Retirement Benefits (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
DB Pension Plans | Volatility Mechanism
Defined Benefit Plan Disclosure [Line Items]
Deferred credits	$ 1	$ 5
OPEB Plan | Volatility Mechanism
Defined Benefit Plan Disclosure [Line Items]
Deferred credits	$ 4
OPEB Plan | Volatility Mechanism
Defined Benefit Plan Disclosure [Line Items]
Deferred credits		$ 1