Leases - Supplemental Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Assets
Operating lease assets	$ 1,451	$ 1,699
Finance lease assets	314	329
Total leased assets	$ 1,765	$ 2,028
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other, net	Other, net
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property, plant and equipment, net of accumulated depreciation of $19,271 and $31,596	Property, plant and equipment, net of accumulated depreciation of $19,271 and $31,596
Current
Operating	$ 385	$ 379
Finance	$ 19	$ 26
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Long-term Debt and Lease Obligation, Current	Long-term Debt and Lease Obligation, Current
Noncurrent
Operating	$ 1,171	$ 1,405
Finance	$ 251	$ 267
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other	Other
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	LONG-TERM DEBT	LONG-TERM DEBT
Total lease liabilities	$ 1,826	$ 2,077
Weighted-average remaining lease term (years)
Operating leases	6 years 9 months 18 days	6 years 8 months 12 days
Finance leases	13 years 1 month 6 days	12 years 1 month 6 days
Weighted-average discount rate
Operating leases	5.54%	6.01%
Finance leases	4.89%	4.94%