Annual report pursuant to Section 13 and 15(d)

Common Stock - Summary of Fair Value of Warrants Issued (Detail)

v3.8.0.1
Common Stock - Summary of Fair Value of Warrants Issued (Detail) - Series A and Series B Warrants issued in July 2014 Financing [Member]
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Risk-free interest rates 1.82%  
Expected dividend yield 0.00%  
Expected life 1 year 6 months 0 years
Expected volatility 86.00%