Benefit Plans and Other Postretirement Benefits Net Periodic Benefit Cost (Credit) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Operating and maintenance expenses	$ 2,540,000,000	$ 2,444,000,000	$ 2,491,000,000
transferred	0	0
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	76,000,000	74,000,000	97,000,000
Operating and maintenance expenses	$ 8,000,000	$ 0	$ 9