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Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
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3 Months Ended | 9 Months Ended | 124 Months Ended | |||
|---|---|---|---|---|---|---|
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Feb. 28, 2014
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Feb. 28, 2013
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Feb. 28, 2014
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Feb. 28, 2013
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Feb. 28, 2014
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May 31, 2013
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| Class of Stock [Line Items] | ||||||
| Net loss | $ (3,274,397) | $ (2,359,107) | $ (9,435,541) | $ (7,082,759) | $ (41,836,448) | |
| Accumulated deficit | (43,438,360) | (43,438,360) | (43,438,360) | |||
| Insurance coverage, per depositor at each financial | 250,000 | 250,000 | 250,000 | 250,000 | ||
| Deposit in excess of federally insured limits | 7,464,000 | 7,464,000 | 7,464,000 | 386,000 | ||
| Estimated future unvested option forfeitures | 0.00% | |||||
| Deferred offering costs | 68,292 | 68,292 | 68,292 | 96,930 | ||
| Direct costs associated with the convertible notes | 120,000 | |||||
| Amortization of deferred offering costs | 3,332 | 120,000 | 120,000 | |||
| Common stock options and warrants to purchase | 95,100 | 95,100 | 95,100 | 95,100 | ||
| Common stock options and warrants to purchase | 31,970,327 | 18,038,297 | ||||
| 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 | 6,028,333 | |||||
| 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 | 4,521,250 | 4,521,250 | 4,521,250 | |||
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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 | $ 68,300 | $ 68,300 | $ 68,300 | $ 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 | |||||