Investment Securities (Fair Value of Securities Pledged and Accepted as Collateral) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Summary of Investment Holdings [Line Items]
Permitted by contract or custom to sell or repledge	$ 755	$ 1,266
Permitted amount repledged to others	755	1,266
Asset Pledged as Collateral
Summary of Investment Holdings [Line Items]
Pledged to others	$ 29,878	$ 24,708