Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Additional Information (Detail)

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Stockholders' Equity - Additional Information (Detail) (USD $)
 1 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended 12 Months Ended 1 Months Ended 1 Months Ended 1 Months Ended 12 Months Ended
Sep. 30, 2010
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Dec. 31, 2012
Maximum
Dec. 31, 2012
2002 Stock Incentive Plan
Dec. 31, 2011
Ceo
Dec. 31, 2012
Ceo
May 07, 2012
Consultant
Dec. 31, 2011
Offering Agreement
Dec. 23, 2010
Offering Agreement
Dec. 31, 2012
April 2011 Registered Direct Placement
Apr. 07, 2011
April 2011 Registered Direct Placement
Aug. 02, 2011
June 2011 Securities Purchase Agreement
Jun. 30, 2011
June 2011 Securities Purchase Agreement
Aug. 02, 2011
June 2011 Securities Purchase Agreement
Maximum
Sep. 30, 2010
First Tranche
Nov. 08, 2012
IR Warrant 2
Nov. 08, 2012
IR Warrant 2
Maximum
Nov. 08, 2012
IR Warrant 2
Minimum
May 24, 2012
Comerica Bank
May 31, 2010
MidCap Financial Llc and Silicon Valley Bank
Dec. 31, 2012
Preferred Stock Purchase Rights Under Stockholder Rights Plan
Dec. 31, 2012
Preferred Stock Purchase Rights Under Stockholder Rights Plan
Minimum
Dec. 31, 2012
Preferred Stock Purchase Rights Under Stockholder Rights Plan
Initially
Dec. 31, 2012
Series B Junior Participating Cumulative Preferred Stock
Stockholders Equity [Line Items]                                                      
Preferred stock, shares authorized   1,000,000 1,000,000     1,000,000                                         500,000
Preferred stock, shares outstanding   0 0                                                
Single person ownership percentage that triggers preferred stock rights                                                 15.00%    
Sale of assets or earning power that triggers preferred stock rights                                                 50.00%    
Exercise price of right                                                   30.00  
Preferred stock purchase right expiration date                                               Dec. 31, 2018   Dec. 31, 2008  
Preferred stock purchase right redemption price per share prior to becoming exercisable                                               0.001      
Common stock issued   33,248,000 32,502,000               2,200,000   320,000     1,625,947                      
Common stock, shares outstanding   31,284,000 30,538,000                                                
Common stock, shares authorized   50,000,000 50,000,000                                                
Treasury stock, shares repurchased   1,964,000 1,964,000                                                
Maximum issuable shares under offering agreement                       3,000,000                              
Share issuance fee as a percentage of gross proceeds                       3.75%   4.50%                          
Gross proceeds from sale of common stock                     $ 7,500,000   $ 1,800,000     $ 9,000,000                      
Net proceeds from sale of common stock     17,223,000               7,200,000   1,700,000     8,400,000                      
Warrant exercise price per share                         $ 5.60     $ 5.55                      
Cost associated with transaction                         124,000     622,000                      
Warrants issued for term                               5 years                      
Warrants issued to purchase common stock                               812,974       50,000   80,000 101,694        
Exercise price of Warrants                               6.50     2.50     2.83 1.77        
Total fees paid for offering services                               451,000                      
Reimbursed expenses                               50,000                      
Maximum penalty percentage for late registration filling                                 3.00%                    
Total number of warrants repurchased                             90,000                        
value of warrants repurchased                             99,900                        
Warrant repurchase price per share                             $ 1.11                        
Warrant repurchase expense                             30,000                        
Minimum required closing price of common stock on the NASDAQ in order to exercise                                         $ 7.00            
Warrant expiration date                                     Nov. 07, 2015                
Warrants granted, subsequently reduced price per share                                           $ 2.00 $ 0.84        
IR Warrants to purchase common stock granted                                   50,000                  
IR warrants issued to purchase common stock $ 0.74                                                    
Recognized expense related to the IR Warrants   23000 273000                                                
Common stock authorized for issuance under the 2002 Plan             6,950,000     65,000                                  
Common stock issued pursuant to options exercised             2,498,000                                        
Options outstanding   3,860,000 3,858,000 4,130,000 3,650,000   3,860,000                                        
Options available for future grant             592,000                                        
Grant price of stock options   $ 1.39 $ 2.97 $ 1.09       $ 2.58   $ 2.55                                  
Option expiry term                   5 years                                  
Accelerated vesting of stock options granted - CEO               95,833                                      
Vesting period of stock options granted - CEO               4 years                                      
Recognized stock compensation cost - CEO                 $ 183,000