For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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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, 2024	Mar. 31, 2025	Mar. 31, 2024
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer		$ 18	$ 24
Estimated future employer contributions in current fiscal year		62
United States
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, cost recognized		56	49
United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, cost recognized		$ 56	$ 52
United Kingdom \| Pension and Postretirement Benefit Plan, Defined Benefit \| Geographic Concentration Risk
Defined Benefit Plan Disclosure [Line Items]
Concentration risk percentage (as a percent)	78.00%
Equity Funds \| United States
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation, percentage (as a percent)		50.00%
Actual asset allocation percentage of equity (as a percent)		50.00%
Equity Funds \| United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation, percentage (as a percent)		12.00%
Actual asset allocation percentage of equity (as a percent)		10.00%
Fixed Income Funds \| United States
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation, percentage (as a percent)		50.00%
Actual asset allocation percentage of equity (as a percent)		50.00%
Fixed Income Funds \| United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation, percentage (as a percent)		88.00%
Actual asset allocation percentage of equity (as a percent)		90.00%