Investments - Summary of Short and Long-term Investments (Detail) - USD ($)	Jun. 30, 2015	Sep. 30, 2014
Schedule Of Held To Maturity Securities [Line Items]
Commercial notes (due within one year), amortized cost	$ 23,280,640	$ 21,653,032
Commercial notes (due after one year through two years), amortized cost	1,085,282	23,088,346
Total	24,365,922	44,741,378
Gross Unrealized Losses	(237,577)	(407,523)
Fair Value	24,128,345	44,333,855
Commercial Notes Due Within One Year
Schedule Of Held To Maturity Securities [Line Items]
Gross Unrealized Losses	(207,165)	(189,830)
Fair Value	23,073,475	21,463,202
Commercial Notes Due After One Year Through Two Years
Schedule Of Held To Maturity Securities [Line Items]
Gross Unrealized Losses	(30,412)	(217,693)
Fair Value	$ 1,054,870	$ 22,870,653