Acquisitions and Dispositions (Acquired Finite-Lived Intangibles Assets) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($)
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets	$ 2,664
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets	2,539
Other
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets	125
Mc Griff Insurance Services L L C
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets	2,142
Mc Griff Insurance Services L L C | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets	$ 2,082
Weighted Average Amortization Period (in years)	14 years 6 months
Mc Griff Insurance Services L L C | Other
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets	$ 60
Weighted Average Amortization Period (in years)	2 years
Other
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets	$ 522
Other | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets	$ 457
Weighted Average Amortization Period (in years)	12 years 6 months
Other | Other
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets	$ 65
Weighted Average Amortization Period (in years)	4 years 4 months 24 days