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Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
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3 Months Ended | 6 Months Ended | 121 Months Ended | |||
|---|---|---|---|---|---|---|
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Nov. 30, 2013
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Nov. 30, 2012
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Nov. 30, 2013
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Nov. 30, 2012
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Nov. 30, 2013
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May 31, 2013
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| Class of Stock [Line Items] | ||||||
| Net loss | $ 3,587,593 | $ 1,908,486 | $ 6,161,144 | $ 4,723,652 | $ 38,562,054 | |
| Accumulated deficit | 40,163,966 | 40,163,966 | 40,163,966 | |||
| Working capital deficit | 7,973,301 | 7,973,301 | 7,973,301 | |||
| Estimated future unvested option forfeitures | 0.00% | |||||
| Deferred offering costs | 96,929 | 96,929 | 96,929 | 96,930 | ||
| Direct costs associated with the convertible notes | 120,000 | |||||
| Amortization of deferred offering costs | 96,668 | 116,668 | 116,668 | |||
| Deferred finance costs, current | 3,332 | 3,332 | 3,332 | |||
| Common stock options and warrants to purchase | 95,100 | 95,100 | 95,100 | 95,100 | ||
| Common stock options and warrants to purchase | 34,366,833 | 17,968,340 | ||||
| Face amount of notes | 7,221,250 | 7,221,250 | 7,221,250 | 6,588,250 | ||
| Additional common shares if convertible debt is converted to common stock | 6,182,179 | |||||
| Unrecognized benefits | 0 | 0 | 0 | 0 | 0 | |
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Convertible Debt
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| Class of Stock [Line Items] | ||||||
| Face amount of notes | 4,621,250 | 4,621,250 | 4,621,250 | |||
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Equity Securities
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| Class of Stock [Line Items] | ||||||
| Deferred offering costs | 2,084,000 | 2,084,000 | 2,084,000 | |||
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Stock Rescission Liability
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| Class of Stock [Line Items] | ||||||
| Deferred offering costs | $ 97,000 | $ 97,000 | $ 97,000 | $ 97,000 | ||
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Series B convertible preferred stock
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| Class of Stock [Line Items] | ||||||
| Common stock options and warrants to purchase | 95,100 | 95,100 | 95,100 | |||
| Common shares issued upon conversion of preferred stock | 951,000 | |||||