Subsequent Events - Additional Information (Detail) - Subsequent Event $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended
	Feb. 28, 2018 USD ($) $ / shares shares
Subsequent Event [Line Items]
Warrants to purchase common stock, shares	1.4
Proceed from private placement and equity issuances, gross | $	$ 59.1
Exercise price | $ / shares	$ 8.31
Warrant expiration period	7 years
Common Stock
Subsequent Event [Line Items]
Stock issued during period	4.1
Series A Convertible Preferred Stock
Subsequent Event [Line Items]
Stock issued during period	3.0