XML 25 R17.htm IDEA: XBRL DOCUMENT v2.4.0.6
Significant Accounting Policies - Additional Information (Detail) (USD $)
Share data in Millions, except Per Share data, unless otherwise specified
 3 Months Ended
Mar. 31, 2012
Mar. 31, 2011
Dec. 31, 2011
Year
Dec. 31, 2010
Significant Accounting Policies [Line Items]        
Potentially dilutive securities excluded from computation of diluted earnings per share because their effect would have been anti-dilutive 51.5 1.1    
Fair value of derivative liability $ 191,387,000   $ 123,125,000  
Warrant derivative liability fair value assumptions, risk-free rate 0.42%      
Warrant derivative liability fair value assumptions, remaining term 2 years 6 months      
Warrant derivative liability fair value assumptions, volatility rate 119.00%      
Loss (Gain) on change in fair value of derivative liability (66,209,000) 25,342,000    
Compensation expense for change in fair value of warrants issued to former employees 3,874,000 1,540,000    
Market price of stock $ 11.32      
Warrant liability value increase based on hypothetical 10% increase in the market price of common stock
        
Significant Accounting Policies [Line Items]        
Hypothetical increase in the market price 10.00%      
Market price of stock $ 12.45      
Increase (decrease) in the fair value of the warrant derivative liability 20,700,000      
Maximum
        
Significant Accounting Policies [Line Items]        
Short term highly liquid instruments, maturity date 90 days      
Warrants Issued October 2009
        
Significant Accounting Policies [Line Items]        
Fair value of derivative liability 191,387,000 174,819,000 123,125,000 230,069,000
Warrant derivative liability valuation assumptions, risk-free rate     0.36%  
Warrant derivative liability valuation assumptions, remaining term     2.8  
Warrant derivative liability valuation assumptions, volatility rate     118.00%  
Increase (Decrease) in the fair value of warrant derivative liability 68,300,000      
Transfers to equity 321,000 29,229,000    
Loss (Gain) on change in fair value of derivative liability 66,209,000 (25,342,000)    
Compensation expense for change in fair value of warrants issued to former employees $ (2,374,000) $ 679,000