Fair Value Measurements (Fair Value Hierarchy Classification) (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Portion at Other than Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Customer financing notes receivable	$ 167	$ 169
Long-term debt (excluding finance leases)	34,175	31,201
Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities held in trusts	703	774
Derivative assets	91	84
Derivative liabilities	389	386
Customer financing notes receivable	157	161
Long-term debt (excluding finance leases)	32,207	28,049
Marketable securities held in trusts	703	774
Fair Value Level 1 [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities held in trusts	643	713
Derivative assets	0	0
Derivative liabilities	0	0
Customer financing notes receivable	0	0
Long-term debt (excluding finance leases)	0	0
Fair Value Level 2 [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities held in trusts	60	61
Derivative assets	91	84
Derivative liabilities	389	386
Customer financing notes receivable	157	161
Long-term debt (excluding finance leases)	32,161	28,003
Fair Value Level 3 [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities held in trusts	0	0
Derivative assets	0	0
Derivative liabilities	0	0
Customer financing notes receivable	0	0
Long-term debt (excluding finance leases)	$ 46	$ 46