Debt and Credit Agreements - Schedule of Long-term Debt Instruments (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Finance Leases Average Interest Rate	6.10%
Subtotal Long-term Debt (including current portion)	$ 16,366	$ 16,705
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Long-term Debt (excluding current portion)	Long-term Debt (excluding current portion)
Finance Leases	$ 47	$ 3
Less Debt Due within One Year	(181)	(401)
Long-term Debt (excluding current portion)	$ 16,185	16,304
Notes
Debt Instrument [Line Items]
Debt Average Interest Rates	4.20%
Subtotal Long-term Debt (including current portion)	$ 16,166	16,542
Equipment Obligations
Debt Instrument [Line Items]
Debt Average Interest Rates	6.20%
Subtotal Long-term Debt (including current portion)	$ 153	$ 160

Amount of short-term and long-term debt and lease obligation.

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The average effective interest rate during the reporting period.

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Present value of lessee's discounted obligation for lease payments from finance lease.

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Amount of long-term debt and lease obligation, classified as noncurrent.

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Amount of long-term debt and lease obligation, classified as current.

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