v3.26.1
Investment securities - Schedule of Investments Classified by Credit Rating (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities $ 4,337 $ 4,371
Agency mortgage-backed residential    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 1,337 1,303
Mortgage-backed residential    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 2,957 3,018
Asset-backed    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 43 50
AAA    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 2,931 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 2,893 2,951
AAA | Asset-backed    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 38 45
AA    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 1,403 1,371
AA | Agency mortgage-backed residential    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 1,337 1,303
AA | Mortgage-backed residential    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 63 66
AA | Asset-backed    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 3 2
A    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity securities 2 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 1 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