Goodwill and Other Intangibles (Amortized Intangible Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Finite-Lived Intangible Assets [Line Items]
Gross Cost	$ 4,793	$ 4,728
Accumulated Amortization	2,162	2,098
Net Carrying Amount	2,631	2,630
Client relationships
Finite-Lived Intangible Assets [Line Items]
Gross Cost	4,424	4,337
Accumulated Amortization	1,836	1,761
Net Carrying Amount	2,588	2,576
Other
Finite-Lived Intangible Assets [Line Items]
Gross Cost	369	391
Accumulated Amortization	326	337
Net Carrying Amount	$ 43	$ 54