Annual report pursuant to Section 13 and 15(d)

Stock Plans - Summary of Fair Value Assumptions of Stock Purchase Plan (Detail)

v3.20.1
Stock Plans - Summary of Fair Value Assumptions of Stock Purchase Plan (Detail) - $ / shares
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Performance-based Stock Options [Member] | CEO and President [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected dividend yield 0.00% 0.00%
Grant date stock price   $ 16.82
Risk-free interest rate 2.70% 2.90%
Estimated volatility 65.00% 73.00%
Minimum [Member] | Performance-based Stock Options [Member] | CEO and President [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Grant date stock price $ 4.65  
Maximum [Member] | Performance-based Stock Options [Member] | CEO and President [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Grant date stock price $ 8.34  
Employee Stock Purchase Plan [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term (in years)   6 months
Expected volatility, minimum 62.00% 51.00%
Expected volatility, maximum 71.00% 53.00%
Risk-free interest rate, minimum 1.70% 1.20%
Risk-free interest rate, maximum 2.50% 1.90%
Employee Stock Purchase Plan [Member] | Minimum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term (in years) 6 months  
Employee Stock Purchase Plan [Member] | Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term (in years) 2 years