Quarterly report pursuant to Section 13 or 15(d)

Common Stock - Stock Options - Additional Information (Detail)

v3.19.1
Common Stock - Stock Options - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common shares reserved for options currently outstanding 967,685   665,585
Unrecognized compensation expense related to stock options granted $ 2.5   $ 1.8
Anti-dilutive securities excluded from earning per share computation 5,038,584 173,515  
Warrant [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Anti-dilutive securities excluded from earning per share computation 4,055,890    
Stock Options [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Anti-dilutive securities excluded from earning per share computation 967,685    
Restricted Stock Unit [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Anti-dilutive securities excluded from earning per share computation 15,009    
Stock Options [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Weighted-average period, restricted stock awards 2 years 9 months 18 days    
Stock Options [Member] | Employees and Consultants [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 4 years    
Stock Options [Member] | Minimum [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award expiration period 7 years    
Stock Options [Member] | Minimum [Member] | Board of Directors [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 1 year    
Stock Options [Member] | Maximum [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award expiration period 10 years    
Stock Options [Member] | Maximum [Member] | Board of Directors [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 3 years    
Restricted Stock Unit [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 4 years    
Common shares reserved for awards currently outstanding 15,009   15,142
Weighted-average period, restricted stock awards 2 years 3 months 29 days    
2018 Equity Incentive Plan [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common shares reserved for issuance under incentive plan 647,305    
Award expiration period 10 years    
2018 Equity Incentive Plan [Member] | Minimum [Member] | Employees and Consultants [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 3 years    
2018 Equity Incentive Plan [Member] | Minimum [Member] | Board of Directors [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 1 year    
2018 Equity Incentive Plan [Member] | Maximum [Member] | Employees and Consultants [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 4 years    
2018 Equity Incentive Plan [Member] | Maximum [Member] | Board of Directors [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 3 years    
2018 Equity Incentive Plan [Member] | Stock Options [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common shares reserved for issuance under incentive plan 1,336,055    
Common shares reserved for options currently outstanding 688,750    
2017 Equity Incentive Plan [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award expiration period 10 years    
2017 Equity Incentive Plan [Member] | Minimum [Member] | Employees and Consultants [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 3 years    
2017 Equity Incentive Plan [Member] | Minimum [Member] | Board of Directors [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 1 year    
2017 Equity Incentive Plan [Member] | Maximum [Member] | Employees and Consultants [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 4 years    
2017 Equity Incentive Plan [Member] | Maximum [Member] | Board of Directors [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 3 years    
2017 Equity Incentive Plan [Member] | Stock Options [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common shares reserved for issuance under incentive plan 272,660    
2010 Performance Incentive Plan [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award expiration period 10 years    
2010 Performance Incentive Plan [Member] | Minimum [Member] | Employees and Consultants [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 3 years    
2010 Performance Incentive Plan [Member] | Minimum [Member] | Board of Directors [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 1 year    
2010 Performance Incentive Plan [Member] | Maximum [Member] | Employees and Consultants [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 4 years    
2010 Performance Incentive Plan [Member] | Maximum [Member] | Board of Directors [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 3 years    
2010 Performance Incentive Plan [Member] | Stock Options [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common shares reserved for issuance under incentive plan 20,932    
Common shares reserved for options currently outstanding 5,923    
2010 Performance Incentive Plan [Member] | Restricted Stock Unit [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common shares reserved for awards currently outstanding 15,009