Investment Securities (Fair Value of Securities Pledged and Accepted as Collateral) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Summary of Investment Holdings [Line Items]
Permitted by contract or custom to sell or repledge	$ 1,677	$ 1,231
Permitted amount repledged to others	1,677	1,231
Asset Pledged as Collateral
Summary of Investment Holdings [Line Items]
Debt securities, pledged to others	$ 67,334	$ 69,330