Leases (Supplemental Balance Sheet Information Related to Leases) (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Operating Leases
Operating lease right-of-use assets	$ 21,619	$ 21,814
Accounts payable and accrued liabilities	$ 3,530	$ 3,547
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accounts payable and accrued liabilities	Accounts payable and accrued liabilities
Operating lease obligation	$ 18,413	$ 18,659
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Operating lease obligation	Operating lease obligation
Total operating lease obligation	$ 21,943	$ 22,206
Finance Leases
Property, plant and equipment, at cost	2,972	2,770
Accumulated depreciation and amortization	(1,314)	(1,224)
Property, plant and equipment, net	$ 1,658	$ 1,546
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Debt maturing within one year	Debt maturing within one year
Current portion of long-term debt	$ 209	$ 170
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Long-Term Debt	Long-Term Debt
Long-term debt	$ 1,758	$ 1,647
Total finance lease obligation	$ 1,967	$ 1,817
Weighted-Average Remaining Lease Term (years), Operating leases	8 years 1 month 6 days		8 years 2 months 12 days
Weighted-Average Remaining Lease Term (years), Finance leases	7 years 3 months 18 days		8 years 6 months
Weighted-Average Discount Rate, Operating leases	3.80%		3.70%
Weighted-Average Discount Rate, Finance leases	7.80%		8.10%