Leases (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Nov. 15, 2024
Concentration Risk [Line Items]
Right of use assets	$ 1,498,000,000	$ 1,541,000,000
Long-term lease liabilities	1,590,000,000	1,661,000,000
ROU assets impairment loss	15,000,000	$ 27,000,000
Lessee, operating lease, lease not yet commenced, amount	$ 0
Mc Griff Insurance Services L L C
Concentration Risk [Line Items]
Right of use assets			$ 76,000,000
Long-term lease liabilities			$ 76,000,000
Minimum
Concentration Risk [Line Items]
Lessee, operating lease, term of contract (years)	10 years
Maximum
Concentration Risk [Line Items]
Lessee, operating lease, term of contract (years)	25 years