Pension, Postretirement And Other Employee Benefit Plans - Pension and Other Postretirement Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	$ 322	$ 333	$ 435
Pension Benefits
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	3,599	3,467	4,626
Pension Benefits | Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	87	64
Pension Benefits | Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	501	569
Pension Benefits | Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	276	285
Pension Benefits | Assets Measured at NAV
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	2,735	2,549
Pension Benefits | Equity securities funds
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	1,265	1,183
Pension Benefits | Equity securities funds | Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	74	58
Pension Benefits | Equity securities funds | Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	3	26
Pension Benefits | Equity securities funds | Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	134	114
Pension Benefits | Equity securities funds | Assets Measured at NAV
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	1,054	985
Pension Benefits | Fixed-income securities
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	1,325	1,316
Pension Benefits | Fixed-income securities | Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Fixed-income securities | Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	411	527
Pension Benefits | Fixed-income securities | Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	3	5
Pension Benefits | Fixed-income securities | Assets Measured at NAV
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	911	784
Pension Benefits | Alternatives
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	779	887
Pension Benefits | Alternatives | Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Alternatives | Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Pension Benefits | Alternatives | Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	136	161
Pension Benefits | Alternatives | Assets Measured at NAV
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	643	726
Pension Benefits | Other investments
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	230	81
Pension Benefits | Other investments | Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	13	6
Pension Benefits | Other investments | Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	87	16
Pension Benefits | Other investments | Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	3	5
Pension Benefits | Other investments | Assets Measured at NAV
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	127	54
Other Postretirement Benefits
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	46	48	$ 49
Other Postretirement Benefits | Deposit administration fund
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	46	48
Other Postretirement Benefits | Deposit administration fund | Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Deposit administration fund | Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Deposit administration fund | Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	46	48
Other Postretirement Benefits | Deposit administration fund | Assets Measured at NAV
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	$ 0	$ 0