Retirement Benefits and Trusteed Assets (Pension Plan - Other Changes in Plan Assets and Benefit Obligations recognized in Regulatory Assets and OCI) (Details) - Pension plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss)
Net actuarial loss	$ 62	$ 156
Amortization of net actuarial loss and settlements	(14)	(209)
Amortization of prior service credit	2	1
Total recognized in Regulatory assets and Other comprehensive income (loss)	50	(52)
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	$ (19)	$ 71