Summary of Significant Accounting Policies (Reclassification of Fiduciary Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total current assets	$ 21,748	$ 18,959
Total assets	48,030	44,114	$ 44,010
Total current liabilities	$ 19,795	17,832
As Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total current assets		8,299
Total assets		33,454
Total current liabilities		$ 7,172