Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 0	$ 0	$ 0	$ 0
Net income	$ 23,896,982	$ (14,884,311)	$ 35,934,235	$ (28,083,189)