Pension and Other Postretirement Employee Benefit Plans - Narrative (Details) - USD ($) $ in Billions	Sep. 30, 2025	Dec. 31, 2024
Retirement Benefits [Abstract]
Fair value of plan assets	$ 23.4	$ 22.2

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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