v3.25.2
Document and Entity Information - shares
 6 Months Ended
Jun. 30, 2025
Jul. 18, 2025
Document And Entity Information [Line Items]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2025  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Entity Registrant Name QUANTUMSCAPE CORPORATION  
Entity Central Index Key 0001811414  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Incorporation, State or Country Code DE  
Entity File Number 001-39345  
Entity Tax Identification Number 85-0796578  
Entity Address, Address Line One 1730 Technology Drive  
Entity Address, City or Town San Jose  
Entity Address, State or Province CA  
Entity Address Postal Zip Code 95110  
City Area Code 408  
Local Phone Number 452-2000  
Document Quarterly Report true  
Document Transition Report false  
Title of 12(b) Security Class A Common Stock, par value $0.0001 per share  
Trading Symbol QS  
Security Exchange Name NYSE  
Class A Common Stock    
Document And Entity Information [Line Items]    
Entity Common Stock, Shares Outstanding   522,939,205
Class B Common Stock    
Document And Entity Information [Line Items]    
Entity Common Stock, Shares Outstanding   43,082,932