Financings - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended	9 Months Ended
	Sep. 12, 2019	Nov. 11, 2018	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Common stock, par value			$ 0.001	$ 0.001	$ 0.001
Gross proceeds received			$ 2,971	$ 2,971
Proceeds from private placement	$ 52,500
At The Market Offering [Member]
Class of Stock [Line Items]
Stock issued during period			639,442	639,442
Sale of stock consideration received on transaction			$ 3,000	$ 3,000
Private Placement [Member]
Class of Stock [Line Items]
Class of warrant or right, number of securities called by warrants or rights	17,803,031		18,939,394	18,939,394
Warrant Exercise Price per share	$ 3.01		$ 3.01	$ 3.01
Placement agent fees and other expenses	$ 1,100
Private Placement [Member] | New Warrants [Member]
Class of Stock [Line Items]
Class of warrant or right, number of securities called by warrants or rights	17,803,031
Warrant Exercise Price per share	$ 7.00
Securities Purchase Agreement [Member]
Class of Stock [Line Items]
Stock issued during period		18,939,394
Common stock, par value		$ 0.001
par value per share		$ 2.64
Gross proceeds received		$ 47,100		$ 47,100