Investment Securities - Amortized Cost, Fair Value of MBS Issued by FNMA and FHLMC Exceeding 10% of Shareholders' Equity (Details) $ in Millions	Jun. 30, 2025 USD ($)
FNMA investments
Schedule of Debt Securities Exceeding Ten Percent of Stockholders Equity [Line Items]
Securities, amortized cost	$ 29,017
Pledged securities	24,713
FHLMC investments
Schedule of Debt Securities Exceeding Ten Percent of Stockholders Equity [Line Items]
Securities, amortized cost	29,349
Pledged securities	$ 24,842