5 0.2 1.2 0.4  
Total unrecognized compensation expense related to the Company's restricted stock awards                   $ 2.5   $ 2.5    
Warrants outstanding 1,587,301                          
Exercise price of warrants $ 20                          
Warrants expiration date 2015-10                          
Warrants exercised 0 0