Investments - Summary of Short and Long-term Investments (Detail) (USD $)	6 Months Ended	12 Months Ended
	Mar. 31, 2014	Sep. 30, 2013
Schedule Of Investments [Line Items]
Gross Unrealized Gains	$ 0	$ 7,500
Gross Unrealized Losses	(283,376)	(41,643)
Fair Value	51,563,458	10,698,271
Commercial notes (due within one year), amortized cost	17,798,475	9,030,261
Commercial notes (due after one year through two years), amortized cost	34,048,359	1,702,153
Total	51,846,834	10,732,414
Commercial Notes Due Within One Year
Schedule Of Investments [Line Items]
Gross Unrealized Gains	0	7,500
Gross Unrealized Losses	(115,181)	(39,281)
Fair Value	17,683,294	8,998,480
Commercial Notes Due After One Year Through Two Years
Schedule Of Investments [Line Items]
Gross Unrealized Gains	0
Gross Unrealized Losses	(168,195)	(2,362)
Fair Value	$ 33,880,164	$ 1,699,791