Leases (Supplemental Balance Sheet Information Related to Leases) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Operating Leases
Operating lease right-of-use assets	$ 21,001	$ 21,814
Accounts payable and accrued liabilities	$ 3,538	$ 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	$ 17,730	$ 18,659
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Operating lease obligation	Operating lease obligation
Total operating lease obligation	$ 21,268	$ 22,206
Finance Leases
Property, plant and equipment, at cost	2,962	2,770
Accumulated depreciation and amortization	(1,424)	(1,224)
Property, plant and equipment, net	$ 1,538	$ 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	$ 178	$ 170
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Long-Term Debt	Long-Term Debt
Long-term debt	$ 1,663	$ 1,647
Total finance lease obligation	$ 1,841	$ 1,817
Weighted-Average Remaining Lease Term (years), Operating leases	7 years 9 months 18 days		8 years 1 month 6 days
Weighted-Average Remaining Lease Term (years), Finance leases	7 years 3 months 18 days		7 years 10 months 24 days
Weighted-Average Discount Rate, Operating leases	4.00%		3.60%
Weighted-Average Discount Rate, Finance leases	8.20%		7.90%