Stockholders' Equity - Additional Information (Detail) - At-the-Market Equity Offering - Sales Agreement - Cantor Fitzgerald & Co. - USD ($)	Sep. 30, 2017	Mar. 31, 2017
Stockholders Equity Note Disclosure [Line Items]
Maximum number of shares can sell pursuant to sales agreement, value		$ 20,000,000
Number of shares sold under sales agreement	170,191
Average price of shares sold	$ 2.37
Net proceeds after deducting sales commissions	$ 391,000