v3.26.1
Fair value measurement - Assets on Nonrecurring Basis (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other assets $ 2,125 $ 1,666
Measured at fair value on a nonrecurring basis    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Loans 20 21
Other assets 533 440
Total assets 553 461
Measured at fair value on a nonrecurring basis | Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Loans 0 0
Other assets 0 0
Total assets 0 0
Measured at fair value on a nonrecurring basis | Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Loans 20 21
Other assets 533 440
Total assets 553 461
Measured at fair value on a nonrecurring basis | Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Loans 0 0
Other assets 0 0
Total assets $ 0 $ 0