Annual report pursuant to Section 13 and 15(d)

Stock Plans - Additional Information (Detail)

v3.20.4
Stock Plans - Additional Information (Detail)
 1 Months Ended 3 Months Ended 12 Months Ended
Aug. 31, 2020
USD ($)
Customer
Apr. 30, 2017
shares
Mar. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
$ / shares
shares
Dec. 31, 2019
USD ($)
$ / shares
shares
Oct. 31, 2020
shares
Performance-based Stock Options [Member]            
Class of Stock [Line Items]            
Cost of share-based compensation awards, recognition period       1 year 7 months 6 days    
Weighted Average Grant Date Fair Value, Granted | $ / shares       $ 7.36 $ 2.55  
Total grant date fair value of stock options vested | $       $ 0 $ 0  
Unrecognized compensation expense related to stock options | $       $ 16,268,000    
Performance-based Stock Options [Member] | Scenario Forecast [Member]            
Class of Stock [Line Items]            
Unrecognized compensation accelerated recognized as one-time expense | $     $ 16,268,000      
Timebased Stock Option [Member]            
Class of Stock [Line Items]            
Vesting period       4 years    
Restricted Stock Units [Member]            
Class of Stock [Line Items]            
Restricted stock granted       914,157    
Weighted Average Grant Date Fair Value, Granted | $ / shares       $ 10.94    
2018 Performance Base Stock Incentive Plan [Member]            
Class of Stock [Line Items]            
Number of employees | Customer 215          
Incremental compensation cost | $ $ 3,011,000          
Restricted Stock [Member]            
Class of Stock [Line Items]            
Restricted stock granted       6,903    
Weighted Average Grant Date Fair Value, Granted | $ / shares       $ 4.47    
Maximum [Member] | Restricted Stock Units [Member]            
Class of Stock [Line Items]            
Vesting period       2 years    
Minimum [Member] | Restricted Stock Units [Member]            
Class of Stock [Line Items]            
Vesting period       1 year    
2017 Stock Incentive Plan [Member]            
Class of Stock [Line Items]            
Common stock reserved for future issuance   2,000,000   596,816    
Annual shares increase for future issuance by percentage under employee stock purchase plans   3.00%        
2017 Stock Incentive Plan [Member] | Performance-based Stock Options [Member]            
Class of Stock [Line Items]            
Vesting period       30 days    
2017 Stock Incentive Plan [Member] | Timebased Stock Option [Member]            
Class of Stock [Line Items]            
Vesting period       3 years    
2017 Stock Incentive Plan [Member] | Restricted Stock Units [Member]            
Class of Stock [Line Items]            
Vesting period       1 year    
2017 Stock Incentive Plan [Member] | Maximum [Member]            
Class of Stock [Line Items]            
Increase in common stock reserved for future issuance   750,000        
2018 Performance Base Stock Incentive Plan [Member]            
Class of Stock [Line Items]            
Common stock reserved for future issuance       183    
Number of shares authorized for issuance       4,200,000    
2018 Performance Base Stock Incentive Plan [Member] | Performance-based Stock Options [Member] | Chad Steelberg [Member]            
Class of Stock [Line Items]            
Common stock granted       1,809,900    
2018 Performance Base Stock Incentive Plan [Member] | Performance-based Stock Options [Member] | Ryan Steelberg [Member]            
Class of Stock [Line Items]            
Common stock granted       1,357,425    
Inducement Grant Plan [Member]            
Class of Stock [Line Items]            
Common stock reserved for future issuance       408,000   750,000
Inducement Grant Plan [Member] | Performance-based Stock Options [Member]            
Class of Stock [Line Items]            
Vesting period       30 days    
2018 Stock Incentive Plan [Member] | Performance-based Stock Options [Member]            
Class of Stock [Line Items]            
Vesting period       30 days    
Stock Plan [Member] | Restricted Stock [Member]            
Class of Stock [Line Items]            
Unrecognized cost of share-based compensation awards | $       $ 0    
Restricted stock granted       6,903 0  
Fair value of restricted stock vested | $       $ 238,000 $ 299,000  
2014 Plan Stock Options/Stock Issuance Plan, 2017 Stock Incentive Plan and Inducement Grant Plan [Member] | Restricted Stock Units [Member]            
Class of Stock [Line Items]            
Unrecognized cost of share-based compensation awards | $       4,593,000    
Fair value of restricted stock vested | $       $ 2,519,000 $ 362,000  
Cost of share-based compensation awards, recognition period       8 months 12 days    
Weighted Average Grant Date Fair Value, Granted | $ / shares       $ 10.94 $ 6.97  
2014 Plan Stock Options/Stock Issuance Plan, 2017 Stock Incentive Plan and Inducement Grant Plan [Member] | Stock Options [Member]            
Class of Stock [Line Items]            
Cost of share-based compensation awards, recognition period       2 years 8 months 12 days    
Weighted Average Grant Date Fair Value, Granted | $ / shares       $ 4.69 $ 3.47  
Total grant date fair value of stock options vested | $       $ 5,205,000 $ 10,226,000  
Unrecognized compensation expense related to stock options | $       5,792,000    
Aggregate intrinsic value of the options exercised | $       $ 2,238,000 189,000  
Employee Stock Purchase Plan [Member]            
Class of Stock [Line Items]            
Common stock reserved for future issuance   1,000,000        
Annual shares increase for future issuance by percentage under employee stock purchase plans   1.00%        
Number of shares authorized for issuance   200,000        
ESPP offering description       Under the ESPP, each offering period is generally 24 months with four, six-month purchase intervals, and new offering periods generally commence every six months, as determined by the Compensation Committee of the Board of Directors.    
Maximum number of shares per employee in each purchase   1,000        
Employee payroll deductions accrued | $       $ 135,000 $ 196,000  
Common stock were purchased under ESPP       126,550 129,514  
Weighted average purchase price | $ / shares       $ 1.90 $ 4.65  
Employee Stock Purchase Plan [Member] | Maximum [Member]            
Class of Stock [Line Items]            
Increase in common stock reserved for future issuance   250,000        
Employee Stock Purchase Plan [Member] | Minimum [Member]            
Class of Stock [Line Items]            
Percentage of purchase price of common stock fair value   85.00%