v3.25.2
Cover - shares
 6 Months Ended
Jun. 30, 2025
Jul. 25, 2025
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2025  
Document Transition Report false  
Entity File Number 001-38683  
Entity Registrant Name GUARDANT HEALTH, INC.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 45-4139254  
Entity Address, Address Line One 3100 Hanover Street  
Entity Address, City or Town Palo Alto  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 94304  
City Area Code 855  
Local Phone Number 698-8887  
Title of 12(b) Security Common Stock, $0.00001 par value per share  
Trading Symbol GH  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   124,705,857
Amendment Flag false  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Entity Central Index Key 0001576280  
Current Fiscal Year End Date --12-31