Benefit Plans - Schedule of Components of Net Cost (Benefit) for Pension and Other Postretirement Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Defined Benefit Plan Disclosure [Line Items]
Costs and expenses	$ 9	$ 16
Remeasurement (gains) losses	78	(2)
Total net cost	87	14
Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	25	33
Interest cost	60	58
Expected return on plan assets	(78)	(77)
Costs and expenses	7	14
Remeasurement of projected benefit obligation	53	(25)
Remeasurement of plan assets	23	25
Remeasurement (gains) losses	76	0
Total net cost	83	14
Postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost	2	2
Costs and expenses	2	2
Remeasurement of projected benefit obligation	2	(2)
Remeasurement of plan assets	0	0
Remeasurement (gains) losses	2	(2)
Total net cost	$ 4	$ 0