Net Loss Per Share - Schedule of Antidilutive Options not Included in Computation of Weighted Average Common Shares (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of weighted average common shares	4,488,878	311,877
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of weighted average common shares	1,661,750	252,850
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of weighted average common shares	10,390	10,390
Restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of weighted average common shares	30,000	48,637
Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of weighted average common shares	2,750,000	0
Employee Stock Purchase Program
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of weighted average common shares	36,738	0