Fair Value Measurements (Not Carried At Fair Value) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt (excluding finance leases)	$ 41,004	$ 40,991
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt (excluding finance leases)	38,342	37,956
Fair Value | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt (excluding finance leases)	0	0
Fair Value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt (excluding finance leases)	35,563	35,180
Fair Value | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt (excluding finance leases)	$ 2,779	$ 2,776