v3.26.1
Litigation and regulatory matters (Details)
£ in Millions, $ in Millions, $ in Millions
1 Months Ended 6 Months Ended 12 Months Ended
Jan. 31, 2026
GBP (£)
Dec. 31, 2025
USD ($)
Mar. 31, 2025
GBP (£)
Nov. 30, 2023
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Jun. 30, 2023
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May 31, 2022
GBP (£)
Dec. 31, 2021
action
item
Dec. 31, 2020
GBP (£)
Dec. 31, 2019
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Jul. 31, 2019
item
May 31, 2019
AUD ($)
item
Oct. 31, 2018
item
Sep. 30, 2018
item
Oct. 31, 2012
item
Jun. 30, 2026
USD ($)
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Dec. 31, 2018
GBP (£)
item
Jul. 31, 2026
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Jun. 30, 2026
GBP (£)
action
lawsuit
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Feb. 28, 2026
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Dec. 31, 2025
GBP (£)
Jul. 31, 2022
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Aug. 31, 2021
action
Litigation and regulatory matters                                            
Financial Assets | £                                   £ 745,367.0   £ 714,553.0    
Federal Court of Australia FX antitrust litigation                                            
Litigation and regulatory matters                                            
Number of other parties subject to lawsuit or legal investigation                     4                      
Federal Court of Australia FX antitrust litigation | Minimum                                            
Litigation and regulatory matters                                            
Transaction value of investigated trades | $                     $ 0.5                      
Tel Aviv District Court FX antitrust litigations                                            
Litigation and regulatory matters                                            
Number of motions to certify FX-related class actions                       2 2                  
Number of pending motions                                   1        
US investigations relating to fixed-income securities                                            
Litigation and regulatory matters                                            
Number of counts of wire fraud             1                              
Number of counts of securities fraud             1                              
Period during which entity is suspected of fraudulent trading                               3 months            
Number of traders conducted trading and breached the NPA                               2            
London Interbank Offered Rate (LIBOR)                                            
Litigation and regulatory matters                                            
Number of class action lawsuits | lawsuit                                   1        
Number of Non-Class Actions Pending | lawsuit                                   2        
Other IBOR-related litigations                                            
Litigation and regulatory matters                                            
Number of class action lawsuits | lawsuit                                   2        
UK Competition Appeal Tribunal, FX litigation                                            
Litigation and regulatory matters                                            
Number of applications for opt-out collective proceedings       2         2 2                        
Time given to applicants to reformulate their claims as opt-in claims       3 months                                    
Swaps antitrust litigation                                            
Litigation and regulatory matters                                            
Number of swap execution facilities                             3              
Spoofing litigation                                            
Litigation and regulatory matters                                            
Number of class action lawsuits | action             3                           1  
Oracle Securities Litigation, New York State court                                            
Litigation and regulatory matters                                            
Number of class action lawsuits                                     2      
Oracle Securities Litigation, Tennessee State court | Commencement of major litigation                                            
Litigation and regulatory matters                                            
Number of class action lawsuits                                 2          
Tandanor Litigation in Argentina                                            
Litigation and regulatory matters                                            
Number of private individuals that are co-defendants in case                           11                
Entity's percentual participation in privatisation of disputed entity                           2.90%                
IFRS Loss Contingency, Damages Sought, Value | $   $ 1,100                                        
Rockfire litigation | Rockfire Investment Finance P                                            
Litigation and regulatory matters                                            
IFRS Loss Contingency, Damages Sought, Value | £     £ 179.2                                      
Rockfire litigation | Rockfire Capital Limited                                            
Litigation and regulatory matters                                            
IFRS Loss Contingency, Damages Sought, Value | £ £ 73.1                                          
Madoff                                            
Litigation and regulatory matters                                            
Number of class action lawsuits | action                                   2       1
Damages claimed | $                             $ 300              
Offshoring VAT assessments | HMRC                                            
Litigation and regulatory matters                                            
Claimed unpaid VAT after tax assessment | £                               £ 143.0            
Number of branches subject to tax assessment                               2            
Payments for tax assessments | £           £ 153.0   £ 153.0                            
Offshoring VAT assessments | Recoverable deposit                                            
Litigation and regulatory matters                                            
Financial Assets | £                                   £ 153.0        
Review and investigation of treatment of tracker mortgage customers in Ulster Bank Ireland DAC                                            
Litigation and regulatory matters                                            
Number of FSPO adjudications challenged in court         3