Leases (Lease Cost and Additional Information) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 82	$ 84	$ 243	$ 262
Short-term lease cost	1	1	4	3
Variable lease cost	31	35	94	99
Sublease income	(2)	(3)	(8)	(12)
Net lease cost	$ 112	$ 117	333	352
Operating cash outflows from operating leases			284	286
Right of use assets obtained in exchange for new operating lease liabilities			$ 177	$ 148
Real Estate Lease
Lessee, Lease, Description [Line Items]
Weighted-average remaining lease term – real estate	8 years 1 month 6 days	8 years 4 months 24 days	8 years 1 month 6 days	8 years 4 months 24 days
Weighted-average discount rate – real estate leases	3.28%	2.87%	3.28%	2.87%