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Assumptions used to Value Warrants (Detail) (USD $)
3 Months Ended
Sep. 30, 2012
Y
Jun. 30, 2012
Y
Warrants issued on December 20, 2007
   
Class of Warrant or Right [Line Items]    
Estimated life in years 0.25 0.50
Risk-free interest rate 0.09% [1] 0.15% [1]
Volatility 72.00% 75.00%
Dividend paid      
Warrants issued on December 20, 2007 | Minimum
   
Class of Warrant or Right [Line Items]    
Estimated probabilities 10.00% 10.00%
Estimated strike prices $ 0.32 $ 0.33
Warrants issued on December 20, 2007 | Maximum
   
Class of Warrant or Right [Line Items]    
Estimated probabilities 50.00% 50.00%
Estimated strike prices $ 0.35 $ 0.36
Warrants issued on June 30, 2008
   
Class of Warrant or Right [Line Items]    
Estimated life in years 0.75 1.00
Risk-free interest rate 0.15% [1] 0.21% [1]
Volatility 72.00% 75.00%
Dividend paid      
Warrants issued on June 30, 2008 | Minimum
   
Class of Warrant or Right [Line Items]    
Estimated probabilities 10.00% 10.00%
Estimated strike prices $ 0.32 $ 0.33
Warrants issued on June 30, 2008 | Maximum
   
Class of Warrant or Right [Line Items]    
Estimated probabilities 50.00% 50.00%
Estimated strike prices $ 0.35 $ 0.36
Warrants issued on April 1, 2010
   
Class of Warrant or Right [Line Items]    
Estimated life in years 2.50 2.75
Risk-free interest rate 0.30% [1] 0.39% [1]
Volatility 75.00% 78.00%
Dividend paid      
Estimated probabilities 15.00% 15.00%
[1] Represents the interest rate on a U.S. Treasury security with a maturity date corresponding to that of the warrant term.