Goodwill and Other Intangibles (Amortized Intangible Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Finite-Lived Intangible Assets [Line Items]
Gross Cost	$ 7,126	$ 4,728
Accumulated Amortization	2,306	2,098
Net Carrying Amount	4,820	2,630
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Cost	6,650	4,337
Accumulated Amortization	1,961	1,761
Net Carrying Amount	4,689	2,576
Other
Finite-Lived Intangible Assets [Line Items]
Gross Cost	476	391
Accumulated Amortization	345	337
Net Carrying Amount	131	$ 54
Customer List And Other Intangible assets | Mc Griff Insurance Services L L C
Finite-Lived Intangible Assets [Line Items]
Gross Cost	$ 2,100