v3.26.1
Income Tax - Additional Information (Detail) - EUR (€)
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Income Tax [Line Items]          
Deferred tax liability decreased € 300,000 € 1,000,000 € 200,000 € 2,000,000  
Income tax paid     € 1,326,000 € 5,445,000  
Statutory tax rate 30.60% 30.20% 30.60% 30.20%  
Corporate income tax rate 21.00%   21.00%    
Current income tax € 0 € 0 € 0 € 0  
Current tax expense (income) 0 0 0 0  
Profit (62,766,000) (71,349,000) (120,528,000) (112,200,000)  
Current tax liabilities, current 834,000   834,000   € 2,318,000
Deferred tax liabilities 3,585,000   3,585,000   € 3,807,000
Immatics N V, Immatics Biotechnologies GmbH and Immatics US Inc [Member]          
Income Tax [Line Items]          
Current income tax 0 0 0 0  
Current tax expense (income) € 0 € 0 € 0 € 0  
GERMANY          
Income Tax [Line Items]          
Corporate income tax rate 70.00%   70.00%    
Trade tax rate     60.00%    
CorporateTax | GERMANY | Immatics Biotechnologies GmbH [Member]          
Income Tax [Line Items]          
Percentage Of Pretax Income Subject To Income Tax     30.00%    
Trade Tax | GERMANY | Immatics Biotechnologies GmbH [Member]          
Income Tax [Line Items]          
Percentage Of Pretax Income Subject To Income Tax     40.00%