v3.25.2
Fair values of financial instruments not carried at fair value - Fair value of financial instruments not carried at fair value and bases of valuation (Details) - GBP (£)
£ in Millions
Jun. 30, 2025
Dec. 31, 2024
Deposits by banks    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities £ 34,439 £ 26,515
Deposits by banks | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 75 0
Deposits by banks | Fair value    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 34,440 26,518
Deposits by banks | Fair value | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 75 0
Customer accounts    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 229,804 242,303
Customer accounts | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 13,332 4,288
Customer accounts | Fair value    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 229,817 242,320
Customer accounts | Fair value | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 13,332 4,288
Repurchase agreements – non-trading    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 36,832 40,384
Repurchase agreements – non-trading | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 0 0
Repurchase agreements – non-trading | Fair value    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 36,832 40,385
Repurchase agreements – non-trading | Fair value | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 0 0
Debt securities in issue | At cost    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 13,882 19,461
Debt securities in issue | At cost | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 0 0
Debt securities in issue | Fair value | At cost    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 13,893 19,472
Debt securities in issue | Fair value | At cost | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 0 0
Subordinated liabilities | At cost    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 16,297 16,908
Subordinated liabilities | At cost | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 0 0
Subordinated liabilities | Fair value | At cost    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 16,803 17,267
Subordinated liabilities | Fair value | At cost | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial liabilities 0 0
Loans and advances to banks    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 15,803 14,521
Loans and advances to banks | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 124 115
Loans and advances to banks | Fair value    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 15,805 14,523
Loans and advances to banks | Fair value | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 124 115
Loans and advances to customers    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 78,881 82,666
Loans and advances to customers | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 1,448 769
Loans and advances to customers | Fair value    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 78,878 81,752
Loans and advances to customers | Fair value | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 1,448 771
Repurchase agreements – non-trading    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 68,408 53,612
Repurchase agreements – non-trading | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 0 0
Repurchase agreements – non-trading | Fair value    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 68,410 53,614
Repurchase agreements – non-trading | Fair value | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 0 0
Financial investments – at amortised cost    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 14,953 12,226
Financial investments – at amortised cost | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 0 0
Financial investments – at amortised cost | Fair value    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets 15,063 12,176
Financial investments – at amortised cost | Fair value | Disposal groups classified as held for sale    
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]    
Financial assets £ 0 £ 0