Investments - Summary of Short and Long-term Investments (Detail) - USD ($)	Sep. 30, 2015	Sep. 30, 2014
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