Pension and Other Postretirement Employee Benefit Plans (Fair Values of Pension Plan Assets) (Details) - Pension Benefits - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	$ 2,693	$ 2,704
Quoted Prices in Active Market (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	604	638
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	708	706
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	1,312	1,344
Cash and equivalents | Quoted Prices in Active Market (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	209	116
Cash and equivalents | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Cash and equivalents | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Cash and equivalents | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	209	116
Equity securities, common stock | Quoted Prices in Active Market (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	276	410
Equity securities, common stock | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Equity securities, common stock | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Equity securities, common stock | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	276	410
Equity securities, preferred stock | Quoted Prices in Active Market (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	1	0
Equity securities, preferred stock | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Equity securities, preferred stock | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Equity securities, preferred stock | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	1	0
Fixed income securities, corporate bonds | Quoted Prices in Active Market (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Fixed income securities, corporate bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	252	278
Fixed income securities, corporate bonds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Fixed income securities, corporate bonds | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	252	278
Fixed income securities, government issued | Quoted Prices in Active Market (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Fixed income securities, government issued | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	24	25
Fixed income securities, government issued | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Fixed income securities, government issued | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	24	25
Mutual funds | Quoted Prices in Active Market (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	118	112
Mutual funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	164	167
Mutual funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Mutual funds | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	282	279
Insurance contracts | Quoted Prices in Active Market (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Insurance contracts | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	268	236
Insurance contracts | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Insurance contracts | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	268	236
Common/collective trusts | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	1,013	906
Venture capital, partnerships and other private investments | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	$ 368	$ 454