Investments - Summary of Short and Long-term Investments (Detail) (USD $)	Mar. 31, 2015	Sep. 30, 2014
Schedule Of Held To Maturity Securities [Line Items]
Gross Unrealized Gains	$ 784
Gross Unrealized Losses	(412,938)	(407,523)
Fair Value	31,510,086	44,333,855
Commercial notes (due within one year), amortized cost	19,561,172us-gaap_HeldToMaturitySecuritiesCurrent	21,653,032us-gaap_HeldToMaturitySecuritiesCurrent
Commercial notes (due after one year through two years), amortized cost	12,361,068	23,088,346
Total	31,922,240us-gaap_HeldToMaturitySecurities	44,741,378us-gaap_HeldToMaturitySecurities
Commercial Notes Due Within One Year
Schedule Of Held To Maturity Securities [Line Items]
Gross Unrealized Gains	784
Gross Unrealized Losses	(285,310)	(189,830)
Fair Value	19,276,646	21,463,202
Commercial Notes Due After One Year Through Two Years
Schedule Of Held To Maturity Securities [Line Items]
Gross Unrealized Losses	(127,628)	(217,693)
Fair Value	$ 17,540,073	$ 22,870,653

Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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