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Debt - Additional Information (Detail) - Senior secured loan - USD ($)		3 Months Ended		6 Months Ended
	Dec. 19, 2014	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Mar. 17, 2017	Mar. 16, 2017
FIrst Warrants \| Hercules Technology Growth Capital
Debt Instrument [Line Items]
Number of shares received from warrants received to purchase common stock (in shares)	13,927
Fair value of warrants issued	$ 400,000
Second Warrants \| Hercules Technology Growth Capital
Debt Instrument [Line Items]
Number of shares received from warrants received to purchase common stock (in shares)	25,641
Fair value of warrants issued	$ 200,000
Hercules Warrants \| Hercules Technology Growth Capital
Debt Instrument [Line Items]
Number of shares received from warrants received to purchase common stock (in shares)	58,823
Warrant exercise price (in dollars per share)	$ 7.85	$ 7.85		$ 7.85
Term Loan
Debt Instrument [Line Items]
Interest expense, debt (less than)		$ 100,000	$ 100,000	$ 100,000	$ 300,000
Non-cash interest expense amortization of debt discount (less than)		$ 100,000	$ 100,000	$ 100,000	$ 100,000
Term Loan C \| Hercules Technology Growth Capital
Debt Instrument [Line Items]
Debt, face amount	$ 1,500,000.0
Net proceeds from debt	$ 1,400,000
Interest rate, stated percentage						11.25%	11.00%
Debt instrument, maturity date				Jun. 01, 2017