Basis of Presentation and Significant Accounting Policies - Summary of Status of Company's Non-Vested Shares (Detail)	6 Months Ended
	Mar. 31, 2019 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Outstanding Beginning Balance (in shares)	2,029,741
Shares, Granted (in shares)	199,850
Options, Forfeited (in shares)	(523,668)
Options, Outstanding Ending Balance (in shares)	1,705,923
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted-Average Grant Date Fair Value, Granted (in usd per share) | $ / shares	$ 2.23
Non-Vested Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Outstanding Beginning Balance (in shares)	680,720
Shares, Granted (in shares)	199,850
Shares, Vested (in shares)	(289,836)
Options, Forfeited (in shares)	(29,137)
Options, Outstanding Ending Balance (in shares)	561,597
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted-Average Grant Date Fair Value, Non-vested Beginning Balance (in usd per share) | $ / shares	$ 1.46
Weighted-Average Grant Date Fair Value, Granted (in usd per share) | $ / shares	2.23
Weighted-Average Grant Date Fair Value, Vested (in usd per share) | $ / shares	2.02
Weighted-Average Grant Date Fair Value, Forfeited (in usd per share) | $ / shares	1.22
Weighted-Average Grant Date Fair Value, Non-vested Ending Balance (in usd per share) | $ / shares	$ 0.94