Document and Entity Information
Mar. 09, 2022
Cover [Abstract]  
Document Type 8-K
Amendment Flag false
Document Period End Date Mar. 09, 2022
Entity Registrant Name Poseida Therapeutics, Inc.
Entity Central Index Key 0001661460
Entity Emerging Growth Company true
Entity Ex Transition Period false
Entity File Number 001-39376
Entity Incorporation, State or Country Code DE
Entity Tax Identification Number 47-2846548
Entity Address, Address Line One 9390 Towne Centre Drive
Entity Address, Address Line Two Suite 200
Entity Address, City or Town San Diego
Entity Address, State or Province CA
Entity Address, Postal Zip Code 92121
City Area Code 858
Local Phone Number 779-3100 
Written Communications false
Soliciting Material false
Pre-commencement Tender Offer false
Pre-commencement Issuer Tender Offer false
Security 12b Title Common Stock, par value $0.0001 per share
Trading Symbol PSTX
Security Exchange Name NASDAQ