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Retirement Benefits (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Dec. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer		$ 26	$ 45	$ 47	$ 113
Estimated future employer contributions in current fiscal year		59		59
United States
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, cost recognized		44	40	88	83
United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, cost recognized		$ 38	$ 33	$ 81	$ 77
United Kingdom \| Non-U.S. Plans \| Geographic Concentration Risk
Defined Benefit Plan Disclosure [Line Items]
Concentration risk percentage	79.00%
Equity Funds \| United States
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation, percentage		50.00%		50.00%
Actual asset allocation percentage of equity		50.00%		50.00%
Equity Funds \| United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation, percentage		14.00%		14.00%
Actual asset allocation percentage of equity		13.00%		13.00%
Fixed Income Funds \| United States
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation, percentage		50.00%		50.00%
Actual asset allocation percentage of equity		50.00%		50.00%
Fixed Income Funds \| United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation, percentage		86.00%		86.00%
Actual asset allocation percentage of equity		87.00%		87.00%