Retirement Benefits (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
DB Pension Plans | Volatility Mechanism
Defined Benefit Plan Disclosure [Line Items]
Deferred credits (costs)		$ 12
DB Pension Plans | Volatility Mechanism
Defined Benefit Plan Disclosure [Line Items]
Deferred credits (costs)	$ (1)
OPEB Plan | Volatility Mechanism
Defined Benefit Plan Disclosure [Line Items]
Deferred credits (costs)	$ 7	$ 8