Net Loss per Share - Additional Information (Detail) - shares		6 Months Ended
	Apr. 05, 2017	Jun. 30, 2017	Jun. 30, 2016
Common Stock [Member] | Follow-on Public Offering [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock issued	5,117,500	5,117,500
Employee Options [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive common stock equivalents		3,118,786	2,256,700