Fair Value Measurements - Additional Information (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2017	Jan. 31, 2013	Dec. 31, 2012
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contingent consideration obligations	$ 0	$ 0
2012 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants issued to acquire Common Stock						912,543
Warrants cancelled upon expiration				143,811
2013 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants issued to acquire Common Stock					833,530
Warrants outstanding	0
Warrant
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Non-cash gain (loss) from change in fair value of the derivative liability	$ 432,141	$ 870,760	$ (293,072)