Employee Retirement Benefits - Net Periodic Income Cost Regulatory Assets (Details) - Pension Benefits [Member] - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost Recognized In Regulatory Assets Liabilities	$ 2	$ 0
Unrecognized gains	(96)	(129)
Total	$ (94)	$ (129)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details