Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

v3.20.4
Document and Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2020
Feb. 23, 2021
Jun. 30, 2020
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2020    
Document Transition Report false    
Entity File Number 001-37368    
Entity Registrant Name ADAPTIMMUNE THERAPEUTICS PLC    
Entity Incorporation, State or Country Code X0    
Entity Tax Identification Number 00-0000000    
Entity Address, Address Line One 60 Jubilee Avenue, Milton Park    
Entity Address, City or Town Abingdon, Oxfordshire    
Entity Address, Country GB    
Entity Address, Postal Zip Code OX14 4RX    
City Area Code 44    
Local Phone Number 1235 430000    
Title of 12(b) Security American Depositary Shares, each representing    
Trading Symbol ADAP    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
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    
ICFR Auditor Attestation Flag true    
Entity Shell Company false    
Entity Public Float     $ 1,359,787,192
Entity Common Stock, Shares Outstanding   930,827,670  
Entity Central Index Key 0001621227    
Current Fiscal Year End Date --12-31    
Document Fiscal Year Focus 2020    
Document Fiscal Period Focus FY    
Amendment Flag false