Basis of Presentation and Significant Accounting Policies - Summary of Status of Company's Non-Vested Shares (Detail)	3 Months Ended
	Dec. 31, 2018 $ / 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)	197,850
Options, Forfeited (in shares)	(52,032)
Options, Outstanding Ending Balance (in shares)	2,175,559
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	$ 2.18
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)	197,850
Shares, Vested (in shares)	(147,842)
Options, Forfeited (in shares)	(24,585)
Options, Outstanding Ending Balance (in shares)	706,143
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	2.24
Weighted-Average Grant Date Fair Value, Vested (in usd per share) | $ / shares	2.34
Weighted-Average Grant Date Fair Value, Forfeited (in usd per share) | $ / shares	1.31
Weighted-Average Grant Date Fair Value, Non-vested Ending Balance (in usd per share) | $ / shares	$ 0.90