Annual report pursuant to Section 13 and 15(d)

Common Stock - Summary of Fair Value of Option Awards (Detail)

v3.19.1
Common Stock - Summary of Fair Value of Option Awards (Detail)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]    
Risk-free interest rates 2.93% 1.95%
Expected dividend yield 0.00% 0.00%
Expected life 5 years 8 months 4 days 6 years 7 days
Expected volatility 88.23% 86.06%