Investment Securities (Fair Value of Securities Pledged and Accepted as Collateral) (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Summary of Investment Holdings [Line Items]
Permitted by contract or custom to sell or repledge	$ 1,454	$ 755
Permitted amount repledged to others	1,454	755
Asset Pledged as Collateral
Summary of Investment Holdings [Line Items]
Debt securities, pledged to others	$ 71,329	$ 29,878