Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

v3.20.2
Document and Entity Information - shares
9 Months Ended
Sep. 30, 2020
Oct. 30, 2020
Cover [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Sep. 30, 2020  
Document Fiscal Year Focus 2020  
Document Fiscal Period Focus Q3  
Trading Symbol ATRA  
Entity Registrant Name ATARA BIOTHERAPEUTICS, INC.  
Entity Central Index Key 0001604464  
Entity Current Reporting Status Yes  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Entity Shell Company false  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Common Stock, Shares Outstanding   77,714,302
Entity File Number 001-36548  
Entity Tax Identification Number 46-0920988  
Entity Address, Address Line One 611 Gateway Blvd.  
Entity Address, Address Line Two Suite 900  
Entity Address, City or Town South San Francisco  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 94080  
City Area Code 650  
Local Phone Number 278-8930  
Entity Incorporation, State or Country Code DE  
Title of 12(b) Security Common Stock, par value $0.0001 per share  
Security Exchange Name NASDAQ  
Entity Interactive Data Current Yes  
Document Quarterly Report true  
Document Transition Report false