Pension and Other Postretirement Employee Benefits (OPEB) Plans - Schedule of Pension and OPEB Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Total benefit costs recognized as expense	$ 14	$ 14	$ 6
Pension costs
Defined Benefit Plan Disclosure [Line Items]
Total benefit costs recognized as expense	9	9	2
OPEB costs
Defined Benefit Plan Disclosure [Line Items]
Total benefit costs recognized as expense	$ 5	$ 5	$ 4