Common Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 11, 2018
Class Of Stock [Line Items]
Net proceeds from issuance of common stock	$ 1,525
At-The-Market Offering Program [Member] | Sales Agreement [Member] | Cantor Fitzgerald & Co [Member]
Class Of Stock [Line Items]
Gross proceeds from issuance of common stock	1,600
Net proceeds from issuance of common stock	$ 1,500
At-The-Market Offering Program [Member] | Sales Agreement [Member] | Cantor Fitzgerald & Co [Member] | Maximum [Member]
Class Of Stock [Line Items]
Authorized offering value		$ 200,000
Common stock available for issuance		$ 50,000
Common Stock [Member]
Class Of Stock [Line Items]
Issuance of stock, shares	119,090
Common Stock [Member] | At-The-Market Offering Program [Member] | Sales Agreement [Member] | Cantor Fitzgerald & Co [Member]
Class Of Stock [Line Items]
Issuance of stock, shares	119,090
Share price	$ 13.22