Employee Benefits - Cost Allocation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Affiliated Entity
Employee Benefits
Allocated expenses by parent entities (as a percent)	86.00%	87.00%	72.00%
Pension Plan
Employee Benefits
Defined benefit plan, service cost	$ 20	$ 22	$ 31
Post-Retirement Benefit Plan
Employee Benefits
Defined benefit plan, service cost	$ 4	$ 4	$ 7