Employee Postretirement Benefits (Pension Plan Assets of the Principal Plans Measured at Fair Value) (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Defined Benefit Plan, Plan Assets, Category [Line Items]
Percentage of plan assets at NAV	60.00%
Principal Plans
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	$ 1,819	$ 1,795
Principal Plans | Assets at Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	147	132
Principal Plans | Assets at Significant Observable Inputs (Level 2)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	357	382
Principal Plans | Assets at Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	196	194
Cash and Cash Equivalents | Principal Plans | Fair Value, Inputs, Level 1, Level 2, and Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	28	25
Cash and Cash Equivalents | Principal Plans | Assets at Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	19	16
Cash and Cash Equivalents | Principal Plans | Assets at Significant Observable Inputs (Level 2)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	9	9
Cash and Cash Equivalents | Principal Plans | Assets at Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
U.S. government and municipals | Principal Plans | Fair Value, Inputs, Level 1, Level 2, and Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	119	112
U.S. government and municipals | Principal Plans | Assets at Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	100	94
U.S. government and municipals | Principal Plans | Assets at Significant Observable Inputs (Level 2)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	19	18
U.S. government and municipals | Principal Plans | Assets at Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
U.S. government and municipals | Principal Plans | Net Asset Value
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	272	289
U.S. corporate debt | Principal Plans | Fair Value, Inputs, Level 1, Level 2, and Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	288	304
U.S. corporate debt | Principal Plans | Assets at Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
U.S. corporate debt | Principal Plans | Assets at Significant Observable Inputs (Level 2)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	288	304
U.S. corporate debt | Principal Plans | Assets at Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
U.S. securitized | Principal Plans | Fair Value, Inputs, Level 1, Level 2, and Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	1
U.S. securitized | Principal Plans | Assets at Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
U.S. securitized | Principal Plans | Assets at Significant Observable Inputs (Level 2)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	1
U.S. securitized | Principal Plans | Assets at Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
International bonds | Principal Plans | Fair Value, Inputs, Level 1, Level 2, and Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	41	50
International bonds | Principal Plans | Assets at Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
International bonds | Principal Plans | Assets at Significant Observable Inputs (Level 2)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	41	50
International bonds | Principal Plans | Assets at Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
International bonds | Principal Plans | Net Asset Value
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	524	509
Non-U.S. securitized | Principal Plans | Net Asset Value
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	74	69
U.S. equity | Principal Plans | Fair Value, Inputs, Level 1, Level 2, and Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	16	14
U.S. equity | Principal Plans | Assets at Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	16	14
U.S. equity | Principal Plans | Assets at Significant Observable Inputs (Level 2)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
U.S. equity | Principal Plans | Assets at Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
International equity | Principal Plans | Fair Value, Inputs, Level 1, Level 2, and Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	12	11
International equity | Principal Plans | Assets at Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	12	11
International equity | Principal Plans | Assets at Significant Observable Inputs (Level 2)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
International equity | Principal Plans | Assets at Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Non-U.S. equity | Principal Plans | Net Asset Value
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	3	2
Global equity | Principal Plans | Net Asset Value
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	246	218
Insurance Contracts | Principal Plans | Fair Value, Inputs, Level 1, Level 2, and Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	196	194
Insurance Contracts | Principal Plans | Assets at Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Insurance Contracts | Principal Plans | Assets at Significant Observable Inputs (Level 2)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Insurance Contracts | Principal Plans | Assets at Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	196	194
Other | Principal Plans | Fair Value, Inputs, Level 1, Level 2, and Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	(3)
Other | Principal Plans | Assets at Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	(3)
Other | Principal Plans | Assets at Significant Observable Inputs (Level 2)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Other | Principal Plans | Assets at Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	$ 0	$ 0