Retirement Benefits (Summary of the U.S. and Non-U.S. Plan Investments Measured At Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 13,452	$ 13,042
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	977	1,535
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7,130	5,509
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	303	309	$ 663
NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,042	5,689
Total investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14,256	14,647
Total investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	977	1,535
Total investments | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7,934	7,114
Total investments | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	303	309
Total investments | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,042	5,689
Common/collective trusts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,578	4,038
Common/collective trusts | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	43	43
Common/collective trusts | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,535	3,995
Corporate obligations
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,806	2,402
Corporate obligations | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,806	2,402
Corporate stocks
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	265	564
Corporate stocks | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	227	527
Corporate stocks | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	37	36
Corporate stocks | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	1	1
Private equity/partnerships
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,444	1,433
Private equity/partnerships | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,444	1,433
Government securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,100	4,677
Government securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23	15
Government securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,077	4,662
Real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	63	261
Real estate | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	63	261
Short-term investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	488	612
Short-term investment funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	488	609
Short-term investment funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		3
Company common stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	189	331
Company common stock | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	189	331
Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	323	329
Other investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	10
Other investments | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14	11
Other investments | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	302	308	$ 662
Net derivative liabilities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(804)	(1,605)
Net derivative liabilities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Net derivative liabilities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(804)	(1,605)
Net derivative liabilities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0