Quarterly report pursuant to Section 13 or 15(d)

Equity Incentive Plans, Employee Stock Purchase Plan and Stock-Based Compensation - Additional Information (Details)

v3.21.1
Equity Incentive Plans, Employee Stock Purchase Plan and Stock-Based Compensation - Additional Information (Details) - USD ($)
1 Months Ended 3 Months Ended 12 Months Ended
Sep. 26, 2018
Sep. 25, 2018
Aug. 31, 2019
Feb. 28, 2017
Mar. 31, 2021
Mar. 31, 2020
Dec. 31, 2020
Jan. 01, 2021
Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Reserved common stock         10,718,984   8,331,103    
Aggregate intrinsic value of stock options exercised         $ 1,900,000 $ 76,000      
Weighted-average estimated grant-date fair value of employee stock options granted         $ 15.13 $ 4.94      
Share-based compensation arrangement by share-based payment award options, shares granted         266,724   266,724    
Stock-based compensation expense         $ 3,952,000 $ 2,707,000      
Liability attributable to call option plan         $ 79,000       $ 109,000
Restricted Stock Units                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Restricted common stock granted         1,435,750        
Shares vesting period         4 years        
2018 Equity Incentive Plan                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Reserved common stock   2,300,000              
Annual increase period of common stock reserved for issuance   10 years              
Maximum number of shares issuable               2,287,605  
Shares available for grant         1,787,323        
2018 Equity Incentive Plan | Restricted Stock Units                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Total unrecognized compensation cost related to unvested granted         $ 33,900,000        
Remaining unrecognized compensation cost expected to be recognized over weighted-average period         3 years 9 months 18 days        
2018 Equity Incentive Plan | Employee Stock Options                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Total unrecognized compensation cost related to unvested granted         $ 28,300,000        
Remaining unrecognized compensation cost expected to be recognized over weighted-average period         2 years 10 months 24 days        
2018 Equity Incentive Plan | Employee Stock Purchase Plan                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Unrecognized stock-based compensation expense         $ 300,000        
2018 Equity Incentive Plan | Maximum                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Increase in stock reserved for issuance as percentage of capital stock outstanding on last day of preceding year   5.00%              
2018 Employee Stock Purchase Plan                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Reserved common stock 230,000                
Annual increase period of common stock reserved for issuance 10 years                
Maximum number of shares issuable 2,300,000       725,714        
Shares available for grant         421,277        
Shares available for grant, increase               457,521  
2018 Employee Stock Purchase Plan | Maximum                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Increase in stock reserved for issuance as percentage of capital stock outstanding on last day of preceding year 1.00%                
Call Option Plan                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Stock-based compensation expense         $ 20,000 138,000      
Other expense net         $ 30,000 $ 193,000      
Call Option Plan | Option Granted in February 2017                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Share-based compensation arrangement by share-based payment award options, shares granted       248,944          
Call options expiration period       1 year          
Call Option Plan | Option Granted in February 2017 | January 1 , 2017                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Call options vesting percentage       25.00%          
Call Option Plan | Option Granted in February 2017 | January 1 , 2018                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Call options vesting percentage       25.00%          
Call Option Plan | Option Granted in February 2017 | January 1 , 2019                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Call options vesting percentage       25.00%          
Call Option Plan | Option Granted in February 2017 | January 1 , 2020                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Call options vesting percentage       25.00%          
Call Option Plan | Option Granted in August 2019                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Share-based compensation arrangement by share-based payment award options, shares granted     17,780            
Call options expiration period     1 year            
Call Option Plan | Option Granted in August 2019 | January 1 , 2019                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Call options vesting percentage     25.00%            
Call Option Plan | Option Granted in August 2019 | January 1 , 2020                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Call options vesting percentage     25.00%            
Call Option Plan | Option Granted in August 2019 | January 1 , 2021                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Call options vesting percentage     25.00%            
Call Option Plan | Option Granted in August 2019 | January 1 , 2022                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Call options vesting percentage     25.00%            
Call Option Plan | Vaxcyte, Inc.                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Reserved common stock         266,724