v3.25.4
Retirement benefits - Disclosure of actuarial valuation of schemes (Details) - UK - Pension defined benefit plans - GBP (£)
£ in Billions
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Actuarial assumption of key financial assumptions | Barclays Bank Section    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Discount rate 5.46%  
Inflation rate (RPI) 2.92%  
Actuarial assumption of key financial assumptions | UKRF    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Discount rate   5.44%
Inflation rate (RPI)   3.32%
Life expectancy at 60 for current pensioners, males | UKRF    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Assumed life expectancy at 60 26 years 7 months 6 days 26 years 6 months
Life expectancy at 60 for current pensioners, females | UKRF    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Assumed life expectancy at 60 29 years 3 months 18 days 29 years 4 months 24 days
Life expectancy at 40 for future pensioners at 40 years, males | UKRF    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Assumed life expectancy at 60 28 years 28 years
Life expectancy at 40 for future pensioners at 40 years, females | UKRF    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Assumed life expectancy at 60 30 years 7 months 6 days 30 years 9 months 18 days
0.5% change in discount rate per annum | UKRF    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Percentage of reasonably possible increase in actuarial assumption 0.50%  
Percentage of reasonably possible decrease in actuarial assumption 0.50%  
(Decrease)/Increase in defined benefit obligation £ (0.9) £ (1.0)
(Decrease)/Increase in defined benefit obligation £ 1.0 1.1
0.25% change in discount rate per annum | UKRF    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Percentage of reasonably possible increase in actuarial assumption 0.25%  
Percentage of reasonably possible decrease in actuarial assumption 0.25%  
(Decrease)/Increase in defined benefit obligation £ (0.4) (0.5)
(Decrease)/Increase in defined benefit obligation £ 0.5 0.5
0.5% change in RPI per annum | UKRF    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Percentage of reasonably possible increase in actuarial assumption 0.50%  
Percentage of reasonably possible decrease in actuarial assumption 0.50%  
(Decrease)/Increase in defined benefit obligation £ 0.7 0.7
(Decrease)/Increase in defined benefit obligation £ (0.6) (0.7)
0.25% change in RPI per annum | UKRF    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Percentage of reasonably possible increase in actuarial assumption 0.25%  
Percentage of reasonably possible decrease in actuarial assumption 0.25%  
(Decrease)/Increase in defined benefit obligation £ 0.3 0.3
(Decrease)/Increase in defined benefit obligation (0.3) (0.4)
Change in life expectancy by one year | UKRF    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
(Decrease)/Increase in defined benefit obligation 0.5 0.5
(Decrease)/Increase in defined benefit obligation £ (0.5) £ (0.5)
Increase in actuarial assumption, duration 1 year  
Decrease in actuarial assumption, duration 1 year  
Life Expectancy At 60 For Remaining Population Of The Membership | UKRF    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Assumed life expectancy at 60 60 years  
Mortality assumption, percentage 60.00%  
Life Expectancy At 60 For Remaining Population Of The Membership | UKRF | Low    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Assumed life expectancy at 60 26 years 4 months 24 days  
Life Expectancy At 60 For Remaining Population Of The Membership | UKRF | High    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Assumed life expectancy at 60 29 years 3 months 18 days