The Company and Basis of Presentation - Additional Information (Detail) - Follow on Offering [Member] $ / shares in Units, $ in Millions	Mar. 06, 2018 USD ($) $ / shares shares
Class of Stock [Line Items]
Stock issued, shares | shares	21,850,000
Shares issued, price per share | $ / shares	$ 2.25
Proceeds from issuance of common stock, net of deferred financing costs	$ 46.0
Underwriting discounts and commissions and offering expenses	$ 3.2