Leases (Supplemental Balance Sheet Information) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Property leases
Operating lease ROU assets	$ 2,417	$ 2,368
Short-term operating lease liabilities	536	496
Long-term operating lease liabilities	1,918	1,910
Operating lease liabilities	$ 2,454	$ 2,406
Weighted average remaining lease term	8 years 7 months 6 days	8 years 9 months 18 days
Weighted average discount rate	3.81%	3.84%
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accounts Payable and Accrued Liabilities, Current	Accounts Payable and Accrued Liabilities, Current