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Investments - Summary of Short and Long-term Investments (Detail) - USD ($) | Sep. 30, 2015 | Sep. 30, 2014
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Schedule Of Held To Maturity Securities [Line Items] |  |
Commercial notes (due within one year), amortized cost | $ 17,539,902 | $ 21,653,032
Commercial notes (due after one year through two years), amortized cost |  | 23,088,346
Total | 17,539,902 | 44,741,378
Gross Unrealized Losses | (304,942) | (407,523)
Fair Value | 17,234,960 | 44,333,855
Commercial Notes Due Within One Year |  |
Schedule Of Held To Maturity Securities [Line Items] |  |
Gross Unrealized Losses | (304,942) | (189,830)
Fair Value | $ 17,234,960 | 21,463,202
Commercial Notes Due After One Year Through Two Years |  |
Schedule Of Held To Maturity Securities [Line Items] |  |
Gross Unrealized Losses |  | (217,693)
Fair Value |  | $ 22,870,653

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