Quarterly report pursuant to Section 13 or 15(d)

Fair Value of Warrants - Summary of Derivative Warrant Activity (Detail)

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Fair Value of Warrants - Summary of Derivative Warrant Activity (Detail) (USD $)
3 Months Ended 9 Months Ended
Sep. 30, 2014
Sep. 30, 2013
Sep. 30, 2014
Sep. 30, 2013
Class of Warrants Outstanding [Roll Forward]        
Beginning balance     $ 594,000  
Fair value of warrants exercised     (125,000)  
Change in fair value of warrant liability (129,000) 1,033,000 (324,000) (4,096,000)
Ending balance 145,000   145,000  
Debt Guarantee [Member]
       
Class of Warrants Outstanding [Roll Forward]        
Beginning balance     64,000  
Fair value of warrants exercised     (87,000)  
Change in fair value of warrant liability     23,000  
Ending balance 0   0  
Consulting [Member]
       
Class of Warrants Outstanding [Roll Forward]        
Beginning balance     1,000  
Fair value of warrants exercised     0  
Change in fair value of warrant liability     0  
Ending balance 1,000   1,000  
Financing [Member]
       
Class of Warrants Outstanding [Roll Forward]        
Beginning balance     412,000  
Fair value of warrants exercised     0  
Change in fair value of warrant liability     (293,000)  
Ending balance 119,000   119,000  
Series B Preferred Stock [Member]
       
Class of Warrants Outstanding [Roll Forward]        
Beginning balance     117,000  
Fair value of warrants exercised     (38,000)  
Change in fair value of warrant liability     (54,000)  
Ending balance $ 25,000   $ 25,000