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Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Amount of cost for defined contribution plan.

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Retirement Benefits (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended
	Dec. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer		$ 24	$ 21
Estimated future employer contributions in current fiscal year		69
United States
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, cost recognized		49	44
United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, cost recognized		$ 52	$ 43
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%
Actual asset allocation percentage of equity		51.00%
Equity Funds \| United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation, percentage		14.00%
Actual asset allocation percentage of equity		14.00%
Fixed Income Funds \| United States
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation, percentage		50.00%
Actual asset allocation percentage of equity		49.00%
Fixed Income Funds \| United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation, percentage		86.00%
Actual asset allocation percentage of equity		86.00%