Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pension Benefits
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 1	$ 1	$ 2	$ 2
Interest cost	28	20	84	57
Expected return on plan assets	(32)	(41)	(96)	(124)
Amortization of unrecognized net loss	9	8	27	24
Settlements	47		48	2
Regulatory asset decrease		(1)		1
Net periodic (benefit) cost	53	(13)	65	(38)
Other Postretirement Benefits
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost			1	1
Expected return on plan assets	(1)		(2)	(1)
Amortization of unrecognized net loss	1		1
Net periodic (benefit) cost	$ 0	$ 0	$ 0	$ 0