v3.25.2
Cover Page - shares
6 Months Ended
Jul. 04, 2025
Jul. 21, 2025
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jul. 04, 2025  
Document Transition Report false  
Entity File Number 000-30235  
Entity Registrant Name EXELIXIS, INC.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 04-3257395  
Entity Address, Address Line One 1851 Harbor Bay Parkway  
Entity Address, City or Town Alameda,  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 94502  
City Area Code 650  
Local Phone Number 837-7000  
Title of 12(b) Security Common Stock, $0.001 Par Value per Share  
Trading Symbol EXEL  
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 (in shares)   269,202,521
Amendment Flag false  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Entity Central Index Key 0000939767  
Current Fiscal Year End Date --01-02