v3.26.1
Investment securities - Schedule of Investments Classified by Credit Rating (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities $ 4,286 $ 4,371
Agency mortgage-backed residential    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 1,364 1,303
Mortgage-backed residential    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 2,886 3,018
Asset-backed    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 36 50
AAA    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 2,856 2,996
AAA | Agency mortgage-backed residential    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 0 0
AAA | Mortgage-backed residential    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 2,825 2,951
AAA | Asset-backed    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 31 45
AA    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 1,428 1,371
AA | Agency mortgage-backed residential    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 1,364 1,303
AA | Mortgage-backed residential    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 60 66
AA | Asset-backed    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 4 2
A    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 1 3
A | Agency mortgage-backed residential    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 0 0
A | Mortgage-backed residential    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 1 1
A | Asset-backed    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 0 2
BBB    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 1 1
BBB | Agency mortgage-backed residential    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 0 0
BBB | Mortgage-backed residential    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 0 0
BBB | Asset-backed    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities $ 1 $ 1