v3.26.1
Expected credit loss measurement - Comparison of shock factors (Detail) - Baseline
 6 Months Ended
Jun. 30, 2026
2025 | Real GDP growth (annual percentage change) | US  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 2.10%
2025 | Real GDP growth (annual percentage change) | Eurozone  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 1.50%
2025 | Real GDP growth (annual percentage change) | Switzerland  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 1.40%
2025 | Unemployment rate (%, annual average) | US  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 4.20%
2025 | Unemployment rate (%, annual average) | Eurozone  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 6.30%
2025 | Unemployment rate (%, annual average) | Switzerland  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 2.80%
2025 | Fixed income: 10-year government bonds (%, Q4) | USD  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 4.20%
2025 | Fixed income: 10-year government bonds (%, Q4) | EUR  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 2.90%
2025 | Fixed income: 10-year government bonds (%, Q4) | CHF  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 0.30%
2025 | Real estate (annual percentage change, Q4) | US  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 1.30%
2025 | Real estate (annual percentage change, Q4) | Eurozone  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 5.00%
2025 | Real estate (annual percentage change, Q4) | Switzerland  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 3.80%
2026 | Real GDP growth (annual percentage change) | US  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 2.20%
2026 | Real GDP growth (annual percentage change) | Eurozone  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 0.80%
2026 | Real GDP growth (annual percentage change) | Switzerland  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 1.10%
2026 | Unemployment rate (%, annual average) | US  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 4.50%
2026 | Unemployment rate (%, annual average) | Eurozone  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 6.40%
2026 | Unemployment rate (%, annual average) | Switzerland  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 3.10%
2026 | Fixed income: 10-year government bonds (%, Q4) | USD  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 4.50%
2026 | Fixed income: 10-year government bonds (%, Q4) | EUR  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 2.90%
2026 | Fixed income: 10-year government bonds (%, Q4) | CHF  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 0.30%
2026 | Real estate (annual percentage change, Q4) | US  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 2.00%
2026 | Real estate (annual percentage change, Q4) | Eurozone  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 3.80%
2026 | Real estate (annual percentage change, Q4) | Switzerland  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 2.50%
2027 | Real GDP growth (annual percentage change) | US  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 2.10%
2027 | Real GDP growth (annual percentage change) | Eurozone  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 1.20%
2027 | Real GDP growth (annual percentage change) | Switzerland  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 1.10%
2027 | Unemployment rate (%, annual average) | US  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 4.50%
2027 | Unemployment rate (%, annual average) | Eurozone  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 6.30%
2027 | Unemployment rate (%, annual average) | Switzerland  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 3.00%
2027 | Fixed income: 10-year government bonds (%, Q4) | USD  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 4.50%
2027 | Fixed income: 10-year government bonds (%, Q4) | EUR  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 3.00%
2027 | Fixed income: 10-year government bonds (%, Q4) | CHF  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 0.40%
2027 | Real estate (annual percentage change, Q4) | US  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 3.10%
2027 | Real estate (annual percentage change, Q4) | Eurozone  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 4.10%
2027 | Real estate (annual percentage change, Q4) | Switzerland  
Disclosure of Key Macro Economic Variables Used For Expected Credit Loss Model [Line Items]  
Economic forecast 2.00%