Retirement Benefits (Narrative) (Details) £ in Millions, $ in Millions		1 Months Ended	12 Months Ended
	Jan. 01, 2017	Nov. 30, 2022 USD ($)	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Nov. 30, 2022 GBP (£)
Defined Benefit Plan Disclosure [Line Items]
Assumed health care cost trend rate for Medicare eligibles and non-Medicare eligibles			8.87%
Future assumed health care cost trend rate			4.46%
Automatic employer contribution of employee's eligible base pay (as a percent)	4.00%
401(k) Plan's assets invested in common stock			$ 726	$ 677
U.S.
Defined Benefit Plan Disclosure [Line Items]
Cost of defined contribution plans			173	161	$ 150
U.S. | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions, next fiscal year			31
U.S. | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions, next fiscal year			$ 2
U.S. | Equities and Equity Alternatives
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentage			50.00%
Actual asset allocation percentage			49.00%
U.S. | Equities and Equity Alternatives | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentage			46.00%
U.S. | Equities and Equity Alternatives | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentage			54.00%
U.S. | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentage			50.00%
Actual asset allocation percentage			51.00%
U.S. | Fixed Income | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentage			46.00%
U.S. | Fixed Income | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentage			54.00%
Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation for plans with accumulated benefit obligations in excess of plan assets			$ 427	935
Aggregate fair value of plan assets for plans with accumulated benefit obligations in excess of plan assets			210	718
Projected benefit obligation for plans with projected benefit obligations in excess of plan assets			1,300	1,000
Fair value of plan assets for plans with projected benefit obligations in excess of plan assets			1,000	723
United Kingdom (b)
Defined Benefit Plan Disclosure [Line Items]
Cost of defined contribution plans			$ 158	140	$ 141
United Kingdom (b) | Pension Plan Funded Status Guarantee
Defined Benefit Plan Disclosure [Line Items]
Annual deficit contributions (GBP)		$ 576				£ 450
Annual deficit contributions, period		7 years
United Kingdom (b) | United Kingdom Pension and Postretirement Benefit Plan, Defined Benefit | Geographic Concentration Risk
Defined Benefit Plan Disclosure [Line Items]
Concentration risk (as a percent)			79.00%
United Kingdom (b) | Equities and Equity Alternatives
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentage			14.00%
Actual asset allocation percentage			13.00%
United Kingdom (b) | Equities and Equity Alternatives | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentage			11.00%
United Kingdom (b) | Equities and Equity Alternatives | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentage			17.00%
United Kingdom (b) | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentage			86.00%
Actual asset allocation percentage			87.00%
United Kingdom (b) | Fixed Income | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentage			83.00%
United Kingdom (b) | Fixed Income | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentage			89.00%
Pension and Postretirement Benefits | U.S.
Defined Benefit Plan Disclosure [Line Items]
Assumed health care cost trend rate for Medicare eligibles and non-Medicare eligibles			6.10%
Future assumed health care cost trend rate			4.00%
Cap on employer share of health care trend (as a percent)			5.00%
Pension  Benefits | U.S.
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation for plans with accumulated benefit obligations in excess of plan assets			$ 4,700	4,900
Aggregate fair value of plan assets for plans with accumulated benefit obligations in excess of plan assets			4,200	4,300
Projected benefit obligation for plans with projected benefit obligations in excess of plan assets			4,700	4,900
Fair value of plan assets for plans with projected benefit obligations in excess of plan assets			4,200	4,300
Employer contributions			33	30
Pension  Benefits | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions, next fiscal year			78
Employer contributions			78	139
Pension  Benefits | United Kingdom (b)
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions, next fiscal year			$ 38
Period between legally-prescribed negotiations between the Company and the plans' trustee			3 years
Employer contributions			$ 41
Post-retirement Benefits | U.S.
Defined Benefit Plan Disclosure [Line Items]
Number of shares held in defined benefit plan (in shares) | shares			1,000,000
Change in plan assets (as a percent)			4.50%
Employer contributions			$ 5	4
Post-retirement Benefits | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Employer contributions			$ 2	$ 2