Investment Securities - Amortized Cost, Fair Value of MBS Issued by FNMA and FHLMC Exceeding 10% of Shareholders' Equity (Details) $ in Millions |
Mar. 31, 2025
USD ($)
|
|---|---|
| FNMA investments | |
| Schedule of Debt Securities Exceeding Ten Percent of Stockholders Equity [Line Items] | |
| Securities, amortized cost | $ 29,331 |
| Pledged securities | 24,928 |
| FHLMC investments | |
| Schedule of Debt Securities Exceeding Ten Percent of Stockholders Equity [Line Items] | |
| Securities, amortized cost | 29,693 |
| Pledged securities | $ 25,086 |