v3.26.1
Credit Risk - Narrative (Details)
£ in Millions
 6 Months Ended
Jun. 30, 2026
GBP (£)
economic_scenario
Mar. 31, 2026
GBP (£)
Dec. 31, 2025
GBP (£)
Jun. 30, 2025
GBP (£)
Disclosure of financial assets [line items]        
Expected credit loss rate 100.00%      
Average        
Disclosure of financial assets [line items]        
Value at risk £ 20   £ 18 £ 19
Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets £ 5,969   5,727  
Credit risk        
Disclosure of financial assets [line items]        
Number of economic scenarios | economic_scenario 5      
Stress horizon period, ECL 5 years      
Credit risk | Average        
Disclosure of financial assets [line items]        
Value at risk £ 17   14 £ 16
Baseline        
Disclosure of financial assets [line items]        
Weighted expected credit loss, uplift percentage 2.10%      
Total weighted model ECL | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets £ 4,328   4,358  
Post-model adjustment | Impairment allowance        
Disclosure of financial assets [line items]        
Increase (decrease) in financial assets 81      
Financial assets 66      
Post-model adjustment | Impairment allowance | Barclays UK        
Disclosure of financial assets [line items]        
Financial assets   £ 10    
Post-model adjustment | Impairment allowance | Barclays US Consumer Bank        
Disclosure of financial assets [line items]        
Financial assets   £ 25    
Post-model adjustment | Impairment allowance | Barclays Investment Bank        
Disclosure of financial assets [line items]        
Financial assets (66)      
ECL from held for sale assets (AA portfolio) | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets     (235)  
ECL from held for sale assets (AA portfolio) | Impairment allowance | Barclays US Consumer Bank        
Disclosure of financial assets [line items]        
Financial assets (4)      
ECL from other financial assets subject to impairment, adjustment | Impairment allowance | Barclays Investment Bank        
Disclosure of financial assets [line items]        
Financial assets (2)      
Loans and advances | Impairment allowance        
Disclosure of financial assets [line items]        
Increase (decrease) in financial assets (1,497)      
Loans and advances | Total weighted model ECL | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 4,300   4,300  
Loans and advances | Financial assets at amortised cost        
Disclosure of financial assets [line items]        
Financial assets (371,301)   (361,523)  
Loans and advances | Financial assets at amortised cost | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 5,516   5,289  
Loans and advances | Financial assets at amortised cost | Total weighted model ECL | Credit risk | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 4,328   4,358  
Loans and advances | Financial assets at amortised cost | Total weighted model ECL | Baseline | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 4,240   4,302  
Loans and advances | Financial assets at amortised cost | Total weighted model ECL | Downside 2 | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 5,666   5,443  
Retail mortgages | Impairment allowance        
Disclosure of financial assets [line items]        
Increase (decrease) in financial assets (18)      
Financial assets £ 127   117  
Retail mortgages | Baseline        
Disclosure of financial assets [line items]        
Weighted expected credit loss, uplift percentage 28.60%      
Retail mortgages | Financial assets at amortised cost        
Disclosure of financial assets [line items]        
Financial assets £ (181,542)   (177,333)  
Retail mortgages | Financial assets at amortised cost | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 127   117  
Retail mortgages | Financial assets at amortised cost | Total weighted model ECL | Credit risk | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 81   62  
Retail mortgages | Financial assets at amortised cost | Total weighted model ECL | Baseline | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 63   51  
Retail mortgages | Financial assets at amortised cost | Total weighted model ECL | Downside 2 | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 294   190  
Retail credit cards | Impairment allowance        
Disclosure of financial assets [line items]        
Increase (decrease) in financial assets (916)      
Financial assets £ 3,436   3,329  
Retail credit cards | Baseline        
Disclosure of financial assets [line items]        
Weighted expected credit loss, uplift percentage 0.90%      
Retail credit cards | Financial assets at amortised cost        
Disclosure of financial assets [line items]        
Financial assets £ (37,667)   (36,952)  
Retail credit cards | Financial assets at amortised cost | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 3,436   3,329  
Retail credit cards | Financial assets at amortised cost | Total weighted model ECL | Credit risk | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 3,290   3,336  
Retail credit cards | Financial assets at amortised cost | Total weighted model ECL | Baseline | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 3,261   3,332  
Retail credit cards | Financial assets at amortised cost | Total weighted model ECL | Downside 2 | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 3,821   3,715  
Retail other | Impairment allowance        
Disclosure of financial assets [line items]        
Increase (decrease) in financial assets (137)      
Financial assets £ 536   517  
Retail other | Baseline        
Disclosure of financial assets [line items]        
Weighted expected credit loss, uplift percentage 0.50%      
Retail other | Financial assets at amortised cost        
Disclosure of financial assets [line items]        
Financial assets £ (14,235)   (13,914)  
Retail other | Financial assets at amortised cost | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 536   517  
Retail other | Financial assets at amortised cost | Total weighted model ECL | Credit risk | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 189   192  
Retail other | Financial assets at amortised cost | Total weighted model ECL | Baseline | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 188   185  
Retail other | Financial assets at amortised cost | Total weighted model ECL | Downside 2 | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 225   259  
Corporate loans | Impairment allowance        
Disclosure of financial assets [line items]        
Increase (decrease) in financial assets (426)      
Financial assets £ 1,417   1,326  
Corporate loans | Baseline        
Disclosure of financial assets [line items]        
Weighted expected credit loss, uplift percentage 5.50%      
Corporate loans | Financial assets at amortised cost        
Disclosure of financial assets [line items]        
Financial assets £ (137,857)   (133,324)  
Corporate loans | Financial assets at amortised cost | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 1,417   1,326  
Corporate loans | Financial assets at amortised cost | Total weighted model ECL | Credit risk | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 768   768  
Corporate loans | Financial assets at amortised cost | Total weighted model ECL | Baseline | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets 728   734  
Corporate loans | Financial assets at amortised cost | Total weighted model ECL | Downside 2 | Impairment allowance        
Disclosure of financial assets [line items]        
Financial assets £ 1,326   £ 1,279