Basis of Presentation and Significant Accounting Policies - Summary of Option Activity (Detail) - $ / shares	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Outstanding Beginning Balance (in shares)	1,602,822
Options, Granted (in shares)	300,270
Options, Exercised (in shares)	0
Options, Forfeited (in shares)	(12,124)
Options, Outstanding Ending Balance (in shares)	1,890,968	1,602,822
Options, Exercisable Ending Balance (in shares)	1,283,111
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Outstanding Beginning Balance (in usd per share)	$ 9.51
Weighted Average Exercise Price, Granted (in usd per share)	4.75
Weighted Average Exercise Price, Exercised (in usd per share)	0.00
Weighted Average Exercise Price, Forfeited (in usd per share)	30.67
Weighted Average Exercise Price, Outstanding Ending Balance (in usd per share)	8.62	$ 9.51
Weighted Average Exercise Price, Exercisable Ending Balance	$ 9.62
Weighted Average Remaining Contractual Period in Years, Outstanding Ending Balance	6 years 8 months 12 days	6 years 7 months 6 days
Weighted Average Remaining Contractual Period in Years, Granted	9 years 9 months 18 days
Weighted Average Remaining Contractual Period in Years, Exercised	0 days
Weighted Average Remaining Contractual Period in Years, Forfeited	1 year 10 months 24 days
Weighted Average Remaining Contractual Period in Years, Exercisable Ending Balance	5 years 7 months 6 days