Employee Retirement Benefits - Net Periodic Income Cost Regulatory Assets (Details) - Pension Benefits [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost Recognized In Regulatory Assets Liabilities	$ (2)	$ 2
Unrecognized losses (gains)	(56)	375
Amortization of prior service benefit	0	1
Amortization Of Unrecognized Losses Recognized In Regulatory Assets Liabilities	0	(18)
Total	$ (58)	$ 360