Organization and Significant Accounting Policies - Additional Information (Detail) - USD ($)		9 Months Ended
	Jan. 22, 2018	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2017	Sep. 30, 2016
Organization And Significant Accounting Policies [Line Items]
Public offering price per share		$ 5.25
Cash and cash equivalents		$ 27,995,386	$ 38,383,135	$ 24,838,567	$ 85,366,448
Short term investments		32,484,708		40,769,539
Long term investments		17,672,658
Net increase (decrease) in cash and investments		12,500,000
Net proceeds received from public offering		56,585,035	12,419,119
Cash outflows related to operating activities		(44,543,099)	$ (14,735,498)
Restricted Cash		0		0
Fair value of contingent consideration obligation due to discontinuation of clinical trials		0		$ 0
Maximum
Organization And Significant Accounting Policies [Line Items]
Amount insured in FDIC per account		$ 250,000
Property, Plant and Equipment, Useful Life		7 years
Minimum
Organization And Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life		3 years
Underwritten Public Offering
Organization And Significant Accounting Policies [Line Items]
Common stock shares sold	11,500,000
Public offering price per share	$ 5.25
Net proceeds, after deducting underwriting commissions and discounts and offering expenses payable	$ 56,600,000