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Investments - Summary of Short-term Investments (Detail) - USD ($)	Mar. 31, 2018	Sep. 30, 2017
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	$ 21,736,820	$ 40,769,539
Commercial Notes Due Within One Year
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	21,736,820	40,769,539
Gross Unrealized Losses	(241,377)	(334,755)
Fair Value	$ 21,495,443	$ 40,434,784

X

- Definition

Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (c)
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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity, expected to be converted to cash, sold or exchanged within one year or the normal operating cycle.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26626-111562

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Fair value of investments in debt securities classified as held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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