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Fair Value Measurements & Derivative Instruments - Assumptions Used in Valuing Derivative Asset (Detail) (Derivative assets [Member])
12 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Derivative assets [Member]
   
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Risk free interest rate 0.23% 0.40%
Expected life 1 year 3 months 18 days 2 years 3 months 18 days
Dividend yield      
Volatility 72.00% 72.00%