Fair Value Measurements (Fair Value Hierarchy Classification) (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
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	$ 198	$ 195
Long-term debt (excluding finance leases)	31,204	31,250
Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities held in trusts	788	965
Derivative assets	58	70
Derivative liabilities	367	213
Customer financing notes receivable	187	192
Long-term debt (excluding finance leases)	29,505	35,828
Marketable securities held in trusts	788	965
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	725	890
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	63	75
Derivative assets	58	70
Derivative liabilities	367	213
Customer financing notes receivable	187	192
Long-term debt (excluding finance leases)	29,457	35,778
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)	$ 48	$ 50