Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Apr. 10, 2018	Mar. 31, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Common stock, capital shares reserved for future issuance		15,312,223
Shares of common stock issued	3,450,000
Underwriters' Option [Member]
Class Of Stock [Line Items]
Shares of common stock issued	450,000
Purchase price per share	$ 8.60
Net proceeds received after deducting underwriters' discounts and commissions and offering costs	$ 28,000
Series A Convertible Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred Stock, shares authorized		1,000,000	1,000,000
Preferred stock dividends issued		0
Dividends in arrears		$ 8
Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred Stock, shares authorized		50,000,000