Fair Value of Financial Assets and Liabilities - Rollforward of Aggregate Fair Values of Warrants (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Series 1 Nonconvertible Preferred Stock [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 762	$ 159
Warrants exercised	766	549
Increase (Decrease) in fair value	100	54
Ending Balance	1,628	762
Warrant Liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	807	1,251
Warrants exercised	(766)	(549)
Warrants expired	$ (41)
Increase (Decrease) in fair value		105
Ending Balance		$ 807